Suit area vs flyer weight.....

[Zoter 0]

Just quick question.
OK two jumpers...
Jumper A is 6ft tall weighing 200Lbs
Jumper B is 5ft tall weighing 130lbs.

Both jumping the same type of suit, and consider them as both having similar experience.
Who would get better performance....?

The taller guy although heavier must surely have more material (longer arm span therefore larger upper wing) and longer legs when opened ( therefore larger lower wing area)

The smaller guy would have a reduced wing area but less weight......therefore would take less effort on the wing for the same amount of wing....

So how would they compare in performance in this scenario ??

[nicknitro71 0]

First you have to define "performance".

Robi among others already talked about this issue several times.

My understanding is like having a 200Lb person under let say a Stiletto 97 and a 120 Lb under the same wing, for the sake of the argument. If they start flying on a straight line next to each other in a no wind day, chances are the heavy guy will fly faster but in the end the glide ratio is the same and both jumpers will land close to one another.

The glide ratio is a property of the design of the wing. The higher the WL the faster you go down the slope but the glide ratio stays the same. Of course in real life there are things, like wind, drag, and such, but the basic idea stays.

I believe the same applies to WS.

Two identical WSs, the one with higher WL will fly faster than the one with lower WL but the glide ratio will be the nearly the same.

I think any gain in lift generated by the extra speed by the heavy guy is canceled out by the extra drag.

Again in the end all we should care performance speaking, is glide ratio and that is more an intrinsic characteristic of the WS design and body position than WL.

Of course I could have all this wrong! Just relying on intuitions is not science and without any hard data you always end up speaking out of your ass!

Memento Audere Semper

903

[LouDiamond 1]

Think of it in terms of wing loading.An increase in weight will cause a faster vertical descent rate but does not affect glide ratio, only the airspeed needed to obtain that glide ratio will change with an increase in weight. Nick you're on the right track bro

"It's just skydiving..additional drama is not required"
Some people dream about flying, I live my dream
SKYMONKEY PUBLISHING

[riggerrob 643]

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Think of it in terms of wing loading.An increase in weight will cause a faster vertical descent rate but does not affect glide ratio, only the airspeed needed to obtain that glide ratio will change with an increase in weight. Nick you're on the right track bro

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Yes, that works until you get near the edge of the wing-loading envelope.

If I may make a comparison with canopies. Stilettos fly great until you exceed wing-loadings of about 1.6 or 1.7 pounds per square foot (at sea level). If you load Stilettos beyond 1.6, they may fly faster, but glide ratio suffers because drag increases with the square of the velocity and they do not generate much more lift, ergo, landings become "foot slappers."
Wing suits tend to have 1/10 th the wing area and wing-loadings 10 times heavier, but the theory still applies.

[nicknitro71 0]

I was talking about glide ratio not flaring performance. I have yet tried to land my suit

Anyhow, Atair found out that @ 4.45 WL the glide ratio increased.

Here is the thread:

http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=1605132;search_string=glide%20ratio%20cobalt;#1605132

Memento Audere Semper

903

[Martini 0]

I'd love to see a chart or something demonstrating wingloadings for various suits in various sizes. It would be very interesting although not necessarily very useful because you can't change your wingload on a wingsuit except by wearing weights (not typically a good thing) or finding a suit with more surface area (not necessarily increasing "performance"). I fly with a couple of guys who clearly have higher wingloadings than I do but generally outperform me simply because they are better fliers. Humbling and inspirational. On the other hand a couple of my friends are much taller than I am and weigh about the same, I'll never come close to their performance no matter how good I get. As a friend said, just do the best you can that day. For flocking purposes it doesn't matter much as we try to fly in the midrange of the low to middle flyer's ability. Prolly more than you wanted to hear, I swear it's the wine's fault.

Sometimes you eat the bear..............

[diablopilot 2]

Agree with ya, except the Stiletto 120 is good through about 1.8 easy....

