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  1. #1
    Join Date
    21st March 2009

    How fast is too fast???

    I'm buliding a PML small endeavour for dual deploy and I was wondering if the 50ft/sec drogue and 30ft/sec main I am getting in rocketsim is an acceptable rate of descent. As little rain as we have been recieving this summer it will probally be a hard surface landing.


  2. #2
    Join Date
    18th January 2009
    Well, I would say faster on the drogue and slower on the main. If the drogue slows the rocket down too much, the main might have trouble opening. I think 60-70fps would work better, though I know that people on here have had success at 50fps. 15-20fps for the main is a common practice. Since you are saying hard surface, I would say closer to 15fps, otherwise you may damage the rocket on landing.

    TRA L1

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    Aerospace engineer, w00t!

  3. #3
    Join Date
    2nd April 2009
    West Texas
    50-60 ft/s should be fine for the drogue, but 30ft/s sounds a little fast for the main, paricularly if your going to be landing on a hard packed surface. If you have the room, I'd go with as big a chute as I could reliably pack for the main.

    I like to bring my rockets down pretty fast from apogee,(usually drogueless or with a streamer for visibilty) and then slow them way down on the main for a nice soft landing. I shoot for 15-17ft/s. I know folks that go as high as 22ft/s, but the risk of damage goes up proportional to speed.

    Good luck with your project!

  4. #4
    Join Date
    2nd May 2002
    My 4" Thor falls at approximately 57fps.. my 6" Thor falls at approximately 91 fps.. both worked fine.. both were built slightly different to handle the different speeds..

    If my main is too big or slightly on the large side i want it to fall faster to help the main catch air.. if the main is on the small side then i want it to fall a bit slower to ease the deployment on the smaller chute.
    Jason V.
    TRA 9672 L3

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