Parachute Reefing-Ring Deployment Testing
HTML-код
- Опубликовано: 5 сен 2024
- This test is a stepping stone for another project. Stay tuned.
Rather than pack 2 parachutes in a mid-power model rocket for dual deployment, I wanted to test the feasibility of a passive "reefing ring" used to choke the canopy and reduce the high snatch loads that occur during parachute deployment at high speed.
Woah, it works very well!
I don't suppose you gathered any strain gauge data for the snatch load for both cases? Seems to work well though!
No strain gauge data, sorry. More of a qualitative test.
If you don't mind me asking, why no dual parachutes? With dual parachutes, you can either deploy a small one(or a drogue) first to slow it and then deploy main chute at a few thousand feet to ensure not too much positional drift occurs. Your ring certainly seems effective however. It looks like it will be good for all parachutes, drogue and main chutes.
dual parachutes is certainly an option. I just thought I might be able to come up with something a little simpler.
It looks like the ring didn't move all the way down the shroud lines to reach the end of the shock cord, leaving the chute partly reefed. Am I imagining this?
You are correct, I saw this too. At some point the wind force pushing the ring towards the canopy equalizes with the force pushing the ring away due to the shroud lines creating a ramp from the parachute opening. I'm not too concerned though, as obviously the parachute opened all 3 times without issue. On a real flight, the parachute will have slowed the craft down, plus it will be hanging vertical, allowing the ring to fall further (theoretically).
Right, but the descent rate will be greater if not fully open. I've found the descent rate calculations of Rocksim and Openrocket to be very close to measured and the lack of full unfurling could be simulated within those sims by reducing the shroud line lengths input to the sims.
An acquaintance of mine uses a 1/2" length of 1/4" launch lug on his beautiful home-made plastic 24 to 32" chutes with 12 shroud lines for low/mid power flights and the effect it has on the opening sequence is smooth and beautiful to watch. Rapid but smooth and gradual full opening with no pop. I don't know what you're using, but I wonder if a short cylinder rather than ring would work better assuming that's not what you're already using. When the parachute isn't horizontal as in your tests, a heavier cylinder might slide down due to its weight.
Winston Smith thanks for the info. perhaps I will do some tests with tube instead of the keyring I used here.