Difference between revisions of "FlightGear Newsletter October 2019"

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(Support for transonic flow effects in YASim: Prandtl/Glauert plot and warning about supersonic use)
(In the hangar: ASK13 update)
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====Schleicher ASK13====
The Schleicher ASK13 glider has received a big update including a better FDM, more realistic interior as well as a basic electrical system. You can find more about this aircraft at [[ASK13|its wiki article.]]
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Revision as of 11:59, 19 October 2019

Enjoy reading the latest edition!
Please help us write the coming edition!
October 2019

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 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!

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 the code and report any issues to the developer mailing list.

In the hangar

Updated aircraft

Schleicher ASK13

The Schleicher ASK13 glider has received a big update including a better FDM, more realistic interior as well as a basic electrical system. You can find more about this aircraft at its wiki article.


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 AI subforum This is a link to the FlightGear forum..

Scenery corner

Community news

FlightGear on Facebook

Since early December 2010, FlightGear has an official Facebook page. If you have a Facebook account please feel free to join the page.

FlightGear on Instagram

In January 2018 the @flightgear_sim Instagram account was brought back to life. If you've got nice screenshots to be featured, feel free to contact the maintainer This is a link to the FlightGear forum..

FlightGear on FlightSim.com

Flightgear has also a 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


Translators needed

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.
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 Help:Traduire.
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 Help:Übersetzen an.
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 Help:Vertalen.
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 Help:Traducir.
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 Help:Traduir.
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 Help:Traduzir.
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.


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 this subforum This is a link to the FlightGear forum.. 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 FlightGear Newsletter October 2019!