Two parachutes?

i'm close to flying a scratch built rocket that has two body tubes about three inches apart. - part of EMRR's 2008 challenge. The design of the rocket means that the rear fins will probably not do so well on landing.

The model is quite draggy and weighs in at just under 6 oz.
so here's my idea, two parachutes. the first a 12 inch, to eject at or before apogee (hopefully) on a B6-2. then a second 18 inch deployed four seconds later on a B6-6. the idea being that i want to cut down on drift, but want a slow soft landing.

(i know 2x B is slightly under powered, that will be for the first flight, 2xC , with 3 and 7 delays will be then next - if she survivel the first flight)

The first parachure will be on a shock cord that is three foot longer than the second, so hopefully nothing gets caught up.

Any advice? Will it work?

It SHOULD work..The only thing I could think of is that the 2nd chute being bigger(by 50&#37 then the 1st chute is that it will slow it down enough to deflate the 1st chute..Not really sure..I don't have any experience with multi chute setups...

Pantherjon said:

I don't have any experience with multi chute setups...

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Gotta start practicing!!

dwmzmm said:

Gotta start practicing!!

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You're absolutely right Dave, I do!

Pantherjon said:

You're absolutely right Dave, I do!

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Sometimes the engine's ejection charge maybe a bit weak for multi-chute
models. Happened to my Centuri 1/35 scale Mercury Redstone's first flight
several years ago; only the capsule's 12" chute came out while the main 18"
chute stayed inside the bodytube. The Centuri MR uses a baffle ejection
system, so I KNOW the chutes were loose fitting in the bodytube. The free
fall of my MR's main body tube damaged one fin mad, but that's the way
things happen sometimes. Was able to make repairs and the MR has flown
several times since; in fact, Nick at EMRR has been begging me to do a product review on the Centuri MR (and FSI BB-II and Centuri Saturn - V)....

dwmzmm said:

Sometimes the engine's ejection charge maybe a bit weak for multi-chute
models. Happened to my Centuri 1/35 scale Mercury Redstone's first flight
several years ago; only the capsule's 12" chute came out while the main 18"
chute stayed inside the bodytube. The Centuri MR uses a baffle ejection
system, so I KNOW the chutes were loose fitting in the bodytube. The free
fall of my MR's main body tube damaged one fin mad, but that's the way
things happen sometimes. Was able to make repairs and the MR has flown
several times since; in fact, Nick at EMRR has been begging me to do a product review on the Centuri MR (and FSI BB-II and Centuri Saturn - V)....

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i had that happen to me when i swapped a 24 inch for three 12 inch. should not happen with my scratch build as each rocket is in a separate body tube.

I always pack the capsule chute behind the main booster chute. This way when the nose or capsule ejects it pulls the main chute out. I have never had a problem this way. I always use this method on multi chute rockets rather it is my Estes Saturn V or my HPR Mercury Redstone.

Brent said:

I always pack the capsule chute behind the main booster chute. This way when the nose or capsule ejects it pulls the main chute out. I have never had a problem this way. I always use this method on multi chute rockets rather it is my Estes Saturn V or my HPR Mercury Redstone.

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I do the same.
I learned the hard way a long time ago with my Aerotech Astrobee D.

just flown the rocket, 2xB not powerful enough. second chute ejected on the floor. just waiting for the glue to dry for its second 2xC flight.

Usually chutes will repel each other, so the longer shock cord isn't needed.

Smith said:

Usually chutes will repel each other, so the longer shock cord isn't needed.

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Could this be due to opposite charges in the ejection??? :surprised:

bigone5500 said:

Could this be due to opposite charges in the ejection??? :surprised:

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It could, but if it's going to get tangled it's going to do the same thing, if more, with a longer shock cord when it's coming out of the tube. Once the chute opens they will be pushed apart. (unless you have a large spillhole)

I would think a longer shock cord would be worse, if the chutes are one on top of the other they won't separate and the shock cords will tangle. You want what's going on in the pic.

I have done a two-chute configuration with only one rocket. After flying my Estes Renegade a few times and learning that the first stage has a tendency to hit hard, especially after I gave it a boost with D12s instead of C6s, so I decided to modify it to bring the booster down softly. I put two small parachutes in the side tubes and set it up so that when the booster separated, the chutes would come out. It worked fine and I did not have any tangling issues.
Reed

flown the repaired rocket again (twice), worked great on the 2xC.
as the two parachutes are each on their own shock cord, in their own bodytube, which are about 3 inch apart, the danger was that the second ejection might shoot the nose cone and chute into the first deployed chute.
What happened with mine, was that the rocket tipped to one side after the first chute deployed, pointing the second nose cone off at about 15 degrees, then the second ejection occured and the second parachute deployed clear of the first.
no damage on landing.