XRW and canopy area vs WS area

[angryelf 0]

XRW is going on at few places these days. Trim tabs from 4-5 years ago are pretty much gone in favor of super high wingloads as the "discipline" continues to progress. There seems to be two totally different ways of measuring compatibilty in regards to canopy size/WL vs WS model.

Just for fun-what are the WS surface areas? Canopies are measured in surface area (ft or m squared) and wingloading is an ever present discussion as it pertains to the canopies. In contrast, the wingsuiters only seem to care about glide ratio, descent rate in mph or kph, etc.

In short-is there common way to measure compatibility other than "so and so flew a X bird/C Race/ Whatever next to a VK/ Petra/Whatever with 43 lbs of lead and it worked so thats the standard..."

Obviously there is a WS pilot and a Canopy pilot component to this. A marginal WS'er cant get max float needed and a marginal canopy pilot can't/shouldn't be risking the WL's necessary for XRW.

And there will be a variance for every suit as it is scaled to the pilot making each suit a different size as measured in the usual manner prescribed for canopies...

Lastly-is there even a crossover between canopy/WS size, or should the standard of measure be Glide ratio or descent rate dependant?

Just throwing it out there....


-Harry

"Sometimes you eat the bar,
and well-sometimes the bar eats you..."

[Anachronist 2]

Apples and oranges. They are fundamentally different in how they function, you already pointed out a few of those differences.

Wingsuit span, chord, camber, airfoil, angle of attack, and planform can all substantially change depending on body position (and be different between the arm and leg wings). In short, it is a much more dynamic surface(s).

When it comes to wing loading, which isn't a really good way to look at it anyway, there is much more variation between jumpers. Take a hypothetical perfect square 6' by 6' person, bigger than any wingsuit on the market, 36 sqft. A 150lb jumper would load it at ~4.2:1, a 250lb jumper ~7:1. As you can see there is an incredible difference. The variation is even greater because even the biggest wingsuits are actually a good bit smaller than that in surface area (how much I don't know but I would guess 1/2 to 2/3).

To add to the complexity, someone who is say 5'6" has a smaller surface area than someone who is 6' jumping the same model suit (because they are scaled to fit as you mentioned).

So the answer is a performance "window" rather than any sort of area comparison. And different WS pilots can get different performance out of the same model suit based on height, weight, and skill. But put "x" amount of weight under a certain canopy and in straight and level flight the only difference is going to be the drag of the pilot (not insignificant but not comparable to the variation in WSs).

So say that a 6' 150lb wingsuiter can XRW with "Z" wingsuit; a 5'6" 200lb wingsuiter with the same model suit might not be able to, regardless of their ability/skill (or maybe they can, which invalidates a WL comparison).

Then there is the whole tail vs. arm wing relationship with wingsuits that doesn't apply to canopies.

Though I'm sure you could make some arbitrary comparison by averaging suits that don't XRW and those that do and make the statement "you need "x" sqft of wingsuit per "y" sqft of canopy, but such a correlation doesn't tell you anything meaningful other than "you need a big-ish suit to XRW."

Wing loading is a somewhat useful tool (though limited) in evaluating a canopy's performance but not so much for wingsuits, too many other variables.

And for what it is worth, canopy manufacturers measure size differently. A few examples are projected size (think the size of the wing's shadow), inflated size (which is smaller than it is laid out flat), and the literal amount of top skin fabric. Who uses what I don't know, but suffice it to say, a VK and a Petra that are the same size won't be made out of exactly the same amount of fabric. There is also some rounding of actual numbers that occurs to conform to industry standards. (One rumor I've heard (and cannot substantiate) is that some "high 90s" are actually over 100 sqft but "90-something" makes swooper's dicks harder.)

[yuri_base 1]

> In short-is there common way to measure compatibility other than "so and so flew a X bird/C Race/ Whatever next to a VK/ Petra/Whatever with 43 lbs of lead and it worked so thats the standard..."

This problem can be solved scientifically by measuring canopy's and wingsuit's polar curves and finding their intersection. To fly together, you need to have exact same horizontal and vertical sustained speeds - i.e. both of you should fly at the same polar point. I wrote about somewhat similar thing here - two WS jumpers with vastly different wingloading flying together.

[inline PhatVsSkinny.png]

If there's no intersection, canopy's polar curve can be scaled to different belly belt weights to see if intersection is possible.

So, it is possible to know in advance what to aim for instead of blind trial/error.

Tools for measuring polar curve do exist.

Android+Wear/iOS/Windows apps:
L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP
iOS only: L/D Magic
Windows only: WS Studio

[Anachronist 2]

There is so much wrong with that, "I can't even..."

