Forums: Skydiving Disciplines: Swooping and Canopy Control:
Canopy Downsizing Chart by Brian Germain

 

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BrianSGermain  (D 11154)

Jan 27, 2009, 3:42 PM
Post #1 of 39 (25034 views)
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Canopy Downsizing Chart by Brian Germain Can't Post

Many folks believe that we need better guidelines for canopy downsizing. I have spent a great deal of time putting together a chart for exactly that purpose, along with 21 pages of ideas that make sense of the chart.

Here is the link:

http://www.bigairsportz.com/pdf/bas-sizingchart.pdf


(This post was edited by ianmdrennan on Jan 29, 2009, 1:10 PM)


frost  (D 25011)

Jan 27, 2009, 7:32 PM
Post #2 of 39 (24908 views)
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Re: [BrianSGermain] Canopy Downsizing Chart by Brian Germain [In reply to] Can't Post

Thank you! This should be a locked sticky for all future new jumpers.


Premier ianmdrennan  (D 25821)
Moderator
Jan 27, 2009, 7:48 PM
Post #3 of 39 (24899 views)
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Re: [frost] Canopy Downsizing Chart by Brian Germain [In reply to] Can't Post

Suggestion noted Wink


rmarshall234  (D 18793)

Jan 28, 2009, 8:01 AM
Post #4 of 39 (24806 views)
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Re: [BrianSGermain] Canopy Downsizing Chart by Brian Germain [In reply to] Can't Post

AWESOME!

I haven't digested it all yet but what a nice piece of work. Also, kudos for having the guts to do what needs to be done. Thank you.


BrianSGermain  (D 11154)

Jan 28, 2009, 10:34 AM
Post #5 of 39 (24764 views)
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Re: [rmarshall234] Canopy Downsizing Chart by Brian Germain [In reply to] Can't Post

If you look at the numbers carefully, you will see that the wingloading recommendations are not linear. Smaller canopies match you with a somewhat lighter loading, while big ones suggest a heavier load, to reflect the non-linear nature of scale effects.


dragon2  (D 101989)

Jan 28, 2009, 1:56 PM
Post #6 of 39 (24722 views)
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Re: [ianmdrennan] Canopy Downsizing Chart by Brian Germain [In reply to] Can't Post

This should also be a sticky: Downsizing Checklist By Bill von Novak


Cornholio  (D License)

Mar 12, 2009, 6:41 PM
Post #7 of 39 (23880 views)
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Re: [BrianSGermain] Canopy Downsizing Chart by Brian Germain [In reply to] Can't Post

Sweet!! According to the chart at exit wt 235 (don't laugh) and 500+ jumps, I should be jumping between a 150 and 139.

Kidding aside, I'm very happy with my 190 and have no plans to downsize anytime soon. However, much thanks Brian for putting that together. That should help a lot in helping the young (and stupid) from jumping a canopy that's too small for them.


GLIDEANGLE  (D 30292)

Mar 13, 2009, 8:00 PM
Post #8 of 39 (23730 views)
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Re: [Cornholio] Canopy Downsizing Chart by Brian Germain [In reply to] Can't Post

I think you misunderstand the chart. The chart is describing the MINIMUM canopy size.

Note the following direct quote from the chart:

*Jumpers are welcome to use a larger parachute than the chart suggests.


Hausse  (C 1)

Mar 15, 2009, 9:37 PM
Post #9 of 39 (23586 views)
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Re: [GLIDEANGLE] Canopy Downsizing Chart by Brian Germain [In reply to] Can't Post

Gllideangle, I think you misunderstand ironyWink


jf951  (D License)

Mar 25, 2009, 9:03 PM
Post #10 of 39 (23346 views)
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Re: [Hausse] Canopy Downsizing Chart by Brian Germain [In reply to] Can't Post

HOLY HELPFUL!!!!
ur awesome!!!


EXTremeWade  (D 29835)

Mar 26, 2009, 5:51 AM
Post #11 of 39 (23304 views)
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Re: [jf951] Canopy Downsizing Chart by Brian Germain [In reply to] Can't Post

Awesome..I really am impressed. Brain, do you have a degree in AE?

wade


regulator  (A 53175)

May 25, 2010, 8:54 AM
Post #12 of 39 (18351 views)
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Re: [EXTremeWade] Canopy Downsizing Chart by Brian Germain [In reply to] Can't Post

It looks like my canopy choice was correct according to Mr. Germain. I currently have 35 jumps with my Sabre2 190 and I weigh 155 lbs. I guess I payed attention after all!


anycz100  (C License)

Jun 3, 2010, 8:30 PM
Post #13 of 39 (18166 views)
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Re: [BrianSGermain] Canopy Downsizing Chart by Brian Germain [In reply to] Can't Post

I just tried to stall my 168 Pilot loaded at 1.17. I pulled the brakes all the way down and held it for good 10s. It did not collapse or anything like that. It was square, stable and slow. I already shortened the brakes cause it had no flare. Is it normal? Are the brakes still too long?


phoenixlpr  (D 3049)

Jun 3, 2010, 10:04 PM
Post #14 of 39 (18148 views)
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Re: [anycz100] Canopy Downsizing Chart by Brian Germain [In reply to] Can't Post

In reply to:
I pulled the brakes all the way down and held it for good 10s. It did not collapse or anything like that. It was square, stable and slow. I already shortened the brakes cause it had no flare. Is it normal? Are the brakes still too long?
What is the connection? How would anyone able to tell if they are long or not from this info you provided?


