Kasper wing and trapped vortices

AeroFranz

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I came across a high lift concept called "Kasper wing" or "trapped vortex". It seems like an elegant way of achieving high lift coefficients, but I find limited information. Does anybody know more about this? i would be interested in knowing if the windtunnel tests achieved good performance, and if a flight vehicle was built.

the picture comes from patent "AIRCRAFT WING WITH VORTEX GENERATION" by Witold Kasper, filed in the seventies
 

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sferrin

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Towards the back of the British Secret Projects: Hypersonics there is a concept that uses a wing like this.
 

KJ_Lesnick

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AeroFranz,

Honestly I would have never thought such a design would have produced that kind of airflow pattern... or at least produced an airflow pattern that would be beneficial to increasing lift.

I guess you learn something new every day...


Sferrin,

There's a hypersonic design that uses a wing set-up like this?

KJ
 

Simon666

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AeroFranz said:
i would be interested in knowing if the windtunnel tests achieved good performance, and if a flight vehicle was built.
From what I remember, NASA tested it and found nowhere near the by Kasper claimed lift coefficient and sink rate. Though there are some papers around on trapped vortices that show theoretically high lift coefficients can be obtained.
 

AeroFranz

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KJ_Lesnick said:
Honestly I would have never thought such a design would have produced that kind of airflow pattern... or at least produced an airflow pattern that would be beneficial to increasing lift.

Yeah, I guess that trapped vortices aerodynamics is not the most intuitive of things...I do know that wind tunnel tests proved that pick-up trucks get lower drag with the tailgate UP, as opposed to down, which is counter-intuitive.
Normally, the empty volume behind the cab gets filled with turbulent air and eddies.
But apparently, with the gate up, the space behind the cab gets filled with a trapped vortex, and the rest of the air flows over the trapped vortex as if that same space was faired over.
I guess that the whole point of te Kasper airfoil is to use trapped vortices to make oncoming air "think" that it's meeting a smooth, thick airfoil.
Question is, does this really work? i did read the abstract of a paper that tried to reproduce the experiments Kasper made, and that came somewhat short. But one paper is not enough evidence, especially since it was a grad student who performed it. I'd like to find out more before dismissing the idea as ineffective.
 

sferrin

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KJ_Lesnick said:
Sferrin,

There's a hypersonic design that uses a wing set-up like this?

KJ

No. It's a subsonic design. The hypersonics book has much (probably more than half) that isn't strictly "hypersonic" projects. Not that that's a bad thing as the book covers a lot of stuff that doesn't really fit in the other releases.
 

Trident

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I vaguely remember being shown something similar that was researched in windtunnel tests at the University of Stuttgart. It looked a bit different, in that it was essentially a zig-zag corrugated sheet but the principle was the same IIRC. Apparently, the project drew inspiration from insect wings, in particular dragon flies.
 

AeroFranz

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Trident said:
I vaguely remember being shown something similar that was researched in windtunnel tests at the University of Stuttgart. It looked a bit different, in that it was essentially a zig-zag corrugated sheet but the principle was the same IIRC. Apparently, the project drew inspiration from insect wings, in particular dragon flies.

Interesting. Do you remember if meant to work at low Reynolds numbers only (just like a dragonfly) or at full scale?
 

Trident

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I should perhaps mention that I saw it at an open day more than 10 years ago which means I was something like 12 years old. Being an aircraft nut I was intrigued enough that it stuck in my mind, but the finer points of its engineering context like Reynolds numbers were way above my head at the time, sorry ;) As far as I can remember research was very basic, just testing the properties of that airfoil without an eye on any concrete application.

If you're REALLY interested I could ask some questions, since I'm a student there nowadays. It could take a while though.
 

KJ_Lesnick

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AeroFranz,
Interesting. Do you remember if meant to work at low Reynolds numbers only (just like a dragonfly) or at full scale?

I actually was going to post something to that effect. Scale poses a huge issue on such things.


KJ Lesnick
 

AeroFranz

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Trident said:
If you're REALLY interested I could ask some questions, since I'm a student there nowadays. It could take a while though.

No pressure :). Low Re aerodynamics are still somewhat over my head, and I don't do anything at work on that scale anyway.
 

AeroFranz

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Good finds. Thanks Simon.
I think I will order that package of info from TWITT.
 

AeroFranz

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Thanks for the link. I think Boeing called that an "Apex" flap. It probably traps a vortex on the leading edge and mimicks a rounder, thicker leading edge. I don't know if another vortex forms behind that leading edge fence, though. Maybe they don't need it and can get by with the improvement in lift coefficient achieved on the leading edge.
 

Mike Pryce

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IIRC it was intended to create a 'thicker' leading edge, as you say, by trapping a vortex in front of it. This moved the cp forward, giving a nose up moment without needing elevon 'up' deflections, which reduce lift and require high AoA on approach (getting round the weakness of deltas on carriers). Seems to have worked - note the elevons are used mainly as flaps on the approach (plus roll commands).

The name Apex flap may have been due to copyright/patents.
 