Lets just say, "extrapolating beyond the bounds for your data," it will work in some cases but not all, or even "many."

#neither of these is a ridged wing glider, and a WS falls completely out of this analysis because a complete change occurs in drag, span, chord, camber, airfoil, angle of attack, and planform to attain each of those data points, and the same data point can be reached by several combinations of each.

For all the XRW hopefuls out there, the window is
Classic engineer "can't see the forrest for the trees."

[yuri_base 1]

> neither of these is a ridged wing glider, and a WS falls completely out of this analysis because a complete change occurs in drag, span, chord, camber, airfoil, angle of attack, and planform to attain each of those data points, and the same data point can be reached by several combinations of each.

Yes, unlike rigid gliders, wingsuits have polar regions, not curves (the areas on the graph above are shaded to show this) due to variable geometry. However, every glider has an "envelope" (bright colored curves above) that it cannot go beyond. For wingsuits, this envelope is flying with fully stretched suit, but at different angles of attack. If wingsuit polar region does have an intersection with canopy polar curve, XRW is possible, and wingsuiter can fly in any flight mode along canopy's curve inside the WS region.

If canopy and wingsuit manufacturers measured polar curves/envelopes for various canopies/sizes and wingsuits for average body build - "technical passports" like they have it for gliders - these curves don't need to be measured by users, they can be just scaled for different wingloadings to find the intersection. Unfortunately, we've never seen any hard data from manufacturers and it's not likely to happen soon, but technically-minded enthusiasts can build their curves using L/D Vario and L/D Magic.

Here's an example of polar region of one jump (flying the swiss crack) - bright green on the bottom graph, ignore darker green as it's from Kalman filter catching up with data in the first few seconds after exit:

[inline Sputnik_2013-08-15-2.png]

Android+Wear/iOS/Windows apps:
L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP
iOS only: L/D Magic
Windows only: WS Studio

[roostnureye 2]

I was just in Deland this weekend at the XRW camp.
we had canopy pilots ranging from 3.2/1 all the way up to 4.1/1 we found out that just because you load a canopy more does not mean it will descend faster. we realized that in some instances more weight actually equaled more glide.

most of our jumps were loaded around 3.2-3.4 this was on petras. the 4.1 was on a 58jvx.
most of the wingsuiters that were taking docks and getting surfed were wearing large suits (rebel3,Aura,Apache,Rbirdpro,Freak) some of the smaller suits did struggle with heavier pilots.

I was averaging a 36mph fall rate on most jumps. ranging from 24-44.

one of the larger guys there did actually measure his surface area, he was right at 35 square feet on his wing suit.

I think surface area loading has more of an influence in this sport than most other aspects other that proper loading of canopy pilot. this is just my personal opinion....

I believe the sweet spot for loading a wingsuit for xrw is between 4 and 5lbs per square foot.
there are people that can do xrw at a higher wingsuit loading, but they are few and far between.

Flock University FWC / ZFlock
B.A.S.E. 1580
Aussie BASE 121

[Anachronist 2]

yuri_base

However, every glider has an "envelope" (bright colored curves above) that it cannot go beyond. For wingsuits, this envelope is flying with fully stretched suit, but at different angles of attack. If wingsuit polar region does have an intersection with canopy polar curve, XRW is possible, and wingsuiter can fly in any flight mode along canopy's curve inside the WS region.

No no no...

Maximum glide isn't necessarily a completely flat or extended suit because the added drag can impede forward speed or change in camber cause boundary layer separation from having too much AoA. Yes some of the newer varieties are being built to be fully extended and flat most of the time and may get max glide in a very flat position but that is far from a cosmopolitan trait. And do you have data for glide coupled with quantitative data on body position and wing shape, dihedral, and dimension? No, no you don't.

And on top of all of that wingsuits often cycle in and out of equilibrium glide and almost certainly rely on form drag (maybe a lot) to reduce decent rather than producing lift alone. Not to mention lift (more like inertial redirection) from producing a large pressure wave rather than "aerodynamic lift," I don't know what the technical term for that is. I would say "bow shock" but that is supersonic talk. Could it simply be massive drag?

You're trying to apply theories developed for fixed wing, constant velocity, and highly streamlined aerodynamics (which do work to a limited degree), wingsuits are none of those (sometimes constant velocity but rarely). You also have no data on the wing shape, it would be like taking flight data from an airliner and not knowing what the flaps or slats were set at (or that they even had flaps or slats) and trying to infer it's flight envelope. If you really quantified a wingsuit's performance with all of its variable geometry you would end up with dozens of curves that would have to be compiled to produce something useable.

