FlightGear wiki - User contributions [en]

Howto:Syntax highlighting for Nasal

2021-05-29T17:36:57Z

DanielHL: /* KDE Editors */ fix path typo

There's '''[[Nasal]] syntax-highlighting''' support available for some editors, which is a big advantage, as it makes Nasal coding much easier.

Syntax highlighting can often point to syntax errors and so reduce the number of tedious time-consuming and unproductive [[FlightGear]] runs. It can also be a sort of "guide" to the language, highlighting functions or keywords that are builtin, so you can quickly check if it is "type" or "typeof" by typing each. In addition makes understanding other people's code easier, since you have all of the parts visually separated out, like loops, strings, constants, and builtin functions.

== Atom ==
Script is available from [https://github.com/www2000/atom-language-nasal Github] and can also be found in the [https://atom.io/packages/language-nasal Atom's packages repository].

Manual installation:

# Download the latest release from https://github.com/www2000/atom-language-nasal
# Unpack the tar.bz2
# Copy/move the language-nasal package to ~/.atom/packages

For installation from atom's packages repository:

# Open Atom
# Go to Preferences Edit -> Preferences or {{key press|Ctrl|+}},
# Click on packages and search for nasal
# Click install for Language Nasal

== Emacs ==
[[File:Emacs-nasal-syntax-highlighting.png|400px|thumb|Nasal syntax highlighting in GNU Emacs]]

There is a Emacs major mode for Nasal available here: https://github.com/andyross/nasal/blob/master/misc/nasal-mode.el

Under Linux just drop the file where you have the rest of your manually installed packages and add the following to your .emacs file:
<nowiki>(require 'nasal-mode)</nowiki>

If you don't have a directory to place your manually installed packages, put the file in the directory ''~/.emacs.d/lisp/'' (create it if it doesn't exist) and then put the following in your .emacs file before the ''require'':
<nowiki>;; Tell emacs where is your personal elisp lib dir
(add-to-list 'load-path "~/.emacs.d/lisp/")</nowiki>

Reload .emacs via <code>'''M-x''' load-file</code> or by restarting Emacs.

== Geany ==

A syntax highlighting solution for [https://www.geany.org/ Geany], a lean text editor/IDE is available from [https://forum.flightgear.org/viewtopic.php?f=30&t=36838#p360677 this thread] in the FlightGear forum.

== gedit ==
[[File:Philosopher's nasal highlighting in gEdit.jpeg|400px|thumb|Screen shot illustrating syntax highlighting in gedit]]

'''Philosopher''' on the FlightGear Forum has created syntax highlighting for gedit, a popular and simple text editor for Mac OS X, Linux, and Windows.


To install, copy the ''nasal.lang'' file  from the first post of the forum topic {{forum link|p=164133}} and:

* If you use Mac, move it into your ''Applications/gedit/Contents/Resources/share/gtksourceview-X.0/language specs'' folder.
* For Linux, move it into your ''/usr/share/gtksourceview-X.0/language-specs'' folder.

In the same post given above, there are instructions for how to edit ''xml.lang'' (in the same directory) to add the embedded XML content support (with this minor edit, Nasal highlighting will be used inside of certain tags, instead of plain text).

For "snippets" support, nasal.xml from the above post has to be moved into ''/usr/share/gedit/plugins/snippets/'' folder or installed using the "import" feature. See this image for more details:

[[:File:Install nasal snippets in gedit.png|how to import Nasal snippets]].
{{-}}

== jEdit ==
There's a syntax highlighting mode for jEdit, programmer's text editor

Included are some of Nasal's internal functions and those functions currently implemented in NasalSys.cxx
To use, add the content of the catalog inside your own catalog (do NOT overwrite the file) and nasal.xml in /home/USER/.jedit/modes

Restart jEdit and you can use it. Current extension is .nas, you can add your own extension and functions.
This mode is heavily based on the Javascript mode.

Get it here: https://sourceforge.net/projects/fgscheduleview/files/jedit/catalog.zip/download

== KDE Editors ==
There's a highlighting definition for nasal available at '''opendesktop.org''' (https://www.opendesktop.org/p/1187022/)

Download the file and copy it into:
:~/.kde4/share/apps/katepart/syntax/ (for KDE4)
:or
:~/.local/share/katepart5/syntax/ (for KF5 pre 5.29)
:or
:~/.local/share/org.kde.syntax-highlighting/syntax/ (for current KF5 versions)

(you can create the folders if they don't exist yet).

Note that the syntax highlighting in KDE doesn't set colors, it just identifies structural elements, colors are defined by the '''schemas''' used by each editor, thus you get consistent highlighting between different languages.

The highlighting file should work with all editors based on the katepart: KWrite, Kate, and the editor component of KDevelop.

== Notepad++ ==
[[File:Highlight parse.png|400px|thumb|Screenshot of Nasal support for Notepad++]]
Provides comprehensive syntax highlighting and a function list parser with support for hierarchical display of both inline and out-of-body class member functions.
* [http://github.com/Slaiyer/nasal-npp GitHub repository for download and instructions]

'''Alternative (syntax highlighting only):'''
* [http://dl.dropbox.com/u/1463693/nasal.xml Download here]
** [http://superuser.com/questions/62474/notepad-custom-syntax-highlighting-setting-where-to-look-for-it Instructions are here]
{{-}}

== Sublime Text 2 ==
[[File:Sublime Text 2 syntax highlighting.png|400px|thumb|Sublime Text 2 syntax highlighting]]

Scripts and installation instructions are here: https://github.com/freevryheid/nasal
{{-}}

== Vim ==
[[File:Vim-nasal-syntax-highlighting.png|400px|thumb|Screen shot illustrating syntax highlighting in Vim]]

One such editor is the free vim or its GUI variant gvim.

It's not for everyone but it's free, and testing it doesn't hurt: http://www.vim.org/.

The syntax definition file comes with the FlightGear code ({{flightgear file|scripts/syntax/nasal.vim}}). Highlighting works even for Nasal embedded in XML files (type ":set ft=nasal", where ft stands for file-type)

Here's an example, which demonstrates a short code segment with three syntax errors as well as the highlighting of a matching pair of parentheses (yellow) and trailing spaces (blue x). (The leading blue dots aren't on by default. They help to spot tab crimes.)
{{-}}

== Visual Studio Code ==
[[File:Vscode-sintaxhighlight.jpg|thumb|Screen shot illustrating syntax highlighting in VSCode]]

[https://code.visualstudio.com Visual Studio Code] is a source-code editor developed by Microsoft for Windows, Linux and macOS. Its open source and free.

The nasal extension is available from [https://github.com/RenanMsV/nasal-vscode Github] and can also be found in the [https://marketplace.visualstudio.com/items?itemName=RenanMsV.nasal-lang VSCode's marketplace].
It supports basic syntax highlighting and snippets to improve development speed.

For installation from the marketplace:

# Open VSCode
# Go to File -> Preferences -> Extensions or {{key press|Ctrl|Shift|X}},
# Search for nasal
# Click install for Nasal-lang

Manual installation:

# Download the latest release from the repository, it should be a .vsix file.
# Install the extension manually by doing the command 'code --install-extension path_to_extension.vsix'

{{-}}

== Other editors ==
Nasal being syntactically very close to other programming languages like C, Php or JavaScript, you can get some usable highlighting even without real Nasal support:

* TextMate {{forum link|hilit=syntax+nasal|p=127828}}
* SciTe {{forum link|hilit=syntax+nasal|p=94521}}

== FlightGear Wiki ==
{{Note|As of 02/2016, we do not currently have a dedicated Nasal module available [http://wiki.flightgear.org/FlightGear_wiki:Village_pump/Archive_2016#Nasal_Syntaxhighlighting]}}
{{main article|Help:Formatting#Syntax highlighting}}

Using the <syntaxhighight> tag with a lang="nasal" attribute, we can have highlighting right here on the wiki. Use enclose="div" to wrap the text, if it happens to be particularly wide.

<nowiki><syntaxhighlight lang="nasal">
# hello.nas
print('Hello World!');
</syntaxhighlight></nowiki>

Which renders into:
<syntaxhighlight lang="nasal">
# hello.nas
print('Hello World!');
</syntaxhighlight>

== Syntax highlighting test ==
Just a collection of keywords, etc. to test whether highlighting works (you can copy this to test your own highlighting):
<syntaxhighlight lang="nasal">
# this is a comment
# operators (if applicable):
!a ? a+b - c/d*e : f~g; expr1 and expr2 or expr3;
# Builtin functions, strings
print('Hello World!');
die("We have an error, Houston!", arg[0]);
cmdarg().getNode("setting").getValue();
streq(typeof(id(keys(hash))),10);
# Loopoids
foreach (var a; ["haha", {command:"NASAL!"}, me]) {
if(0) break;
elsif(1) continue;
else return;
while(1) sprintf("%s%s\n%s=%f", "Spam", "spam", "spam", 0e-0);
for (var i=0; i < 0.00; i += 0x0) printf("%d", int(i));
forindex(var o; a) (func {
var o = o;
setlistener("/", func print(o), 1, 2);
})();
}
# String escaping stress tests:
'\a\b\c\"\\\?' # none of these
"\e\?\'\f\a" # none of these
'\'' # this one
"\"\r\n\t\\\t" # and all of these
# And optionally string formatting:
"%s%%s%.0f%8d" # the second "s" shouldn't be highlighted, otherwise everything else
# Syntax error!:
%$@&^|\`
</syntaxhighlight>

== Related content ==
* {{forum url|p=164155}}
* {{forum url|t=12495}}
* {{forum url|t=15972}}
* {{forum url|t=9812}}

[[Category:Nasal howto]]

YASim

2020-08-11T07:44:21Z

DanielHL: /* YASim design notes */ Corrected link

[[File:yasimlogo.png|thumb]]

'''YASim''' is one of two [[flight dynamics model]]s commonly used in [[FlightGear]]. The flight dynamics model (FDM) determines how the [[aircraft]] moves and flies.

Gary Neely wrote in his [http://www.buckarooshangar.com/flightgear/ introduction to YASim]:

:''The FDM is the mathematical model that controls the physics of flight within the simulator. The physical 3D aircraft model has nothing to do with flight dynamics-- in essence it's just a picture to look at. It's the FDM that dictates how the model flies.''

:''Why YASim? YASim uses the geometry of the aircraft to generate the base flight characteristics. While this suggests a 'realistic' or out-of-the-box approach, it is a only rough approximation that will require much tweaking before you get a result that approaches realism. If you have solid flight data for your aircraft such as wind-tunnel data or you are looking to eventually generate a hyper-realistic simulation, JSBSim is probably a better approach. If you lack such data but know the geometry of the aircraft and have access to the same flight characteristics and limits as a real pilot would, then YASim can provide a solution that is more than sufficient for most simulation needs.''

== Coordinate system notes ==
All positions specified are in metres (which is weird, since all other units in the file are English). The X axis points forward, Y is left, and Z is up. Take your right hand, and hold it like a gun. Your first and second fingers are the X and Y axes, and your upwards-pointing thumb is the Z. This is slightly different from the coordinate system used by [[JSBSim]]. Sorry. The origin can be placed anywhere, so long as you are consistent. I use the nose of the aircraft.

(In the [[JSBSim_Aerodynamics#Frames|JSBSim coordinate system]], X and Z are the same as in YASim, but Y points to the right instead of left.)

== YASim design notes ==
Andy Ross's original design notes for YASim can be found in [https://pdfhost.io/v/~iYsLl7xS_alldvi.pdf this PDF file]. These provide some useful background for how YASim works.

== XML Elements ==

=== airplane ===
The top-level element for the file. It contains the following attributes:
* '''mass:''' The empty (no fuel) weight, in pounds. It does include the weight of the engine(s), so when you add the engine weight in its tag, it acts just like a ballast.
* '''version:''' The version attribute is used to maintain compatibility when updating yasim (e.g. bugfixes). If this attribute i not given, the original version will be used. Several bugfixes to YASim were implemented in FlightGear 3.2 (see [[FlightGear Newsletter April 2014]]), some more are fixed in FlightGear 2017.2.
Available versions are:
* <code>YASIM_VERSION_ORIGINAL</code> explicitly use the old buggy calculations (same as no version attribute at all)
* <code>YASIM_VERSION_32</code> enable bugfixes up to version 3.2
* <code>2017.2</code> enable bugfixes up to version 2017.2
* <code>2018.1</code> (FIXME) no bugfixes by now. Use this version if your aircraft makes use of new features in YASim 2018.1 so it will cause at least a warning with older FG versions.
* <code>YASIM_VERSION_CURRENT</code> use latest version compiled into the users FlightGear.
{{Warning| Using YASIM_VERSION_CURRENT might make the aircraft unusable in case of future changes to YASim without updating the aircraft accordingly.}}

'''New in 2018.1'''
* '''mtow-lbs''' and '''mtow-kg:''' use one of them to specify max. takeoff weight. Does not affect the FDM, but is used by CLI tool to calculate some numbers.

=== approach ===
The approach parameters for the aircraft. The solver will generate an aircraft that matches these settings (by adjusting the parameters of the surface like drag and lift). It is extremely important to give parameters which could be really achieved by defined aircraft geometry, otherwise, it gives an unstable or not flyable result. The element can (and should) contain <control> elements indicating pilot input settings, such as flaps and throttle, for the approach.

* '''speed:''' The approach airspeed, in knots TAS.
* '''aoa:''' The approach angle of attack, in degrees
* '''fuel:''' Fraction (0-1) of fuel in the tanks. Default is 0.2.

=== cruise ===
The cruise speed and altitude for the solver to match. As above, this should contain <control> elements indicating aircraft configuration. Especially, make sure the engines are generating enough thrust at cruise!
* '''speed:''' The cruise speed, in knots TAS.
* '''alt:''' The cruise altitude, in feet MSL.
* '''fuel:''' Fraction (0-1) of fuel in the tanks. Default is 0.2.
=== cockpit ===
The location of the cockpit (pilot eyepoint).
* '''x,y,z:''' eyepoint location (see coordinates note)

=== fuselage ===
This defines a tubelike structure. It will be given an even mass and aerodynamic force distribution by the solver. You can have as many as you like, in any orientation you please.
* '''ax,ay,az:''' One end of the tube (typically the front)
* '''bx,by,bz:''' The other ("back") end.
* '''width:''' The width of the tube, in metres.
* '''taper:''' The approximate radius at the "tips" of the fuselage expressed as a fraction (0-1) of the width value.
* '''midpoint:''' The location of the widest part of the fuselage, expressed as a fraction of the distance between A and B.
* '''idrag:''' Multiplier for the "induced drag" generated by this object. Default is one. With idrag=0 the fuselage generates only drag.
* '''cx,cy,cz:''' Factors for the generated drag in the fuselages "local coordinate system" with x pointing from end to front, z perpendicular to x with y=0 in the aircraft coordinate system. E.g. for a fuselage of a height of 2 times the width you can define cy=2 and (due to the doubled front surface) cx=2.

