Dual deploy in single 3" tube

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bigone5500

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I have a custom 3" LOC Patriot and want to know how I could make it into a DD setup. I am thinking of putting an ebay in and having the nose eject with a small 10" drogue and main deploy with the normal chute. The only thing I am having trouble with is figuring out how to do this...:lol: I am thinking that the main will probably tangle with the drogue which is 36". I have launched this rocket on an H180W and it screamed. I also had to walk a half mile to recover it. I'll attach the rocksim file and let you guys figure out what I should do. I have some ideas but I am leary of the way I have it thought out. I will be using a MAWD for electronics.

View attachment 3-Patriot LOC.rkt
 
Off the top of my head an internal 2" tube to hold the main? The internal tube could also be used to house the MAWD..I think that you could rig the chutes up so that the drogue is attached at the nose cone, have a length of cord running from the nose cone down into the internal tube holding your main so that when the charge goes off to eject the main it will be above the nose cone when it inflates..

Here is an edited RS file..I think it would work..;)

View attachment 3-Patriot LOC Dual Deploy.rkt
 
Put the eletronics bay in the nose cone and use a "burrito" to contain the main chute.
 
Skip the drogue 'chute. You shouldn't need one in a rocket this size.

Jim
 
I am thinking of putting an ebay in and having the nose eject with a small 10" drogue and main deploy with the normal chute. The only thing I am having trouble with is figuring out how to do this

Have you ever seen the device known as a Chute Tamer? It will allow you to do exactly what you're wanting to do, according to the folks that have used it.

ct_ready_20sec.jpg
 
Have you ever seen the device known as a Chute Tamer? It will allow you to do exactly what you're wanting to do, according to the folks that have used it.


You know I completely forgot about this thing. I am wondering if it will work well. As I understand, you rely on a heater wire to melt a fishing line in two and release the chute. In really cold weather, will this affect the unit's ability to melt the line? And does it have user selectable deployment altitudes?

This would be a very good investment IMO...anyone out there in rocket land used one of these much? What are the drawbacks?
 
DOn't even bother with the chute tamer. It is nopt made well and it is hard to tie the chute down, even if you follow their enhanced instructions. The nylon strap attaching it to the D ring tore off mine and it was lost.
 
I'm currently building a 3 incher (about 80" long) and was planning to put the avionics in the middle between the 2 chutes. The drogue will be in the middle above the motor (below the e-bay) and the main in a long nose cone/tube above the e-bay in a wrap that will pull it clear and will unfold when the tether pulls on it from the nose cone. Motor is a K (2200 Ns) and should go to 8000 or so. With the chute I have, 3 inches is close to being snug and requires some careful rigging.

I'll let you know how it goes.
 
Due to motor failure, it didn't work.

The concept of a single bay, dual deployment can be found at www.pvconly.com

No pictures, though. You'll have to be good at mentalizing this one.

basically you wrap a steel leader around your burrito'ed main and put pvc caps on the ends of the leaders. These caps push onto a short piece of pvc with a charge in the middle. The drogue is attached to the top of the main and deploys when the apogee charge blows off the nosecone. the main deploys at lower altitudes when the pvc caps blow apart 'letting-go-of' the main and allowing the drogue to pull it put of the burrito.

Be sure everything slides in and out easily. 3" tubes can be tight. Use lots of baby powder.
 
I did the equivalent of a dual deploy in a single 24mm booster tube. First it set off a separation charge, and then it ejected the parachute. The electronics fired the first charge through a 2-pin connector on a piston and then fired the second charge to eject the parachute later.
Here is a picture:

DSC00366.jpg


The electronics in the picture above are in back, sealed off by the first red coupler. Then there is a deployment charge, a 2-pin connector and some shock cord between the first and second couplers. The wires for the front deployment charge go past the yellow streamer and past a third red piston. That front deployment charge was used for stage separation in my application, but it could have been an apogee deployment, with a larger main in place of the yellow streamer in the picture above. The 2-pin connector gets separated by the same charge that ejects the streamer

There are more details in this thread.
 
I really, REALLY like that 2 pin idea. That will solve some problems in tight designs and I can use it for telemetry to additional electronics. it would be easy enough just to use bare pins and insulate them with tape to keep them from shorting together instead of using a connector body. I think I'll use that idea if it's okay with you
 
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