KJ_Lesnick

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I didn't know that's what a vortex flap looks like! I thought it was a flap with vortex-generators on it...

Just to be certain here, the apex flap also produces, in addition to the "thicker-wing" effect the characteristics common with vortex lift (ultra high AoA's without stalling and such)?


BTW: I take it such a flap must be really precisely designed using CFD to make it work right (I'm amazed such a flap could work at a reasonable scale/reynolds-number without producing a horrifying amount of drag and turbulence)
 

AeroFranz

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KJ_Lesnick said:
Just to be certain here, the apex flap also produces, in addition to the "thicker-wing" effect the characteristics common with vortex lift (ultra high AoA's without stalling and such)?

BTW: I take it such a flap must be really precisely designed using CFD to make it work right (I'm amazed such a flap could work at a reasonable scale/reynolds-number without producing a horrifying amount of drag and turbulence)

I haven't bought any of the relevant papers yet, but it seems like Kasper Witold claimed gliding his tailless light airplane at 35 degree angle of attack with full controllability and low sinkspeeds in the order of 100 fpm. All the while getting an L/D of around 17, so if this were true (and I don't know that yet), the system should be very well behaved without much turbulence.
And yes, i suspect that trapping the vortex requires getting everything just right, like matching Reynolds number to appropriate location of the fences, and three-dimensional parameters such as sweep on the wing.
 

henryk

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-short video with taxiing Kasper KC200 (wooden 70-s construction with vortex generating flaps=red/black).

X-32CV have identical LE devices(APEX flaps).

-for moore see poz.4; "The Kasperwing" book.

(Cl max=16-25!!!).

PS. Witold Kasper(Kasprzyk) was working in Seattle Boeing.
 
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henryk

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AeroFranz said:
I came across a high lift concept called "Kasper wing" or "trapped vortex". It seems like an elegant way of achieving high lift coefficients, but I find limited information. Does anybody know more about this? i would be interested in knowing if the windtunnel tests achieved good performance, and if a flight vehicle was built.

the picture comes from patent "AIRCRAFT WING WITH VORTEX GENERATION" by Witold Kasper, filed in the seventies

-that wing airfoil was realised in Kaspers KC200 2-place aircraft (70-es).
 

henryk

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henryk said:
Simon666 said:
If you want an interesting paper:


and link:



View: http://www.youtube.com/watch?v=VwbtaX8k8CE&feature=related


-short video with taxiing Kasper KC200(wooden 70-s construction with vortex generating flaps=red/black).

X-32CV have identical LE devices(APEX flaps).
-the only difference; hinge line is moore aft from leading age.[/quote]
 
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JEDI

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I am new to this list and this is my first post here. I am a long time member on homebuiltairplanes.com and have many posts there as JEDI for reference.

I have been following the Kasper story since the mid 70's and spent a day with Kasperik (Sp?) discussing his projects. I am interested in having discussions with others having that interest.

I am an engineer by training and a pilot by profession interested in low speed aerodynamics and very light man carrying aircraft.

My short answer is that there is some truth and some overstatement to the Kasper theory of vortex lift. His work was a work in progress and he did not have all the answers yet but he did have a basic understanding of the processes involved. More understanding of those processes is what is needed and those that do not understand fail to achieve the desired result.

I will try to check this list for further comments.
 

JEDI

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Now that I see I am "in" I will add a little more.

I was not around the area when Kasper was doing his flying and have only seen the videos and heard the stories. I have had detailed discussions with the daughter of the designer of the original BKB, the aircraft that started all of these discussions.

After the loss of the BKB in the fatal crash Kasper tried to improve upon the original BKB with the longer wing span Bekas. The Bekas was only a partial success in demonstrating the desired performance.

The Kasper power plane was designed to take full advantage of what Kasper understood at the time. That plane crashed on takeoff on the first flight so very little is known about the flight characteristics or its potential success.

After that crash is when I met Kasper. He was too old to actively continue his work at that time and his goal was to help others with his knowledge.

Some time after my meetings with Kasper he returned to Poland and had detailed discussions with Henryk.

Kasper worked with Steve Grussic (Sp?) on the design of Cascade Ultralights, Kasper Wing Ultralight, but was disappointed that Steve did not follow all of his suggestions. I have flown the Kasper Wing Ultralight and have had discussions with other pilots that have considerable experience with the design. I believe the Kasper Wing Ultralight has incorporated some of the short comings of the Bekas. By "short comings" I do not intend to imply design flaws but only design decisions that impacted the display and application of the "Kasper aerodynamic theory".

There is obviously more work to do in this area if the theory is to be proven and put to good use.

I would like to consult with anyone that has an interest in developing the "Kasper Wing" design applications.

I am currently working on design proposals that may utilize what I call the "Kasper aerodynamic theory".
 
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publiusr

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I have always had a fascination with vortices, tornadoes etc. suction vortices explain how one nearby home can be largely untouched and another nearby leveled. On the north side of a SW-NE bound track…a 100 mph twister moving forward at 40 mph means you only have 60 mph winds. The south side? You add the two to get 140. A suction vortex can add another 100 mph….and you have a brief swath of 240 mph winds yards from 60 mph winds. The difference in angles of attack have sent truck trailers flying like box kites.