Yes, what you are trying to do is possible, but you are making way too many assumptions and are severely underestimating the complexity of the data needing to be collected. You aren't producing anything more comprehensive than what someone with a FlySight could tell you after a few jumps and very little data analysis.

[Anachronist 2]

Interesting that more weight didn't always help, guess it could result in more speed and thus more lift. A little surprising.

roostnureye

one of the larger guys there did actually measure his surface area, he was right at 35 square feet on his wing suit.

I find this very hard to believe, though concede it might be possible. A queen mattress is 33.33sqft, he would have to be well over 6' tall and have an enormous tail to boot. It is also not a simple measurement outside of CAD because of how dynamic the shape is.

What was the suit and about how tall was the jumper?

[Jiggs 0]

Hey,

We have found the best thing is to set a benchmark of vertical speed as a starting point - for us we use 35mph vertical as that benchmark for the canopy side of things. It gives the ws a decent range. Using a benchmark also helps people to figure out if they are in the window to play with others. We originally tried to work out a list of what canopies would work but there are so many variables. We therefore just went with a this speed works well, do what you need to do to fly at this speed.

Canopies have very different glide ratios (duh). Size for size, the petra is the steepest, followed by the peregrine, then the leia, velo and the JVX (can't comment on VK). E.g. me on a 67 petra at 2.9 outsunk my teammate on a 71 penguin (3.1) who outsunk ve79 (3.2) who outsunk JVX69 (3.4 or 3.6)

On my 67 Petra I can load as low as 2.8 and still fly with a few people (that is my unleaded exit)

Type, then size seems to be more important than absolute loading, you can chuck on a lot of weight and you dont get so much gains in vertical descent. (I have flown with up to 32kgs on a 69 @3.8 - I wear 6kgs on my petra @ 3.1 for a higher descent speed). The gains from more weight you see more in the forward speed.

When we were doing bigger mixed formations, I would drop my lead and others would lead up. Basically if it is larger or a less ground hungry type, you are going to need to add some more loading (which will only make up for a marginal difference). Body position and leaning on fronts also helps

Less drag is also appreciated by the WS pilots

FWIW - Woody's Aura is slightly more than 50% of the size of my canopy. - I don't think it means anything

"Don't blame malice for what stupidity can explain."

"In our sleep, pain that cannot forget falls drop by drop upon the heart and in our despair, against our will comes wisdom" - Aeschylus

[The111 0]

roostnureye

we found out that just because you load a canopy more does not mean it will descend faster.

Yes, it does mean just that. This is Aerodynamics 101.

www.WingsuitPhotos.com

[yuri_base 1]

> You're trying to apply theories developed for fixed wing, constant velocity, and highly streamlined aerodynamics (which do work to a limited degree), wingsuits are none of those (sometimes constant velocity but rarely). You also have no data on the wing shape, it would be like taking flight data from an airliner and not knowing what the flaps or slats were set at (or that they even had flaps or slats) and trying to infer it's flight envelope.

The Wingsuit Theory is developed using only two fundamental laws of physics: 2nd Newton's law (F=ma) and proportionality of the aerodynamic force at high Reynolds numbers and subsonic speeds to the square of airspeed (F ~ V^2). That's it. It applies to any wing shape, dihedral, AoA, fully stretched or collapsed wings, flaps, slats - anything. Any dynamic changes in flight configuration - AoA, shape, surface area, wing profile, trim, etc. - are encapsulated in "magic" coefficients of lift and drag Kl and Kd which can be measured by the tools I created based on WST. Velocity does not need to be constant - constant velocity is simply a point on a polar curve that can be used in Wingsuit Equations to calculate any dynamic situation. (see Wingsuit Studio) Of course, for acrobatics this won't be applicable (because for flips and barrel rolls the rotational dynamics needs to be taken into account), but for any normal flying it works. It even works for no-lift freefall (belly, headdown, sit) - it's just Kl=0 for these, that's all, WSE still work.

So, unless the XRW participants are trying to win the Darwin Prize:

[inline DarwinPrizeXRW.jpg]

- it's better to be smooth and make only slow adjustments, in which case WST works like a fine swiss watch.

> If you really quantified a wingsuit's performance with all of its variable geometry you would end up with dozens of curves that would have to be compiled to produce something useable.

Exactly. One way of doing this would be to gather all polar points in one spreadsheet and plot them all on the same chart using a circle of low opacity (1%) with radius representing error margin for each data point, with sustained horizontal and vertical speeds adjusted to sea level to eliminate the effects of variable air density. After a lot of jumps in various flight configurations in the same suit, points will be ending up on top of each other, making opaque regions that will be more defined the more time was spent in these flight modes. A shape in polar space will be formed (with somewhat fuzzy edges due to measurement errors) which is what we're looking for - wingsuit's polar region/envelope.