=== Surfaces ===
==== wing ====
This defines the main wing of the aircraft. You can have only one (but see below about using vstab objects for extra lifting surfaces). The wing should have a <stall> subelement to indicate stall behavior, control surface subelements (flap0, flap1, spoiler, slat) to indicate what and where the control surfaces are, and <control> subelements to map user input properties to the control surfaces.
* '''x,y,z:''' The "base" of the wing, specified as the location of the mid-chord (not leading edge, trailing edge, or aerodynamic center) point at the root of the LEFT (!) wing.
* '''length:''' The length from the base of the wing to the midchord point at the tip. Note that this is not the same thing as span.
* '''chord:''' The chord of the wing at its base, along the X axis (not normal to the leading edge, as it is sometimes defined).
* '''incidence:''' The incidence angle at the wing root, in degrees. Zero is level with the fuselage (as in an aerobatic plane), positive means that the leading edge is higher than the trailing edge (as in a trainer).
* '''twist:''' The difference between the incidence angle at the wing root and the incidence angle at the wing tip. Typically, this is a negative number so that the wing tips have a lower angle of attack and stall after the wing root (washout).
* '''taper:''' The taper fraction, expressed as the tip chord divided by the root chord. A taper of one is a hershey bar wing, and zero would be a wing ending at a point. Defaults to one.
* '''sweep:''' The sweep angle of the wing, in degrees. Zero is no sweep, positive angles are swept back. Defaults to zero.
* '''dihedral:''' The dihedral angle of the wing. Positive angles are upward dihedral. Defaults to zero.
* '''idrag:''' Multiplier for the "induced drag" generated by this surface. In general, low aspect wings will generate less induced drag per-AoA than high aspect (glider) wings. This value isn't constrained well by the solution process, and may require tuning to get throttle settings correct in high AoA (approach) situations.
* '''effectiveness:''' Multiplier for the "normal" drag generated by the wing. Defaults to 1. Arbitrary, dimensionless factor.
* '''camber:''' The lift produced by the wing at zero angle of attack, expressed as a fraction of the maximum lift produced at the stall AoA.
* '''flow:''' The flow regime for the wing. Valid values are "SUBSONIC" (default) and "TRANSONIC". Setting surface to transonic adds more lift above mach number 0.6 by applying a Prandl/Glauert correction term to each surface-element. The effect is a more balanced lift/drag distribution reported by the solver. Use for anything that flies faster than mach 0.6 or has supercritical airfoils.
* '''mcrit:''' The critical mach number for the wing. This point defines the begin of exponential drag rise due to mach speed. Default "0.6", only available if flow="TRANSONIC".

'''Wing section support (since 2018.1):'''

Wing section support to define variable geometry (geometry parameters per section)
* More than one <wing>-element is allowed now.
* x, y, z, chord and incidence attribute shall be specifed only for the first <wing> in the XML file. They will be overridden for subsequent <wing>-elements.
* Use '''append="1"''' for additional '''wing''' elements to skip x, y, z, chord and incidence attribute as the will be calculated from previous '''wing''' element tip chord. This workaround is currently needed due to limitations in the XML parser.

==== hstab ====
These define the horizontal stabilizer of the aircraft. Internally, it is just a wing object and therefore works the same in XML.
You are allowed only one hstab object; the solver needs to know which wing's incidence to play with to get the aircraft trimmed correctly.

'''New in 2018.1:'''
* '''hstab''' supports sections in the same way '''wing''' does, but it is still considered as /the/ (only) hstab used by the solver.
* '''incidence-min-deg''' and '''incidence-max-deg''': optional attributes to limit valid result range fore the solver. Use with care or you won't get a solution.

==== vstab ====
A "vertical" stabilizer. Like hstab, this is just another wing, with a few special properties. The surface is not "mirrored" as are wing and hstab objects. If you define a left wing only, you'll only get a left wing. The default dihedral, if unspecified, is 90 degrees instead of zero. But all parameters are equally settable, so there's no requirement that this object be "vertical" at all. You can use it for anything you like, such as extra wings for biplanes. Most importantly, these surfaces are not involved with the solver computation, so you can have none, or as many as you like.

==== mstab ====
A mirrored horizontal stabilizer. Exactly the same as wing, but not involved with the solver computation, so you can have none, or as many as you like.

==== stall ====
A subelement of a wing (or hstab/vstab/mstab) that specifies the stall behavior.
* '''aoa:''' The stall angle (maximum lift) in degrees. Note that this is relative to the wing, not the fuselage (since the wing may have a non-zero incidence angle).
* '''width:''' The "width" of the stall, in degrees. A high value indicates a gentle stall. Low values are viscious for a non-twisted wing, but are acceptable for a twisted one (since the whole wing will not stall at the same time).
* '''peak:''' The height of the lift peak, relative to the post-stall secondary lift peak at 45 degrees. Defaults to 1.5. This one is deep voodoo, and probably doesn't need to change much. Bug me for an explanation if you're curious.

==== flap0, flap1, slat, spoiler ====
These are subelements of wing/hstab/vstab objects, and specify the location and effectiveness of the control surfaces.
* '''start:''' The position along the wing where the control surface begins.Zero is the root, one is the tip.
* '''end:''' The position where the surface ends, as above.
* '''lift:''' The lift multiplier for a flap or slat at full extension. One is a no-op, a typical aileron might be 1.2 or so, a giant jetliner flap 2.0, and a spoiler 0.0. For spoilers, the interpretation is a little different -- they spoil only "prestall" lift. Lift due purely to "flat plate" effects isn't affected. For typical wings that stall at low AoA's essentially all lift is pre-stall and you don't have to care. Jet fighters tend not to have wing spoilers, for exactly this reason. This value is not applicable to slats, which affect stall AoA only.
* '''drag:''' The drag multiplier, as above. Typically should be higher than the lift multiplier for flaps.
* '''aoa:''' Applicable only to slats. This indicates the angle by which the stall AoA is translated by the slat extension.

=== Engine ===
==== Thruster ====
A very simple "thrust only" engine object. Useful for things like thrust vectoring nozzles. All it does is map its THROTTLE input axis to its output thrust rating. Does not consume fuel, etc...
* '''thrust:''' Maximum thrust in pounds
* '''x,y,z:''' The point on the airframe where thrust will be applied.
* '''vx,vy,vy:''' The direction of the thrust in airframe coordinates. The vector will be normalized automatically, so any non-zero vector will work fine.

Example:

<syntaxhighlight lang="xml" line>
<thruster x="0" y="0" z="0.03" vx="1" vy="0" vz="0" thrust="6.61">
<control-input axis="/controls/engines/engine[0]/throttle" control="THROTTLE" src0="-1" src1="1" dst0="-1" dst1="1"/>
</thruster>
</syntaxhighlight>

==== Jet ====
A turbojet/fan engine. It accepts a <control> subelement to map a property to its throttle setting, and an <actionpt> subelement to place the action point of the thrust at a different position than the mass of the engine.
* '''x,y,z:''' The location of the engine, as a point mass. If no actionpt is specified, this will also be the point of application of thrust.
* '''mass:''' The mass of the engine, in pounds.
* '''thrust:''' The maximum sea-level thrust, in pounds.
* '''afterburner:''' Maximum total thrust with afterburner/reheat, in pounds [defaults to "no additional thrust"].
* '''rotate:''' Vector angle of the thrust in degrees about the Y axis [0].
* '''n1-idle:''' Idling low pressure core / fan speed [55].
* '''n1-max:''' Maximum low pressure core / fan speed [102].
* '''n2-idle:''' Idling high pressure core speed [73].
* '''n2-max:''' Maximum high pressure core speed [103].
* '''tsfc:''' Thrust-specific fuel consumption [0.8]. This should be considerably lower for modern turbofans.
* '''atsfc:''' (version >= 2016.3.1) Thrust specific fuel consumption with afterburner on. When set to zero defaults to older behaviour where it is calculated from dry fuel consumption [0].
* '''egt:''' Exhaust gas temperature at takeoff in K [1050].
* '''epr:''' Engine pressure ratio at takeoff [3.0].
* '''exhaust-speed:''' The maximum exhaust speed in knots [~1555].
* '''spool-time:''' Time, in seconds, for the engine to respond to 90% of a commanded powersetting.

==== Propeller ====
A propeller. This element requires an engine subtag. Currently <piston-engine> and <turbine-engine> are supported.
* '''x,y,z:''' The position of the mass (!) of the engine/propeller combination. If the point of force application is different (and it will be) it should be set with an <actionpt> subelement.
* '''mass:''' The mass of the engine/propeller, in pounds.
* '''moment:''' The moment, in kg-metres^2. This has to be hand calculated and guessed at for now. A more automated system will be forthcoming. Use a negative moment value for counter-rotating ("European" -- CCW as seen from behind the prop) propellers. A good guess for this value is the radius of the prop (in meters) squared times the mass (kg) divided by three; that is the moment of a plain "stick" bolted to the prop shaft.
* '''radius:''' The radius, in meters, or the propeller.
* '''cruise-speed:''' The max efficiency cruise speed of the propeller. Generally not the same as the aircraft's cruise speed.
* '''cruise-rpm:''' The RPM of the propeller at max-eff. cruise.
* '''cruise-power:''' The power sunk by the prop at cruise, in horsepower.
* '''cruise-alt:''' The reference cruise altitude in feet.
* '''takeoff-power:''' The takeoff power required by the propeller...
* '''takeoff-rpm:''' ...at the given takeoff RPM.
* '''gear-ratio:''' The factor by which the engine RPM is multiplied to produce the propeller RPM. Optional (defaults to 1.0).
* '''contra:''' When set (contra="1"), this indicates that the propeller is a contra-rotating pair. It will not contribute to the aircraft's net gyroscopic moment, nor will it produce asymmetric torque on the aircraft body. Asymmetric slipstream effects, when implemented, will also be zero when this is set.

YASim assumes a fixed-pitch propeller by default. If your engine is using a constant-speed propeller, you'll also need to provide these attributes:

* '''min-rpm:''' The minimum operational RPM for a constant speed propeller. This is the speed to which the prop governor will seek when the blue lever is at a minimum. The coarse-stop attribute limits how far the governor can go into trying to reach this RPM.
* '''max-rpm:''' The maximum operational RPM for a constant speed propeller. See above. The fine-stop attribute limits how far the governor can go in trying to reach this RPM.
* '''fine-stop:''' The minimum pitch of the propeller (high RPM) as a ratio of ideal cruise pitch. This is set to 0.25 by default -- a higher value will result in a lower RPM at low power settings (e.g. idle, taxi, and approach).
* '''coarse-stop:''' The maximum pitch of the propeller (low RPM) as a ratio of ideal cruise pitch. This is set to 4.0 by default -- a lower value may result in a higher RPM at high power settings.

===== piston-engine =====

A piston engine definition. This must be a subelement of an enclosing <propeller> tag.

* '''eng-power:''' Maximum BHP of the engine at sea level.
* '''eng-rpm:''' The engine RPM at which eng-power is developed
* '''displacement:''' The engine displacement in cubic inches.
* '''compression:''' The engine compression ratio.

<syntaxhighlight lang="xml" line>
<piston-engine eng-power="2" eng-rpm="3800" displacement="20" >
<control-input axis="/controls/engines/engine[0]/throttle" control="THROTTLE"/>
<control-input axis="/controls/engines/engine[0]/starter" control="STARTER"/>
<control-input axis="/controls/engines/engine[0]/magnetos" control="MAGNETOS"/>
<control-input axis="/controls/engines/engine[0]/mixture" control="MIXTURE"/>
</piston-engine>
</syntaxhighlight>

===== electric-engine =====

A simplified electric DC engine model. The model is available since the end of April 2020, therefore it is currently available in daily build FlightGear snapshots. This definition must be a subelement of an enclosing <propeller> tag.

* '''Kv''' electric engine constant in revolutions per minute to volt.
* '''voltage''' The voltage applied to the motor e.g. Nominal battery voltage in Volts.
* '''Rm''' The engine winding resistance in Ohms.

Example:

<syntaxhighlight lang="xml" line>
<propeller x="0.02" y="0" z="0.03"
mass="0.05"
moment="0.0006"
radius="0.203"
cruise-speed="26"
cruise-rpm="7000"
cruise-power="0.5"
cruise-alt="2000"
takeoff-power="0.70"
takeoff-rpm="9200"
contra="1">
<actionpt x="0" y="0" z="0.03"/>
<electric-engine Kv="750" voltage="15" Rm="0.02" >
<control-input axis="/controls/engines/engine[0]/throttle" control="THROTTLE"/>
</electric-engine>
</propeller>
</syntaxhighlight>

=== Landing gear ===
==== gear ====
Defines a landing gear. Accepts <control> subelements to map properties to steering and braking. Can also be used to simulate floats. Although the coefficients are still called ..fric, it is calculated in fluids as a drag (proportional to the square of the speed). In fluids gears are not considered to detect crashes (as on ground).
* '''x,y,z:''' The location of the fully-extended gear tip.
* '''compression:''' The distance in metres along the "up" axis that the gear will compress.
* '''initial-load:''' The initial load of the spring in multiples of compression. Defaults to 0. (With this parameter a lower spring-constants will be used for the gear-> can reduce numerical problems (jitter)) '''Note:''' the spring-constant is varied from 0% compression to 20% compression to get continuous behavior around 0 compression. (could be physically explained by wheel deformation)
* '''upx/upy/upz:''' The direction of compression, defaults to vertical (0,0,1) if unspecified. These are used only for a direction -- the vector need not be normalized, as the length is specified by "compression".
* '''sfric:''' Static (non-skidding) coefficient of friction. Defaults to 0.8.
* '''dfric:''' Dynamic friction. Defaults to 0.7.
* '''stiction:''' Stiction to ground. Defaults to 0. stiction = "1" ensures the gear isn't sliding unintentionally (Note: please correct docu here for more detailed facts, developers didn't document this extension here and this is based on trial and guessing only)
* '''spring:''' A dimensionless multiplier for the automatically generated spring constant. Increase to make the gear stiffer, decrease to make it squishier.
* '''damp:''' A dimensionless multiplier for the automatically generated damping coefficient. Decrease to make the gear "bouncier", increase to make it "slower". Beware of increasing this too far: very high damping forces can make the numerics unstable. If you can't make the gear stop bouncing with this number, try increasing the compression length instead.
* '''on-water:''' if this is set to "0" the gear will be ignored if on water. Defaults to "0"
* '''on-solid:''' if this set to "0" the gear will be ignored if not on water. Defaults to "1"
* '''speed-planing:'''
* '''spring-factor-not-planing:''' At zero speed the spring factor is multiplied by spring-factor-not-planing. Above speed-planing this factor is equal to 1. The idea is, to use this for floats simulating the transition from swimming to planing. speed-planing defaults to 0, spring-factor-not-planing defaults to 1.
* '''reduce-friction-by-extension:''' at full extension the friction is reduced by this relative value. 0.7 means 30% friction at full extension. If you specify a value greater than one, the friction will be zero before reaching full extension. Defaults to "0"
* '''ignored-by-solver:''' with the on-water/on-solid tags you can have more than one set of gears in one aircraft, If the solver (who automatically generates the spring constants) would take all gears into account, the result would be wrong. E. G. set this tag to "1" for all gears, which are not active on runways. Defaults to "0". You can not exclude all gears in the solving process.

<syntaxhighlight lang="xml" line>


<gear x="0.0" y="0.0" z="-0.205"
spring="0.9"
damp="0.8"
dfric="0.9"
sfric="1.1"
compression="0.051">
<control-input axis="/controls/flight/rudder" control="STEER" square="true" src0="-1.0" src1="1.0" dst0="-0.3" dst1="0.3"/>
<control-input axis="/controls/gear/brake-right" control="BRAKE" split="true"/>
<control-input axis="/controls/gear/brake-parking" control="BRAKE" split="true"/>
</gear>



<gear x="-0.4" y="0.25" z="-0.205"
spring="0.9"
damp="0.8"
dfric="0.9"
sfric="1.1"
compression="0.051">
<control-input axis="/controls/gear/brake-right" control="BRAKE" split="true"/>
<control-input axis="/controls/gear/brake-parking" control="BRAKE" split="true"/>
</gear>

<gear x="-0.4" y="-0.25" z="-0.205"
spring="0.9"
damp="0.8"
dfric="0.9"
sfric="1.1"
compression="0.051">
<control-input axis="/controls/gear/brake-left" control="BRAKE" split="true"/>
<control-input axis="/controls/gear/brake-parking" control="BRAKE" split="true"/>
</gear>
</syntaxhighlight>

==== Launchbar ====
Defines a catapult launchbar or strop.
* '''x,y,z:''' The location of the mount point of the launch bar or strop on the aircraft.
* '''length:''' The length of the launch bar from mount point to tip
* '''down-angle:''' The max angle below the horizontal the launchbar can achieve.
* '''up-angle:''' The max angle above the horizontal the launchbar can achieve.
* '''holdback-{x,y,z}:''' The location of the holdback mount point on the aircraft.
* '''holdback-length:''' The length of the holdback from mount point to tip. Note: holdback up-angle and down-angle are the same as those defined for the launchbar and are not specified in the configuration.