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

[Tonto 1]

The sizing doesn't scale.

That's why there are no 200lb flying squirrels.

I used to think of the 5 body types, in order of performance as

1. Tall and light
2. Short and light
3. Medium and medium
4. Tall and heavy
5. Short and heavy

I now think you can swap the top two.

6ft people weigh a lot - regardless of how skinny they are.
(Athletic) 5ft people weigh around 100lbs less.

That's half the weight for a foot less height.

t

It's the year of the Pig.

[TomAiello 26]

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1. Tall and light
2. Short and light

...

I now think you can swap the top two.

I concur. My experience has been that the absolutely tiny people can pull out more performance than the tall, skinny people. I'm not sure why this is, because I'd expect the tall skinny people to have bigger wings, and hence better wingloading.

-- Tom Aiello

Tom@SnakeRiverBASE.com
SnakeRiverBASE.com

[The111 1]

What about short people with disproportionately long ape-arms?

www.WingsuitPhotos.com

[mccordia 74]

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I concur. My experience has been that the absolutely tiny people can pull out more performance than the tall, skinny people.

They are probably just trying to compensate for being short and tiny

JC
FlyLikeBrick
I'm an Athlete?

[TomAiello 26]

Quote

What about short people with disproportionately long ape-arms?

It's the next great wingsuit advancement: stilts and canes!

-- Tom Aiello

Tom@SnakeRiverBASE.com
SnakeRiverBASE.com

[LouDiamond 1]

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I concur. My experience has been that the absolutely tiny people can pull out more performance than the tall, skinny people. I'm not sure why this is, because I'd expect the tall skinny people to have bigger wings, and hence better wingloading.

This is a hard one to conclusively nail down because of all the variables involved that you don't find when dealing with fixed wings or canopies since we are the wings and we bend in all sorts of ways that the later 2 don't. The "average" wingsuit pilot has roughly 15 to 16 square feet of surface area with a wing loading in the neighborhood of about 10.5 to 12.5 pounds per square foot.

Also , something to think about, a large guy in type X suit has wings that are proportionate to his body size. Small/medium guy in type X suit likewise has wings that are proportionate to his size. Same model suit, same wing shape but difference is in overall wing size. But when you put a big guy in a suit with smaller wings what happens?(this is more of a mind teaser and the instructors should have an idea where I am going with this)

Remember how it is we fly in a wingsuit, we need airspeed to generate lift. How the pilot goes about converting airspeed into useable lift is where some excel over others.

"It's just skydiving..additional drama is not required"
Some people dream about flying, I live my dream
SKYMONKEY PUBLISHING

[outrager 6]

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I concur. My experience has been that the absolutely tiny people can pull out more performance than the tall, skinny people. I'm not sure why this is, because I'd expect the tall skinny people to have bigger wings, and hence better wingloading.

How absolutely tiny? Is that relative to an infamous "fat american" scale or what?

Just curious who are you talking about...

I kinda agree with this observation, for the following reason:

Maxing out and holding a current high-perfomance suit in a perfect position for a long time takes a huge muscle effort. Most people notice a significant degradation of perfomance after about a minute. It is harder for tall and skinny people to hold the position. They do have a better body to fly, but smaller people can make up for it by better muscle endurance.

I begin to believe that more perfomance gains at this point are to come from physical body strengthening, as opposed to better suits.

There are already some examples where on long (2min range) flights a pilot gets an equal (or even better) overall distance in an intermediate suit, compared to an advanced one, because of fatigue issues at the end of the flight.

bsbd!

Yuri.

[The111 1]

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There are already some examples where on long (2min range) flights a pilot gets an equal (or even better) overall distance in an intermediate suit, compared to an advanced one, because of fatigue issues at the end of the flight.