> You aren't producing anything more comprehensive than what someone with a FlySight could tell you after a few jumps and very little data analysis.

Flysight is just a GPS and thus wind is blended in the data and cannot be reliably removed. Also, current (momentary) speeds are not easily translated into sustained (polar curve) speeds. One needs to fly at really, really constant speeds for prolonged periods of time - and subtract wind accurately, or fly in true zero wind - to claim that these speeds represent a point on a polar curve. It is quite common that people slowly bleed horizontal speed (most of the time, subconciously) to get better dynamic glide. L/D Vario and L/D Magic, when used with a vane, are completely independent of the wind, and calculate sustained horizontal and vertical airspeeds for every moment, even if current speeds are changing.

Android+Wear/iOS/Windows apps:
L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP
iOS only: L/D Magic
Windows only: WS Studio

[Anachronist 2]

Ugggghhhhh, aerodynamics aren't as pretty as we'd like to think they are and the actual mechanism of a lot of forces is not truly known, but with lots of trial and error and tons of money there is a collective of "stuff that works" but it doesn't mean that it is accurate at all times or that basic tenets are absolute.

Aerodynamic surprises abound as our understanding changes, you can't just plug data into a formula and expect it to work, case in point http://www.ntsb.gov/news/events/Pages/2012_Roswell_NM_BMG.aspx

You people are dense, and Yuri just wants to sell his product. Peace out

[yuri_base 1]

> You people are dense, and Yuri just wants to sell his product.

My products are free, except for some advanced features in L/D Magic only a handful of people in the world would buy.

What I truly want is to better understand human flight, have fun applying physics anywhere I can apply it (afterall, my PhD in Physics can be used for betterment of humanity , as my current profession - programmer - does not involve any physics), and - hopefully, but in reality mostly hopeless - let people know that while they are free to cling to the past, to the era of horses, candles, fire stoves, and abacus, and live in denial... the future is here and it's ok to live in the era of fast cars, jetliners, electricity, and computers that fit on your wrist.

It's ok to wake up.

[inline WakeUp.jpg]

Android+Wear/iOS/Windows apps:
L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP
iOS only: L/D Magic
Windows only: WS Studio

[The111 0]

Anachronist

Ugggghhhhh, aerodynamics aren't as pretty as we'd like to think they are and the actual mechanism of a lot of forces is not truly known

There is some truth to that statement (ignoring your assumptions about what "we" think), but zero relevance to what I was saying.

While there are certainly unanswered questions in both physics and aerodynamics, these questions have no bearing on the many things that we do know, and one example of such a thing that we do know is that if you take two identical airframes and load one higher than the other, it will descend faster. More specifically, if you load a canopy higher, it will descend faster. To claim otherwise is unbelievably wrong. A skydiver with any experience should know this with no other knowledge of aerodynamics; I'm surprised they would give a USPA license to anybody who did not understand this. Do you honestly think loading a canopy higher might somehow make it magically go slower?

www.WingsuitPhotos.com

[angryelf 0]

I appreciate the replies. Was at the DeLand camp as well and the difference in canopy design was huge. The engineering banter is pretty interesting, though admittedly a lot of it is over my head.

It will be interesting to see how the discipline evolves.

"Sometimes you eat the bar,
and well-sometimes the bar eats you..."

[angryelf 0]

111,

I don't think he was saying that loading the canopy made it descend slower. What he was trying to say was that the canopy's forward speed increased with more lead to the point of it outrunning the wingsuits, thereby defeating the purpose of adding weight to improve overlap of performance envelopes. I have personally loaded a VK 90 to the point where the WS'er was able to match descent rate easily, but was "pinning" the suit to keep up.

I think everyone gets that higher wing loads generally equal faster descending/faster forward. (At some point loading will result in descent rates being unlandable/openings being uncontrollable/etc. I say "generally" because this discussion is pertaining to canopies being loaded in the neighborhood of 3:1 and 4:1 respectively.

The question as it pertains to XRW is: whether or not the resulting glide ratio works for the Canopy and the WS? And what are reasonable ways to (somewhat objectively) predict compatibility of a Canopy and a WS?

Thus far it seems like a Flysight graph of both the canopy and the WS would be a good starting place with out getting into some complex math or programming.

"Sometimes you eat the bar,
and well-sometimes the bar eats you..."

