what is difference between these parachutes

Discussion in 'High Power Rocketry (HPR)' started by yucel, Jul 11, 2019 at 6:40 PM.

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  1. Jul 11, 2019 at 6:40 PM #1

    yucel

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  2. Jul 11, 2019 at 6:45 PM #2

    Bat-mite

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    Iris Ultra is made by Fruity Chutes. It is designed to give a high coefficient of drag but pack in a smaller space. Top Flight Recovery chutes are very good and not as expensive. Send an PM to pnobile here on TRF. He owns Top Flight.
     
  3. Jul 11, 2019 at 8:14 PM #3

    yucel

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    thank you for your answer and advices i will send pm now.
     
  4. Jul 11, 2019 at 8:35 PM #4

    manixFan

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    Also it's important to realize that the Fruity chute is much more 'powerful' in slowing down a rocket. For example, for a 25lb (11.3 kilos) rocket, the Iris chute will bring it down at a safe 19fps (5.8 meters per second), but the Topflight chute would be an unsafe 32fps (9.8 m/sec). So you can see that for the same size of chute the Fruity chute is much more effective, but at a far greater cost. The 70" Topflight chute would be great for a rocket up to about 9lbs. (4 kilos)

    I use both kinds of chutes. For most rockets I can use the less expensive chutes and they work just fine. But I fly a lot of minimum diameter rockets that are tight on space so the Fruity chutes work great for those and are worth the extra expense.

    Fruitychutes has a great descent rate calculator:

    https://fruitychutes.com/help_for_parachutes/parachute-descent-rate-calculator.htm

    It allows you to compare their chutes to other brands. There are other similar calculators available. It is really important to make sure the chute is correctly sized to how heavy your rocket is and for the space you have available. While the two chutes you are looking at are the same diameter, they are not meant for rockets of similar weight.


    Tony
     
    Last edited: Jul 11, 2019 at 8:45 PM
  5. Jul 11, 2019 at 8:44 PM #5

    yucel

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    Thenk you for your reply Tony
    actually we are a team for a competition and we calculate the size of parachute with a formule and it must be 180 cm and competititon rule say you cant use under 180 cm and it must be bring down 9 m/s . so if their packing volume is same ı should use the cheap one right? in top flight recover site is no information about packing volume. our parachute areas diameter is 12.2 cm and 20 cm high so 70" top flight recovery parachute is okey for this size what is your opinion.
     
  6. Jul 11, 2019 at 10:03 PM #6

    manixFan

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    Well, since this is a competition, here is a great paper that discusses packing density:

    https://fruitychutes.com/files/blog/NARCON 2013 - Rocket Recovery Technology.pdf

    You will find information on parachutes and their density and packing. I can't answer if the chute will fit because it depends on how much space your recovery harness and chute protector will take. Don't forget that you much protect the chute from the ejection gases or it will get burned and melt. Generally it is wrapped in a Nomex cloth - that will take up extra room. If you are using tubular nylon for your recovery harness that takes up a lot more room than a Kevlar harness. Also add in things like quick links and the overall space required can be quite a bit more than just the chute itself.

    You haven't said how heavy your rocket is - that is really the best way to determine what parachute to use. You can have several chutes that are 180cm in diameter but they can have very different descent rates. A simple flat sheet chute compared to a domed panel chute will perform very differently, as will an Iris chute. Some of that is discussed in the link above.

    A simple test would be to get a large sheet of plastic, like a heavy duty garbage bag or a thin plastic drop cloth like used for painting, and cut a circle out of it that matches your estimated size. Even if you have to use several pieces that's ok. Then you can use that to get a rough estimate of how large a volume you need to pack your chute, keeping in mind the other things you'll need to get in that same space. To estimate the Nomex cloth, you can use the material from a cotton t-shirt (but only for the estimate!)

    Good luck,


    Tony
     
  7. Jul 12, 2019 at 3:11 PM #7

    Nytrunner

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    If I recall correctly, this Turkish competition uses non-pyro deployment, so that's a bonus
     
  8. Jul 12, 2019 at 7:46 PM #8

    yucel

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    thank you so much
     
    Last edited: Jul 13, 2019 at 5:56 AM
  9. Jul 12, 2019 at 7:48 PM #9

    yucel

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    exactly we are using mechanical deployment and ejection
     

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