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Advice-Dual Deploy

  • Robert Veilleux
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8 months 3 weeks ago #8546 by Robert Veilleux
Hello every one, I'm hoping to get a bit of advice. I built my first dual deploy rockets (Screech and Frenzy), fun builds and I can't wait till I can paint them/fly them. I've watched videos on apogee, I've researched online, and I've seen a lot of you launch dual deploy rockets. Even with all that, I'm a little confused about one thing...Does the main chute go in the main tube or the payload. I ask for two reasons, I've seen websites and videos that show people putting the main in either one. The other reason is because the 36" main chute barely fits in the payload tube even without the parachute protector.
I want to actually put a larger parachute in the Frenzy to allow for a slower decent, so I was thinking about using a motor with no ejection charge and put the main chute in the main body tube. From what I can see on some sites and videos, this allows more room for the chute (or larger chute) and the drogue chute can also help in slowing the decent.
What do you guys recommend or prefer?
Any help you can offer will be appreciated and I can't wait till our first launch!

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8 months 3 weeks ago - 8 months 3 weeks ago #8547 by Boris Katan
It is essential that the recovery system deploys easily: the chute, harness and chute protector must slide easily out of its compartment.

It is desirable to have as much redundancy as possible.
So if it is possible to have the lower compartment be the apogee drogue deployment, then it is usually possible to set motor delay to 1-2 seconds after simmed (flight simulation prediction) apogee, and have motor backup. This puts the main chute in the upper compartment.
Splitting the rocket closer to its middle is also better for a slower drogue-less recovery as the rocket is more likely to fall in a flatter position.

If the main recovery system can not be made to fit in the upper compartment, then it can be positioned in the lower compartment. But motor deployment backup is no longer possible.

Always angle the launch rod/rail away from the crowd.
Last Edit: 8 months 3 weeks ago by Boris Katan.
The following user(s) said Thank You: Kenn Blade, Robert Veilleux

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8 months 3 weeks ago #8551 by Claude Maina
I agree with Boris that you want redundancy. So, I don't think you should remove the motor ejection. There have been at least three occasions when the motor ejection saved my rocket. There are different techniques to folding parachutes that you can find on TRF or on the web pages of chute vendors. I would try them to see if any work better. Also, if the rocket has a plastic, hollow nose cone, you can cut the bottom off and use the extra space of the nose cone for your chute.

Finally, whatever you do - ground test, ground test, and ground test again.

Good luck.
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8 months 3 weeks ago #8553 by Claude Maina
PS

I would recommend learning and practicing dual deploy on mid-power rocket(s) that do not need it before you use it on a larger rocket. When I was learning dual deploy I used two relatively inexpensive rockets. I flew them on F and G motors to about 1000 ft (max) and used a full size chute for both drogue and main. I practiced until I was confident with the technique - several flights over a season - before I used it on a rocket that needed it. I had a number of failures that season but the rockets survived and I was glad I did it.
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8 months 1 week ago #8584 by Robert Veilleux
Thanks for the information, things now make more sense to me. I didn't even think about the rocket falling flatter when it's split in the middle, even though I've seen it many times. After reading your response, I'm worry about people putting information or videos out showing the main chute being in the sustainer tube.

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