[lyosha 46]

Anachronist

Interesting that more weight didn't always help, guess it could result in more speed and thus more lift. A little surprising.

***
one of the larger guys there did actually measure his surface area, he was right at 35 square feet on his wing suit.

I find this very hard to believe, though concede it might be possible. A queen mattress is 33.33sqft, he would have to be well over 6' tall and have an enormous tail to boot. It is also not a simple measurement outside of CAD because of how dynamic the shape is.

What was the suit and about how tall was the jumper?

There were people there who were 6'5"-6'6", and flying Freebirds (for all intents and purposes a square mattress with a long tailwing).

I find it funny that after like 20 paragraphs of breaking down the aerodynamics of wingsuit flight you find it hard to believe that people over 6' tall exist lol.

[jakee 1,254]

Quote

one of the larger guys there did actually measure his surface area, he was right at 35 square feet on his wing suit.

His wingsuit is a 6ft tall, 6ft wide square?

Do you want to have an ideagasm?

[jakee 1,254]

Quote

There were people there who were 6'5"-6'6", and flying Freebirds (for all intents and purposes a square mattress with a long tailwing).

I find it funny that after like 20 paragraphs of breaking down the aerodynamics of wingsuit flight you find it hard to believe that people over 6' tall exist lol.

Right... but the distance between the top of your head and the top of your shoulder is at least 12" so your 6'6" guy just became 5'6". And then if you spread your legs wide enough to create the points of a 6' square (which you won't do in the air anyway but that's another problem) then you'll be another 8-10" shorter again, so you're down below 5' for the suit already. Then OK you've got a load of extra tail wing, but at best that's going to fill in the surface area you've lost through arm sweep and the cut in under the grippers, though realistically not even that.

So a 35 square foot wingsuit? Measure it again.

Do you want to have an ideagasm?

[The111 0]

angryelf

I don't think he was saying that loading the canopy made it descend slower.

That's exactly what he said. Read the words:

just because you load a canopy more does not mean it will descend faster.

"Not faster" means slower.

angryelf

I think everyone gets that higher wing loads generally equal faster descending/faster forward.

I'd hope so, but I'm not sure, since Anachronist seems to think it might be one of the great unsolved mysteries of aerodynamics.

Also, the next sentence from the post I originally responded to claims that higher loading can equal "more glide" which is also 100% false. It equals the same glide, only faster in both directions (as you clearly understand).

www.WingsuitPhotos.com

[roostnureye 2]

The111

***Ugggghhhhh, aerodynamics aren't as pretty as we'd like to think they are and the actual mechanism of a lot of forces is not truly known

There is some truth to that statement (ignoring your assumptions about what "we" think), but zero relevance to what I was saying.

While there are certainly unanswered questions in both physics and aerodynamics, these questions have no bearing on the many things that we do know, and one example of such a thing that we do know is that if you take two identical airframes and load one higher than the other, it will descend faster. More specifically, if you load a canopy higher, it will descend faster. To claim otherwise is unbelievably wrong. A skydiver with any experience should know this with no other knowledge of aerodynamics; I'm surprised they would give a USPA license to anybody who did not understand this. Do you honestly think loading a canopy higher might somehow make it magically go slower?
I highly respect you as a wingsuiter, but flysight data is a pretty solid tool for figuring out fall rates and forward speed. why would I make shit up? I was flying with TJ and Curt B. I think they might know a thing or two on interpreting data from a flysight? no? these are world champion canopy pilots here man.

Flock University FWC / ZFlock
B.A.S.E. 1580
Aussie BASE 121

[The111 0]

roostnureye

I highly respect you as a wingsuiter, but flysight data is a pretty solid tool for figuring out fall rates and forward speed. why would I make shit up? I was flying with TJ and Curt B. I think they might know a thing or two on interpreting data from a flysight? no? these are world champion canopy pilots here man.

So to be clear, you are saying that adding weight to a canopy can make it descend slower?

www.WingsuitPhotos.com

[roostnureye 2]

I'll try and get the flysight data for you. I'm not into bickering back and forth over the Internet. I was there flying with them, I know what I heard.

Flock University FWC / ZFlock
B.A.S.E. 1580
Aussie BASE 121

[Joellercoaster 6]

jakee

His wingsuit is a 6ft tall, 6ft wide square?

That doesn't sound totally crazy.

I mean, it does when thinking about early wingsuit designs I guess.

Truly, we are living in the future!

--
"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?

[jakee 1,254]

Joellercoaster

***His wingsuit is a 6ft tall, 6ft wide square?

That doesn't sound totally crazy.

Think about it some more

Do you want to have an ideagasm?