=== Fuel ===
==== tank ====
A fuel tank. Tanks in the aircraft are identified numerically (starting from zero), in the order they are defined in the file. If the left tank is first, "tank[0]" will be the left tank.
* '''x,y,z:''' The location of the tank.
* '''capacity:''' The maximum contents of the tank, in pounds. Not gallons -- YASim supports fuels of varying densities.
* '''jet:''' A boolean. If present, this causes the fuel density to be treated as Jet-A. Otherwise, gasoline density is used. A more elaborate density setting (in pounds per gallon, for example) would be easy to implement. Bug me.

=== Center of Gravity ===
==== Ballast ====
This is a mechanism for modifying the mass distribution of the aircraft. A ballast setting specifies that a particular amount of the empty weight of the aircraft must be placed at a given location. The remaining non-ballast weight will be distributed "intelligently" across the fuselage and wing objects. Note again: this does NOT change the empty weight of the aircraft.
* '''x,y,z:''' The location of the ballast.
* '''mass:''' How much mass, in pounds, to put there. Note that this value can be negative. I find that I often need to "lighten" the tail of the aircraft.

<syntaxhighlight lang="xml" line>
<ballast x="-0.24" y="0.0" z="0.33" mass-kg="0.5"/>
</syntaxhighlight>

==== Weight ====
This is an added weight, something not part of the empty weight of the aircraft, like passengers, cargo, or external stores. The actual value of the mass is not specified here, instead, a mapping to a property is used. This allows external code, such as the panel, to control the weight (loading a given cargo configuration from preference files, dropping bombs at runtime, etc...)
* '''x,y,z:''' The location of the weight.
* '''mass-prop:''' The name of the fgfs property containing the mass, in pounds, of this weight.
* '''size:''' The aerodynamic "size", in metres, of the object. This is important for external stores, which will cause drag. For reasonably aerodynamic stuff like bombs, the size should be roughly the width of the object. For other stuff, you're on your own. The default is zero, which results in no aerodynamic force (internal cargo).
* '''solve-weight:''' Subtag of approach and cruise parameters. Used to specify a non-zero setting for a <weight> tag during solution. The default is to assume all weights are zero at the given performance numbers.
* '''idx:''' Index of the weight in the file (starting with zero).
* '''weight:''' Weight setting in pounds.

<syntaxhighlight lang="xml" line>
<weight x="-0.06471" y="0.225" z="-0.2" mass-prop="/sim/weight[0]/weight-kg"/>
</syntaxhighlight>

=== Controls ===
==== control-input ====
This element manages a mapping from fgfs properties (user input) to settable values on the aircraft's objects. Note that the value to be set MUST (!) be valid on the given object type. This is not checked for by the parser, and will cause a runtime crash if you try it. Wing's don't have throttle controls, etc... Note that multiple axes may be set on the same value. They are summed before setting.
* '''axis:''' The name of the double-valued fgfs property "axis" to use as input, such as "/controls/flight/aileron".
* '''control:''' Which control axis to set on the objects. It can have the following values:
** THROTTLE - The throttle on a jet or propeller.
** MIXTURE - The mixture on a propeller.
** REHEAT - The afterburner on a jet
** PROP - The propeller advance
** BRAKE - The brake on a gear.
** STEER - The steering angle on a gear.
** INCIDENCE - The incidence angle of a wing.
** FLAP0 - The flap0 deflection of a wing.
** FLAP1 - The flap1 deflection of a wing.
** SLAT - The slat extension of a wing.
** SPOILER - The spoiler extension for a wing.
** CYCLICAIL - The "aileron" cyclic input of a rotor
** CYCLICELE - The "elevator" cyclic input of a rotor
** COLLECTIVE - The collective input of a rotor
** ROTORENGINEON - If not equal zero the rotor is rotating
** WINCHRELSPEED - The relative winch speed
** {... and many more, see [https://sourceforge.net/p/flightgear/flightgear/ci/next/tree/src/FDM/YASim/ControlMap.cpp#l25 ControlMap.cpp] ...}
* '''invert:''' Negate the value of the property before settling on the object.
* '''split:''' Applicable to wing control surfaces. Sets the normal value on the left-wing, and a negated value on the right-wing.
* '''square:''' Squares the value before setting. Useful for controls like a steering that needs a wide range, yet lots of sensitivity in the center. Obviously only applicable to values that have a range of [-1:1] or [0:1].
* '''src0/src1/dst0/dst1:''' If present, these define a linear mapping from the source to the output value. Input values in the range src0-src1 are mapped linearly to dst0-dst1, with clamping for input values that lie outside the range.

==== control-output ====
This can be used to pass the value of a YASim control axis (after all mapping and summing is applied) back to the property tree.
* '''control:''' Name of the control axis. See above.
* '''prop:''' Property node to receive the value.
* '''side:''' Optional, for split controls. Either "right" or "left"
* '''min/max:''' Clamping applied to output value.

==== control-speed ====
Some controls (most notably flaps and hydraulics) have maximum slew rates and cannot respond instantly to pilot input. This can be implemented with a control-speed tag, which defines a "transition time" required to slew through the full input range. Note that this tag is semi-deprecated, complicated control input filtering can be done much more robustly from a Nasal script.
* '''control:''' Name of the control axis. See above.
* '''transition-time:''' Time in seconds to slew through input range.

==== control-setting ====
This tag is used to define a particular setting for a control axis inside the <cruise> or <approach> tags, where obviously property input is not available. It can be used, for example, to inform the solver that the approach performance values assume full flaps, etc...
* '''axis:''' Name of the control input (i.e. a property name)
* '''value:''' Value of the control axis.

=== Winch and Aerotow ===
==== hitch ====
A hitch, can be used for winch-start (in gliders) or aerotow (in gliders and motor aircraft) or for external cargo with helicopter. You can do aerotow over the net via multiplayer (see j3 and bocian as an example).
* '''name:''' the name of the hitch. must be aerotow if you want to do aerotow via multiplayer. You will find many properties at /sim/hitches/name. Most of them are directly tied to the internal variables, you can modify them as you like. You can add a listener to the property "broken", e. g. for playing a sound.
* '''x,y,z:''' The position of the hitch
* '''force-is-calculated-by-other:''' if you want to simulate aerotowing over the internet, set this value to "1" in the motor aircraft. Don't specify or set this to zero in gliders. In a LAN the time lag might be small enough to set it on both aircraft to "0". It's intended, that this is done automatically in the future.
==== tow ====
The tow used for aerotow or winch. This must be a subelement of an enclosing <hitch> tag.
* '''length:''' upstretched length in metres
* '''weight-per-meter:''' in kg/metre
* '''elastic-constant:''' lower values give higher elasticity
* '''break-force:''' in N
* '''mp-auto-connect-period:''' the every x seconds a towed multiplayer aircraft is searched. If found, this tow is connected automatically, parameters are copied from the other aircraft. Should be set only in the motor aircraft, not in the glider
==== winch ====
The tow used for aerotow or winch. This must be a subelement of an enclosing <hitch> tag.
* '''max-tow-length:''' in m
* '''min-tow-length''': in m
* '''initial-tow-length:''' in m. The initial tow length also defines the length/search radius used for the mp-autoconnect feature
* '''max-winch-speed:''' in m/s
* '''power:''' in kW
* '''max-force:''' in N

<syntaxhighlight lang="xml" line>
<hitch name="winch" x="0.0" y="0.0" z="0.0">
<tow length="50" weight-per-meter="0.0035" elastic-constant="40000" break-force="10000"/>

<winch max-tow-length="1000" min-tow-length="1" initial-tow-length="1000" max-winch-speed="20" power="2" max-force="80"/>
<control-input axis="/controls/winch/place" control="PLACEWINCH"/>
</hitch>
<hitch name="aerotow" x="0.0" y="0.0" z="0.0" force-is-calculated-by-other="0">
<tow length="60" weight-per-meter="0.0035" elastic-constant="9000" break-force="100" mp-auto-connect-period="0.0"/>
<winch max-tow-length="1000" min-tow-length="60" initial-tow-length="60"/>
<control-input axis="/controls/aerotow/find-aircraft" control="FINDAITOW"/>
</hitch>
</syntaxhighlight>

== Visualization ==

=== Blender visualization tool ===

[[File:Yasim_visualisation_dc6.png|thumb|dc6 FDM in Blender]]To make the programmed aircraft visible it is possible to load and compare it with the 3D model within [[Blender]]. They applaud for this ''very'' useful script goes to M. Franz, thank you very much!

For Blender versions <= 2.4 the script is located in FlightGears source code {{flightgear file|utils/Modeller/yasim_import.py}}.

For Blender versions newer than 2.4, please see [[Blender YASim import]].

The howto, taken from inside the script:

yasim_import.py loads and visualizes a YASim FDM geometry
=========================================================

It is recommended to load the model superimposed over a greyed out and immutable copy of the aircraft model:

(0) put this script into ~/.blender/scripts/
(1) load or import aircraft model (menu -> "File" -> "Import" -> "AC3D (.ac) ...")
(2) create new *empty* scene (menu -> arrow button left of "SCE:scene1" combobox -> "ADD NEW" -> "empty")
(3) rename scene to yasim (not required)
(4) link to scene1 (F10 -> "Output" tab -> arrow button left of text entry "No Set Scene" -> "scene1")
(5) now load the YASim config file (menu -> "File" -> "Import" -> "YASim (.xml) ...")

This is good enough for simple checks. But if you are working on the YASim configuration, then you need a
quick and convenient way to reload the file. In that case, continue after (4):

(5) switch the button area at the bottom of the blender screen to "Scripts Window" mode (green python snake icon)
(6) load the YASim config file (menu -> "Scripts" -> "Import" -> "YASim (.xml) ...")
(7) make the "Scripts Window" area as small as possible by dragging the area separator down
(8) optionally split the "3D View" area and switch the right part to the "Outliner"
(9) press the "Reload YASim" button in the script area to reload the file

If the 3D model is displaced with respect to the FDM model, then the <offsets> values from the
model animation XML file should be added as comment to the YASim config file, as a line all by
itself, with no spaces surrounding the equal signs. Spaces elsewhere are allowed. For example:

<offsets>
<x-m>3.45</x-m>
<z-m>-0.4</z-m>
<pitch-deg>5</pitch-deg>
</offsets>

becomes:



Possible variables are:

x ... <x-m>
y ... <y-m>
z ... <z-m>
h ... <heading-deg>
p ... <pitch-deg>
r ... <roll-deg>

Of course, absolute FDM coordinates can then no longer directly be read from Blender's 3D view.
The cursor coordinates display in the script area, however, shows the coordinates in YASim space.
Note that object names don't contain XML indices but element numbers. YASim_hstab#2 is the third
hstab in the whole file, not necessarily in its parent XML group. A floating-point part in the
object name (e.g. YASim_hstab#2.004) only means that the geometry has been reloaded that often.
It's an unavoidable consequence of how Blender deals with meshes.

Elements are displayed as follows:

cockpit -> monkey head
fuselage -> blue "tube" (with only 12 sides for less clutter); center at "a"
vstab -> red with yellow flaps
wing/mstab/hstab -> green with yellow flaps/spoilers/slats (always 20 cm deep);
symmetric surfaces are only displayed on the left side
thrusters (jet/propeller/thruster) -> dashed line from center to actionpt;
arrow from actionpt along thrust vector (always 1 m long);
propeller circle
rotor -> radius and rel_len_blade_start circle, direction arrow,
normal and forward vector, one blade at phi0
gear -> contact point and compression vector (no arrow head)
tank -> cube (10 cm side length)
weight -> inverted cone
ballast -> cylinder
hitch -> circle (10 cm diameter)
hook -> dashed line for up angle, T-line for down angle
launchbar -> dashed line for up angles, T-line for down angles
A note about step (0) for Windows users: the mentioned path is inside the folder where Blender lives, something like <code>C:\Program Files\Blender Foundation\Blender\.blender\scripts</code>.

=== Visualize model in OpenSCAD or FreeCAD ===

There exist a possibility to display the YASim XML elements in the OpenSCAD or FreeCAD tools. This could be extremely useful in the case of UAV aircraft development.

[https://github.com/ThunderFly-aerospace/YASim2SCAD YASim2SCAD] - This tool converts YASim XML to scad file which could be displayed as an overlay in OpenSCAD or FreeCAD project.

=== Gnuplot visualization tool ===

[https://github.com/bitwisetech/yasiVers yasiVers] is a tool for visualization of YASim calculations.

== Export of YASim internals to property tree ==
Ever wondered what is going on inside yasim? See the property tree under /fdm/yasim/

Some information is static and shows what yasim has compiled from your XML.
Other information is "run-time" like forces, speed, acceleration, c.g.

If note noted otherwise:
* expect metric unit (meter, kilogram, newton, ...)
* expect minimum version 2017.2

{| class="wikitable"
|-
! Path !! Description !! Information type !! min. version
|-
| accelerations/ || linear and rot. accelerations in aircraft coord. || run time ||
|-
| debug/ || misc internals, for now subject to change without notice || run time || 2018.1
|-
| forces/ || aerodynamic forces in N || run time ||
|-
| velocities/ || linear and rot. velocities in aircraft coord. || run time ||
|-
| model/cg-x-range-aft || desired CG range || compile time ||
|-
| model/cg-x-range-front || desired CG range || compile time ||
|-
| model/cg-x-max || CG hard limit from gear position || compile time ||
|-
| model/cg-x-min || CG hard limit from gear position || compile time ||
|-
| model/masses || shows the calculated mass points || compile time ||
|-
| model/wings || wing parameters || compile time ||
|}

== Command Line ==
=== Windows ===
By using the standard command line, we can see what the YASim solver is calculating. First, open up Command Prompt, enter in the location of yasim.exe, and then the location of the YASim XML file. For example, here's what you would type in for a standard Windows [[Changelog_2.12|FlightGear 2.12.0]] installation, and viewing the [[F-14_Tomcat|F-14B's]] YASim file.
{{Note|You can copy & paste the examples into Command Prompt by right-clicking on the title and navigate to Edit > Paste. Then, click Enter to execute.}}

<code>"C:\Program Files\FlightGear\bin\Win32\yasim.exe" "C:\Program Files\FlightGear\data\Aircraft\f-14b\f-14b-yasim.xml"</code>

The results will give many different values.

* '''Drag Coefficient:''' The drag coefficient of the aircraft.
* '''Lift Ratio:''' The lift ratio of the aircraft.
* '''Cruise AoA:''' The cruise AoA, from conditions at [[YASim#cruise|<cruise>]] in the xml file.
* '''Tail Incidence:''' The incidence angle of the tail, "solved" by YASim as a way to stabilize the aircraft.
* '''Approach Elevator:''' The approach elevator, from conditions at [[YASim#approach|<approach>]] in the xml file.
* '''CG:''' Center of gravity of the aircraft in coordinates. Unless it's supposed to be offset, it should always have a Y value of 0.

The YASim standalone solver also has some command line flags that change it's behaviour.

<code>"C:\Program Files\FlightGear\bin\Win32\yasim.exe" "C:\Program Files\FlightGear\data\Aircraft\f-14b\f-14b-yasim.xml" -g -a 1000 -s 490</code>

* '''-g:''' Instructs YASim to generate space-separated tabular data instead of the usual solver output. This can be redirected to a file and used in various plotting programs to visualize the actual lift, drag, L/D curves. The columns of the output from left to right are: AoA, Lift, Drag, L/D. (aoa in degrees, lift and drag in G's).
* '''-a <altitude in meter:>''' Run the solver at the given altitude in meter.
* '''-s <speed in knots>:''' Also run at the given airspeed in knots.

