for FM part, that's aeronautic experts' field.
I post my humble findings about non-FM part here.. in case i forgot them and do it again.

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1. Gear position X, Y, Z, RNG.
i try to tweak Z value, make ac looks nose-up on the ground. As i increase the Z value of nose gear, the result is - yes, my ac looks pitch up on the ground, but not stable.. it starts shaking, restless.. when i throttle up, the acshaking stop, stablized, then takeoff. when landing, the nose gear seems sink into ground, not resume the nose-up posture. My AI wingman can not stand with this shaking - he refuse to take off, just taxi outside the runway! So, a stable nose-up can only be achieved by applying XDOF on ac model ATM.
2. PitchGearFactor 0
This flag seems useless.. whatever value i put in, no effect on 3d. it won't help making ac nose-up on the ground.
3. Swing wing angle setting,
i found several swing-wing ac have same sweep angle settings: 20, 50. but in ac like Su17/20, these values cause OVER-swept at high speed. i changed the max swept angle value, can not limit the wing animation. wierd. my only solution is limiting the max angle with XDOF limits on 3d model.