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Booster falling activating 2nd stage?

Posted: Wed Aug 22, 2018 8:51 pm
by Braaainz
I'm sure people must have tried this, so hoping for feedback.

Basically, boosters and primary sustainer launch. When boosters fall away, they also pull on simple cable release stager (like what is found in simple cable release launchers) thereby releasing 2nd stage

The other thought was to have booster detachment release a radial deployment mechanism that unwraps a plastic sleeve around the stager.

I haven't used multi stage or boosters before, so pardon my ignorance, just trying to think of ideas at the moment.

Re: Booster falling activating 2nd stage?

Posted: Wed Aug 22, 2018 10:26 pm
by anachronist
The boosters I have seen just fall away. I'm not sure the drag on them would be enough to pull anything. Also the ones I've seen fall away only because the main engine is still thrusting when the boosters run out of fuel. That is, the boosters use a regular bottle nozzle while the main engine has a smaller-diameter gardena nozzle. Admittedly I have no experience in this beyond videos I've seen.

Re: Booster falling activating 2nd stage?

Posted: Thu Aug 23, 2018 10:31 am
by retrotec29
A parallel stager works much like anachronist describes. Boosters attached at the sides of the primary out preform the sustainer. That difference in thrust keeps them attached by a simple hook. Soon as the boosters are depleted they drag separate by falling away or off the hook. Designing the hook so they simply fall away is the real trick. Getting the sustainer to power through all that and beyond can be complex as well. Water rockets deplete their resources so fast all that needs to happen in couple seconds. Inline staging has all its own problems. Crush sleeves and couplers need to react fast. Most staging happens less than a second from the pad. The idea of a radial deployed Clark cable tie coupler sounds cool. The weight of the thing would be the Achilles heel of it. Using a falling away parallel booster to trip it would be a slick way not to add a servo or timer. A simple one way vale between the first second stage sustainer could safely pressurize the final stage. Complex, cool and I would love to see any part of it manifest. I will stay tuned,

Re: Booster falling activating 2nd stage?

Posted: Fri Aug 24, 2018 4:27 am
by addstogether2

George at air command rockets has examples of drop away boosters as described above to great effect. ... ayBoosters



Re: Booster falling activating 2nd stage?

Posted: Fri Aug 24, 2018 4:32 am
by addstogether2

Re: Booster falling activating 2nd stage?

Posted: Tue Sep 18, 2018 12:30 pm
by anoymous
adding to what anachronist said:
i wonder if it would be possible to start with a small nozzle while the boosters are thrusting, and when the boosters fall away (because only the main rocket still thrusts), it pulls away the small nozzle to get a bigger one