When I got my S3 I could go 135 seconds in my GTi. It took me many jumps on my S3 before I could break 120 seconds, because of my endurance. I still can't break 160 seconds for the same reason; my fallrate is sub-40 for the first minute sometimes, and at or above 50 by the end.

www.WingsuitPhotos.com

[KrisFlyZ 0]

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What about short people with disproportionately long ape-arms?

In Indian Mythology, the Gods are described as having arms that reached their knees.

Apparently, the Gods would make good wingsuit flyers.

Kris.

[kallend 2,150]

Quote

Quote

What about short people with disproportionately long ape-arms?

In Indian Mythology, the Gods are described as having arms that reached their knees.

Apparently, the Gods would make good wingsuit flyers.

Kris.

Especially the one with the 6 arms. But what about Ganesh?

...

The only sure way to survive a canopy collision is not to have one.

[Costyn 1]

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When I got my S3 I could go 135 seconds in my GTi. It took me many jumps on my S3 before I could break 120 seconds, because of my endurance. I still can't break 160 seconds for the same reason; my fallrate is sub-40 for the first minute sometimes, and at or above 50 by the end.

Indeed, I was getting lower vertical speeds and longer flight times in my classic than I now have in my S3S. The S3S is a lot more work to fly and gets tiring quicker. I'm thinking of starting some training to increase my stamina. I hope this will decrease my fatigue at the end of a day of wingsuiting as well. At the moment I can only do some 5 or 6 wingsuit jumps in a day. I don't have the energy for more.

Cheers,

Costyn.

Costyn van Dongen - http://www.flylikebrick.com/ - World Wide Wingsuit News

[nathaniel 0]

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I concur. My experience has been that the absolutely tiny people can pull out more performance than the tall, skinny people. I'm not sure why this is, because I'd expect the tall skinny people to have bigger wings, and hence better wingloading.

I'm not knowledgeable enough about aerodynamics to say conclusively, but I suspect it has a lot to do with lift / drag ratios, viscosity, airspeed &c.
Cessna 172: 4 people, 36 ft wingspan, 27ft length
Cessna 208: 16 people, 52 ft wingspan, 41ft length
Ever wonder why they don't make 16-seat Cessnas in the exactly the same shape as a Cessna 172 only double the size? (double size ~ 4x surface area)
Equations for lift, drag and such, not to mention strength and rigidity are generally not linear in length and weight. Likewise the whole linear WL phenomenon for canopies is just a crude approximation that subjectively seems to "work" for some heretofore unquantified aspect of canopy flight. At least that fad seems to be passing. It's too bad, in a way, because most people have a hard time thinking in non-linear terms. Scientists and engineers spend a good portion of their time finding forumlas they can distill into functions of linear variables.
I strongly suspect that contemporary wingsuits and pilots are at a point where WL is not a particularly descriptive measure for whatever subjective factor we use--subjectively there seems to be a dramatic difference between small light people and large heavy people.

My advice is to do what your parents did; get a job, sir. The bums will always lose. Do you hear me, Lebowski?

[phoenixlpr 0]

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Cessna 172: 4 people, 36 ft wingspan, 27ft length
Cessna 208: 16 people, 52 ft wingspan, 41ft length

Do you know that there ~16 cm difference between of the wingspan of C172 and C207? Believe or not C172 is wider in wingspan.

[nicknitro71 0]

Some of the variables you mentioned do apply to WS flight some don't.

Nonetheless, weight seems to be one of the most critical variables when it comes to L/D.

I am not an engineer but I remember few things from comparative physiology.

Let’s talk about few features about birds that relate to weight.

Bones: hollow and elastic, made of much more cartilage then human bones.

Lungs: always inflated to keep the trunk always is a predetermined shape.

Feather: light, strong, they provide shape to the airfoil and insulation to the core.

Fat: non migrant birds are lean (~3% BF). Migrant species can have up to 100% BF! This fat is not for insulation (see feathers) but only for energy.

