What are these? Canopy Warts?

[diablopilot 2]

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But yes, I agree with your basic observation that it is a contradiction of design to make the stabilizers smaller while at the same time adding winglets.

The idea was both to make the stabilizer smaller, and put it under tension. Flapping things cause drag.

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You're not as good as you think you are. Seriously.

[diablopilot 2]

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I haven't owned one!!

Cool....take your boxing gloves to Eloy then.....

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You're not as good as you think you are. Seriously.

[VectorBoy 0]

Someone could always just duct tape the nipple on one side down and see if there is a magnanamous flight & flare difference. Difference enough to spend the time and money to maim a canopy cell like that during manufacturing.

Hi-per doesn't claim this design flies bigger as a result of the warts does it? Just checking.

[diablopilot 2]

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Hi-per doesn't claim this design flies bigger as a result of the warts does it? Just checking.

No they don't. They do say that the canopy will be able to be slowed down upon landing more easily.

BTW both teir lower end model (the Nitro) and their high performance model (the Blade) have the "winglets".

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You're not as good as you think you are. Seriously.

[quade 3]

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I can understand skepticism, but until you've flown it you really won't know.

The beauty of aerodynamics is that it's not really a subjective thing -- it simply is.

What it would take to convince me these things work would be what we call "hard data". Throw the thing in a wind tunnel and do some testing, then publish the results. Hell, I'd even take a software simulation, but I have a -really- big feeling this just isn't going to happen.

There's a reason why the guys were able to sell the Emperor his new clothes -- he wanted to believe in them.

quade -
The World's Most Boring Skydiver

[pilotdave 0]

Ever seen empirical data to back up any claims by a parachute manufacturer? Air locks, cross braces, skinny lines, no stabilizers, slider sizing, etc. Ever seen wind tunnel results or any aerodynamic analysis of a canopy? Do most canopy manufacturers even do real aerodynamic analysis or wind tunnel testing (i'd imagine a canopy would be a complete pain to test in a wind tunnel).

How about the wingtips on a piper archer (or similar). They're designed to throw the wingtip vortices outward, giving the aircraft more effective aspect ratio (lower induced drag). I'd imagine they did some testing. Think they published the results?

I wouldn't expect a canopy manufacturer to share that kind of data if they had it.

But I do agree that aerodynamics isn't subjective. But it's also not always obvious either.

Dave

[diablopilot 2]

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The beauty of aerodynamics is that it's not really a subjective thing -- it simply is.

Yes, and no. You're trying to apply aerodynamics to a canopy the same way you apply it to an airplane. The theory is the same, the subject is not.

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You're not as good as you think you are. Seriously.

[ltdiver 3]

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They do say that the canopy will be able to be slowed down upon landing more easily.

Indeed they do exactly this.

Case in point...Mine. I demo'd the original Nitron when it was introduced way back when. About 40 jumps on a 135. I stood every one of those landings up nicely!

ltdiver

Don't tell me the sky's the limit when there are footprints on the moon

[billvon 2,426]

>From my experience (and I've test jumped ALOT of canopies)
>they do indeed make a difference in how the canopy flies.

I don't think anyone can say that with any authority until they've jumped a Nitro with the winglets removed. I've jumped other canopies with better bottom-end flare without winglets, for example, so there's probably more to flare than winglets.

[billvon 2,426]

>Ever seen empirical data to back up any claims by a parachute manufacturer?

Rarely. Brian Germain did some test jumps with airlocked canopies modified in various ways; such testing provides some comparative, if not quantitative, data. (Interestingly, one such test seemed to suggest the "airlocks increase the internal pressure and thus make the canopy more rigid" theory isn't correct.) About the only hard numbers I've seen are glide and descent rate since they can be measured directly. One problem is that so many things about a canopy relate to how it "feels" rather than what its boundary layer looks like that such data is rarely meaningful to anyone.

[quade 3]

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Think they published the results?

You're not suggesting that papers haven't been published on rigid wing winglets are you, because I can assure you they have been numerous times.

For instance;

Green, Sheldon I (editor). Fluid Vortices, Kluwer Academic Press, 1995.


Milne-Thompson LM. Theoretical Aerodynamics, MacMillan Co., London, 1966.


Clancy JC. Aerodynamics, John Wiley, New York, 1975.


Jones RT. Wing Theory, Princeton Univ. Press, Princeton, NJ. 1990.

Hoerner SF. Fluid Dynamic Drag, Hoerner Fluid Dynamics, 1965.


Larson, G. "How Things Work: Winglets", Air and Space Magazine, Aug/Sept 2001. Smithsonian Inst., Washington DC.


Whitcomb RT. A Design Approach and Selected Wind-Tunnel Results at High Subsonic Speeds for Wing-Tip Mounted Winglets. NASA TN D-8260, July 1976.

http://oea.larc.nasa.gov/PAIS/Concept2Reality/winglets.html

What I haven't seen is anything in the way of canopy winglets in publications.

I suppose we could take the position that the manufacturer actually has discovered something and is keeping it as a trade secret, but a lifetime in aviation tells my eyes a different story.

Tell ya what -would- be interesting . . . Rutan is supposed to give the keynote at PIA. It'd be interesting to run it by him to get his thoughts on the subject.

quade -
The World's Most Boring Skydiver

[pilotdave 0]

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Rutan is supposed to give the keynote at PIA. It'd be interesting to run it by him to get his thoughts on the subject.

