Quick look up chart - Decent rates - anyone have one?

Discussion in 'Recovery' started by dr wogz, Jun 17, 2019.

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  1. Jun 17, 2019 #1

    dr wogz

    dr wogz

    dr wogz

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    Hi all,

    Does anyone have a quick 'look-up chart' for typical chute diameters vs. weight?

    I know of a few calculators, and webs sites that state their decent rates for available sizes. But I'm looking for a static chart or spreadsheet that can be a quick reference once at the field, some simple spreadsheet type thing.. Something that can be added to the field box or binder..
     
  2. Jun 17, 2019 #2

    timbucktoo

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    the problem I see is what do you call "typical chute"? Every chute design has it's own descent rate table/chart.
     
  3. Jun 17, 2019 #3

    Bat-mite

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    Would be a manual effort of visiting every chute manufacturer, pulling their data, and combining into a spreadsheet. That might be useful, but would be a pain.

    But the reality is that no two types of chutes behave the same way. Round, hexagonal, octagonal, proprietary, etc., there is no one size fits all.
     
  4. Jun 17, 2019 #4

    dr wogz

    dr wogz

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    thanks,

    While I am aware of the variables, I thought there might have been a general 'rule of thumb' or some basics that a size might offer...

    (Is there really that much of a difference of a flat chute, but round vs hex vs octo shaped?)

    might be an interesting study..
     
  5. Jun 17, 2019 #5

    manixFan

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    To me a typical chute is a round, hex, or octogonal flat sheet. Lots of calculators to deal with those. Plus of course Rocketman and Fruitychutes have their descent rates on their website. Here's what I have:

    https://descentratecalculator.onlinetesting.net

    https://www.apogeerockets.com/education/downloads/Newsletter149.pdf

    https://www.apogeerockets.com/education/downloads/Newsletter496.pdf

    https://www.rocketreviews.com/parachute-size-calculator.html

    http://www.rocket-simulator.com/parachute.php

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

    https://www.pcprg.com/rounddes.htm

    http://www.rocketmime.com/rockets/descent.html

    http://www.sunward1.com/images-tarc/Streamer Calculations (Cooke) (Jun 09).pdf

    I'm sure there are others but that's what I have in my bookmarks. The Apogee articles have links to a lot of great source material. The Fruitychute link has lots of other manufacturers chutes as well. I could not find the link for the PDF I uploaded that is listed below, but it is what you originally asked for - a simple chart showing descent rates.


    Tony

    (the chart on the PDF is unusual - it is a mix of Imperial and metric units. The lines represent a descent rate of about 15fps which to me is pretty conservative.)
     

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    Last edited: Jun 17, 2019
  6. Jun 17, 2019 #6

    Bat-mite

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    Ah, we do that all the time in rocketry. "I've got an 8-inch rocket with a 98mm MMT." ;)
     
  7. Jun 17, 2019 #7

    crossfire

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    Top flight has info on there site.
     
  8. Jun 17, 2019 #8

    Steve Shannon

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  9. Jun 17, 2019 #9

    IputtheAinBAMA

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    My suggestion is to just print out a weight vs descent rate graph for each chute you purchase or make. That way you can take the graphs to the field and decide which chute works best with the given conditions and rocket. You could probably even put all of your chutes onto one graph for a single page, quick reference. Unless you are planning or already own hundreds of chutes I would just focus on what you have and what you acquire. If you need help let me know but there are a few different programs to help; mathway, desmos, graphmatica. If you want example of parachute graphs go to bamachutes.com
     
  10. Jun 17, 2019 #10

    caveduck

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    I especially like the Fruity Chutes calculator, which seems to have a lot of the right engineering in it and is oriented to sport rocketry. If you've ever talked to Gene you'll know he's a serious parachute expert. The difference in Cd between the various chute designs is huge. A spherical chute is way better than a flat sheet, and a toroidal is way better than a spherical. Tables of descent rate vs mass and chute size could be handy, but you need a different table for each major chute design.
     
  11. Jun 18, 2019 #11

    dr wogz

    dr wogz

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    Bama, at this point, that's what I'm planning to do, probably the easiest..
    Yes, will be looking at everyone's charts & such.
     
  12. Jun 18, 2019 #12

    manixFan

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    Not to derail the thread, but a quick point about graphs:

    * black backgrounds are the worst possible choice - they are hard to read on screen and will use a ton of toner/ink
    * don't use different colors for lines, use different patterns or weights if needed - many lighter colors will disappear when printed, especially if printed on a black and white printer
    * save charts as PNG format, not JPG. JPG will add artifacts that shows up as noise, especially when printed
    * make two versions - one that works for screen resolution and one for print
    * use consistent units
    * Label everything!


    Tony
     

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