AeroTech aft end closure without thrust ring?

[Rschub]

Buckling stiffness increases as the 4th power of diameter, I believe, so the failure mode is probably local crippling at the tube edge where there is a seam between the body tube and the nose cone or payload bay. Any small deflection due to a less than tight fit will be a problem.

 

[mholmes]

good timing, just witnessed it happen on a guy's flight this morning, on one of these flush motor mount setups. Didn't get a great look, but the tube failed, probably in buckling. The threaded rod remained in the tube, which was located. The motor was not found, so I'm not sure the nature of that attachment failure.