this has to be adressed, the mig21s damage model is just bad, it comes to a point where a single hit just makes the aircraft unable to fly because it just decides to defy gravity and air resistance
example:
based on basic knowledge of how aerodynamics works, this amount of vertical stabilizer is more than enough to maintain a certain amount of horizontal stability.
even with that in mind and even if the wobble was bad enough the plane would not just start to hover like it does in game, the moment some sort of speed is gained the amount of tail thats left would stabilize the plane anyways and if there is not enough tail then it would flatspin. it would not hover in place as it happens in game
