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Old 06-18-2016, 08:02 AM
Brent Brent is offline
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Default Strap on Boosters /Parallel Staging

I am thinking about building another Titan III where the SRBs drop off and return via their own parachutes. Maybe E12-6 in the center and C6-3 in the SRBs. I would use clear fins on the center BT60. I am sure this has been done before . What methods have been used for the drop off boosters attachments?
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Old 06-18-2016, 06:09 PM
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You might find this thread on TRF to be of interest: http://www.rocketryforum.com/showth...Maximilian-quot
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Old 06-18-2016, 06:42 PM
aeppel_cpm aeppel_cpm is offline
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You mean like this? I flew mine at Bong today. E9-4 with C11-0 in both boosters.
http://www.youtube.com/watch?v=k8UCxDqQvGA


It takes a LOT of nose weight - though mine is weighted for 29mm core and 24mm in the boosters.

What I didn't anticipate is that it's a high speed deployment. Killed the chutes.
Something to work on, I suppose.

The build threads are here on YORF, though I don't have a link handy.
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Old 06-18-2016, 06:46 PM
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Apogee has an article in this newsletter
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Old 06-18-2016, 06:49 PM
Brent Brent is offline
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Default Titan III

Quote:
Originally Posted by aeppel_cpm
You mean like this? I flew mine at Bong today. E9-4 with C11-0 in both boosters.
http://www.youtube.com/watch?v=k8UCxDqQvGA


It takes a LOT of nose weight - though mine is weighted for 29mm core and 24mm in the boosters.

What I didn't anticipate is that it's a high speed deployment. Killed the chutes.
Something to work on, I suppose.

The build threads are here on YORF, though I don't have a link handy.


Thanks I will look for it.
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Old 06-18-2016, 06:54 PM
aeppel_cpm aeppel_cpm is offline
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Old 06-18-2016, 07:42 PM
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Quote:
Originally Posted by aeppel_cpm
You mean like this? I flew mine at Bong today. E9-4 with C11-0 in both boosters.
http://www.youtube.com/watch?v=k8UCxDqQvGA


It takes a LOT of nose weight - though mine is weighted for 29mm core and 24mm in the boosters.

What I didn't anticipate is that it's a high speed deployment. Killed the chutes.
Something to work on, I suppose.

The build threads are here on YORF, though I don't have a link handy.


Charles, it was hard to tell from your video just exactly what you meant by 'it killed the 'chutes'. I assume it was the 'chutes in the strap ons. Could you use something in the strap ons with a delay? I'm thinking maybe D12-3's.

Joe
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Old 06-18-2016, 08:20 PM
aeppel_cpm aeppel_cpm is offline
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One booster snapped the shock cord. 1/8" sewing elastic on a kevlar thread anchor. If you look closely, the nosecone floats down gently on the chute and the boost flings up and then falls.

The other booster stripped all but one threads on the chute - the orange Estes chute - 12"??

Neither had any zippering problems.

If you want to keep the look of boosters separating with the core continuing on, then I don't know a solution. A C11-3 or D12-3 would push the separation higher - The E burnout would be about then - but none of the delay to slow towards apogee. So still fast.

If you went with a longer delay - like a -7, then you would be closer to apogee - but loose the effect - and all your pieces would be higher.

If I hadn't used too-thick plexiglass fins, then the boosters would be light enough that I wouldn't worry about using a streamer. In fact, the booster with the chute with 1 thread only came down fine, the motor hook is just a little bent. The booster that came down free fall cracked the custom tail piece that Sandman turned for me pretty badly. But in big chunks, so some CA put it all back together.
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Old 06-18-2016, 08:58 PM
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Jerry Irvine Jerry Irvine is offline
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Quote:
Originally Posted by aeppel_cpm
What I didn't anticipate is that it's a high speed deployment. Killed the chutes. Something to work on, I suppose.
Slide rings on the chutes to prevent explosive deployment. Outsized spill holes.

http://v-serv.com/usr/kits/sentrasrb2.7.htm

In case you don't know, a slide ring is a small key ring like device that is slid all the way up the shrouds to the canopy during prep. On deployment the ring prevents full canopy inflation until the ring has time to slide down. Typically the ring is >10x the area of the shrouds so it slides easily.

Nothing wrong with a 15-30% area spill hole.

Report results please.

Tech Jerry
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Last edited by Jerry Irvine : 06-18-2016 at 09:15 PM.
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Old 06-19-2016, 08:05 PM
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I've slid large plastic beads over some shroud lines to act as a "limiter" like Jerry mentions above. Works pretty good and a quick easy fix.

I've got a couple "ring parachutes" where the "spill hole" is about half the diameter of the chute... acts more like a streamer-- fast descent, but easy deployment even in fast/hard deploy situations...

That's a quick-n-easy solution too...

Later! OL J R
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