simulators

Well, pretty much all game-type consumer flight simulators I know calculate
aerodynamic forces (and moments, too!) in real time.

I think most use look-up tables based on data from the real planes.
They look in a table to determine how much force a given shape will
produce with a certian amount of dynamic pressure and AOA. They then
interpolate and extrapolate for data points not in thr table. X-plane
attempts to calculate the forces without look-up tables.

(Peterson, David) wrote in message

Well, pretty much all game-type consumer flight simulators I know calculate
aerodynamic forces (and moments, too!) in real time.

I think most use look-up tables based on data from the real planes.
They look in a table to determine how much force a given shape will
produce with a certian amount of dynamic pressure and AOA. They then
interpolate and extrapolate for data points not in the table. X-plane
attempts to calculate the forces without look-up tables.

The lookup table yields a *coefficient* - NOT a force or moment. Each
coefficient is multiplied by qbar and reference area (and some are
multiplied by additional reference length and/or control values) to
get a force or moment. Several coefficients might produce components
of lift, for example, which need to be multiplied by their respective
dimensional parameters, and then all summed, to produce total lift.
This is done realtime. So, yes, the *forces* and *moments* are
calculated in realtime. Interpolation is always done, but
extrapolation outside the tables domain is questionable. I should add
that not only do most game-type simulators use this approach, but so
do the space shuttle training and engineering simulations I work with,
and the USAF F-16 training simulator I worked on years ago. The
difference between the game-type and space/military sims is the size
and complexity of the lookup tables.