{{Note|The values generated by this method are for the aircraft taken as a whole, as solved by YASim, so they differ from the values of the wing airfoil.}}

To get the tabular output for the example above at 1000 m and 150 knots, and to redirect this to a file, one would issue:

<code>"C:\Program Files\FlightGear\bin\Win32\yasim.exe" "C:\Program Files\FlightGear\data\Aircraft\f-14b\f-14b-yasim.xml" -g -a 1000 -s 150 > "C:\Program Files\FlightGear\yasim.txt"</code>

== New features and bugfixes in version 2017.2 ==

=== XML parser ===
==== support for metric and imperial units ====
To make life easier for aircraft developers, the parser supports new additional attributes with a unit suffix, e.g. speed-kt for knots and speed-kmh for kilometers per hour.
* <code><airplane {mass, mass-lbs, mass-kg}="12345" ></code>
* <code><approach {speed, speed-kt, speed-kmh}="123" ></code>
* <code><cruise {speed, speed-kt, speed-kmh}="123" ></code>
* <code><solve-weight {weight, weight-lbs, weight-kg}="123" ></code>
* <code><jet {mass, mass-lbs, mass-kg}="1234" ></code>
* <code><tank {capacity, capacity-lbs, capacity-kg}="12345" ></code>
* <code><ballast {mass, mass-lbs, mass-kg}="1234" ></code>

{{Note|Aircraft using this new attributes will not run on older versions of FlightGear, so it is probably wise to publish those only after a reasonable number of users switched version 2017.2 or newer.}}

==== CG tuning help ====
{{Note| The feature described in this section is not fully implemented yet, however, it may be of some help already.
It is currently implemented for the yasim CLI tool only. It does not affect the airplane behaviour while running FlightGear. }}

New attributes have been added to <airplane> to assist tuning the center of gravity (CG).
The CG position is often expressed relative to the [https://en.wikipedia.org/wiki/Chord_(aeronautics)#Mean_aerodynamic_chord MAC] of the wing in percent. You can specify a desired range for CG in % relative to MAC, it will show up in the output of the yasim CLI tool (see example below):

* cg-min: default 25% (just a guess, better numbers are welcome)
* cg-max: default 30% (just a guess, better numbers are welcome)

{{Note| By convention 0% is leading edge, 100% is trailing edge, however the absolute values on x-axis are the other way round, e.g. nose is +x, tail is -x }}
{{warning|The MAC calculation in version 2017.2 works only on the <wing> element. Numbers will be wrong, if your model uses a combination of <wing> and <mstab> to build a wing with two or more sections.
Section support will be added in version 2018.1}}
YASim will print the leading edge coordinates of the MAC (x,y) and its length.

'''Example output'''
<pre>
$ yasim Citation-II-yasim.xml
This aircraft uses yasim version '2017.2'
==========================
= YASim solution results =
==========================
Iterations: 2210
Drag Coefficient: 12.304669
Lift Ratio: 85.317558
Cruise AoA: 4.016746 deg
Tail Incidence: -3.053278 deg
Approach Elevator: -0.377542

CG: x:-6.543, y:-0.000, z:0.044
Wing MAC (*1): x:-6.00, y:3.83, length:2.0
CG-x rel. MAC: 0.272
CG-x desired: -6.599 < -6.543 < -6.198

Inertia tensor [kg*m^2], origo at CG:

18009.289, -0.000, 7120.470
-0.000, 42459.316, 0.000
7120.470, 0.000, 56980.656

(*1) MAC calculation works on <wing> only! Numbers will be wrong for segmented wings, e.g. <wing>+<mstab>.
</pre>

=== Aircraft developer helpers ===
The command line utility got some new options. For some strange reason, the -a parameter expects altitude in meters instead of ft. This is now visible in the usage message but left unchanged for compatibility.
<syntaxhighlight>Usage:
yasim <aircraft.xml> [-g [-a meters] [-s kts] [-approach | -cruise] ]
yasim <aircraft.xml> [-d [-a meters] [-approach | -cruise] ]
yasim <aircraft.xml> [-m]
-g print lift/drag table: aoa, lift, drag, lift/drag
-d print drag over TAS: kts, drag
-a set altitude in meters!
-s set speed in knots
-m print mass distribution table: id, x, y, z, mass</syntaxhighlight>

=== Bugfixes ===
The following bugfixes require <airplane version="2017.2"> for backward compatibility
* Ground effect: corrected the calculation of the height where g.e. ends
* Stall parameters were set wrong for wings with camber=0

== New features and bugfixes in version 2018.1 ==
The following is under development and hopefully finds its way into FG version 2018.1

=== Wing Section Support ===
Many airliners have wings with a geometry that is just a little more complex than what YASim supported initially (tapered wing with some angles like sweep, dihedral, ...), e.g. they have an inboard section and an outboard section that can be described with YASim wing syntax. You can use a wing + a mstab XML element to describe this geometry but it is easier if YASim can just append more wing sections by simply adding more wing XML elements. This is now (Version 2018.1) possible, yasim will simply append sections if it finds more than one wing or hstab in the XML.
You should use '''<wing append="1" ... >''' for all but the first wing/hstab declaration.
{{Note|YASim will ignore the root point (x,y,z), the chord length and the incidence attributes, if you add "append" and calculate those from the previous wing section. }}
MAC calculation works for the whole wing.

{{warning|Aircrafts using this feature will not work with older versions of flightgear. }}
To keep the aircraft backward compatible for a while, it is recommended to create a copy of its yasim XML file for development.
Once you are happy with the CG and wing parameters you can use the output of the YASim CLI tool to modifiy the original XML.
The tool will output the needed x,y,z etc per wing section to create a XML in old format with (only one) <wing> + <mstab>.

=== More information from CLI tools ===
You should configure the maximum take of weight (MTOW) in your XML file by adding either ''mtow-lbs'' or ''mtow-kg'' attribute to the airplane:

<code> <airplane mass="7500" version="2018.1" mtow-lbs="12500"> </code>

'''Example output'''
<pre>
yasim CRJ700.xml
==========================
= YASim solution results =
==========================
Iterations : 1024
Drag Coefficient : 17.707
Lift Ratio : 145.841
Cruise AoA : -0.11 deg
Tail Incidence : 3.47 deg
Approach Elevator : -0.792

CG : x:-0.046, y:0.000, z:-1.222
Wing MAC : (x:0.79, y:4.99), length:3.4
hard limit CG-x : 14.232 m
soft limit CG-x : -0.058 m
CG-x : -0.046 m
CG-x rel. MAC : 25%
soft limit CG-x : -0.228 m
hard limit CG-x : -0.986 m

wing lever : -0.012 m
tail lever : -13.997 m

max thrust : 157.18 kN
thrust/empty : 0.81
thrust/mtow : 0.49

wing span : 22.64 m
sweep lead. edge : 30.2 .. 30.6 deg
wing area : 58.70 m^2
wing load empty : 336.15 kg/m^2 (Empty 19731 kg)
wing load MTOW : 562.18 kg/m^2 (MTOW 32999 kg)

tail span : 8.533 m
tail area : 14.838 m^2

#wing sections: 2
Section 0 base point (0.450, 1.226, -2.034), chord 5.085, incidence at section root 5.0deg
Section 1 base point (-0.663, 4.754, -1.942), chord 3.204, incidence at section root 3.0deg

Inertia tensor [kg*m^2], origo at CG:

195646, 0, 122265
0, 1757279, 0
122265, 0, 1904528
</pre>

=== Variable tail incidence / elevator trim ===
Small GA aircrafts usually trim with a trim tab on the elevator. For efficiency, airliners normally do not trim the elevator ("flap")
but rotate the whole stabilizer (=tail) wing, e.g. they change the incidence for this wing. While this feature was somehow foreseen,
it was not implemented yet, most likely because the "tail incidence" is one of the free variables used by the YASim solver.
However, it is possible now to use the control="INCIDENCE" within the <hstab> to implement an alternative trim '''while maintaining full elevator authority'''.
<pre>
<hstab ... incidence-min-deg="-13.0" incidence-max-deg="2.0">
...
<control-input axis="/controls/flight/hstab-trim" control="INCIDENCE" />
<control-speed control="INCIDENCE" transition-time="20.0" />
<control-output control="INCIDENCE" prop="/surface-positions/hstab-rad" />
</hstab>
</pre>
{{Note|The control output of INCIDENCE is the angle in radians, not in degree, as that is the unit internally used by YASim.}}
{{warning|The OPTIONAL incidence-min-deg and incidence-max-deg set the limits for the solver. You must make sure to select a sufficiently large range or solver will fail. }}
First experiments with this feature were successful in that the aircraft pitch could be changed as expected but fine tuning will be necessary.

== Related content ==
* [[Howto:Make a helicopter#XML Elements]] – Rotor and rotorgear YASim elements
* [[Towing]]
* [[YASim Development Tools]]

== External links ==
* {{cite web
| url = http://www.buckarooshangar.com/flightgear/yasimtut.html
| title = Guide to YASim
| first = Gary R. "Buckaroo"
| last = Neely
| authorlink = http://www.buckarooshangar.com/flightgear/
| date = 2013
| accessdate = April 16, 2020
}} - A very helpful guide
* {{cite web
| url = https://sourceforge.net/projects/dacpei/
| title = DACPEI
| author = pytoche
| date = February 2012
| publisher = SourceForge
| accessdate = April 16, 2020
}} - A fixed wing light aircraft WYSIWUG concept design suite that can export an YASim FDM to FlightGear.

{{FDM}}

[[Category:Flight Dynamics Model]]

[[fr:YASim]]

FlightGear Newsletter October 2019

2019-10-03T09:47:53Z

DanielHL: /* Support for transonic flow effects in YASim */ Prandtl/Glauert plot and warning about supersonic use

{{User:Skybike/Template:Newsletter-header-translate|2019-10}}
{{TOC_right|limit=2}}
''We would like to emphasize that the monthly newsletter can not live without the contributions of FlightGear users and developers. Everyone with a wiki account (free to register) is welcome to contribute to the newsletter. If you know about any FlightGear related news or projects such as for example updated scenery or aircraft, please do feel invited to add such news to the newsletter.''

== Development news ==

=== Support for transonic flow effects in YASim ===
YASim now supports [[YASim#Surfaces|transonic compressibility effects]] on flight surfaces. Aircraft that fly faster than Mach 0.6 often have supercritical airfoils, where the flow on the upper surface reaches supersonic speeds even if the aircraft itself is below mach 1. These airfoils are optimized for lower drag in this flight regime.

YASim now has a parameter "flow" which is valid for wing, mstab, vstab and hstab. If set to "TRANSONIC", YASim applies a Prandtl/Glauert compressibility correction for each surface of the wing which results in more lift above mach 0.6 with a peak at Mach 1 (see figure). The default value is "SUBSONIC" which turns the behavior off and computes just like previous YASim versions. Use this parameter for all jets with supercritical airfoils or anything that flies faster than mach 0.6. The result is a more balanced lift/drag result from the solver. Please do not use this parameter for supersonic aircraft!

[[File:Prandtl-glauert-transform.png|thumb|Plot of the subsonic and supersonic Prandtl/Glauert transformation.]]

Also you can specify a critical mach number for each wing (and mstab, vstab, hstab) using the parameter "mcrit". In aerodynamics the critical mach number is the flight mach number above which drag due to mach (also called wave drag) becomes relevant. If flow="TRANSONIC" is set, YASim looks for mcrit (default is 0.6) and adds exponential mach drag above that mach number. The estimation is done by a method according to Perkins and Hage. Future versions may tune and expand this behavior a bit.

As always with YASim, these parameters are no drop-in solution. Setting the flow and mcrit parameters will change the flight behavior of existing aircraft and other settings may need to be corrected after that. Also this feature is experimental at the moment - please review [https://sourceforge.net/u/jsb1685/flightgear/ci/44e1f43e914ed35e6fdf5265842056ab3d2d991c/ the code] and report any issues to the developer mailing list.




== In the hangar ==












== AI ==


The AI team makes FlightGear more realistic, colorful and lively every month. You can support the important development of ''Interactive Traffic'' and contribute at the FlightGear {{forum link|title=AI|f=23}}.



== Scenery corner ==














== Community news ==







=== FlightGear on Facebook ===
Since early December 2010, FlightGear has an [http://www.facebook.com/FlightGear official Facebook page]. If you have a Facebook account please feel free to join the page.

=== FlightGear on Instagram ===
In January 2018 the [https://www.instagram.com/flightgear_sim/ @flightgear_sim Instagram account] was brought back to life. If you've got nice screenshots to be featured, feel free to {{forum link|text=contact the maintainer|t=33636}}.

=== FlightGear on FlightSim.com ===
Flightgear has also a [https://www.flightsim.com/vbfs/forumdisplay.php?102-FlightGear sub-forum] on flightsim.com - just like the commercial flightsims. It is an opportunity to showcase what FG can do, get people curious and answer any questions they may have with regard to the software or the project.

== Multiplayer events ==









== Contributing ==

=== Translators needed ===
{|
| [[File:en.gif]]
| The FlightGear Wiki still needs help for translating it into various languages. If you are interested in making the FlightGear Wiki multilingual, you can start by looking at [[Help:Translate]].
|-
| [[File:fr.gif]]
| Le wiki de FlightGear a toujours besoin d'aide pour être traduit en différentes langues. Si vous êtes intéressé par le rendre multilingue, commencez par lire [[:fr:Help:Traduire|Help:Traduire]].
|-
| [[File:de.gif]]
| Das FlightGear Wiki benötigt immer noch Hilfe bei der Übersetzung in verschiedene Sprachen. Wenn Du Interesse daran hast, das FlightGear Wiki mehrsprachig zu machen, dann fang mit dem [[:de:Help:Übersetzen|Help:Übersetzen]] an.
|-
| [[File:nl.gif]]
| De FlightGear Wiki kan nog steed hulp gebruiken bij het vertalen van artikelen. Als je interesse hebt om de wiki meertalig te maken, raden we je aan om een kijkje te nemen bij [[:nl:Help:Vertalen|Help:Vertalen]].
|-
| [[File:es.gif]]
| La wiki de FlightGear todavía necesita ayuda para traducirla a varios lenguajes. Si estás interesado en hacer la FlightGear wiki multilingüe, entonces comienza en [[:es:Help:Traducir|Help:Traducir]].
|-
| [[File:cat.gif]]
| La wiki de FlightGear encara necessita ajuda per traduir-la a diverses llengües. Si esteu interessat en fer la wiki de FlightGear multilingüe, llavors comenceu a [[:ca:Help:Traduir|Help:Traduir]].
|-
| [[File:pt.gif]]
| A wiki de FlightGear ainda necessita de ajuda para traduzi-la em vários idiomas. Se estás interessado em tornar a wiki de FlightGear multi-lingual, por favor começa em [[:pt:Help:Traduzir|Help:Traduzir]].
|-
| [[File:zh.gif]]
| FlightGear 百科仍然需要志愿者将其翻译为各种语言。如果你有兴趣让FlightGear百科支持更多语言, 你可以查看 [[Help:Translate]].
|}

=== FlightGear logos ===
If you want some graphic elements for your FlightGear-related site (such as a hangar or YouTube channel), please feel free to visit [[FlightGear logos]] for a repository of logos. And if you have some art skills, please don't hesitate to contribute with your own design creations.

=== Screenshots ===
The FlightGear project always needs screenshots, which show features that were added since the last release. These should be of good quality, especially in content and technical image properties. It is therefore recommended to use the best viable filter settings ([[anti-aliasing]], texture sharpening, etc.). More info at [[Howto:Make nice screenshots]].

==== Screenshot of the Month ====


If you want to participate in the screenshot contest , you can submit your candidate to {{forum link|title=this|f=19|t= }}. Be sure to see the first post for participation rules. For purposes of convenience and organization, after all the entries have been submitted, a new forum topic will be started containing all shots in an easy-to-view layout. The voting will then take place there. Once the voting has finished, the best screenshot will be presented in the Newsletter.

''Thanks for reading {{PAGENAME}}!''

{{Appendix}}

[[Category:Changes after 2018.3]]
[[Category:FlightGear Newsletter|2019 10]]

[[de:FlightGear Newsletter {{#time: F Y | 2019-10 | de }}]]

File:Prandtl-glauert-transform.png

2019-10-03T09:46:12Z

DanielHL: User created page with UploadWizard

=={{int:filedesc}}==
{{Information
|description={{en|1=Plot of the subsonic and supersonic Prandtl/Glauert transformation.}}
|date=2019-10-03
|source=https://en.wikipedia.org/wiki/File:Prandtl-glauert-transform.png
|author=VallWoodshadow
|permission=
|other versions=
}}

=={{int:license-header}}==
{{cc-zero}}

[[Category:Flight Dynamics Model]]

FlightGear Newsletter October 2019

2019-10-03T08:51:43Z

DanielHL: Created preloaded page, YASim compressibility effects

{{User:Skybike/Template:Newsletter-header-translate|2019-10}}
{{TOC_right|limit=2}}
''We would like to emphasize that the monthly newsletter can not live without the contributions of FlightGear users and developers. Everyone with a wiki account (free to register) is welcome to contribute to the newsletter. If you know about any FlightGear related news or projects such as for example updated scenery or aircraft, please do feel invited to add such news to the newsletter.''

