The rocket streaks skyward: I suspect the "shadow" is a side effect
of grabbing this frame from an HD movie. You get the idea though..
These 9 frames represent 0.3s of flight. The thing is moving. Just
not fast "enough".

In an attempt to reduce leakage around the base of the rocket I
wrapped the entire launch tube w a layer of thick paper. The 8"
rockets fit snugly, but moved freely: it worked well at low
pressures, but exhibited total failure above about 130 psi.

In an attempt to reduce leakage a bit less I removed the top half
of the wrapper around the launch tube. The 8" rockets fit snugly
at the bottom but were free to leak all they wanted during the
last 2.5" of their fight along the tube. This too worked well at
low pressures, but again exhibited above 130 psi. Subsequent
investigation revealed a large CRACK in the rocket tube between
it's fins!

Replacing the rocket with an unCRACKED rocket produced altitudes
in the ABMM system 30% higher than previously recorded. Vindicated.