SpaceX Falcon 9 and Fairing Flying Model Rocket Kit

Discussion in 'Low Power Rocketry (LPR)' started by OverTheTop, May 24, 2017.

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  1. Dec 30, 2019 #31

    Falcon Flights

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    I'm trying to find the instructions. After further evaluation, I almost wonder if I glied the fairing improperly. As in, the nose cone should separate from the fairing, and the fairing should be glued to the coupling.

    The issue seems to be the the shock cord is not pulling the chute from the fairing. If the nose cone separated from the fairing, the chute would deploy more easily.
     
  2. Dec 30, 2019 #32

    Andrew_ASC

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    Well to me it looks like your chute is being trapped inside the fairing even after the fairing and nose come off. If you could prevent the chute from being trapped inside the fairing, the aerodynamic forces should inflate the chute when it’s exposed to air after ejection charge deploys it.
     
  3. Dec 30, 2019 #33

    kuririn

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    Yeah, nose cone and payload tube separate from the plastic payload transition.
    1229191659.jpg
     
  4. Dec 30, 2019 #34

    Falcon Flights

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    Yes, that is the issue. I need see why the chute is not being pulled out. After first 2 flights, we thought it was a chute wrapping issue. Then we wrapped it better and it had plenty of room inside the fairing. But, on launches 3 and 4, it seems that as the cord is pulled, the chute expands inside the fairing and doesn't fully extract.

    Seems like a simple problem, but I need to think more carefully about it. And, I need to find the instructions to verify I did the build properly.
     
  5. Dec 30, 2019 #35

    Falcon Flights

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    That is how ours us built, but I can't get chute to deploy. Thanks for the pic!
     
  6. Dec 30, 2019 #36

    kuririn

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    This is perplexing. Check to see that your shock cord anchor is flat as possible. Could be snagging the chute.
    Maybe a wrap of wadding loosely around the chute to keep it from expanding in the fairing?
    Also check fit of payload shoulder. Not too tight.
    Also baby powder on the chute to help it slide out couldn't hurt.
    Flew mine only once, with full deployment.
    Good luck!
     
  7. Dec 30, 2019 #37

    les

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    Two suggestions:
    1) Tie a loop onto the shock cord about a third of the way down. Attach the chute to this loop. This provides some pull from the cord to help pull the chute out
    2) Pack as much of the shock cord in first, then the chute. Then as the shock cord is being pulled out it will "push" the chute out
     
  8. Dec 30, 2019 #38

    Falcon Flights

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    Thanks, all! Will keep suggestions in mind as we engineer a solution!
     
  9. Dec 30, 2019 #39

    Falcon Flights

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    As I look more into this, why is there a kevlar string connected to the shock cord? The kevlar string is tied to the reducer coupling, which is epoxied to the rocket body. If I attach the shrouds to the kevlar cord, any initial shock from separation should not exceed the epoxied joint between the reducer and rocket body. This would also serve to better pull the chute out of the fairing.
     
  10. Dec 30, 2019 #40

    Falcon Flights

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    I adjusted the loop in the shock cord way down towards the connection with the kevlar string. I now have 21" between the reducer and the fairing, and the loop is at 15". That means there is effectively only 1" of the shock cord doing the majority of the work. Also experimenting with chute folding techniques and baby powder. 20191229_224036.jpg
     
  11. Dec 30, 2019 #41

    neil_w

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    Hmm. You’ve got a relatively short piece of Kevlar and only an inch or two of elastic between the airframe and the parachute. I was initially worried that you’d be subjecting the chute and/or airframe to a severe shock, but now I’m thinking its more likely to be ok. Bigger worry is that when suspended from the chute, the payload section will be bonking against the main rocket. Generally you want the main rocket hanging well below the nose section on descent.
     
  12. Jan 2, 2020 #42

    shreadvector

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    Simple problem: you are leaving the parachute shroud lines loose.

    the chute should be folded and the shroud lines wrapped around the folded chute like the stripes on a candy cane/barber pole.

    this will allow the chute to be pulled out of the fairing and then it will quickly unroll and open.
     
  13. Jan 18, 2020 at 7:35 PM #43

    Falcon Flights

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    Went 2 for 2 today, my son was very excited! Thanks for the tips!
     

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