== Development news ==

=== Support for transonic flow effects in YASim ===
YASim now supports [[YASim#Surfaces|transonic compressibility effects]] on flight surfaces. Aircraft that fly faster than Mach 0.6 often have supercritical airfoils, where the flow on the upper surface reaches supersonic speeds even if the aircraft itself is below mach 1. These airfoils are optimized for lower drag in this flight regime.

YASim now has a parameter "flow" which is valid for wing, mstab, vstab and hstab. If set to "TRANSONIC", YASim applies a Prandtl/Glauert compressibility correction for each surface of the wing which results in more lift above mach 0.6 with a peak at Mach 1 (see figure). The default value is "SUBSONIC" which turns the behavior off and computes just like previous YASim versions. Use this parameter for all jets with supercritical airfoils or anything that flies faster than mach 0.6. The result is a more balanced lift/drag result from the solver.

Also you can specify a critical mach number for each wing (and mstab, vstab, hstab) using the parameter "mcrit". In aerodynamics the critical mach number is the flight mach number above which drag due to mach (also called wave drag) becomes relevant. If flow="TRANSONIC" is set, YASim looks for mcrit (default is 0.6) and adds exponential mach drag above that mach number. The estimation is done by a method according to Perkins and Hage. Future versions may tune and expand this behavior a bit.

As always with YASim, these parameters are no drop-in solution. Setting the flow and mcrit parameters will change the flight behavior of existing aircraft and other settings may need to be corrected after that. Also this feature is experimental at the moment - please review [https://sourceforge.net/u/jsb1685/flightgear/ci/44e1f43e914ed35e6fdf5265842056ab3d2d991c/ the code] and report any issues to the developer mailing list.




== In the hangar ==












== AI ==


The AI team makes FlightGear more realistic, colorful and lively every month. You can support the important development of ''Interactive Traffic'' and contribute at the FlightGear {{forum link|title=AI|f=23}}.



== Scenery corner ==














== Community news ==







=== FlightGear on Facebook ===
Since early December 2010, FlightGear has an [http://www.facebook.com/FlightGear official Facebook page]. If you have a Facebook account please feel free to join the page.

=== FlightGear on Instagram ===
In January 2018 the [https://www.instagram.com/flightgear_sim/ @flightgear_sim Instagram account] was brought back to life. If you've got nice screenshots to be featured, feel free to {{forum link|text=contact the maintainer|t=33636}}.

=== FlightGear on FlightSim.com ===
Flightgear has also a [https://www.flightsim.com/vbfs/forumdisplay.php?102-FlightGear sub-forum] on flightsim.com - just like the commercial flightsims. It is an opportunity to showcase what FG can do, get people curious and answer any questions they may have with regard to the software or the project.

== Multiplayer events ==









== Contributing ==

=== Translators needed ===
{|
| [[File:en.gif]]
| The FlightGear Wiki still needs help for translating it into various languages. If you are interested in making the FlightGear Wiki multilingual, you can start by looking at [[Help:Translate]].
|-
| [[File:fr.gif]]
| Le wiki de FlightGear a toujours besoin d'aide pour être traduit en différentes langues. Si vous êtes intéressé par le rendre multilingue, commencez par lire [[:fr:Help:Traduire|Help:Traduire]].
|-
| [[File:de.gif]]
| Das FlightGear Wiki benötigt immer noch Hilfe bei der Übersetzung in verschiedene Sprachen. Wenn Du Interesse daran hast, das FlightGear Wiki mehrsprachig zu machen, dann fang mit dem [[:de:Help:Übersetzen|Help:Übersetzen]] an.
|-
| [[File:nl.gif]]
| De FlightGear Wiki kan nog steed hulp gebruiken bij het vertalen van artikelen. Als je interesse hebt om de wiki meertalig te maken, raden we je aan om een kijkje te nemen bij [[:nl:Help:Vertalen|Help:Vertalen]].
|-
| [[File:es.gif]]
| La wiki de FlightGear todavía necesita ayuda para traducirla a varios lenguajes. Si estás interesado en hacer la FlightGear wiki multilingüe, entonces comienza en [[:es:Help:Traducir|Help:Traducir]].
|-
| [[File:cat.gif]]
| La wiki de FlightGear encara necessita ajuda per traduir-la a diverses llengües. Si esteu interessat en fer la wiki de FlightGear multilingüe, llavors comenceu a [[:ca:Help:Traduir|Help:Traduir]].
|-
| [[File:pt.gif]]
| A wiki de FlightGear ainda necessita de ajuda para traduzi-la em vários idiomas. Se estás interessado em tornar a wiki de FlightGear multi-lingual, por favor começa em [[:pt:Help:Traduzir|Help:Traduzir]].
|-
| [[File:zh.gif]]
| FlightGear 百科仍然需要志愿者将其翻译为各种语言。如果你有兴趣让FlightGear百科支持更多语言, 你可以查看 [[Help:Translate]].
|}

=== FlightGear logos ===
If you want some graphic elements for your FlightGear-related site (such as a hangar or YouTube channel), please feel free to visit [[FlightGear logos]] for a repository of logos. And if you have some art skills, please don't hesitate to contribute with your own design creations.

=== Screenshots ===
The FlightGear project always needs screenshots, which show features that were added since the last release. These should be of good quality, especially in content and technical image properties. It is therefore recommended to use the best viable filter settings ([[anti-aliasing]], texture sharpening, etc.). More info at [[Howto:Make nice screenshots]].

==== Screenshot of the Month ====


If you want to participate in the screenshot contest , you can submit your candidate to {{forum link|title=this|f=19|t= }}. Be sure to see the first post for participation rules. For purposes of convenience and organization, after all the entries have been submitted, a new forum topic will be started containing all shots in an easy-to-view layout. The voting will then take place there. Once the voting has finished, the best screenshot will be presented in the Newsletter.

''Thanks for reading {{PAGENAME}}!''

{{Appendix}}

[[Category:Changes after 2018.3]]
[[Category:FlightGear Newsletter|2019 10]]

[[de:FlightGear Newsletter {{#time: F Y | 2019-10 | de }}]]

YASim

2019-10-03T08:21:06Z

DanielHL: /* wing */ new features flow and mcrit

[[File:yasimlogo.png|thumb]]

'''YASim''' is one of two [[flight dynamics model]]s commonly used in [[FlightGear]]. The flight dynamics model (FDM) determines how the [[aircraft]] moves and flies.

Gary Neely wrote in his [http://www.buckarooshangar.com/flightgear/ introduction to YASim]:

:''The FDM is the mathematical model that controls the physics of flight within the simulator. The physical 3D aircraft model has nothing to do with flight dynamics-- in essence it's just a picture to look at. It's the FDM that dictates how the model flies.''

:''Why YASim? YASim uses the geometry of the aircraft to generate the base flight characteristics. While this suggests a 'realistic' or out-of-the-box approach, it is a only rough approximation that will require much tweaking before you get a result that approaches realism. If you have solid flight data for your aircraft such as wind-tunnel data or you are looking to eventually generate a hyper-realistic simulation, JSBSim is probably a better approach. If you lack such data but know the geometry of the aircraft and have access to the same flight characteristics and limits as a real pilot would, then YASim can provide a solution that is more than sufficient for most simulation needs.''

== Coordinate system notes ==
All positions specified are in metres (which is weird, since all other units in the file are English). The X axis points forward, Y is left, and Z is up. Take your right hand, and hold it like a gun. Your first and second fingers are the X and Y axes, and your upwards-pointing thumb is the Z. This is slightly different from the coordinate system used by [[JSBSim]]. Sorry. The origin can be placed anywhere, so long as you are consistent. I use the nose of the aircraft.

(In the [[JSBSim_Aerodynamics#Frames|JSBSim coordinate system]], X and Z are the same as in YASim, but Y points to the right instead of left.)

== XML Elements ==

=== airplane ===
The top-level element for the file. It contains the following attributes:
* '''mass:''' The empty (no fuel) weight, in pounds. It does include the weight of the engine(s), so when you add the engine weight in its tag, it acts just like a ballast.
* '''version:''' The version attribute is used to maintain compatibility when updating yasim (e.g. bugfixes). If this attribute i not given, the original version will be used. Several bugfixes to YASim were implemented in FlightGear 3.2 (see [[FlightGear Newsletter April 2014]]), some more are fixed in FlightGear 2017.2.
Available versions are:
* <code>YASIM_VERSION_ORIGINAL</code> explicitly use the old buggy calculations (same as no version attribute at all)
* <code>YASIM_VERSION_32</code> enable bugfixes up to version 3.2
* <code>2017.2</code> enable bugfixes up to version 2017.2
* <code>2018.1</code> (FIXME) no bugfixes by now. Use this version if your aircraft makes use of new features in YASim 2018.1 so it will cause at least a warning with older FG versions.
* <code>YASIM_VERSION_CURRENT</code> use latest version compiled into the users FlightGear.
{{Warning| Using YASIM_VERSION_CURRENT might make the aircraft unusable in case of future changes to YASim without updating the aircraft accordingly.}}

'''New in 2018.1'''
* '''mtow-lbs''' and '''mtow-kg:''' use one of them to specify max. takeoff weight. Does not affect the FDM, but is used by CLI tool to calculate some numbers.

=== approach ===
The approach parameters for the aircraft. The solver will generate an aircraft that matches these settings. The element can (and should) contain <control> elements indicating pilot input settings, such as flaps and throttle, for the approach.
* '''speed:''' The approach airspeed, in knots TAS.
* '''aoa:''' The approach angle of attack, in degrees
* '''fuel:''' Fraction (0-1) of fuel in the tanks. Default is 0.2.
=== cruise ===
The cruise speed and altitude for the solver to match. As above, this should contain <control> elements indicating aircraft configuration. Especially, make sure the engines are generating enough thrust at cruise!
* '''speed:''' The cruise speed, in knots TAS.
* '''alt:''' The cruise altitude, in feet MSL.
* '''fuel:''' Fraction (0-1) of fuel in the tanks. Default is 0.2.
=== cockpit ===
The location of the cockpit (pilot eyepoint).
* '''x,y,z:''' eyepoint location (see coordinates note)

=== fuselage ===
This defines a tubelike structure. It will be given an even mass and aerodynamic force distribution by the solver. You can have as many as you like, in any orientation you please.
* '''ax,ay,az:''' One end of the tube (typically the front)
* '''bx,by,bz:''' The other ("back") end.
* '''width:''' The width of the tube, in metres.
* '''taper:''' The approximate radius at the "tips" of the fuselage expressed as a fraction (0-1) of the width value.
* '''midpoint:''' The location of the widest part of the fuselage, expressed as a fraction of the distance between A and B.
* '''idrag:''' Multiplier for the "induced drag" generated by this object. Default is one. With idrag=0 the fuselage generates only drag.
* '''cx,cy,cz:''' Factors for the generated drag in the fuselages "local coordinate system" with x pointing from end to front, z perpendicular to x with y=0 in the aircraft coordinate system. E.g. for a fuselage of a height of 2 times the width you can define cy=2 and (due to the doubled front surface) cx=2.

=== Surfaces ===
==== wing ====
This defines the main wing of the aircraft. You can have only one (but see below about using vstab objects for extra lifting surfaces). The wing should have a <stall> subelement to indicate stall behavior, control surface subelements (flap0, flap1, spoiler, slat) to indicate what and where the control surfaces are, and <control> subelements to map user input properties to the control surfaces.
* '''x,y,z:''' The "base" of the wing, specified as the location of the mid-chord (not leading edge, trailing edge, or aerodynamic center) point at the root of the LEFT (!) wing.
* '''length:''' The length from the base of the wing to the midchord point at the tip. Note that this is not the same thing as span.
* '''chord:''' The chord of the wing at its base, along the X axis (not normal to the leading edge, as it is sometimes defined).
* '''incidence:''' The incidence angle at the wing root, in degrees. Zero is level with the fuselage (as in an aerobatic plane), positive means that the leading edge is higher than the trailing edge (as in a trainer).
* '''twist:''' The difference between the incidence angle at the wing root and the incidence angle at the wing tip. Typically, this is a negative number so that the wing tips have a lower angle of attack and stall after the wing root (washout).
* '''taper:''' The taper fraction, expressed as the tip chord divided by the root chord. A taper of one is a hershey bar wing, and zero would be a wing ending at a point. Defaults to one.
* '''sweep:''' The sweep angle of the wing, in degrees. Zero is no sweep, positive angles are swept back. Defaults to zero.
* '''dihedral:''' The dihedral angle of the wing. Positive angles are upward dihedral. Defaults to zero.
* '''idrag:''' Multiplier for the "induced drag" generated by this surface. In general, low aspect wings will generate less induced drag per-AoA than high aspect (glider) wings. This value isn't constrained well by the solution process, and may require tuning to get throttle settings correct in high AoA (approach) situations.
* '''effectiveness:''' Multiplier for the "normal" drag generated by the wing. Defaults to 1. Arbitrary, dimensionless factor.
* '''camber:''' The lift produced by the wing at zero angle of attack, expressed as a fraction of the maximum lift produced at the stall AoA.
* '''flow:''' The flow regime for the wing. Valid values are "SUBSONIC" (default) and "TRANSONIC". Setting surface to transonic adds more lift above mach number 0.6 by applying a Prandl/Glauert correction term to each surface-element. The effect is a more balanced lift/drag distribution reported by the solver. Use for anything that flies faster than mach 0.6 or has supercritical airfoils.
* '''mcrit:''' The critical mach number for the wing. This point defines the begin of exponential drag rise due to mach speed. Default "0.6", only available if flow="TRANSONIC".

'''Wing section support (since 2018.1):'''

Wing section support to define variable geometry (geometry parameters per section)
* More than one <wing>-element is allowed now.
* x, y, z, chord and incidence attribute shall be specifed only for the first <wing> in the XML file. They will be overridden for subsequent <wing>-elements.
* Use '''append="1"''' for additional '''wing''' elements to skip x, y, z, chord and incidence attribute as the will be calculated from previous '''wing''' element tip chord. This workaround is currently needed due to limitations in the XML parser.

==== hstab ====
These defines the horizontal stabilizer of the aircraft. Internally, it is just a wing object and therefore works the same in XML.
You are allowed only one hstab object; the solver needs to know which wing's incidence to play with to get the aircraft trimmed correctly.

'''New in 2018.1:'''
* '''hstab''' supports sections in the same way '''wing''' does, but it is still considered as /the/ (only) hstab used by the solver.
* '''incidence-max-deg''' and '''incidence-max-deg''': optional attributes to limit valid result range fore the solver. Use with care or you won't get a solution.

==== vstab ====
A "vertical" stabilizer. Like hstab, this is just another wing, with a few special properties. The surface is not "mirrored" as are wing and hstab objects. If you define a left wing only, you'll only get a left wing. The default dihedral, if unspecified, is 90 degrees instead of zero. But all parameters are equally settable, so there's no requirement that this object be "vertical" at all. You can use it for anything you like, such as extra wings for biplanes. Most importantly, these surfaces are not involved with the solver computation, so you can have none, or as many as you like.

==== mstab ====
A mirrored horizontal stabilizer. Exactly the same as wing, but not involved with the solver computation, so you can have none, or as many as you like.

==== stall ====
A subelement of a wing (or hstab/vstab/mstab) that specifies the stall behavior.
* '''aoa:''' The stall angle (maximum lift) in degrees. Note that this is relative to the wing, not the fuselage (since the wing may have a non-zero incidence angle).
* '''width:''' The "width" of the stall, in degrees. A high value indicates a gentle stall. Low values are viscious for a non-twisted wing, but are acceptable for a twisted one (since the whole wing will not stall at the same time).
* '''peak:''' The height of the lift peak, relative to the post-stall secondary lift peak at 45 degrees. Defaults to 1.5. This one is deep voodoo, and probably doesn't need to change much. Bug me for an explanation if you're curious.

