WOuld be willing to help with this...
Suggestion -- when testing, have one plane in front at slw speed, constant direction. The second, from higher alt and speed, dives in as if making a firing run. (For several reasons, goons would be great for this test; lower speeds, easier course coordination, no guns to confuse things).
The closure speed with this approach FAR lower, making it easier to make the collisions happen, and the course angles leave much less problem with the collider's remnants being subsequently hit by the innocent collid-ee.