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Basjkall

Custom speed suit

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Hi guys,

Check out my new speed suit! I used the body of an old classic 1 and made smoother smaller, thus faster wings on it. (based on VKBs own R&D department) Changed the air inlets and made a neopren front with dobbel zippers. Havent tried it yet, to much winter here, but cant wait to go superterminal with it! Gps data is coming after the first flights.

Take care,
Andreas VKB#12

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I have an idea how to improve the wingsuit performance.

Current wingsuits have wings inline with the body. This sets the same angle of attack for both the wings and the body. The body is as efficient aerodynamically as a log due to its low aspect ratio and shape. That's why birds and airplanes keep the body/fuselage inline with the air flow, to reduce the drag as much as possible and let the wings alone generate the lift.

The idea is to attach the armwings not to the sides, but closer to your belly. Sew the attachment tabs from armpits diagonally to crotch area. This will put your body much more headlow, ideally inline with the relative wind, while keeping the angle of attack for the armwings. So if your L/D=2.5, your body should be at arctan(1/2.5)=22 degrees to the horizon. As for the legwing, just push your hips up more than usual to keep the angle of attack about the same as that of the armwings.

What do you think? And when VKB will go supersonic? ;)

Yuri

PS. Of course, with such a suit the deployment should not be performed from full flight as PC and canopy can be snagged by legs.
Android+Wear/iOS/Windows apps:
L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP
iOS only: L/D Magic
Windows only: WS Studio

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Kris: I think wings are moved up (that is, to back) to decrease the angle of attack (to make it more efficient), while keeping the body almost level. Commercial suits are designed to provide convenient level body position for flocking and safe deployment. However, performance-wise, the body with its L/D = 0.5-1 negates the much higher wings' L/D, averaging the total L/D to 2.5.

Tom: Which models do you have in mind?
Android+Wear/iOS/Windows apps:
L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP
iOS only: L/D Magic
Windows only: WS Studio

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Here are some calculations as a food for thought...

Total lift is a sum of the lift produced by wings, Lw, and by body, Lb. Total drag is a sum of the drag produced by wings, Dw, and by body, Db.

The glide ratio

L/D = (Lw+Lb)/(Dw+Db)

Let's denote this glide ratio for the traditional wingsuit G_old:

G_old = (Lw+Lb)/(Dw+Db) (1)

Let's denote Dw/Db=X and Lb/Db=G_body (as a glide ratio of the body alone).

From (1) let's get this ratio (we'll use it later):

Lw/Db = G_old*(X+1)-G_body (2)

Now, let's modify the wingsuit as I described above: put the body inline with the glide angle so that only head and shoulders are presented to the relative wind, while keeping the wings at the same angle of attack as before. Now the lift generated by body is reduced to zero, and drag is reduced by some factor K, while lift and drag generated by wings remains the same.

The new glide ratio is therefore

G_new = (Lw+0)/(Dw+Db/K) (3)

From (2) and (3) we get

G_new = (G_old*(X+1)-G_body)/(X+1/K) (4)

We want this new glide ratio to be better than the old one:

(G_old*(X+1)-G_body)/(X+1/K) > G_old

or

X+1/K < X+1-G_body/G_old

or

K > 1/(1-G_body/G_old) (5)

Consider a good pilot with wingsuit G_old=2.5, G_body=0.7 (note that it's L/D of the torso alone, without arms & legs). In this case, if we can reduce the body's drag by a factor of

K = 1/(1-0.7/2.5) = 1.4,

the goal is achieved: the glide ratio will become 2.5+.

For example, if we decreased the body's drag by a factor of K=3 by changing the angle of attack of the body from 20 degrees to 0, the new glide ratio will be, according to (4),

G_new = (2.5*(X+1)-0.7)/(X+1/3)

X=Dw/Db for the 'old' wingsuit. From the equation above, we can deduct that the glide ratio of 3.0 can be achieved with X=1.6. Which looks reasonable, if we compare the total area of the wings to the area of the torso.

Anyway, let's just do it... :)
Yuri

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Hello,
I calculate that if a guy buys a few wingsuits, he's bound to have fun.
The puffy billowy clouds rose from 3000-8000 feet today.
Beautiful, no scientific analytical mumbo jumbo.
Close range buzzing of tandems.
Food for life.

God bless you
==================================

I've got all I need, Jesus and gravity. Dolly Parton

http://www.AveryBadenhop.com

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Here are the pictures to clarify what I mean.

In superterminal wingsuit, the arm wing runs from shoulders to crotch (not to hips). The leg wing runs from crotch to toes (not to ankles), with a swoop cord running toe-crotch-toe to help stretch the wing.
Android+Wear/iOS/Windows apps:
L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP
iOS only: L/D Magic
Windows only: WS Studio

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The puffy billowy clouds rose from 3000-8000 feet today.
Beautiful, no scientific analytical mumbo jumbo.
Close range buzzing of tandems.




