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tail cone drogue

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markkoelsch

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Do you mean eject the tailcone and have the drogue come out the back?

If so, I think this might be problematic in that the rocket would the. Likely be in a nose down config when the main deploys out the nose. This in an invitation for the main and harness to get fouled on the rocket.
 

sean_journot

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Yes; I want to make a system that will release a tail cone which forms the apex of a drogue chute. The motor would remain attached to the body of the rocket. The drogue would not be deployed at apogee but during ascent to act as an air brake so that the rocket would be able to target an exact apogee.
 

Steve Shannon

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I've not seen a tailcone deployment. There's really not much room in a tailcone to store a chute. If the tailcone forms the apex of a chute as I think you're describing then I could see how that would work, if the body tube and broad end of the tailcone were large enough that the skirt of the parachute could be gathered inside. It would have to be protected from heat. Neat idea. A more traditional rear ejecting chute system like the Estes Gemini DC would be much easier.


Steve Shannon
 

Incongruent

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What if the tailcone (and body tube as well, possibly) split open to form the airbrake instead?
 

ksaves2

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Stu Barrett, past president of TRA conceived of rear ejection quite a few years ago to help alleviate the zippering problem with "not so accurate" delay grains. This was before there was widespread availability of economical deployment electronics.
I built a 29mm motored project using his design recommendations and by golly it works well.Still fly the rocket too and don't worry so much about the delays. Only thing is the rocket lands nosecone first in a single deploy situation. I've read there have been some dual deploy strategies using his rear ejection concept but never saw one.

Used to be a whole section on the defunct ROL site (Rocketry Online) Kurt
 

markkoelsch

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Stu Barrett, past president of TRA conceived of rear ejection quite a few years ago to help alleviate the zippering problem with "not so accurate" delay grains. This was before there was widespread availability of economical deployment electronics.
I built a 29mm motored project using his design recommendations and by golly it works well.Still fly the rocket too and don't worry so much about the delays. Only thing is the rocket lands nosecone first in a single deploy situation. I've read there have been some dual deploy strategies using his rear ejection concept but never saw one.

Used to be a whole section on the defunct ROL site (Rocketry Online) Kurt
That is traditional anti zipper construction. It does work.
 

sean_journot

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I believe I can turn a custom motor retainer and have the tail cone attach to the motor retainer by gluing neodymium magnets into the motor retainer and gluing a small steel ring into a light weight aluminum tail cone. I can run two tubes next to the motor tube up above the forward bulkhead and use a normal electronics bay set up for tail cone separation. Those parts will be easy enough to make on a manual lathe and mill; just need to figure out a good way of attaching the top of a chute to the tail cone now.
 

sean_journot

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there must be a simple and effective way of kicking the rocket sideways during main deployment using a drogue system like this; I was thinking about seeing if I could cut a slot in the end of the coupling section so that main ejection gasses kick the rocket over to one side during separation. I am not sure if that would do the trick though.
 

Incongruent

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Asymmetrical air brakes or control surfaces.

The ejection method could result in incomplete separation and deployment failure. If the ejection gasses are vented to try and push the rocket sideways, what will deploy the parachute?
 

sean_journot

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Your right, separation would depend on the forward section reaching a high enough velocity before the slot is uncovered to clear the rest of the coupling. The coupling section would also need to be well above the CG to create enough moment to kick the whole rocket over and the slot needs to be long enough so that the full moment caused by ejection gases is passed into the forward section before complete separation. The ejection charge would need to be heavily overloaded also. Not insurmountable problems but not necessarily easy to solve either.
 

ksaves2

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there must be a simple and effective way of kicking the rocket sideways during main deployment using a drogue system like this; I was thinking about seeing if I could cut a slot in the end of the coupling section so that main ejection gasses kick the rocket over to one side during separation. I am not sure if that would do the trick though.
I had an ejection charge failure with a J350 in a LOC tubed 4 inch diameter single deploy. Rocket did the death dive and eventually gravity pushed the loosely fitting parachute down which popped the nosecone off about 100 feet up. The Covert Rocketry parachute "exploded" to shreds, the rocket was zippered of course, got knocked sideways and landed flat. Fincan survived nicely. With the very long 38mm motor stuffer tube I had, I was able to rebuild and decided on a dual deploy as I had a LOC ebay lying around unopened.

Flew the heck out of it until this happened (Reposting): [video=youtube;hMvT9BKzbUg]https://www.youtube.com/watch?v=hMvT9BKzbUg[/video] Believe it or not, it landed flat AGAIN and the fin can survives for ANOTHER rebuild. Going to try again and lay some glass on the sustainer to
reinforce it. Kurt
 

sean_journot

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do you know what your decent rate was during main deployment on that first failure and where did the parachute fail exactly? Covert rocketry chutes are very similar to rocketman chutes right? That poor rocket lol; at least you got some good video from that last launch.
 

sean_journot

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from that video it looks like the failure occurred just above your CG from how the rocket moved during the explosion; was your CG on that destroyed area?
 
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