BrianSGermain  (D 11154)

Jun 4, 2010, 1:00 AM
Post #15 of 39 (18136 views)
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Re: [anycz100] Canopy Downsizing Chart by Brian Germain [In reply to] Can't Post

Canopies over 150 square feet often run into this conundrum. Either you can stall it or you can front riser it, but not both. It is generally less costly to be unable to stall a large wing, since the slow flight prior to the stall is sufficiently slow to allow for good landings. If you tighten the brakes too much in order to reach the stall, you will sacriice the ability to front riser effectively and may be in brakes when you arms are all the way up. It is possible that the optimum configuration for this canopy is right where you are, or even slightly
longer.


anycz100  (C License)

Jun 4, 2010, 8:23 AM
Post #16 of 39 (18082 views)
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Re: [BrianSGermain] Canopy Downsizing Chart by Brian Germain [In reply to] Can't Post

Thanks Brian, my instructor told me a similar thing. I was looking for a second opinion.


linebckr83  (D 30571)

Jun 4, 2010, 9:07 AM
Post #17 of 39 (18065 views)
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Re: [anycz100] Canopy Downsizing Chart by Brian Germain [In reply to] Can't Post

My Pilot 188 was the same way. I had to take a wrap to stall it out on toggles. Like Brian said, the stall speed on those bigger canopies is low enough that the speed you can slow down to with the toggle stroke is more than enough to flare correctly.


bluetwo  (C License)

Jun 9, 2010, 3:33 AM
Post #18 of 39 (17848 views)
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Re: [linebckr83] Canopy Downsizing Chart by Brian Germain [In reply to] Can't Post

Saved the chart to my desktop so I can check it out more later. Can't say I understand all the info there (below the chart that is), but it should be interesting to figure out.

Thanks


Scubadivemaster  (D License)

Jun 20, 2010, 2:26 PM
Post #19 of 39 (17694 views)
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Re: [BrianSGermain] Canopy Downsizing Chart by Brian Germain [In reply to] Can't Post

Nicely presented.

I just had a very heads-up newer jumper ask me to explain to his 150 jump, 88lb girlfriend that she would be fine jumping a Nitro 108 because her geared up wingloading was only .98 to 1. He was surprised when I told him absolutely not. He was operating on the limited information that is readily available that wingloading is the most important (or only) consideration. We are failing new jumpers by giving them incomplete information.

The "Non-linear Nature of Parachute Performance" should be required reading for every new jumper and anyone who advises jumpers on the canopy they should fly.


bluetwo  (C License)

Jun 20, 2010, 4:39 PM
Post #20 of 39 (17673 views)
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Re: [Scubadivemaster] Canopy Downsizing Chart by Brian Germain [In reply to] Can't Post

Help please. I did a search for the Non-linear Nature of Parachute Performance but all I got was this thread...

Can somebody point me to it please?


Scubadivemaster  (D License)

Jun 20, 2010, 4:50 PM
Post #21 of 39 (17669 views)
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Re: [bluetwo] Canopy Downsizing Chart by Brian Germain [In reply to] Can't Post

The link in the original post. Its a few pages down.


Blink  (C 3275)

Jun 20, 2010, 5:07 PM
Post #22 of 39 (17663 views)
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Re: [bluetwo] Canopy Downsizing Chart by Brian Germain [In reply to] Can't Post

In reply to:
Help please. I did a search for the Non-linear Nature of Parachute Performance but all I got was this thread...

Can somebody point me to it please?

http://www.bigairsportz.com/pdf/bas-sizingchart.pdf
Page 4.


pchapman  (D 1014)

Jun 21, 2010, 5:25 AM
Post #23 of 39 (17605 views)
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Re: [Blink] Canopy Downsizing Chart by Brian Germain [In reply to] Can't Post

In reply to:
In reply to:
Can somebody point me to it please?

http://www.bigairsportz.com/pdf/bas-sizingchart.pdf
Page 4.

That seems to touch on the subject but nothing more. (But I just skimmed it.) I believe it was Performance Designs / John Leblanc who have the full article on wing loading vs. overall weight. Must be at PD's web site.


(This post was edited by pchapman on Jun 21, 2010, 6:35 AM)


bluetwo  (C License)

Jun 21, 2010, 4:00 PM
Post #24 of 39 (17518 views)
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Re: [pchapman] Canopy Downsizing Chart by Brian Germain [In reply to] Can't Post

Holy crap, I got three people helping me?

That's cool though. Thanks for recommending students read that. It does seem like a lot at first but surely it's good to know.


(This post was edited by bluetwo on Jun 21, 2010, 4:01 PM)


castrodavidd  (C 33299)

Jul 13, 2010, 11:41 PM
Post #25 of 39 (17204 views)
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Re: [BrianSGermain] Canopy Downsizing Chart by Brian Germain [In reply to] Can't Post

BG,
I have 125 jumps and fly a Heatwave 190 loaded at 1.4. I have been working on 90 degree landings and carving. I have read your book, down sizing chart, and Novack's checklist. I am wondering at what point can a jumper disregard the jump numbers for down sizing and use the ability of the pilot. I would like to get a recomendation from you for a canopy coach in the midwest " Oklahoma Area" that could evaluate me on my ability and not the jump numbers. I would like someones honest opinion weather I could be safe on a smaller canopy.

Also, I was reading about the non-linear nature of scale effect. Your book says that aerodynamics don't scale, and I can't understand why they wouldn't. Having taught aerodynamics for airplanes and helicopters I thought I knew this subject pretty well. Airplane manufactures in the past used scale models to determine stall speeds, stability characteristics, and drag ratios prior to ever building a prototype. If it works on a rigid airfoil how does that differfrom a nonrigid canopy? Are there any theoretical differences between a canoy and an airplane wing?


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