Forums: Skydiving: General Skydiving Discussions:

nutter  (C 1509)

Nov 12, 2002, 12:42 AM
Post #1 of 17 (2186 views)
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I have 2 questions,

Is wing loading the KEY factor in a canopies flight and or fligh characteristics,speed(forward) rate of descent.ect ??

Does the make or design of a canopy have anything to do with the Wing loading (excluding cross braced)ie elliptical and semi-elliptical ??

Sonic  (B 102345)

Nov 12, 2002, 3:13 AM
Post #2 of 17 (2160 views)
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It's both, although I think wingloading is the major factor here. I'm sure one of the more experienced people will be able to explain it better than I can.

ernokaikkonen  (D 12)

Nov 12, 2002, 3:39 AM
Post #3 of 17 (2154 views)
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>Is wing loading the KEY factor in a canopies flight and or fligh
>characteristics,speed(forward) rate of descent.ect ??

IMO, yes. A student could jump a fully elliptical canopy @ <1.0 wingloading relatively safely. On the other hand, a square canopy loaded @ 2.0 would be a killer. Literally.

>Does the make or design of a canopy have anything to do
>with the Wing loading (excluding cross braced)ie elliptical
>and semi-elliptical ??

I'm not sure I understand the question. Wingloading is calculated from the jumpers weight and the surface area of the canopy. Ie 200lbs:200sqft=1.0 lbs/sqft wingloading(1.0:1).

The shape of the canopy has no effect on the wingloading. Elliptical canopies tend to have design charasteristics that allow them to be flown at higher wingloadings.

Sonic  (B 102345)

Nov 12, 2002, 4:04 AM
Post #4 of 17 (2146 views)
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The shape of it has no effect on the wingloading.

(This post was edited by Sonic on Nov 12, 2002, 4:04 AM)

ernokaikkonen  (D 12)

Nov 12, 2002, 4:19 AM
Post #5 of 17 (2139 views)
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Isn't that what I said?

Sonic  (B 102345)

Nov 12, 2002, 4:26 AM
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Yup - I did type something completly different along the lines of how how taper affects speed, but then realsied I misread the question. oops.

nacmacfeegle  (D 11004)

Nov 12, 2002, 4:31 AM
Post #7 of 17 (2135 views)
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"Is wing loading the KEY factor in a canopies flight and or fligh characteristics,speed(forward) rate of descent.ect ??"

No the major factor is the design of the wing, eg I could load up a manta, and a cross brace at the same wing loadings and get different performance.
Also consider parasitic drag, angle of attack, dihedral angles, and materials of construction (zp vs f111 etc). Hell even the altitude of your DZ has a surprising affect on landing performance.

"Does the make or design of a canopy have anything to do with the Wing loading (excluding cross braced)ie elliptical and semi-elliptical ??"

Canopies have different recommended wing loadings, dependent on canopy design, and experience levels. Increased wing loadings generally make for faster landings, but there is a practical limit, dynamic vs static stalls etc.

You list blade running in your profile, so I would have thought that you would have had a more in depth understanding of things like this?? But hey....maybe you just fly them, not build them...

If you have an in depth look at the swooping forum, lots of things like lift, drag, angle of attack etc are discussed by far more knowledgeable people than me. You might have better luck in your quest for understanding there.
Good luck, and awsome swoops.....

ernokaikkonen  (D 12)

Nov 12, 2002, 4:43 AM
Post #8 of 17 (2130 views)
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>No the major factor is the design of the wing,

I have to disagree with that one, did you read my post?

nacmacfeegle  (D 11004)

Nov 12, 2002, 5:00 AM
Post #9 of 17 (2125 views)
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Lets take this offline....to the other place.....

Moderator
Nov 12, 2002, 5:36 AM
Post #10 of 17 (2110 views)
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http://www.performancedesigns.com/education.asp

AndyMan  (D 25698)

Nov 12, 2002, 6:36 AM
Post #11 of 17 (2096 views)
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Quote:
IMO, yes. A student could jump a fully elliptical canopy @ <1.0 wingloading relatively safely.

I disagree. The most common eliptical canopy is the Stileto. At lighter wingloadings the Stileto becomes very prone turbulence, largely because it has a very flat glide - it's easier for the nose to fold under then the "tapered" or "square" canopies.

I presume this is also true for canopies that have a relatively similar wing, like the Crossfire, Heatwave, Etc.

PD does not recomend the Stileto for students or beginners. They do say that very light intermediate jumpers can jump one at an intermediate level.

Icarus does not recomend you jump a Crossfire below a 1.4 wingloading.

Surprisingly, PISA does not make any recomendations for anything on the Heatwave... As far as I can tell from their website, a student could equally jump 190 at 1.0 or a 95 at 2.0. I believe either condition is equally bad, for different reasons.

_Am

The St

bobsoutar  (D 5310)

Nov 12, 2002, 8:51 AM
Post #12 of 17 (2062 views)
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In simple terms - the higher the wingloading, the faster the forward speed. The more eliptical it is the faster and tighter it will turn.

billvon  (D 16479)
Moderator
Nov 12, 2002, 11:53 AM
Post #13 of 17 (2028 views)
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>Is wing loading the KEY factor in a canopies flight and or fligh
>characteristics,speed(forward) rate of descent.ect ??

It is the most significant factor but not the only factor. Planform, trim angle, brake set, etc have a lot to do with it as well.

>Does the make or design of a canopy have anything to do with the
> Wing loading (excluding cross braced)ie elliptical and semi-
>elliptical ??

Nope, even cross bracing doesn't affect it. It might affect how the wing is measured if they use mathematical tricks to deal with the curved edges, but a 120 square foot canopy should have about the same area whether square or highly elliptical.

jumperconway  (D 24335)

Nov 12, 2002, 12:46 PM
Post #14 of 17 (2016 views)
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Andy,
This weekend a very experienced jumper on a Stiletto 120 loaded at maybe 1.2-1 had her canopy collapse twice from about 150'. She was directly over me and there were several loud KUHWHACK! sounds. the wind was bouncing between 17-23mph and turbulent! I watched the end cells touch below 50'and thought she was fixin to get real broken up or killed. I was in the same wind on my Xaos loaded at 2.2-1 coming in on front risers and had no problems what so ever!
I have also watched students on Sabers loaded very lightly seeming to breath and that scares me to death!
C 1035

crazy  (D 23767)

Nov 12, 2002, 9:22 PM
Post #15 of 17 (1974 views)
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there is quite an informative web site: http://www.grc.nasa.gov/WWW/K-12/

To answer more specially your questions, the wing loading affects the flight characteristics but it's not the key factor; many other elements, such as the trim, the airfoil, the planform or the structure can have a more significant effect. Even for the speed, wingloading is not the key factor.

--
Come

bobsoutar  (D 5310)

Nov 13, 2002, 3:24 AM
Post #16 of 17 (1945 views)
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Seen similar (although not quite as dramatic) situations occur with no problems on my Extreme. Do you find the Xaos loaded at 2.2 about right?

jumperconway  (D 24335)

Nov 13, 2002, 7:09 AM
Post #17 of 17 (1923 views)
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