Jürgen N. Thank you for your comments. This thread is off to a good start.
What I am trying to do is modify existing aircraft simulations in the RC9 library so that they perform in RC9 like their real versions perform at the flying field. For example, my 10 year old Pilot SBach 342 that is my avatar has a 107 inch wingspan and a DA 100L engine with MTW canisters. I want to create a simulation of this airplane in RC9 that behaves like the real thing by modifying the existing SBach 342 in the RC9 library. To do this, I believe I need to do the following:
1. Change the size i.e. wingspan from 3 meters to 2.7 meters.
2. Change the mass to 12.5 kg.
3. Change the engine power vs RPM curve so that it has a maximum output power of 9.8 hp or 7.3 kW at 7500 RPM.
4. Change the propellor parameters to 27 inch diameter or 13.5 inch radius and the pitch to 10 inches.
5. Increase the CG distance by around 4 cm so that the airplane maintains a horizontal trajectory with zero elevator deflection.
With these changes I have gotten to a simulated airplane that behaves more like the real airplane than did the unmodified version. The Pilot SBach has a thick wing airfoil that causes the real airplane to fly more slowly at full power than the simulated airplane. I have not yet figured out how to adjust the wing airfoil parameters in the Edit Aircraft window.