May 2023 Scheduled Launch
Quote from Eric Becher on May 5, 2023, 9:08 amI had the Kevlar to nylon setup, and that's what fried. It's a lot of line and stuff to pack into the 2.2" bull pup, so some of the nylon got too close to the ejection. I promptly went to One Bad Hawk and now the Pup has all Kevlar shock cord. You'll have more room in the 4" T-loc, so maybe you can get around it, but I've been "burned" once, so no more nylon for me.
I've flown a lot of HP on nylon (OBH tubular nylon) and no melting at all. I'm not so convinced that the flat braided nylon is the thing to use in rocketry. For the size and weight, kevlar is much stronger and won't burn through from an ejection charge. It can be coiled up in the payload bay to0. For my large rockets with flat tubular kevlar harnesses, I have a winder. It coils the kevlar into pancake-like bundles. Then, some strips of masking tape are used to hold the bundles together when inserted into the airframe. Some fellow was 3D printing the winders before I had a 3D printer. I'd wager he's still selling them. If anybody is interested, I'm sure I could find his email.
With my bigger/wider rockets, my trick has been to stuff some ejection wadding down the top end of the motor mount tube. This helps prevent any of the shock cord or chute sitting directly in the path of the ejection charge.
Some of my rockets have baffles, but I have found that I prefer a "half baffle" -- this is basically a piece of wood with holes in it, mounted into the body tube, which also allows me to mount the eyebolt centrally rather than off to one side. I'm hoping this will prevent "zippering", but it's mostly to prevent the shockcord and chute sliding down the length of the body tube as the rocket launches. This lets me keep the whole recovery system nearer to the nosecone and hopefully prevents too much heat getting to the plastic components of the recovery system (nylon chute, nylon cord.... and nylon is make from plastic). We will see how it all works out.