I rushed home trying to beat the sinking sun for a few test shots with the parachute tube. I threw everything in the truck, and went to the closest safe place to launch a 6 liter rocket - the local school.
The first launch was at 85 PSI with a small water charge - a nice launch, not too high, no chute(!) and a cool perfectly flat gentle horizontal float down. The doors were open, the chute had not moved an inch in the tube. Repacked chute.
Second launch - 100 PSI, one liter of water, a really nice sounding launch, good altitude, NO CHUTE! and a screaming SCUD landing straight into the asphalt running track. The chute was protruding from the tube as in the photo, in the opposite direction of the force of the crash, so I feel like it had partially ejected anyway.
OK, OK, no rationalizing, I'm 0 for 2!
I am still interested enough to this idea to committ to a few more rounds of R & D. I am thinking a steeper angle on the tube, a larger tube, and possibly the bottom hinged upper door/scoop. Or possibly some other thing that pops into my head - I will let you know!