==== flap0, flap1, slat, spoiler ====
These are subelements of wing/hstab/vstab objects, and specify the location and effectiveness of the control surfaces.
* '''start:''' The position along the wing where the control surface begins.Zero is the root, one is the tip.
* '''end:''' The position where the surface ends, as above.
* '''lift:''' The lift multiplier for a flap or slat at full extension. One is a no-op, a typical aileron might be 1.2 or so, a giant jetliner flap 2.0, and a spoiler 0.0. For spoilers, the interpretation is a little different -- they spoil only "prestall" lift. Lift due purely to "flat plate" effects isn't affected. For typical wings that stall at low AoA's essentially all lift is pre-stall and you don't have to care. Jet fighters tend not to have wing spoilers, for exactly this reason. This value is not applicable to slats, which affect stall AoA only.
* '''drag:''' The drag multiplier, as above. Typically should be higher than the lift multiplier for flaps.
* '''aoa:''' Applicable only to slats. This indicates the angle by which the stall AoA is translated by the slat extension.

=== Engine ===
==== Thruster ====
A very simple "thrust only" engine object. Useful for things like thrust vectoring nozzles. All it does is map its THROTTLE input axis to its output thrust rating. Does not consume fuel, etc...
* '''thrust:''' Maximum thrust in pounds
* '''x,y,z:''' The point on the airframe where thrust will be applied.
* '''vx,vy,vy:''' The direction of the thrust in airframe coordinates. The vector will be normalized automatically, so any non-zero vector will work fine.

==== Jet ====
A turbojet/fan engine. It accepts a <control> subelement to map a property to its throttle setting, and an <actionpt> subelement to place the action point of the thrust at a different position than the mass of the engine.
* '''x,y,z:''' The location of the engine, as a point mass. If no actionpt is specified, this will also be the point of application of thrust.
* '''mass:''' The mass of the engine, in pounds.
* '''thrust:''' The maximum sea-level thrust, in pounds.
* '''afterburner:''' Maximum total thrust with afterburner/reheat, in pounds [defaults to "no additional thrust"].
* '''rotate:''' Vector angle of the thrust in degrees about the Y axis [0].
* '''n1-idle:''' Idling low pressure core / fan speed [55].
* '''n1-max:''' Maximum low pressure core / fan speed [102].
* '''n2-idle:''' Idling high pressure core speed [73].
* '''n2-max:''' Maximum high pressure core speed [103].
* '''tsfc:''' Thrust-specific fuel consumption [0.8]. This should be considerably lower for modern turbofans.
* '''atsfc:''' (version >= 2016.3.1) Thrust specific fuel consumption with afterburner on. When set to zero defaults to older behaviour where it is calculated from dry fuel consumption [0].
* '''egt:''' Exhaust gas temperature at takeoff in K [1050].
* '''epr:''' Engine pressure ratio at takeoff [3.0].
* '''exhaust-speed:''' The maximum exhaust speed in knots [~1555].
* '''spool-time:''' Time, in seconds, for the engine to respond to 90% of a commanded powersetting.

==== Propeller ====
A propeller. This element requires an engine subtag. Currently <piston-engine> and <turbine-engine> are supported.
* '''x,y,z:''' The position of the mass (!) of the engine/propeller combination. If the point of force application is different (and it will be) it should be set with an <actionpt> subelement.
* '''mass:''' The mass of the engine/propeller, in pounds.
* '''moment:''' The moment, in kg-metres^2. This has to be hand calculated and guessed at for now. A more automated system will be forthcoming. Use a negative moment value for counter-rotating ("European" -- CCW as seen from behind the prop) propellers. A good guess for this value is the radius of the prop (in metres) squared times the mass (kg) divided by three; that is the moment of a plain "stick" bolted to the prop shaft.
* '''radius:''' The radius, in metres, or the propeller.
* '''cruise-speed:''' The max efficiency cruise speed of the propeller. Generally not the same as the aircraft's cruise speed.
* '''cruise-rpm:''' The RPM of the propeller at max-eff. cruise.
* '''cruise-power:''' The power sunk by the prop at cruise, in horsepower.
* '''cruise-alt:''' The reference cruise altitude in feet.
* '''takeoff-power:''' The takeoff power required by the propeller...
* '''takeoff-rpm:''' ...at the given takeoff RPM.
* '''min-rpm:''' The minimum operational RPM for a constant speed propeller. This is the speed to which the prop governor will seek when the blue lever is at minimum. The coarse-stop attribute limits how far the governor can go into trying to reach this RPM.
* '''max-rpm:''' The maximum operational RPM for a constant speed propeller. See above. The fine-stop attribute limits how far the governor can go in trying to reach this RPM.
* '''fine-stop:''' The minimum pitch of the propeller (high RPM) as a ratio of ideal cruise pitch. This is set to 0.25 by default -- a higher value will result in a lower RPM at low power settings (e.g. idle, taxi, and approach).
* '''coarse-stop:''' The maximum pitch of the propeller (low RPM) as a ratio of ideal cruise pitch. This is set to 4.0 by default -- a lower value may result in a higher RPM at high power settings.
* '''gear-ratio:''' The factor by which the engine RPM is multiplied to produce the propeller RPM. Optional (defaults to 1.0).
* '''contra:''' When set (contra="1"), this indicates that the propeller is a contra-rotating pair. It will not contribute to the aircraft's net gyroscopic moment, nor will it produce asymmetric torque on the aircraft body. Asymmetric slipstream effects, when implemented, will also be zero when this is set.
* '''piston-engine:''' A piston engine definition. This must be a subelement of an enclosing <propeller> tag.
* '''eng-power:''' Maximum BHP of the engine at sea level.
* '''eng-rpm:''' The engine RPM at which eng-power is developed
* '''displacement:''' The engine displacement in cubic inches.
* '''compression:''' The engine compression ratio.

=== Landing gear ===
==== gear ====
Defines a landing gear. Accepts <control> subelements to map properties to steering and braking. Can also be used to simulate floats. Although the coefficients are still called ..fric, it is calculated in fluids as a drag (proportional to the square of the speed). In fluids gears are not considered to detect crashes (as on ground).
* '''x,y,z:''' The location of the fully-extended gear tip.
* '''compression:''' The distance in metres along the "up" axis that the gear will compress.
* '''initial-load:''' The initial load of the spring in multiples of compression. Defaults to 0. (With this parameter a lower spring-constants will be used for the gear-> can reduce numerical problems (jitter)) '''Note:''' the spring-constant is varied from 0% compression to 20% compression to get continuous behavior around 0 compression. (could be physically explained by wheel deformation)
* '''upx/upy/upz:''' The direction of compression, defaults to vertical (0,0,1) if unspecified. These are used only for a direction -- the vector need not be normalized, as the length is specified by "compression".
* '''sfric:''' Static (non-skidding) coefficient of friction. Defaults to 0.8.
* '''dfric:''' Dynamic friction. Defaults to 0.7.
* '''spring:''' A dimensionless multiplier for the automatically generated spring constant. Increase to make the gear stiffer, decrease to make it squishier.
* '''damp:''' A dimensionless multiplier for the automatically generated damping coefficient. Decrease to make the gear "bouncier", increase to make it "slower". Beware of increasing this too far: very high damping forces can make the numerics unstable. If you can't make the gear stop bouncing with this number, try increasing the compression length instead.
* '''on-water:''' if this is set to "0" the gear will be ignored if on water. Defaults to "0"
* '''on-solid:''' if this set to "0" the gear will be ignored if not on water. Defaults to "1"
* '''speed-planing:'''
* '''spring-factor-not-planing:''' At zero speed the spring factor is multiplied by spring-factor-not-planing. Above speed-planing this factor is equal to 1. The idea is, to use this for floats simulating the transition from swimming to planing. speed-planing defaults to 0, spring-factor-not-planing defaults to 1.
* '''reduce-friction-by-extension:''' at full extension the friction is reduced by this relative value. 0.7 means 30% friction at full extension. If you specify a value greater than one, the friction will be zero before reaching full extension. Defaults to "0"
* '''ignored-by-solver:''' with the on-water/on-solid tags you can have more than one set of gears in one aircraft, If the solver (who automatically generates the spring constants) would take all gears into account, the result would be wrong. E. G. set this tag to "1" for all gears, which are not active on runways. Defaults to "0". You can not exclude all gears in the solving process.

==== Launchbar ====
Defines a catapult launchbar or strop.
* '''x,y,z:''' The location of the mount point of the launch bar or strop on the aircraft.
* '''length:''' The length of the launch bar from mount point to tip
* '''down-angle:''' The max angle below the horizontal the launchbar can achieve.
* '''up-angle:''' The max angle above the horizontal the launchbar can achieve.
* '''holdback-{x,y,z}:''' The location of the holdback mount point on the aircraft.
* '''holdback-length:''' The length of the holdback from mount point to tip. Note: holdback up-angle and down-angle are the same as those defined for the launchbar and are not specified in the configuration.

=== Fuel ===
==== tank ====
A fuel tank. Tanks in the aircraft are identified numerically (starting from zero), in the order they are defined in the file. If the left tank is first, "tank[0]" will be the left tank.
* '''x,y,z:''' The location of the tank.
* '''capacity:''' The maximum contents of the tank, in pounds. Not gallons -- YASim supports fuels of varying densities.
* '''jet:''' A boolean. If present, this causes the fuel density to be treated as Jet-A. Otherwise, gasoline density is used. A more elaborate density setting (in pounds per gallon, for example) would be easy to implement. Bug me.

=== Center of Gravity ===
==== Ballast ====
This is a mechanism for modifying the mass distribution of the aircraft. A ballast setting specifies that a particular amount of the empty weight of the aircraft must be placed at a given location. The remaining non-ballast weight will be distributed "intelligently" across the fuselage and wing objects. Note again: this does NOT change the empty weight of the aircraft.
* '''x,y,z:''' The location of the ballast.
* '''mass:''' How much mass, in pounds, to put there. Note that this value can be negative. I find that I often need to "lighten" the tail of the aircraft.

==== Weight ====
This is an added weight, something not part of the empty weight of the aircraft, like passengers, cargo, or external stores. The actual value of the mass is not specified here, instead, a mapping to a property is used. This allows external code, such as the panel, to control the weight (loading a given cargo configuration from preference files, dropping bombs at runtime, etc...)
* '''x,y,z:''' The location of the weight.
* '''mass-prop:''' The name of the fgfs property containing the mass, in pounds, of this weight.
* '''size:''' The aerodynamic "size", in metres, of the object. This is important for external stores, which will cause drag. For reasonably aerodynamic stuff like bombs, the size should be roughly the width of the object. For other stuff, you're on your own. The default is zero, which results in no aerodynamic force (internal cargo).
* '''solve-weight:''' Subtag of approach and cruise parameters. Used to specify a non-zero setting for a <weight> tag during solution. The default is to assume all weights are zero at the given performance numbers.
* '''idx:''' Index of the weight in the file (starting with zero).
* '''weight:''' Weight setting in pounds.

=== Controls ===
==== control-input ====
This element manages a mapping from fgfs properties (user input) to settable values on the aircraft's objects. Note that the value to be set MUST (!) be valid on the given object type. This is not checked for by the parser, and will cause a runtime crash if you try it. Wing's don't have throttle controls, etc... Note that multiple axes may be set on the same value. They are summed before setting.
* '''axis:''' The name of the double-valued fgfs property "axis" to use as input, such as "/controls/flight/aileron".
* '''control:''' Which control axis to set on the objects. It can have the following values:
** THROTTLE - The throttle on a jet or propeller.
** MIXTURE - The mixture on a propeller.
** REHEAT - The afterburner on a jet
** PROP - The propeller advance
** BRAKE - The brake on a gear.
** STEER - The steering angle on a gear.
** INCIDENCE - The incidence angle of a wing.
** FLAP0 - The flap0 deflection of a wing.
** FLAP1 - The flap1 deflection of a wing.
** SLAT - The slat extension of a wing.
** SPOILER - The spoiler extension for a wing.
** CYCLICAIL - The "aileron" cyclic input of a rotor
** CYCLICELE - The "elevator" cyclic input of a rotor
** COLLECTIVE - The collective input of a rotor
** ROTORENGINEON - If not equal zero the rotor is rotating
** WINCHRELSPEED - The relative winch speed
** {... and many more, see ControlMap.cpp ...}
* '''invert:''' Negate the value of the property before setting on the object.
* '''split:''' Applicable to wing control surfaces. Sets the normal value on the left wing, and a negated value on the right wing.
* '''square:''' Squares the value before setting. Useful for controls like steering that need a wide range, yet lots of sensitivity in the center. Obviously only applicable to values that have a range of [-1:1] or [0:1].
* '''src0/src1/dst0/dst1:''' If present, these define a linear mapping from the source to the output value. Input values in the range src0-src1 are mapped linearly to dst0-dst1, with clamping for input values that lie outside the range.

==== control-output ====
This can be used to pass the value of a YASim control axis (after all mapping and summing is applied) back to the property tree.
* '''control:''' Name of the control axis. See above.
* '''prop:''' Property node to receive the value.
* '''side:''' Optional, for split controls. Either "right" or "left"
* '''min/max:''' Clamping applied to output value.

==== control-speed ====
Some controls (most notably flaps and hydraulics) have maximum slew rates and cannot respond instantly to pilot input. This can be implemented with a control-speed tag, which defines a "transition time" required to slew through the full input range. Note that this tag is semi-deprecated, complicated control input filtering can be done much more robustly from a Nasal script.
* '''control:''' Name of the control axis. See above.
* '''transition-time:''' Time in seconds to slew through input range.

==== control-setting ====
This tag is used to define a particular setting for a control axis inside the <cruise> or <approach> tags, where obviously property input is not available. It can be used, for example, to inform the solver that the approach performance values assume full flaps, etc...
* '''axis:''' Name of the control input (i.e. a property name)
* '''value:''' Value of the control axis.

=== Winch and Aerotow ===
==== hitch ====
A hitch, can be used for winch-start (in gliders) or aerotow (in gliders and motor aircraft) or for external cargo with helicopter. You can do aerotow over the net via multiplayer (see j3 and bocian as an example).
* '''name:''' the name of the hitch. must be aerotow if you want to do aerotow via multiplayer. You will find many properties at /sim/hitches/name. Most of them are directly tied to the internal variables, you can modify them as you like. You can add a listener to the property "broken", e. g. for playing a sound.
* '''x,y,z:''' The position of the hitch
* '''force-is-calculated-by-other:''' if you want to simulate aerotowing over the internet, set this value to "1" in the motor aircraft. Don't specify or set this to zero in gliders. In a LAN the time lag might be small enough to set it on both aircraft to "0". It's intended, that this is done automatically in the future.
==== tow ====
The tow used for aerotow or winch. This must be a subelement of an enclosing <hitch> tag.
* '''length:''' upstretched length in metres
* '''weight-per-meter:''' in kg/metre
* '''elastic-constant:''' lower values give higher elasticity
* '''break-force:''' in N
* '''mp-auto-connect-period:''' the every x seconds a towed multiplayer aircraft is searched. If found, this tow is connected automatically, parameters are copied from the other aircraft. Should be set only in the motor aircraft, not in the glider
==== winch ====
The tow used for aerotow or winch. This must be a subelement of an enclosing <hitch> tag.
* '''max-tow-length:''' in m
* '''min-tow-length''': in m
* '''initial-tow-length:''' in m. The initial tow length also defines the length/search radius used for the mp-autoconnect feature
* '''max-winch-speed:''' in m/s
* '''power:''' in kW
* '''max-force:''' in N

== Visualization ==
[[File:Yasim_visualisation_dc6.png|thumb|dc6 fdm in Blender]]To make the programmed aircraft visible it is possible to load and compare it with the 3D model within [[Blender]]. The applaud for this ''very'' usefull script goes to M. Franz, thank you very much!

For Blender versions <= 2.4 the script is located in FlightGears source code {{flightgear file|utils/Modeller/yasim_import.py}}.

For Blender versions newer than 2.4, please see [[Blender YASim import]].

