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Originally Posted by Bill S
Having run some Rocksims of the Vapor on C11-3s, I am starting to see where the chute is popping just before apogee. I was under the impression that this was a good thing, but maybe the rocket is still moving and runs into the chute, hanging it up?
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You want it to be as close to zero velocity as possible. If it is still ascending or already descending at a decent speed, it will sometimes shove the chute and shrouds back into the model, causing it to hang in or on the BT.
Your description sounded to me like the chute hung in the body tube or got wrapped up with the body tube enough to have a nose first ballistic return on the first one, and just enough laundry out on the second to come in tail first. It's hard to say without seeing it.
We all have occasionally gotten entanglement of the NC and/or cord with the shroud lines if we put the chute somewhere between the NC and body as compared to at or near the NC. However, it still ejects completely and even though you don't get a clean canopy, it slows the model enough that usually the worst case is a busted fin.
As far as the Z fold...I just sort of grab the center and pull the chute opposite of the shrouds, then loosely fold the chute around the shrouds to keep them from hanging anything. I then roll the chute up only as tight as I need to. I don't fold tight, never have pleats, etc. The uglier it looks, the better it seems to work.
If the plastic wants to cling to anything at all, I add a little talc. On larger tubes, make sure you have enough wadding to get a piston action and push the chutes out. I've seen dual 24" chutes stay inside a BT-80 tube because the ejection gases just vented through/around the wadding and chutes. It is usually a perfect storm with a combo of large volume tube, some forward velocity (usually still going up), and not enough inertia from the nose cone to pull the chutes by itself.