R/C plane simulation

SwedishWings

I hope i posted on the right forum...

I've been considering writing a simple(?) R/C flight simulator for quite some time. After reading about aerodynamics i concluded that a simulation software are bound to make great simplifications, and may only model a subset of the actual physics involved. However, there seem to be very little written on the subject, when it comes to good simplified simulation software for planes.

Any pointers would be most welcome. Perhaps there are some GPL projects that has related simulation models?

Thanks in advance,
Mike

Cyrus

I do flight simulation. I've made one for a Cessna 172 and a VTOL aircraft. What is your background in flight dynamics? I would start by reading some aircraft stability and controls books to understand what you need to do.

SwedishWings

Thanks for your reply Cyrus!

I'm a total rookie on flight dynamics. I have better understanding of general physics, as I've spent a few years working with AI based games and 3D rendering engines. Honestly, after spending about 30 hours on the net reading about aerodynamics, i felt discouraged by the complexity - it appears mankind still don't know exactly why we can fly =)

Indeed, reading a few books on the subject would be a good thing. However, i was hoping to find some shortcuts in terms of simplified, easy to understand, simulation models that would be a good starting point. Perhaps in the long run, simulation could be refined with experience and knowledge.

I found the sss project (GPL) that has some pointers. Unfortunately, very little documentation exists on the actual flight simulation and the theory behind it.

Any help is most welcome!

Thanks,
Mike

Cyrus

Start doing some background by looking through the lecture slides on this website

http://www.princeton.edu/~stengel/MAE331.html

As a first cut, you may want to consider a very simple linearized simulation.

SwedishWings

Thanks a lot!

I have started reading and find it quite easy to follow, though some explanations would help.

I stumbled on some very simple equations on this NASA page:

Thrust = m(dot) V
Lift = k V^2 A cl
Drag = k V^2 A cd

where k is Smeaton's coefficient (.00327), cl is the lift coefficient and cd is the drag coefficient.

Are this equations (and some basic newton stuff) to far simplified for being useful in a first attempt?

/Mike

Cyrus

What you need are databases of forces (lift, drag, sideforce) and moment (roll,pitch,yaw) aerodynamic data sets (for a given aircraft) if you want a simulation. Note, not values calculated from an equation, actual wind tunnel or flight test data. These need to be a function of angle of attack, airspeed, and body rotation rotes (p,q,r). The simulation will look through the table of values at each time step. This is your aerodynamics model. You will also need a model for the engine, the mass/inertia properties, and the atmosphere.