The howto, taken from inside the script:

yasim_import.py loads and visualizes a YASim FDM geometry
=========================================================

It is recommended to load the model superimposed over a greyed out and immutable copy of the aircraft model:

(0) put this script into ~/.blender/scripts/
(1) load or import aircraft model (menu -> "File" -> "Import" -> "AC3D (.ac) ...")
(2) create new *empty* scene (menu -> arrow button left of "SCE:scene1" combobox -> "ADD NEW" -> "empty")
(3) rename scene to yasim (not required)
(4) link to scene1 (F10 -> "Output" tab -> arrow button left of text entry "No Set Scene" -> "scene1")
(5) now load the YASim config file (menu -> "File" -> "Import" -> "YASim (.xml) ...")

This is good enough for simple checks. But if you are working on the YASim configuration, then you need a
quick and convenient way to reload the file. In that case continue after (4):

(5) switch the button area at the bottom of the blender screen to "Scripts Window" mode (green python snake icon)
(6) load the YASim config file (menu -> "Scripts" -> "Import" -> "YASim (.xml) ...")
(7) make the "Scripts Window" area as small as possible by dragging the area separator down
(8) optionally split the "3D View" area and switch the right part to the "Outliner"
(9) press the "Reload YASim" button in the script area to reload the file

If the 3D model is displaced with respect to the FDM model, then the <offsets> values from the
model animation XML file should be added as comment to the YASim config file, as a line all by
itself, with no spaces surrounding the equal signs. Spaces elsewhere are allowed. For example:

<offsets>
<x-m>3.45</x-m>
<z-m>-0.4</z-m>
<pitch-deg>5</pitch-deg>
</offsets>

becomes:



Possible variables are:

x ... <x-m>
y ... <y-m>
z ... <z-m>
h ... <heading-deg>
p ... <pitch-deg>
r ... <roll-deg>

Of course, absolute FDM coordinates can then no longer directly be read from Blender's 3D view.
The cursor coordinates display in the script area, however, shows the coordinates in YASim space.
Note that object names don't contain XML indices but element numbers. YASim_hstab#2 is the third
hstab in the whole file, not necessarily in its parent XML group. A floating point part in the
object name (e.g. YASim_hstab#2.004) only means that the geometry has been reloaded that often.
It's an unavoidable consequence of how Blender deals with meshes.

Elements are displayed as follows:

cockpit -> monkey head
fuselage -> blue "tube" (with only 12 sides for less clutter); center at "a"
vstab -> red with yellow flaps
wing/mstab/hstab -> green with yellow flaps/spoilers/slats (always 20 cm deep);
symmetric surfaces are only displayed on the left side
thrusters (jet/propeller/thruster) -> dashed line from center to actionpt;
arrow from actionpt along thrust vector (always 1 m long);
propeller circle
rotor -> radius and rel_len_blade_start circle, direction arrow,
normal and forward vector, one blade at phi0
gear -> contact point and compression vector (no arrow head)
tank -> cube (10 cm side length)
weight -> inverted cone
ballast -> cylinder
hitch -> circle (10 cm diameter)
hook -> dashed line for up angle, T-line for down angle
launchbar -> dashed line for up angles, T-line for down angles
A note about step (0) for Windows users: the mentioned path is inside the folder where Blender lives, something like <code>C:\Program Files\Blender Foundation\Blender\.blender\scripts</code>.

== Export of YASim internals to property tree ==
Ever wondered what is going on inside yasim? See the property tree under /fdm/yasim/

Some information is static and shows what yasim has compiled from your XML.
Other information is "run-time" like forces, speed, acceleration, c.g.

If note noted otherwise:
* expect metric unit (meter, kilogram, newton, ...)
* expect minimum version 2017.2

{| class="wikitable"
|-
! Path !! Description !! Information type !! min. version
|-
| accelerations/ || linear and rot. accelerations in aircraft coord. || run time ||
|-
| debug/ || misc internals, for now subject to change without notice || run time || 2018.1
|-
| forces/ || aerodynamic forces in N || run time ||
|-
| velocities/ || linear and rot. velocities in aircraft coord. || run time ||
|-
| model/cg-x-range-aft || desired CG range || compile time ||
|-
| model/cg-x-range-front || desired CG range || compile time ||
|-
| model/cg-x-max || CG hard limit from gear position || compile time ||
|-
| model/cg-x-min || CG hard limit from gear position || compile time ||
|-
| model/masses || shows the calculated mass points || compile time ||
|-
| model/wings || wing parameters || compile time ||
|}

== Command Line ==
=== Windows ===
By using the standard command line, we can see what the YASim solver is calculating. First, open up Command Prompt, enter in the location of yasim.exe, and then the location of the YASim XML file. For example, here's what you would type in for a standard Windows [[Changelog_2.12|FlightGear 2.12.0]] installation, and viewing the [[F-14_Tomcat|F-14B's]] YASim file.
{{Note|You can copy & paste the examples into Command Prompt by right-clicking on the title and navigate to Edit > Paste. Then, click Enter to execute.}}

<code>"C:\Program Files\FlightGear\bin\Win32\yasim.exe" "C:\Program Files\FlightGear\data\Aircraft\f-14b\f-14b-yasim.xml"</code>

The results will give many different values.

* '''Drag Coefficient:''' The drag coefficient of the aircraft.
* '''Lift Ratio:''' The lift ratio of the aircraft.
* '''Cruise AoA:''' The cruise AoA, from conditions at [[YASim#cruise|<cruise>]] in the xml file.
* '''Tail Incidence:''' The incidence angle of the tail, "solved" by YASim as a way to stabilize the aircraft.
* '''Approach Elevator:''' The approach elevator, from conditions at [[YASim#approach|<approach>]] in the xml file.
* '''CG:''' Center of gravity of the aircraft in coordinates. Unless it's supposed to be offset, it should always have a Y value of 0.

The YASim standalone solver also has some command line flags that change it's behaviour.

<code>"C:\Program Files\FlightGear\bin\Win32\yasim.exe" "C:\Program Files\FlightGear\data\Aircraft\f-14b\f-14b-yasim.xml" -g -a 1000 -s 490</code>

* '''-g:''' Instructs YASim to generate space-separated tabular data instead of the usual solver output. This can be redirected to a file and used in various plotting programs to visualize the actual lift, drag, L/D curves. The columns of the output from left to right are: AoA, Lift, Drag, L/D. (aoa in degrees, lift and drag in G's).
* '''-a <altitude in meter:>''' Run the solver at the given altitude in meter.
* '''-s <speed in knots>:''' Also run at the given airspeed in knots.

{{Note|The values generated by this method are for the aircraft taken as a whole, as solved by YASim, so they differ from the values of the wing airfoil.}}

To get the tabular output for the example above at 1000 m and 150 knots, and to redirect this to a file, one would issue:

<code>"C:\Program Files\FlightGear\bin\Win32\yasim.exe" "C:\Program Files\FlightGear\data\Aircraft\f-14b\f-14b-yasim.xml" -g -a 1000 -s 150 > "C:\Program Files\FlightGear\yasim.txt"</code>

== YASim design notes ==
Andy Ross's original design notes for YASim can be found in [ftp://ftp.uni-duisburg.de/FlightGear/Docs/YASim-simnotes.pdf this PDF file]. These provide some useful background for how YASim works.

== New features and bugfixes in version 2017.2 ==

=== XML parser ===
==== support for metric and imperial units ====
To make life easier for aircraft developers, the parser supports new additional attributes with a unit suffix, e.g. speed-kt for knots and speed-kmh for kilometers per hour.
* <code><airplane {mass, mass-lbs, mass-kg}="12345" ></code>
* <code><approach {speed, speed-kt, speed-kmh}="123" ></code>
* <code><cruise {speed, speed-kt, speed-kmh}="123" ></code>
* <code><solve-weight {weight, weight-lbs, weight-kg}="123" ></code>
* <code><jet {mass, mass-lbs, mass-kg}="1234" ></code>
* <code><tank {capacity, capacity-lbs, capacity-kg}="12345" ></code>
* <code><ballast {mass, mass-lbs, mass-kg}="1234" ></code>

{{Note|Aircraft using this new attributes will not run on older versions of FlightGear, so it is probably wise to publish those only after a reasonable number of users switched version 2017.2 or newer.}}

==== CG tuning help ====
{{Note| The feature described in this section is not fully implemented yet, however, it may be of some help already.
It is currently implemented for the yasim CLI tool only. It does not affect the airplane behaviour while running FlightGear. }}

New attributes have been added to <airplane> to assist tuning the center of gravity (CG).
The CG position is often expressed relative to the [https://en.wikipedia.org/wiki/Chord_(aeronautics)#Mean_aerodynamic_chord MAC] of the wing in percent. You can specify a desired range for CG in % relative to MAC, it will show up in the output of the yasim CLI tool (see example below):

* cg-min: default 25% (just a guess, better numbers are welcome)
* cg-max: default 30% (just a guess, better numbers are welcome)

{{Note| By convention 0% is leading edge, 100% is trailing edge, however the absolute values on x-axis are the other way round, e.g. nose is +x, tail is -x }}
{{warning|The MAC calculation in version 2017.2 works only on the <wing> element. Numbers will be wrong, if your model uses a combination of <wing> and <mstab> to build a wing with two or more sections.
Section support will be added in version 2018.1}}
YASim will print the leading edge coordinates of the MAC (x,y) and its length.

'''Example output'''
<pre>
$ yasim Citation-II-yasim.xml
This aircraft uses yasim version '2017.2'
==========================
= YASim solution results =
==========================
Iterations: 2210
Drag Coefficient: 12.304669
Lift Ratio: 85.317558
Cruise AoA: 4.016746 deg
Tail Incidence: -3.053278 deg
Approach Elevator: -0.377542

CG: x:-6.543, y:-0.000, z:0.044
Wing MAC (*1): x:-6.00, y:3.83, length:2.0
CG-x rel. MAC: 0.272
CG-x desired: -6.599 < -6.543 < -6.198

Inertia tensor [kg*m^2], origo at CG:

18009.289, -0.000, 7120.470
-0.000, 42459.316, 0.000
7120.470, 0.000, 56980.656

(*1) MAC calculation works on <wing> only! Numbers will be wrong for segmented wings, e.g. <wing>+<mstab>.
</pre>

=== Aircraft developer helpers ===
The command line utility got some new options. For some strange reason, the -a parameter expects altitude in meters instead of ft. This is now visible in the usage message but left unchanged for compatibility.
<syntaxhighlight>Usage:
yasim <aircraft.xml> [-g [-a meters] [-s kts] [-approach | -cruise] ]
yasim <aircraft.xml> [-d [-a meters] [-approach | -cruise] ]
yasim <aircraft.xml> [-m]
-g print lift/drag table: aoa, lift, drag, lift/drag
-d print drag over TAS: kts, drag
-a set altitude in meters!
-s set speed in knots
-m print mass distribution table: id, x, y, z, mass</syntaxhighlight>

=== Bugfixes ===
The following bugfixes require <airplane version="2017.2"> for backward compatibility
* Ground effect: corrected the calculation of the height where g.e. ends
* Stall parameters were set wrong for wings with camber=0

== New features and bugfixes in version 2018.1 ==
The following is under development and hopefully finds its way into FG version 2018.1

=== Wing Section Support ===
Many airliners have wings with a geometry that is just a little more complex than what YASim supported initially (tapered wing with some angles like sweep, dihedral, ...), e.g. they have an inboard section and an outboard section that can be described with YASim wing syntax. You can use a wing + a mstab XML element to describe this geometry but it is easier if YASim can just append more wing sections by simply adding more wing XML elements. This is now (Version 2018.1) possible, yasim will simply append sections if it finds more than one wing or hstab in the XML.
You should use '''<wing append="1" ... >''' for all but the first wing/hstab declaration.
{{Note|YASim will ignore the root point (x,y,z), the chord length and the incidence attributes, if you add "append" and calculate those from the previous wing section. }}
MAC calculation works for the whole wing.

{{warning|Aircrafts using this feature will not work with older versions of flightgear. }}
To keep the aircraft backward compatible for a while, it is recommended to create a copy of its yasim XML file for development.
Once you are happy with the CG and wing parameters you can use the output of the YASim CLI tool to modifiy the original XML.
The tool will output the needed x,y,z etc per wing section to create a XML in old format with (only one) <wing> + <mstab>.

=== More information from CLI tools ===
You should configure the maximum take of weight (MTOW) in your XML file by adding either ''mtow-lbs'' or ''mtow-kg'' attribute to the airplane:

<code> <airplane mass="7500" version="2018.1" mtow-lbs="12500"> </code>

'''Example output'''
<pre>
yasim CRJ700.xml
==========================
= YASim solution results =
==========================
Iterations : 1024
Drag Coefficient : 17.707
Lift Ratio : 145.841
Cruise AoA : -0.11 deg
Tail Incidence : 3.47 deg
Approach Elevator : -0.792

CG : x:-0.046, y:0.000, z:-1.222
Wing MAC : (x:0.79, y:4.99), length:3.4
hard limit CG-x : 14.232 m
soft limit CG-x : -0.058 m
CG-x : -0.046 m
CG-x rel. MAC : 25%
soft limit CG-x : -0.228 m
hard limit CG-x : -0.986 m

wing lever : -0.012 m
tail lever : -13.997 m

max thrust : 157.18 kN
thrust/empty : 0.81
thrust/mtow : 0.49

wing span : 22.64 m
sweep lead. edge : 30.2 .. 30.6 deg
wing area : 58.70 m^2
wing load empty : 336.15 kg/m^2 (Empty 19731 kg)
wing load MTOW : 562.18 kg/m^2 (MTOW 32999 kg)

tail span : 8.533 m
tail area : 14.838 m^2

#wing sections: 2
Section 0 base point (0.450, 1.226, -2.034), chord 5.085, incidence at section root 5.0deg
Section 1 base point (-0.663, 4.754, -1.942), chord 3.204, incidence at section root 3.0deg

Inertia tensor [kg*m^2], origo at CG:

195646, 0, 122265
0, 1757279, 0
122265, 0, 1904528
</pre>

=== Variable tail incidence / elevator trim ===
Small GA aircrafts usually trim with a trim tab on the elevator. For efficiency, airliners normally do not trim the elevator ("flap")
but rotate the whole stabilizer (=tail) wing, e.g. they change the incidence for this wing. While this feature was somehow foreseen,
it was not implemented yet, most likely because the "tail incidence" is one of the free variables used by the YASim solver.
However, it is possible now to use the control="INCIDENCE" within the <hstab> to implement an alternative trim '''while maintaining full elevator authority'''.
<pre>
<hstab ... incidence-min-deg="-13.0" incidence-max-deg="2.0">
...
<control-input axis="/controls/flight/hstab-trim" control="INCIDENCE" />
<control-speed control="INCIDENCE" transition-time="20.0" />
<control-output control="INCIDENCE" prop="/surface-positions/hstab-rad" />
</hstab>
</pre>
{{Note|The control output of INCIDENCE is the angle in radians, not in degree, as that is the unit internally used by YASim.}}
{{warning|The OPTIONAL incidence-min-deg and incidence-max-deg set the limits for the solver. You must make sure to select a sufficiently large range or solver will fail. }}
First experiments with this feature were successful in that the aircraft pitch could be changed as expected but fine tuning will be necessary.

== Related content ==
* [[Howto:Make a helicopter#XML Elements]] – Rotor and rotorgear YASim elements
* [[YASim Development Tools]]

== External links ==
* [http://www.buckarooshangar.com/flightgear/yasimtut.html Gary "Buckaroo" Neely's guide to YASim] – Very helpful guide

{{FDM}}

[[Category:Flight Dynamics Model]]

[[fr:YASim]]

Bombardier CRJ700 series

2016-02-19T17:41:24Z

DanielHL: Update maintainer and download locations

{{infobox Aircraft
|name = Bombardier CRJ700 series
|image = CRJ700.jpg
|alt = The Bombardier CRJ700
|type = Regional airliner
|livery = Various
|authors = Ryan Miller (see also Docs/Authors.html)
|status-fdm = 3
|status-systems = 3
|status-cockpit = 4
|status-model = 4
|version = 1.0.4
|fdm = YASim
|fgname = various
|download = http://wiki.flightgear.org/index.php?title=Bombardier_CRJ700_series#Downloading
|development = https://github.com/d-jsb/CRJ700-family/
}}
[[File:CRJ700-cockpit.jpg|The 3d cockpit of the CRJ700 series|thumb|350px|right]]
[[File:CRJ700-cockpit-night.jpg|The cockpit at night, demonstrating night lighting capabilities|thumb|350px|right]]
[[File:CRJ700-cabin-night.jpg|The interior cabin, also at night|thumb|350px|right]]

The '''Bombardier CRJ700 series''' is a family of 70- to 100- seat regional jet airliners manufactured by Bombardier Aerospace. Its primary competition is the Embraer E-jet series. The family consists of the Bombardier CRJ700, CRJ900, and CRJ1000. The CRJ700 series was developed from the [[Bombardier CRJ-200LR|Bombardier CRJ200]], and remains one of the most popular regional airliner series in the world.

