How collision shape effects pawn physics

Hello

I’ve been trying to make a flying type pawn using physics as movement. I used a cube as a place holder, while I worked on the movement. It did work fine, but when I replaced the cube with my mesh the movement broke.

After some fiddling with the default assets I figure it out that it wasn’t the mesh responsible for the broken movement but the collision.

Example: Two blueprints with the same properties except the collision. The box stays horizontal but the complex sags.
(properties: addtorque 50k on the z axis, simulate physics, no gravity, override weight).

Curiously, even tho the weight was set to 100 on both the box was slower, I don’t know how to explain it.

The cube had a box collision and the mesh a complex collision. If the mesh had a box collision the movement worked.

How can I make a collision with the properties of a complex collision for collisions and hits and the properties of a box collision for movement.