The best glide ratio canopy

[Sabrekakkonen 0]

Simple question: what skydiving canopy has the best glide ratio?

[Pobrause 6]

Simple question, not so simple answer.
Depends on headwind, downwind, wingload, profile, canopy size, inputs... just to name a few.

Assuming no wind, no inputs I would bet my money on a lighty loaded biggish pulse. And of course nearly every 9cell student canopy.

Last sunday at a DZ I visited however the canopy with the best g/r was a VK75 at 3.4. Everybody else barely made any forward movement or was driving backwards.

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To absent friends

[skydiverek 63]

Pulse and Pilot come to mind. Very flat glide.

[Di0 2]

Pobrause

Simple question, not so simple answer.
Depends on headwind, downwind, wingload, profile, canopy size, inputs... just to name a few.

Agree with most of those, except (counter-intuitively) wingloading.
Within reason (i.e. wingloading not so high or so low to noticeably "deform" the canopy from its intended shape), W/L doesn't affect the glide ratio of a canopy, yes, it affects the vertical and horizontal speeds, BUT the glide angle should remain reasonably unchanged. If I don't remember it wrong, the glide ratio is only a function of Lift/Drag, which are mostly aerodynamic parameters, i.e. they vary based on canopy design, shape, efficiency, etc.
Now, this is *strictly* true for any fixed wing design, on a canopy the suspended weight alters the trim so that also alters the L/D, hence the glide ratio, but I suspect that to be a relatively small effect.
I could be wrong.

I'd like to be corrected by anyone that has every studied the problem from in a rigorous manner (not the "I was flocking with my buddy once and...")

I'm standing on the edge
With a vision in my head
My body screams release me
My dreams they must be fed... You're in flight.

[accumack 14]

Wind has no effect on glide ratio! Distance over the ground yes.

[chuckakers 425]

Sabrekakkonen

Simple question: what skydiving canopy has the best glide ratio?

I haven't jumped everything, but I've jumped a bunch of elliptical stuff and the Stiletto has the flattest glide among elliptical canopies I've seen.

Chuck Akers
D-10855
Houston, TX

[Pobrause 6]

By wingload I meant more the ability to penetrate the wind, not deforming the canopy or altering the factory trimm, both of which would be negligible and most likely not even noticable under standart wings and loadings.

0.8 lbs/sqft --> even light wind impedes forward movement
Same canopy/size with 1.8 --> even high winds allow forward movement

Of course relative to the ground, should have made that clearer

ETA:
After a friendly tipp from hooknswoop I looked up L/D and infact the definition of L/D is the amount of lift generated by a wing or vehicle, divided by the aerodynamic drag it creates by moving through the air.

The ground obviously isn't relevant in aerodynamics, who would have thought
So I retract my former statements about influence of L/D by wind direction and such. But I also want to add, that for skydivers the concept of L/D in a scientific way lacks a lot of important things one should consider before choosing a canopy because of its flat trimm.

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To absent friends

[riggerrob 643]

Rio is correct and Pobrause is learning: both good signs.

Stiletto is one of the flatter-gliding skydiving canopies. Otherwise, few skydiving canopies are trimmed for flat-glide because many skydivers (canopy pilots, canopy formations, etc.) want a canopy ride as fast and as exciting as freefall, therefore their canopies are trimmed steeply nose-down.

If you want a truely flat-gliding canopy, look towards HAHO or para-gliding canopies.
Military High Altitude High Opening jumpers like to open at 30,000 feet fly as far down-wind as possible. The disadvantage is that most HAHO canopies are large enough to jump with rucksack, rifle and snowshoes.

OTOH para-gliders want the slowest possible descent rate to allow them to exploit even the weakest thermals (rising warm air).

[dpreguy 14]

Agree with Akers. Stilletto.

[DBCOOPER 5]

skydiverek

Pulse and Pilot come to mind. Very flat glide.

Pulse with the version one line set.

Replying to: Re: Stall On Jump Run Emergency Procedure? by billvon

If the plane is unrecoverable then exiting is a very very good idea.