=Variants=

* CRJ700 - the original CRJ700
* CRJ700ER - extended range version
* CRJ700LR - long-range version
* CRJ900 - the first stretch of the airframe
* CRJ900ER - extended range version
* CRJ900LR - long-range version
* CRJ1000 - the final stretch of the airframe
* CRJ1000 EuroLite - low-range/low-cost version targeted at European operators
* CRJ1000ER - extended range version

=Aircraft help=

HTML documentation is included in the Docs/ folder.

==Key commands==

{| class="prettytable"
! Key
! Function
|-
! colspan="2" | Speedbrakes/spoilers
|-
| {{key press|Ctrl|B}}
| Cycle speedbrake setting
|-
| {{key press|j}}
| Decrease ground lift dump setting
|-
| {{key press|k}}
| Increase ground lift dump setting
|-
! colspan="2"|Engines
|-
| {{key press|Ctrl|Del}}
| Arm/disarm thrust reversers
|-
| {{key press|Del}}
| Toggle thrust reversers
|-
! colspan="2" | Autopilot
|-
| {{key press|Ctrl|A}}
| Toggle autopilot altitude mode
|-
| {{key press|Ctrl|F}}
|Engage/disengage autopilot
|-
| {{key press|Ctrl|G}}
| Toggle autopilot approach mode
|-
| {{key press|Ctrl|H}}
| Toggle autopilot heading mode
|-
| {{key press|Ctrl|N}}
| Toggle autopilot NAV mode
|-
| {{key press|Ctrl|P}}
| Set autopilot basic pitch mode
|-
| {{key press|Ctrl|W}}
| Set autopilot basic heading/roll mode
|-
| {{key press|F6}}
| Cycle NAV source
|-
! colspan="2" | Tiller/Nose gear steering
|-
| {{key press|q}}
| Steer tiller left
|-
| {{key press|Shift|Q}}
| Set tiller to full left
|-
| {{key press|w}}
| Center tiller
|-
| {{key press|Shift|W}}
| Pop up tiller dialog
|-
| {{key press|e}}
| Steer tiller right
|-
| {{key press|Shift|E}}
| Set tiller to full right
|-
! colspan="2" | Walk view
|-
| {{key press|r}}
| Walk forward toward view
|-
| {{key press|Shift|R}}
| Run forward toward view
|-
| {{key press|f}}
| Walk backwards from view
|}

==Simplified procedures==
===Startup===
#Battery switch ... on
#APU start/stop switch ... on
#Bleed air source ... APU
#Engine 1 thrust lever ... idle
#Engine 1 start sequence ... initiated
#Engine 2 thrust lever ... idle
#Engine 2 start sequence ... initiated
#APU start/stop switch ... off
#Engine 1 electric generator ... on
#Engine 2 electric generator ... on
#Battery switch ... off

===Takeoff===
#Flaps/slats ... 8 or 20
#Landing lights ... on
#Engine thrust modes ... TO/GA

===Climb and cruise===
#Engine thrust modes ... climb
#Autothrottle ... set
Nominal cruise speed Mach 0.78 (0.80 for CRJ900)

===Approach and landing===
#Thrust reversers ... armed
#Flaps/slats ... 45
Remain below 250 knots below 10,000 feet at all times

===Shutdown===
#Engine thrust levers ... shutoff
#Engine 1 electric generator ... off
#Engine 2 electric generator ... off
#Switch to external power

=Downloading=

The latest version is always available on the official FlightGear aircraft download page and will be committed regularly to [[FGAddon]].

The latest development version at GitHub can also be downloaded [https://github.com/d-jsb/CRJ700-family/archive/master.zip here].

=Aircraft of the Week/Month=

The CRJ700 was reviewed by Thorsten R as part of the "Aircraft of the Week/Month" feature on the FlightGear Forums.

====Model====

The 3d cockpit of the CRJ-700 is very detailed and contains not only functionality on the main panel but also on the central console and an overhead panel. However, as often seen, the cockpit surfaces not covered by instrumentation are very simply textured by a monochromatic grey color - a more natural texture resembling a real material with some wear and tear could add a lot here.

[http://www.phy.duke.edu/~trenk/pics/crj700-cockpit.jpg View image]

There is a lot of functionality in the cockpit - a startup procedure using the APU is supported as well as a full set of external lights and no-smoking and seat belt signs for the passengers. A nice touch of the model is that it also contains an interior view of the cabin in which the signs can be observed. Switches and knobs are usually animated, and the clickspots are placed fairly intuitively. The MFD's all have various selectable functions.

The exterior model of the aircraft is also very nicely done, contains good animations and shows all the light switch settings in the cockpit faithfully. An option to switch livery exists as well.

[http://www.phy.duke.edu/~trenk/pics/crj700-model.jpg View image]

====Flight characteristics====

The FDM of the CRJ-700 is quite plausible for an airliner of its size. I haven't really tested the behaviour at the edge of the performance envelope, but during normal operations, the plane behaves well and reaches basic performance characteristics. All in all, the plane is an airliner (albeit a small one) - it turns slowly, it does not descent rapidly without picking up a lot of excess speed and all maneuvers need to be planned well in advance. Having said that, it's actually fun to fly.

I found the AP nicely tuned and able to fly turns, climb or dive at all altitudes without oscillations or weird behaviour. Unfortunately, the support for AP modes involving navaids is not as good: While I could home in on a VOR station, the AP seems to be tracking the station rather than the chosen radial, i.e. the angle under which I approached the station kept changing. Also, I was unable to intercept an ILS glideslope automatically. However, the plane can be operated well in IFR conditions just using the instruments to display the navaid signals and the heading and altitude modes of the AP to control the plane.

====My personal wishlist====

Fixing the AP to a more consistent behaviour with navaids would be high on my priority list - there are currently very few airliners with a well-tuned AP capable of tracking navaids. Some more natural texturing in the cockpit would also be nice. I realize that the CRJ-700 is a fairly recent addition to the aircraft repository of Flightgear - but I like where the model is going very much.

====Things to experience====

Try flying at night - the CRJ-700 has one of the best light concepts I've ever seen. The instrument lights are very beautifully done and can be dimmed at need, the cabin lights likewise, and all lighting is visible both from internal and external views.

''Editor's note: The autopilot VOR-LOC/ILS holds have been fixed as of CRJ700 v1.0.2.''

=Development status/Issues/Todo=
==Key features==
* Startup and shutdown procedures
* Mostly complete cockpit
* Realistic autopilot
* Functional flight management system (FMS), advisory-only vertical navigation system (VNAV), and control display unit (CDU)
* Emergency procedures with ram air turbine (RAT) and auxiliary power unit (APU)
* Small library of tutorials
* Cockpit, cabin, and exterior model lightmaps
* Reflection shader on the engines
* Developed aircraft systems
* Tiller steering system

==Todo==
For rating information, see [[Formalizing Aircraft Status]].
===FDM (current rating 3)===
* Make something a little more refined than my [[YASim]] solution (any [[JSBSim]] masters?)
===Exterior (current rating 4)===
* Add minor elements like antennas, ram air turbine, improve gear bay texturing and geometry
* More liveries!
===Flight deck (current rating 4)===
* Model circuit breakers
* Add more buttons/switches
* Improve texturing

===Systems (current rating 3)===
* Find a real startup procedure and model it
* Improve electrical system
* Add more pages to EICAS

== Development (section added May 2015) ==
D-JSB et al. work on the CRJ700 family.

=== Status without any particular order ===
==== (almost) done ====
* Some bugfixes (e.g. MFD wind indicator, nav pointers, MFD symbols)
* Removed 2D panel which depended on Boing 737-300
* More views (cabin windows, gear)
* OHP switches / switchlights (gimmick: implemented the light test button)
* Details of auto pilot panel behaviour like push function of CRS and HDG
* Modified slats/flaps indicator on EICAS
* APU details on EICAS
* EICAS pages for doors
* Simulation of hydraulic system
* EICAS pages for hydraulic system
* Extend failures dialog (hydraulics)
* Re-implement the electrical system (AC and DC).
* Add cargo doors to model
* Add APU door to model

==== In progress / testing ====
* Update of documentation

==== Planed ====
* Find out what's new with the CRJx00 neo
* Maybe record original sounds if I get a chance

=External links=
* [http://en.wikipedia.org/wiki/Bombardier_CRJ700_series Bombardier CRJ700 series at Wikipedia]
* [http://forum.flightgear.org/viewtopic.php?t=11863 Development thread at the FlightGear Forums]
* [http://www.smartcockpit.com/data/...700.../HGS_00_Pilots_Guide_CRJ_00.pdf GHS Pilots Guide CRJ]
* [http://aligero.us/files/FMS%204200.pdf FMS 4200 Intro]
* [http://www.4shared.com/get/Q_rDeIsz/Collins_FMS-4200_Flight_Manage.html FMS-4200 Manual]

{{Template:Bombardier}}

[[Category:Airliners]]
[[Category:Bombardier Aerospace]]

Changelog 2016.1

2016-02-19T17:30:28Z

DanielHL: Add CRJ700 series to improved aircraft

{{draft|changelog|Please feel free adding screenshots and/or videos that are suitable to highlight some of the developments mentioned in this changelog, thank you!}}

The FlightGear development team is delighted to announce the v2016.1 "San Francisco" release of FlightGear, the free, open-source flight simulator. This new version contains many exciting new features, enhancements and bugfixes. Highlights in this release include an integrated launcher that includes the ability to download aircraft, a reduction in the installation package size, performance improvements and many rendering improvements.

Founded in 1997, FlightGear is developed by a worldwide group of volunteers, brought together by a shared ambition to create the most realistic flight simulator possible that is free to use, modify and distribute. FlightGear is used all over the world by desktop flight simulator enthusiasts, for research in universities and for interactive exhibits in museums.

FlightGear features more than 400 aircraft, a worldwide scenery database, a multiplayer environment, detailed sky and weather modelling, a flexible and open aircraft modelling system, varied networking options, multiple display support, a powerful scripting language and an open architecture. Best of all, being open-source, the simulator is owned by the community and everyone is encouraged to contribute.

Download FlightGear v2016.1 for free from [http://www.flightgear.org/ FlightGear.org].

FlightGear – Fly Free!

[[File:Qt launcher for FlightGear 3.5 on Windows 7.jpg|thumb|The aircraft page of the Qt launcher for FlightGear 3.5 as rendered on Windows 7.]]

=== Major enhancements in this release ===
'''Project Organization'''
* The base package has been reduced in size to 1.3 GB and moved to http://sourceforge.net/p/flightgear/fgdata/. All aircraft except the [[Cessna 172P]] and [[UFO]] have been removed.
* All core repositories have been moved to SourceForge. They can be found at https://sourceforge.net/projects/flightgear/.
* Release are now planned to be quarterly (instead of biannually). The new release number (2016.1) reflects this change: the release numbering format is changed to <code><nowiki>[Year].[Release within year].[Fix Release]</nowiki></code>. We also plan to change the default airport and the scenery that is included with the install image with each release. 2016.1 uses the [[KSFO]] default as we have done for many years, and so has the codename "San Francisco."

'''Core'''
* Interactive traffic system re-enabled, having been disabled by mistake some releases previously.
* Various security improvements, including the disabling of <tt>system.fgfsrc</tt>.
* Reduction in the memory footprint due to scenery.
* Improved performance when displaying large numbers of scenery objects.

'''Aircraft Modeling'''
* [[Tooltips]] can now be positioned at a specific place on-screen.
* [[Wingflexer|Wing flex]] module added, controllable via [[Nasal]] or [[Property rules]].
* Bug-fixes and improvements to the [[Failure Manager]].
* <code><variant-of></code> tag in the [[aircraft-set.xml]] file has been added (see [[FlightGear Newsletter March 2015]]).
* Automatic checklist execution, which can, for example, be used for autostart.
* 8.33 kHz spacing is now supported on comms radios.

'''JSBSim'''
* Sync with the latest version of [[JSBSim]].
* The pitot angle can now be tweaked with the <code><pitot_angle></code> tag in the <code><metrics></code> block.
* The refuel rate is now configurable with the <code><refuel-rate></code> tag in the <code><propulsion></code> block.

'''Rendering'''
* Improved vegetation including 3D grass and shadows for trees
* Better cockpit rendering:
** Interior shadows
** Glass reflections, dynamical raindrops, fogging and frosting
** Panel backlighting
** Irradiance mapping for more realistic distribution of indirect light
** Diffuse illumination of the interior by instrument lighting
* New thruster effect (can be used for afterburners flames, rockets, etc.).
* Lightning strikes illuminating the surrounding clouds during thunderstorms
* Rainbows
* Improved airport rendering, including runway skid marks and better effects for the runways and surrounding grass.
* Optical phenomena in icy hazes:halos, sundogs, parhelic ring and light pillar.
* Aurora Borealis at night
* More realistic rendering of generic lights (runway, PAPI, taxiway, etc.)
* Detailed procedurally generated lights for aircraft
* A dynamical wingflex shader suitable for wing beats (see the [[Dragon]])

'''Usability'''
* Many improvements to [[Phi]], the built-in web interface.
* GUI cleanup to improve support for multiple GUI styles.
* The [[Integrated Qt5 Launcher|built-in Qt launcher]] is available for all of FlightGear's supported operating systems.
* Additional latitude and longitude formats are now supported in the HUD.

'''Scenery'''
* Regional texture definitions for Florida, Brazil, Latin America, Africa, the Middle East and Southeastern Asia.
* <tt>stgmerge</tt> tool added to merge objects in a scenery tile into a smaller number of meshes.

'''Highlighted new and improved aircraft'''
* Complete refresh of the default [[Cessna 172P]], including engine options, various tire sizes and floats.
* A [[dragon]] has been added, complete with fire breath.
* Major enhancements to the [[Space Shuttle]]. The Shuttle can be flown as per the Crew Operations Manual from launch to touchdown.
* The following aircraft have also received significant updates:
** [[McDonnell Douglas F-15 Eagle]]
** [[Rockwell B-1B Lancer]]
** [[Saab JA-37 Viggen]]
** [[Cessna 550 Citation II]]
** [[Lockheed Constellation]]
** [[Boeing 737-300]]
** [[Mirage 2000-5]]
** [[De Havilland Canada DHC-6 Twin Otter]]
** [[Beagle Pup]]
** [[Mikoyan-Gurevich_MiG-15|MiG-15]]
** [[Bombardier CRJ700 series]]

'''Misc/uncategorized'''
* Improved support for KDI572-574 [[DME]] equipment.
* Update to the [http://www.ngdc.noaa.gov/geomag/WMM/DoDWMM.shtml World Magnetic Model] 2015.

'''Nasal Scripting'''
* Global functions <code>createViaTo()</code> and <code>createDiscontinuity()</code> {{flightgear commit|caead6|t=added}}
* <code>activate()</code> method {{flightgear commit|caead6|t=added}} to the <code>flightplan</code> ghost object

'''Documentation'''
* The [[FlightGear Manual]] is now available in Chinese.

'''Bug fixes'''
* See [http://sourceforge.net/p/flightgear/codetickets/search/?q=status%3AFixed+AND+created_date%3A%5B2015-09-23T23%3A11%3A56Z+TO+*%5D our bugtracker] for a list, albeit incomplete, of the bugs fixed in this release.

[[Category:FlightGear changelogs]]
[[Category:New Versioning Scheme]]