Dick though, not Burt. Not sure what his aerodynamic expertise is. Burt on the other hand seems to be able to visualize aerodynamics in a superhuman way.
And yeah, I realize that much independent research has been done on winglet design. But there is as much "voodoo aerodynamics" in general aviation wingtip design as there is in canopy nose shaping or whatever other features. Marketing or aerodynamics? The manufacturers don't share their data.

I dunno if the canopy designer has any data to share other than a qualitative comparison.

I guess my feeling is that if they enhance the bottom end performance of the canopy, it should have really great bottom end performance. Market the flight characteristics of the canopy, not how they were achieved. If the bottom end performance is marginal, the "winglets" may have a huge effect, preventing poor bottom end performance. But who cares? The bottom end performance would still be marginal. I'm not gonna buy a canopy based on what fixes it has for it's own performance issues. I'm gonna buy one based on how it flies.

Dave

[bmcd308 0]

>>I'm not gonna buy a canopy based on what fixes it has for it's own performance issues. I'm gonna buy one based on how it flies. <<

And in that department, Nitro(n)s are pretty good, IMO.

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www.jumpelvis.com

[VectorBoy 0]

Dick though, not Burt. Not sure what his aerodynamic expertise is. Burt on the other hand seems to be able to visualize aerodynamics in a superhuman way.

[VectorBoy 0]

And in that department, Nitro(n)s are pretty good, IMO.

[bodypilot1 0]

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Nothing to say that the owner couldn't have a rigger sew them down with a patch and call it the wart mod or version 2.0.

Then again, "don't fix something that don't need fixing".....
With the 1200 jumps I have put on the 108 I have, it's still a great opening, great flying and great landing canopy with great swooping ability.
A handfull of off heading openings, a few openings with line twists "without a spin", zero lineovers and never had to chop it once.

IMO, there are plenty of other canopies on the market to buy for those that dont believe the winglets work.


Ed

www.WestCoastWingsuits.com
www.PrecisionSkydiving.com

[dorbie 0]

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What it would take to convince me these things work would be what we call "hard data". Throw the thing in a wind tunnel and do some testing, then publish the results. Hell, I'd even take a software simulation, but I have a -really- big feeling this just isn't going to happen.

Maybe it has already happened, except the publishing (unless you call a product line publishing). Canopy manufacturers experiment with all sorts of things that never make it to market. Just because it's not on the canopy doesn't mean it hasn't been tried:

http://www.icaruscanopies.com/techno.htm

Hmm wind tunnel testing by a canopy maker, seems like a "good thing".

[wuffo 1]

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http://www.icaruscanopies.com/techno.htm

Hmm wind tunnel testing by a canopy maker, seems like a "good thing".

That picture of the model canopy in the wind tunnel was taken many years ago, and Icarus' designer mostly did that for the "photo op". He got an opportunity to use a tunnel at a university in New Zealand on one occasion. I can assure you that none of Icarus canopies' are "tested" in a wind tunnel.

[dorbie 0]

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http://www.icaruscanopies.com/techno.htm

Hmm wind tunnel testing by a canopy maker, seems like a "good thing".

That picture of the model canopy in the wind tunnel was taken many years ago, and Icarus' designer mostly did that for the "photo op". He got an opportunity to use a tunnel at a university in New Zealand on one occasion. I can assure you that none of Icarus canopies' are "tested" in a wind tunnel.

Curses, you mean they lied!?

What's this industry coming to?

[wuffo 1]

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Curses, you mean they lied!?

Since there was actually a wind tunnel used at one point, I'd say more like "stretched the truth".

[dorbie 0]

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Curses, you mean they lied!?

Since there was actually a wind tunnel used at one point, I'd say more like "stretched the truth".

Quite a stretch IHMO. From their web page:

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We are the only sport canopy manufacturer using wind tunnel optimization in our design process resulting in superior control range, superior openings, and superior performance.

If all they did was have one photo-op session at the local university's wind tunnel years ago then this is not merely stretching the truth.

[PhreeZone 15]

>Quite a stretch IHMO

What about "Softest opening" "most powerful flare" and other claims like that. There is no hard evidence to support that either.

Yesterday is history
And tomorrow is a mystery

Parachutemanuals.com

[dorbie 0]

Let me try to explain what I think is the difference. An opinion about canopy performance could reasonably be held based on test jumps and other criteria, however it is difficult claim to be innocently mistaken about the use of wind tunnels in the canopy design process, unless of course you're a potential customer who has been mislead by a web site. It's a bald faced deception if the facts about the quick one off visit to the local uni for a photo op are true. Claiming this mythical wind tunnel testing imbues your canopies with superior performance uses the deception to lend credence to the claims.

Sorry to have hijacked a silly thread with an even sillier one.

[VectorBoy 0]

IMO, there are plenty of other canopies on the market to buy for those that dont believe the winglets work.
Ed

[Dougjumper 0]

I agree with you as to your imput.

My Experience is somewhat second hand as I had a very knowledgeable Skydiver tell me about these nice little appendages on the parachute and how their functionality did seem to actually help. You may know of whom im Speaking the Great Chris Martin....Anyway Buy landing and actually flying my Nitro It does seem to deliver on what he spoke of.

Good Day.