@LjSpike The short landing gear's got suspension too. And it's the takeoff that is the problem.

It's got a long rear landing gear because long ones have suspension, project your landing as if it's a taildragger and it should work, or if you like you can land front first instead of rear first, though the forward extension means a front first landing could be hard.

So this plane looks great and has the potential to fly great too. Firstly, the plane wants to yaw uncontrollably. To fix this I just mirrored the plane to make sure everything were the same on both sides. Secondly this plane, like many other of your planes, has a really awkward landing gear position. Either change the rear landing gear to a short one (proper taildragger configuration) or make a tricycle gear instead. For gear position I suggest sticking to those two basic configurations; taildragger and tricycle. The main landing gear (front gear on a taildragger configuration and rear gear on a tricycle configuration) should not be too far away from the CoM. The main gear works as the pivot for the rotation at takeoff. A taildragger should always have a positive attitude when resting on all the wheels. And don't use any more than three gears and don't space them too far apart.