The physics of aeroplanes/airplane movement is the same as general rigid bodies. Once you know how to simulate rigid bodies in space, you can simulate airplane motion----AS LONG AS you are properly computing the aerodynamics forces (lift, drag, side force) and moments/torques (pitching momemt, rolling moment, yawing moment). That said, here's some info of interest.

I have a Master's Degree in Aerospace Engineering with a specialty in computational and experimental airplane flight dynamics. I wrote a chapter for Game Programming Gems 5, called "Back of the Envelope Aerodynamics for Game Physics Systems," which provides some information. It is just an introduction and is really more general purpose than airplane flight simulation, but I think its a good introduction with some possibly helpful insights. It certainly does cover how to quickly compute approximate values for lift/drag on airplane wings, etc., with some limitations. The book is due out in March. There are some things that aren't covered, such as ground effect and other interference effects, downwash/upwash, incremental effects of control surfaces and other things. Upwash/downwash is extremely critical when computing lift/drag/etc. on aircraft with multiple wings, since it ultimately affects the amount of lift/drag/etc. on each surface and therefore affects not only the dynamics but also the stability.

For more details you might check out the following resources. Francis Hale's book in particular is just a fantastic source of simple, simple formulas for approximating aerodynamics forces and moments, as well as propulsion thrust for different types of propulsion systems. These can feed directly into your standard run-of-the-mill rigid body simulator. Raymer has some of this also, and is just a "bible" of all aspects of aircraft design---but in my opinion less accessible than Hale's book for someone just wanting to write a basic flight simulator. Bertin is more about the fundamental theories of aerodynamics and far less of a practical resource, but still might be useful. If you want to really dig a bit deeper, then look at Etkin's book. The solutions for the equations of motion of an airplane, as provided in Hale, Raymer, and Etkin, are linearized solutions, which aren't particularly helpful outside of preliminary aircraft design. But their discussions of how to compute the aerodynamic forces, NACA stability derivatives, etc., are directly applicable to nonlinear rigid body dynamics simulations that are now commonplace.

Unfortunately, none of these books are available for cheap unless you can find them used.

Raymer, Daniel P., Aircraft Design: A Conceptual Approach, AIAA Education Series, American Institute of Aeronautics and Astronautics, Inc., 1992.

Hale, Francis J., Introduction to Aircraft Performance, Selection, and Design, John Wiley & Sons, 1984.

Bertin, John J., and Michael L. Smith, Aerodynamics for Engineers, Prentice Hall, 1979.

Etkin, Bernard, "Dynamics of Flight: Stability and Control." US$115 at amazon, whew. US$81 used. WHEW. As I said, unfortunately not cheap.

(At least I didn't point you to Hoerner's book on aerodynamic drag, currently going for more than US$250 *USED* at amazon...)

If you must have something free, this website might be useful:

Advanced Topics in Aerodynamics

There have been a number of detailed discussions in this forum in the past, which you could try to look for. Some forum members have posted links to code samples/demos they've developed.