drogue or streamer

[jraice]

I was going to use a 24" drogue for my 12.5-13# rocket, would fall about 55-60FPS. + or - a few....... someone said to use a streamer. The rocket is very lightly glassed and I dont want a zipper. Would the streamer stabalize the rocket as much as a drogue? I want the fincan way below the nose while falling. What size streamer? Any other info about streamers as drogues?

 

[thomasrau]

In many cases a small drogue or streamer will actually make your rocket fall faster than if "drogue-less". If your drogue or streamer generates enough drag to keep the booster below the nose, it will more than likely get both sections close to vertical (a low drag orientation). Most rockets I've seen drogueless come in nice and flat (which is a very high drag configuration). Onboard video from my eclipse shows that it is much more stable drogu-less. With the drogue chute the booster and airframe were hitting from time to time, drogue-less was much more stable.
On the negative side it drifts a little bit more drogue-less, since it actually drops a bit slower than it did with a small drogue chute.

 

[jraice]

But if the drogue is in the right position the parts wont bang, that only happens if the parts are equal height when falling but mine wont be. I want a drogue but I cant decide, parachute or streamer, streamer would go a little faster i think, would it have as much drag as a 24" chute is one main question i need answered. Is there a simulater for siming descent rates with streamers???

 

[thomasrau]

Originally posted by jraice
But if the drogue is in the right position the parts wont bang, that only happens if the parts are equal height when falling but mine wont be. I want a drogue but I cant decide, parachute or streamer, streamer would go a little faster i think, would it have as much drag as a 24" chute is one main question i need answered. Is there a simulater for siming descent rates with streamers???

Only true if a fairly large drogue is used. If a small drogue is used (assuming you're doing dual deploy to cut down on drift) there will be times when the booster tumbles horizontally increasing its drag and floating back up to the airframe. On my Eclipse the drogue was attached 1/3 of the way down from the airframe. With a small drogue the airframe tended to stay vertical (nosecone down) and the booster would from time to time get horizontal and "slow down" allowing the airframe to catch it.
Streamer cd's vary quite a bit depending on material and weather or not there are folds or if it starts flapping.