[Sabrekakkonen 0]

Have they trimmed pulse flying steeper?
How many jumps u can jump with pulse? It has low porosity bottom skin.
Do it lose more faster flying performance compared to full zp canopies?
Thanks for answers and sorry my bad english!

[sundevil777 102]

Sabrekakkonen

Have they trimmed pulse flying steeper?
How many jumps u can jump with pulse? It has low porosity bottom skin.
Do it lose more faster flying performance compared to full zp canopies?
Thanks for answers and sorry my bad english!

From a quick look at line trim for the P01 vs P02 revision:
http://www.performancedesigns.com/docs/linetrims/PL-190-260-Line_Trim_Chart.pdf

it does look like the later revision is steeper along with the steering line attachments revised - "inboard".

I think that using non-zero porosity fabric doesn't result in lower performance over time.

When a wing is flying at high angles of attack (such as during a flared landing), it is very important that the airflow over the top of the wing stay "attached"/not separate from the surface of the wing. If air is leaking out through the top skin fabric too much, then I think it has the effect of separating the airflow. Conditions on the bottom skin of the wing are very different, with separation not being an issue, so leakage through non-ZP fabric on the bottom doesn't matter.

If it was possible to actually suck air into the wing through/from the top skin, then you get the ability to produce good lift at even higher angles of attack, as the airflow stays attached when it otherwise would not. This has been done on some experimental airplanes, including a Boeing 757 testbed that had part of the wing drilled with very tiny holes and a vacuum applied to suck air into the wing. So, air leaking out through the fabric matters a lot for the top skin, but not for the bottom, as long as it is not so much that cell pressurization suffers

People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

[Joellercoaster 6]

Agree with the other two.

I have a Pilot 132 and a Stiletto 135 and have jumped them back to back a lot, and the Pilot flies flat but the Stiletto even flatter.

--
"I'll tell you how all skydivers are judged, . They are judged by the laws of physics." - kkeenan

"You jump out, pull the string and either live or die. What's there to be good at?

[Sabrekakkonen 0]

Are there measured info about canopies actual glide ratio?(ofc relative to sir flow, ground speed not taken to account)

How about aerodyne zulu? Manufacturer says that they reahced over 4:1 ratio with computer simulation!?

[mikey348 0]

I've made it back from some seriously long spots with my Stiletto 135 when others on the load didn't and I opened the lowest. Very flat glide ratio.

"Admit nothing, deny everything, and demand proof"

[piisfish 140]

Revoline by REvo-Fly
http://www.revo-fly.com/revoline.php

scissors beat paper, paper beat rock, rock beat wingsuit - KarlM

[Joellercoaster 6]

piisfish

Revoline by REvo-Fly
http://www.revo-fly.com/revoline.php

If anyone is in touch with the people who own that site, could they pass on the potentially useful message that Flash-only websites went out about a decade ago, and mean that nobody can look at their stuff at all with a smartphone?

I'd love to know what their gear looks like, but the security preferences on my laptop won't allow Flash (with good reason) either. Even just some photos would be cool, for the rest of us.

--
"I'll tell you how all skydivers are judged, . They are judged by the laws of physics." - kkeenan

"You jump out, pull the string and either live or die. What's there to be good at?

[Alexg3265 0]

Fluid Wings Prime

I was that kid jumping out if his tree house with a bed sheet. My dad wouldn't let me use the ladder to try the roof...

[Di0 2]

accumack

Wind has no effect on glide ratio! Distance over the ground yes.

Since its definition is simply:
H: Horizontal distance across ground
V: Vertical Distance across ground
and the Glide Ratio is just: H/V.
Yes, it does.

The result L/D is the result of some simple calculations, substitutions etc. and assumptions, namely: glided flight, no wind, rigid wing, being in the linear part of the envelope of lift and drag, and others I might forget.

I'm standing on the edge
With a vision in my head
My body screams release me
My dreams they must be fed... You're in flight.

[accumack 14]

The glide path changes with wind and the perceived glide ratio changes but the actual glide ratio does not unless you make an input i.e.: brakes. Glide ratio is how far forward you go for every foot down no reference to the ground.
http://parachutistonline.com/safety_training/foundations-flight/relative-glide

[pchapman 279]

1. Indeed the "glide ratio" for an aerial vehicle is defined without any wind or reference to the ground. So there's no technical need to keep saying "glide ratio ... without wind".

