RE: Those who have crashed Comp Arf Lightenings
I'm using the cylinders that came with the kit. They appear to be BVM cylinders. You will need three -- one for each door.
To summarize some of the key points on getting the doors right --
1) make sure the door lays flat and closes easily without any assistance from the cylinder. The trick is getting the phenolic tube very close to the wing surface.
2) get the cylinder as low as possible. I shaved some plastic off the end of mine, and also made a pocket by removing some of the wing material.
3) run the phenolic tube to the edge of the gear door, so the pieces that extend through the wing spars are short and will not flex
4) angle the mounting block for the cylinder so the ram travel is parallel to the movement of the hinge control horn