Wikipedia
Flying-Model-Simulator, also known as Flying Model Simulator or FMS is a freeware program written in 2000 by German programmers Roman and Michael Möller.
It has since gone on to become one of the most popular downloads related to radio controlled flight. Alpha versions of upgrades are sometimes made available for the benefit of those proficient in computer programming to help sort out bugs, although last update on official site was released in the middle of 2005.
Though not intended as a replacement for actual hands-on training or as a substitute for a more advanced, off-the-shelf simulator, Flying-Model-Simulator is nevertheless an excellent tool for learning the hand–eye coordination necessary to learn how to fly radio controlled aircraft.
A number of sites are devoted to additional models and landscapes for FMS and there are tools and tutorials available so anyone can make their own.
It is possible to use FMS with nothing more than a keyboard, but anything more responsive than a trainer or slow flyer really needs analog control, such as a twin-stick gamepad controller or PC joystick. Many sources, including radio manufacturer Hitec, make cables to interface most brands of R/C transmitters with the program via the buddy box socket and a computer's USB, microphone or serial port. This adds realism as well as useful transmitter features like trims, dual rates and exponential. A limited amount of exponential can be selected in FMS's setup menu, however. Hitec's website markets their interface cable as a direct connection to FMS and includes a download link on their website.
The program's home page includes links to downloads in German, Swedish, Italian, Russian, Danish and French. Several other languages are supported within the program itself as well. The links page gives details of downloadable models, landscapes and sources of transmitter interface leads.