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Drogue Chute

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Steven88

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Hello. My Loc Big Nuke 3E comes with a 18” drogue chute with a vent hole cut down the center. My rocket weighs substantially more than the stock kit does by about 3.5 lbs to 5 lbs more depending on if I have the 16” extension that I made added to it or not. Would you up the drogue size to maybe a 24” or 30”? 18” just seems so puny, but also don’t want it drifting too far on the drogue either and defeating the whole purpose. I will have a large 96” or 108” main chute on it as well which will be opened somewhere around 1000’. Thanks for the advice.
 

crossfire

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You could go with a 24" but I would go no bigger. An 18" would work fine.
 

Handeman

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Just watch how it falls from apogee to main deployment. If it doesn't have a good inverted V or the fin can is flying too much then you can use a larger drogue. It's usually hard to judge without watching how it actually recovers.
 

Steven88

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Ok. Do you recommend a drogue with a vent hole or is that not a big deal?
 

richP

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You'd have to get the total weight w/motor hardware and then plug it into Openrocket to find an estimated descent rate. You can guesstmate the Cd. to get a good idea. I usually aim for around 75ft/s under drogue.
Keep in mind that many folks go drogueless too, so a chute too small is probably better than on that is too big.
 

JimJarvis50

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Just watch how it falls from apogee to main deployment. If it doesn't have a good inverted V or the fin can is flying too much then you can use a larger drogue. It's usually hard to judge without watching how it actually recovers.
Exactly. Many people don't watch how their rockets fall. The typical error is to go with a drogue that is too big. Then, the parts hang down and the main tangles with the air frame when it deploys. For a first flight, go with a drogue you might think is too small. If the fin can flies above the drogue, then increase the drogue size a little until you get a V shape. Remember, the purpose of the drogue is to get the V, not to acheive any particular descent rate. Normally proportioned rockets will form a V, but rockets that are top-heavy can be problematic. So, just watch the descent and go from there.

Jim
 
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