Ah, I knew I missed out by not jumping today. [:/]
Sinuses are still in repair from the high altitude oxygen in Thailand though...... B|


Be safe
Ed
www.WestCoastWingsuits.com
www.PrecisionSkydiving.com

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Hello,

As this discussion is quite interesting I think it is important to emphasize a few things:

IMHO it is very important to draw a line where the track suit ends and WS begins.

Personally, I was involved in designing and flying both. I like to define the Pants as clothing which helps to provide better flying characteristics, but that MUST still allow you to walk, climb and land easily. To assure this the user must be able, while standing on one leg, to touch their chin with their knee (moving the knee toward the chin) If they cant do this then the "pants" are not pants any more, they are a wingsuit leg wing.

It is also important to note the difference for what is important to BASE jumpers and skydivers (rarely they aim for same goal). Human body flight has at least two different directions: flying for time and flying for distance (and recently a skilled handful of jumpers fly for "proximity" with the
objects)

In BASE they fly for distance and it is very obvious how far you go, how good or bad a flight is.

In skydiving that is not the primary goal (unless one really goes for it, wearing GPS etc)

Having the data recorder with time only, usually gives the wrong perception of what is a good flight, unless you are only interested in time.....

Y-base mentioned the angle of incidence (angle between body and wing )

To assure more lift this angle is very important. However it is hard to say what is the best placement because each jumper has different body proportions, CL and CG is in a different place. In theory each jumper most likely would have different AI.

If you move the wing attachment line more to the front (towards belly) the suit will be slower and more prone to stall. It is very wrong to look at the WS as the three wing system. It must be taken as one piece. With changing the angle of incidence in the way Y-base said the body will not fly under lower angle of attack! What will happen is that the wings will have a higher angle of attack; meaning that it will fly very close to stall position.

*********************************************

Current wingsuits have wings inline with the body. This sets the same angle of attack for both the wings and the body. The body is as efficient aerodynamically as a log due to its low aspect ratio and shape. That's why birds and airplanes keep the body/fuselage inline with the air flow, to reduce the drag as much as possible and let the wings alone generate the lift.
**********************************************

Incorrect. In low speed aviation angle of incidence is up to 6 degrees max. Not "much" but not the same as fuselage.

Also the fuselage generates lift, of course it depends on the type of the plane.... Cessnas not at all but F-14, F-15, MIG-29, SU-27 a lot!!

In WS & human flight the body generates a lot of lift, much more than people think...
Robert Pecnik
robert@phoenix-fly.com
www.phoenix-fly.com

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Hi guys,

Check out my new speed suit! I used the body of an old classic 1 and made smoother smaller, thus faster wings on it. (based on VKBs own R&D department) Changed the air inlets and made a neopren front with dobbel zippers. Havent tried it yet, to much winter here, but cant wait to go superterminal with it! Gps data is coming after the first flights.

Take care,
Andreas VKB#12



Hey Andreas,

Can you post more details of the suit please, like the new inlet design and the front. Can't wait for the flight data B|.

Also in Superterminal there is a one minute plus wingsuit flight. The wings look a bit different on the video, can you post details etc.?

Kris.

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Also the fuselage generates lift, of course it depends on the type of the plane.... Cessnas not at all but F-14, F-15, MIG-29, SU-27 a lot!!

In WS & human flight the body generates a lot of lift, much more than people think...



To reinforce what RobiBird says, there is the Israeli F-15 which was landed with one wing completely gone.
Story: http://www.uss-bennington.org/phz-nowing-f15.html
Photos: http://www.strangemilitary.com/images/content/110099.jpg
"There are only three things of value: younger women, faster airplanes, and bigger crocodiles" - Arthur Jones.

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Y-base mentioned the angle of incidence (angle between body and wing )



Robi is there little, even subtle, ( or no) angle of incidence change from the suit to the wing in your suit designs? I read a review in these forums when the V-1 first came out that eluded to this incidence difference. Maybe I miss understood what the reviewer was taking about.

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Also in Superterminal there is a one minute plus wingsuit flight. The wings look a bit different on the video, can you post details etc.?

Kris.



The WS jumps in Superterminal are all made with the old GTIs...
A minute, huh? With his new suit, Andreas will do it in 45 sec :)

VKB#11

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Thanks, Robert, for your comments!

I agree that it is wrong to consider parts of a WS as separate systems. That is, in (Lw+Lb)/(Dw+Db) it is wrong to think that Lb and Db are the same as if the torso were flying alone. I used equations just to illustrate my point.