Aviation could benefit with greater experimentation with vortices… instead of just trying to avoid them. People were more open to new ideas in the past.
 

JEDI

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One of Kasper's claims was that a lift coefficient of 25 is possible. I think I understand his reasoning but have not attempted to do the math. If any one is interested it would make an interesting project.

Anybody want to be a co-conspirator. There is strength in numbers.
 

AeroFranz

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I'd have to check one of my books, but there is a definite limit to CL. i thought it was well below 25. If you want more lift beyond that, you need powered lift and the like. Of course, it also depends on how you define lift coefficient. If you have a hovering vehicle,
CL = Weight / dynamic pressure * wing area
breaks down...
 

JEDI

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I'd have to check one of my books, but there is a definite limit to CL. i thought it was well below 25. If you want more lift beyond that, you need powered lift and the like. Of course, it also depends on how you define lift coefficient. If you have a hovering vehicle,
CL = Weight / dynamic pressure * wing area
breaks down...
I am not aware of any physical limit but current technology generally limits CL to 2.5 or less due to boundary layer separation. The “Kasper” theory avoids that limitation.

If you are referring to some other limitation I would like to have more details or references.

Kasper has been known to have been misleading on some of his statements according to some sources.

I think it is wise to not accept on faith everything you hear about Kasprzyk.
 

henrykd

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I am new to this list and this is my first post here. I am a long time member on homebuiltairplanes.com and have many posts there as JEDI for reference.

I have been following the Kasper story since the mid 70's and spent a day with Kasperik (Sp?) discussing his projects. I am interested in having discussions with others having that interest.

I am an engineer by training and a pilot by profession interested in low speed aerodynamics and very light man carrying aircraft.

My short answer is that there is some truth and some overstatement to the Kasper theory of vortex lift. His work was a work in progress and he did not have all the answers yet but he did have a basic understanding of the processes involved. More understanding of those processes is what is needed and those that do not understand fail to achieve the desired result.

I will try to check this list for further comments.

Grossruck/Kasper KASPERWING can fly horisontally with 18 km/h speed
(5 m/s !) ,wing surface 16.7 m^2, 160 kg weight...

it may be with Cl>5 !!!
 

henrykd

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everything you hear about Kasprzyk.
-Witold Kasprzyk (Kasper) was born in 1908,Krakow,...polish glider champion before WWII
and after,
was fall in glider cork (tight spiral).

in 1947 "Skrzydlata Polska" in his papers="optimisation in soaring", "new glider concept"
(DIANA 2 like !)

in USA,Seattle =permission on limitless aerobatic on BKB1-A (AEROBATIC)...

View: https://www.youtube.com/watch?v=ldU-A5_35wc


=the main achvement=STATIC stability/contrability =
View: https://www.youtube.com/watch?v=MPOzzzitGu0
 

henrykd

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One of Kasper's claims was that a lift coefficient of 25 is possible.

-do You know Kaspers book "The KASPER WING" ?


(Cl >25...)


-another VORTEX fenomenon=wing DRAG decreasing...!



dr E.Sorokodum=

=SECTION 3=


In 1893 Zhukovsky theoretically opened the effect: at the
wave flow of fixed wing profile, the latter will get the thrust due to
this wave flow.
Later, a similar effect is found Knoller and Betz
This effect could allow, still beginning of the last century,
create aerial vehicles a completely new type, - with very low
drag, economical and more.

But this does not happen until today!

This fact indicates a low level of scientists and
designers in modern aviation and the fact that in modern
civilization much is not well and it will be very difficult to
overcome the many global crises.
3. The annihilation of the aerodynamic resistance of the hull using effect Zhukovsky-Knoller-Betz (KNOW HOW)
 

JEDI

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Post #31 ref:

I do not recall it by name. I will look for it.

Do you know of the experimenter with fin powered boats Kagel
 

henrykd

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After the loss of the BKB in the fatal crash Kasper tried to improve upon the original BKB with the longer wing span Bekas. The Bekas was only a partial success in demonstrating the desired performance.
=AR 10 /15 ...
15. “Flight Testing the Bekas N”, by Witold Kasper, Soaring, November 1969, pp. 12-14.
(investigation of DYNAMIC fly of BEKAS-N,
exerting energy from horisontal gusts=HORISONTAL wind gradient)

from=

 

henrykd

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it seems like Kasper Witold claimed gliding his tailless light airplane at 35 degree angle of attack with full controllability and low sinkspeeds in the order of 100 fpm. All the while getting an L/D of around 17, so if this were true (and I don't know that yet), the system should be very well behaved without much turbulence.


V horisontal=10 m/s,
V vertical (sink) =0.5 m/s

L/D circa 20 !
 

henrykd

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I think it is wise to not accept on faith everything you hear about Kasprzyk.
=end of 22 second towing...after relasing (8 m !) WILGA rapidly gained his level to circa 50 m !
 

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