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.
 
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.
 
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.
 
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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