The aircraft you mention that use lift from fuselage are very different from the WS in that they have almost arbitrary thrust. They have a luxury of generating the lift with relatively poor (in L/D sense) fuselage because they can compensate for the increased drag with the engine thrust.

WS has very limited thrust, precisely the weight times the sine of the glide angle. The better is the glide ratio, the less is the glide angle, the less is the thrust we can work with. I believe that reducing the drag from the torso, while eliminating some lift, will be beneficial for the overall L/D. We have at least one data point supporting this point of view. It's called VKB. ;)

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

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Hi Yuri,

Quote

We have at least one data point supporting this point of view. It's called VKB.



Can you explain how VKB support this argument?

In Norway last year I met the VKB guys and watched them fly from #6, they did achieve some impressive glides ratios and speeds but still opened up around the same place as the other people wearing track pants. The glide ratios attained were not significantly different as the 1000' they use diving steep before starting their flight must also go into the GR calculation. (note: they were not flying along the wall at #6 btw, just straight towards the LZ :P )

BUT of course their exceptional proximity tracking skills are something else :)
Long flights,
J
BASEstore.it

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Interesting point, James. If they lose significantly more altitude initially to get into their superterminal track and yet end up opening at the same point as a traditional tracker, that means they have much better glide after the initial drop. That also means that they will have advantage on a higher wall, e.g. on a 5000ft wall they'll fly much longer distance compared to regular track. (and on the same token, disadvantage on shorter walls)

As far as I understand, this better glide is not caused just by 'flaring' the initial speed. It's a stable configuration and they can maintain the same glide for 1000ft or 10K. There seems to be a 'potential barrier' between the regular flat track and VKB track: if you assume the characteristic VKB body position from the beginning, you will not achieve enough speed for it to work. You have to go superterminal first by diving head down, then when you're past the 'barrier', transition into track.

The above is pure speculation, I hope VKB guys will chime in here and confirm or dismiss it. :)
Yuri
Android+Wear/iOS/Windows apps:
L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP
iOS only: L/D Magic
Windows only: WS Studio

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Dude,

With all the due respect your math does not make much sense and also you are using angle of attack (AOA) when you should have been using angle of incidence (AOI).

Yes the L/D is a ratio and of course the higher the better for our purpose.

However you do not take into account velocity, and AOA.

As we all know, the relationship between velocity and both, L and D, is not linear.

As velocity goes up both the L and D go up by a factor of v^2/2.

Now, the AOA.

AOA is defined as the angle between the airfoil's chord line and the direction of the airflow.

Usually the best lift (NOT L/D) is generated around 18 degrees AOA (this varies a bit for every wing section). After this number the lift drops sharply.

Drag behaves differently. Drag goes up exponentially usually past 14 degrees AOA. At around 22 degrees AOA, no matter what wing structure is used, drag completely overcomes lift.

The critical AOA is usually 16+/-2 degrees.

The best L/D is usually at 0 degrees AOA regardless the wing (subsonic).

Fortunately for us (because we fly at subsonic speeds) lift and AOA have a liner relationship at least until the critical AOA is reached.

Another variable that applies to us is the Reynolds number:

RN = rVd/m

where r = density of the fluid

d= length of the airfoil

m = viscosity of the fluid

The Reynolds number is a linear relationship with V until the flow become very turbulent then it drops sharply. Usually the higher the Reynolds number the higher the lift. Unfortunately there is not much we can do to change density and viscosity and the length of our airfoil is dictated by the length of our body.

Now let's talk about the AOI.

The AOI is defined as the angle between the wing's chord and the longitudinal axis of an aircraft.

Although we as humans really suck at flying we do have one luxury that many aircafts do not: we can change our body AOI in flight! This point is very, very important.

On an aircraft the AOI is usually set at a 6 degree angle with the fuselage.

This makes possible for the fuselage to fly leveled. This number does not apply to us though. For one because our body does produce probably just as much lift as our wings and two because we can change the AOI of our body (not the wings).

On "conventional" aircraft the vast majority of the lift is produced by the wings not the fuselage hence the AOI is never zero. There are few exceptions but think about a conventional airplane flying subsonic.

Again because we produce lift with both, our body and our wings, IMHO the AOI of the wings should just be set close to 0.

There is another little thing that very much applies to us: the longitudinal dihedral AKA decalage. This is the angle between the wing chord line and the tail chord line. And guess what? We can change this as well when flying our WSs.

The angle is very much related to the CG that varies quite a bit from jumper to jumper. Hence each jumper should work on moving their leg wing up and down to find the best decalage angle for her/his own CG.

Said that, Robi thought about all those things and then some long before anybody else.

I agree with him that a near zero AOI for all the wings is the best compromise for commercial suits.

Just my 0.02.
Memento Audere Semper

903

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