Seperation with 16gr CO2 cartridge

Discussion in 'Recovery' started by emre özkan, Aug 26, 2019.

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  1. Aug 26, 2019 #1

    emre özkan

    emre özkan

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    Hi. I'm building two rockets for competition in Turkey. And I have some problems with chute deployment. When I try to separate chutes from the rocket, chutes stuck inside. Or even the nose cone is staying in place. 16gr co2 cartridge supposed to be eject; main chute, drag chute, 4kg payload, and payloads chute. The drag chute is at the top. As I planned drag chute should pull everything from the body. But nose cone is not deploying.

    Can you give me any suggestions, please?
     
  2. Aug 26, 2019 #2

    dhbarr

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    You're trying to push more than 5kg out by expanding 16g of co2 to about 9 litres volume.

    What is the diameter of your tube? That should tell you the surface area, which should give you the pressure.

    I suspect the thing to do would be to either use more gas ( 20g cartridge ; or two 12g cartridges ; etc ).

    Or else to put the gas bottle in the nose so the ejection causes the momentum of the nose to pull the first chute out, and hopefully the first chute can pull the remainder.

    Does your nose fit easily? Are you using shear pins?
     
  3. Aug 26, 2019 #3

    G_T

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    With CO2 there isn't really a minus of going too large a charge, unlike with BP. Go bigger.

    Gerald
     
  4. Aug 26, 2019 #4

    jderimig

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    What is the volume of the chute compartment in liters? What is the altitude at ejection?
     
  5. Aug 26, 2019 #5

    artapplewhite

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    emre özkan,
    Marhaba, Try putting the drogue parachute in the body tube as it would be when the rocket is ready for a flight, but without the nosecone. Turn the body tube upside down. If the drogue parachute doesn't fall out by itself then it's packed too tight.
    It's the momentum of the nosecone that pulls the drogue parachute out, not the pressure of the ejection gas.
    A 16g cylinder of CO2 is roughly equivalent to a 3.2g Black Powder ejection change.
    Art Applewhite
     
  6. Oct 30, 2019 #6

    Bagels and LOX

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    Well, I'd imagine there is the downside of the mass increase, since scaling up a CO2 ejection system comes with a bigger dry mass penalty than a BP system. But of course if it's necessary then it's necessary.
     
  7. Oct 31, 2019 #7

    rocket_troy

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    Well, if it's the rocket competition in Turkey that I've supplied some deployment devices for, which mandates that the deployment be 100% non pyro - then I think I can envisage with some probability the primary cause of your grief.
    Primarily, the piercing of the canister is the key issue with CO2 canisters. Pyro actuated piercing makes easy work of it because there's an abundance of power to ensure the pierced orifice is large enough to allow a high enough throughput for the CO2 itself to provide enough *power* to the deployment process. However, without the luxury of an abundance chemical power, a great deal of thought is required for the design of puncture mechanism without making it impractically heavy and large.
     
  8. Nov 1, 2019 #8

    mpitfield

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    Careful how much powder you use!

    Too much powder can result in too much energy and possibly an embedded piercing piston in the CO2 cartridge. This will either plug the cartridge, or more likely result in a slow leak and no where near enough pressure to seperate your components.

    I am not simply deducing this from logic, this "opinion" comes from first hand experience.
     
  9. Nov 8, 2019 at 7:46 AM #9

    Bagels and LOX

    Bagels and LOX

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    Now I am just guessing, but would I be mistaken in thinking that a piercing piston with a wider cone angle would require more powder, but be less likely to embed if one accidentally overshoots when measuring out the powder, while a sharper cone angle would need less powder to work but be more likely to embed? In your experience, what cone angle do find is the best trade off?
     
  10. Nov 8, 2019 at 11:43 AM #10

    dhbarr

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    My complete hunch would be 45deg but notch the cone.
     
  11. Nov 8, 2019 at 4:11 PM #11

    rharshberger

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    Cone angles on my CDD3 systems piston appear to be about 45°, with no notches.
     
  12. Nov 8, 2019 at 8:21 PM #12

    dhbarr

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