I'd love to have a go at trying this out now, but am stuck in the middle of something else. If I was doing it, I would do as Mike suggested. I always do things the complex way but I'd have 8 rigid body cubes for:
- The main body
- The left and right wings
- The left and right rear wings
- The rudder/stabeliser/whatever it's called
- The lift/ailerons, or whatever they're called on each main wing.
I'd probably do something similar to this:
- Calculate the total forwards velocity of each plane wing, and use that to derive an upwards (on the wings local y-axis) force to apply to the wings. This would simulate the lift from the air running over the wings at the plane moves forwards. If the plane was moving sideways, no upwards force would be generated. If the plane is upside down, a downwards force would be generated. This would have a cap, to simulate the maximum upwards lift the plane can have. Any speed along the y-axis of the main wings would create a negative drag force. Meaning that if you dropped your plane downwards from stand still as it was horizonal, the wings would have a parachute effect. Basically, try and model all the forces that wind would place upon the wings as it moves along its own local axis.
- Apply a similar upwards force to the ailerons/flaps/whatever. So that as you tilt them downwards, it'd apply an upwards lift force, as well as a backwards drag, just like real life.
- Model the rear wings in exactly the same way. You'd have to tweak the effect they'd have so that the plane would stay level at a certain forwards velocity. By applying forces along the rear wings local y-axis in proportion to it's movement on that axis, you would effectively keep the plane level. If the tail rose upwards, downwards forces on it would push it back into line.
- Do exactly the same thing for the rear wing/rudder. It'll just be operating on a different rotational plain.
Now, I'm not saying that not complex.
That's a lot of work there, a lot of trial and error and a lot of maths.
But DP already has the bare bones in place. You just have to bear in mind that airplanes are 100% about wind resistance, and DP has no wind resistance modelling at all, so you have to model that all yourself. Once you've done that, DP will take care of the rotational and linear velocities for you, and the wings snapping off, and the plummeting into the ground.