Many migrants start to pig out about three weeks before their journey increasing their body weight by almost 100%. This added weight assures enough energy to complete the journey. However now the “flying pigs” being so heavy they have to flap they wings at a much higher rate. This rate goes down as the journey continues due to the weigh loss.

Non-migrants, especially big birds, like raptors are very lean (2-3% BF) and they do not like to flap their wings, one because their wing span is quite impressive (some close to 9’) and two because they do not have the energy resources to flap for a long time. The solution? Soaring.

When I used to Hang-glide I was always looking for falcons, eagles, and such to spot thermals.

So here is what we have to do to improve WS performance: bone transplant with hollow bones and while there, get few extra feet of arm length; reduce BF to 2-3%; Keep lungs inflated for the duration of the flight. Trade in the WS for feathers. All these should not be a problem for most of us

Memento Audere Semper

903

[tso-d_chris 0]

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If I may make a comparison with canopies. Stilettos fly great until you exceed wing-loadings of about 1.6 or 1.7 pounds per square foot (at sea level). If you load Stilettos beyond 1.6, they may fly faster, but glide ratio suffers because drag increases with the square of the velocity and they do not generate much more lift

While the L/D may decrease above a certain wingloading, it is not due to drag increasing with the square of the velocity. Lift increases with the square of the velocity as well. In other words, velocity does not affect L/D.

Of course, that assumes the suspended masses (jumpers) have the same area. Usually, heavier jumpers also have more surface area, which applies a torque on the canopy, decreasing its angle of attack, decreasing its angle of attack, decreasing it's L/D.

A lighter suspended weight with an increased jumper surface area (think wingsuit with wings still configured for flight) will also result in a decreased L/D.

For Great Deals on Gear

[980 0]

not the scenario you described, but:

jumper A: 6'0" and 168lbs in a modified S3
jumper B: around 5'6" and 135lbs in a Matter suit

linked exit at 6000ft, then race for distance, pull at 3000ft

jumper B had a shorter flight and higher forward speed, but it was a draw on distance, so the glide ratio was the same for both jumpers on this jump

the ironic bit is that the S3 is generally seen as a faster flying suit and the Matter as more floaty..

the really ironic part is that by racing for distance I ended up getting my lowest descent rate in around 260 jumps on the S3

see the attachment

cya
sam

[F16Driver 0]

Alright, I've lurked enough. I'll see if I can shed a little light on the L/D stuff.

Based on the thread, I think it would take a lot of testing in a horizontal wind tunnel (like birdman uses) to get the best data to find this out. When you discuss some guys flying the same suit better, sometimes it is because they can get to L/D max better than the other guy. Being light on weight (in identical suits) definitely starts you at an advantage, though.

The Total Drag curve (Parasite + Induced drag) is basically an inverted parabola. At the bottom of the curve is where you get the most amount of lift for the least amount of drag. This is because, as discussed earlier, as you speed up, you increase parasite drag (this will steepen your glide angle since you are trying to maintain that airspeed). As you slow down below L/D, you also increase drag because now you're creating induced drag (drag produced from the production of lift). This is due from slowing down, increasing the angle of attack through the air, and causing more air to plow around the wings (there is a little more too it, but this was the easiest I could make it.) This too will steepen your glide angle.

The only way that we can "max perform" a wingsuit is by knowing what that L/D max airspeed is. Unfortunately, we would need to carry an airspeed indicator and try different airspeeds, or be lucky enough to get into a horizontal windtunnel, get hooked up, and check different airspeeds. Body position and wing position adds more variables to the problem, also.

"I promise, I will never die."

[phoenixlpr 0]

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The only way that we can "max perform" a wingsuit is by knowing what that L/D max airspeed is. Unfortunately, we would need to carry an airspeed indicator and try different airspeeds, or be lucky enough to get into a horizontal windtunnel, get hooked up, and check different airspeeds. Body position and wing position adds more variables to the problem, also.

You've just left out the desity of the air. E.g. one tracing position is good @ 4000m and start stalling around 2000m.