Hi fellow wiki editors!

To help newly registered users get more familiar with the wiki (and maybe older users too) there is now a {{Welcome to the wiki}} template. Have a look at it and feel free to add it to new users discussion pages (and perhaps your own).

I have tried to keep the template short, but meaningful. /Johan G

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.

## 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 AI subforum .

## Community news

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 .

### 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.

## Contributing

### 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 this subforum . 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.