But skydivers aren't all trained aero engineers or pilots so inevitably someone is unclear whether someone else is talking about wind or no wind conditions, so in practice we sometime have to remind someone, "I'm talking about the real glide ratio of the parachute... no wind... and not talking about what happens in a wind." (In which case, the best glide ratio canopy would be the slowest descending one, flying downwind in a hurricane...)

2. Hybrid parachutes-paragliders have been around as a concept for a long time, but have never really found a civilian market. RevoFly was mentioned by Piisfish -- and RevoFly mention Nervures being involved, people who were working on that stuff two decades ago. [eg, Paramag did an article on them in 1998]. Even Paraflite / Airborne systems has some high glide military canopies that look like early paragliders. And I jumped a couple experimental PD canopies in the mid 1990s that were easily getting 4.5:1 glide ratio, although squirrely on opening.

3. Want a really high glide production skydiving canopy?
Bigger canopies tend to do better because the payload under them is smaller and less draggy in relative terms. So while a Stiletto is probably great in a medium to small size, an efficient student canopy like the Navigator might have an even better glide ratio. Not sure of that, but just my impression.

[RMURRAY 1]

peter, re experimental pd canopies,,,if i remember right "pink floyd" and "black death".

[gowlerk 2,190]

For crying out loud, don't be so obtuse. Glide ratio is a property of the canopy independent of wind conditions and ground speed. To consider it otherwise would make it a meaningless number with no use at all.

Always remember the brave children who died defending your right to bear arms. Freedom is not free.

[Di0 2]

gowlerk

For crying out loud, don't be so obtuse. Glide ratio is a property of the canopy independent of wind conditions and ground speed. To consider it otherwise would make it a meaningless number with no use at all.

I'm an aerospace engineer and I spent years studying performance and mechanics of flying, so yes, I am "obtuse".

The number IS meaningless if you don't correctly specify the hypothesis under which that number is calculated. It has absolutely no meaning. Untrained people use the right formula in the wrong context all the time.

Also, think of this.
Two canopies, same glide ratio (unrealistic numbers to make math easy).

Zero wind
Canopy A:
Horizontal speed: 40 mph
Vertical speed: 20 mph
Glide Ratio: 2

Canopy A:
Horizontal speed: 20 mph
Vertical speed: 10 mph
Glide Ratio: 2

20 mph headwind
Canopy A:
Glide ratio: 1
Canopy B:
Glide Ratio: 0.

Both changed, and both to two different results. Where with no winds, both canopy would have landed in the same spot, now they are landing in two very different spots. It's not just nitpicking, it's an important difference.

Of course, the aerodynamic characteristic, and the relative performances, of the canopies don't change BUT the glide ratio is a number that can be used to estimate whether an aircraft with failed engines will make it to a landing area or not, etc. so not considering the winds is only half the picture. That's why it's important to specify that the glide ratio is generally a "0 winds" number, and you can define glide ratios with different wind conditions.

EDIT:
I read the link from Parachutist, they basically define Glide Ratio as an absolute measurement and "Relative Glide" as a "Glide Ratio with winds". That doesn't even make sense from an English perspective, as they talk about a "relative glide" which is missing the actual term "ratio", a "relative glide" is not a measurement of something, although I see where they're going with it and the simplification is worth the tiny inaccuracy, we can agree that "glide ratio" is in 0 winds, and relative glide ratio is the glide ratio with winds. I'd be ok with that. Either way, they're both glide ratios. That doesn't change the fact that winds will differently affect two canopies with the same absolute glide ratio to very different results.

I'm standing on the edge
With a vision in my head
My body screams release me
My dreams they must be fed... You're in flight.

[chuckakers 425]

Quote

Of course, the aerodynamic characteristic, and the relative performances, of the canopies don't change....

And I believe this is the only information the OP was looking for. Just a simple answer on what canopies have the best glide ratios when other factors are not considered.

In my experience the Stiletto is one of them.

Chuck Akers
D-10855
Houston, TX