Decent speed

[JimByrne]

What is the best decent speed? In Mark Canepa's book he recommends 15 to 25 ft. per second. In Tim Van Milligan's book he says design for 12 to 15 ft. per second.
I am trying to come up with the best main & drogue sizes for my 12 lb. rocket.

 

[tim cubbedge]

A lot depends on your recovery area. Grass and weeds you can land at 20-25 FPS with no issues. Have had some come in faster with no damage. If your recovery is hard dirt or road, slower definitely better. Also depends how well your rocket is built.

 

[MClark]

A decent descent speed depends on the landing surface, grass vs. hard desert and rocks. Small/light rockets seem to tolerate higher speed.
For 12 lbs. where I launch, Black Rock, I like less than 20 f/s at touch down. Under drogue less than 50 at main deployment, will be higher at apogee.

M

 

[afadeev]

A lot depends on your recovery area. Grass and weeds you can land at 20-25 FPS with no issues. Have had some come in faster with no damage. If your recovery is hard dirt or road, slower definitely better. Also depends how well your rocket is built.

... and what it is built out of.
Beautifully detailed and fragile rockets (e.g.: X-wing, anything with escape tower) need to come down as slow as possible <= 15-20 fps. TVM's recommended descent speeds will take any rocket into the next zip code, and should be avoided, unless you really like hiking, and rocketry is just an excuse to get started.
Fiber glass airframe and fins? I had those descent at 42 fps to minimize drift near corn fields, with zero damage.

YMMV.

 

[teepot]

I fly off a dry lake bed and try to come down between 13 and 15 fps under main. Under drouge between 40 and 50 fps. That's with everything regardless of weight.

 

[JimByrne]

A bit more detail:
I fly from a hard dirt dry lake and the question applies to a 4" fiberglass rocket

 

[Handeman]

I don't think you can pick a speed as the aim when selecting a drogue chute. The rocket under drogue is usually the longest part of the flight. I pick the drogue size to get the controlled flight I want. Too small and you can still get ballistic recover where one half of the rocket falls faster and drags the other half down. Too large and both halves hang together and you get way too much drift. When the drogue is sized right, the two halves fall in a controlled fashion, they hit each other and speed is fast enough to limit the amount of drift.