Wing of the "Kasperwing" in sailing?

Discussion in 'Hydrodynamics and Aerodynamics' started by Konstanty, May 2, 2016.

  1. Skyak
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    Skyak Senior Member

    I don't know what other ULs you are comparing to but climbing and cruising on far less power indicates some value. The other ULs have greater span? Higher aspect ratios? Do they have higher flight speeds? Do any have 2 surfaces for a significant portion of the wing?

    10/1 L/D does not sound very good and 30mph sounds quite slow (again I have no refference). Was it's efficiency based on the ability to fly slower? How does it compare in MPG?

    My interpretation of how it works is that it uses big recirculation that acts like a thick wing. The endplates contain the vortex to keep it from spilling. Winglets would not work because the air is going forward in the aft half of the wing. It's certainly creative. I am not sure how it could work without the prop thrust keeping that vortex from growing and increasing drag.
     
  2. Manfred.pech
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    Manfred.pech Senior Member

    http://images.google.de/imgres?imgu...ved=0ahUKEwimn6_uocbMAhVB3SwKHcE5BcMQ9QEIIjAA

    [​IMG] [​IMG]
    There has been a "TEST" by MULTIHULLS WORLD (MULTICOQUES MAGAZIN). Dutchman TOM BAKKER (Engineer by profession) developed the AEROSKIMMER together with the technical department of the DELFT UNIVERSITY, ERIK VAN DEN BERG (productmanager) and NIELS HAARBOSCH (testpilot and builder). The boat was fast, "we can go 40 kn" (ERIC VAN DEN BERG).

    Aeroskimmer in figures: Length 4,80m; width: 4,80m; weight: 130kg; wing surface: 20m²; mast height (A frame) 4,10m; wingspan: 9,60m

    ANOTHER APPROACH with a small wing (not Kasper) from Bob Quinton http://boatek.club24.co.uk/ :

    [​IMG] [​IMG]

    [​IMG] [​IMG]

    Adaptation in a dissertation: http://citeseerx.ist.psu.edu/viewdoc/download?rep=rep1&type=pdf&doi=10.1.1.221.1541

    [​IMG]

    http://www.ayrs.org/catalyst/Catalyst_N16_Apr_2004.pdf pages 21-36 and http://www.ayrs.org/catalyst/Catalyst_N17_Jul_2004.pdf pages 28-35
     
    Last edited: May 13, 2016
  3. Konstanty
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    Konstanty Junior Member

    Reefing sail type kasperwing

    Super. Even slot has. I will try to insert sail type kasperwing in my drawing proa. It should be able reefing.
     
  4. Manfred.pech
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    Manfred.pech Senior Member

    Good luck!
     
  5. CT249
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    CT249 Senior Member

    The tilt wing's been tried many times, but has it ever done anything but fail in a true test such as a race?

    If the tilt wing cat pictured could do 40 knots, why didn't it take the world record?
     
  6. Manfred.pech
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    Manfred.pech Senior Member

    ...because there is is a small difference between claim and reality.
     
  7. Clarkey
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    Clarkey Senior Member

    And also because at that time the record was already more than 46 knots.
     
  8. Manfred.pech
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    Manfred.pech Senior Member

  9. CT249
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    CT249 Senior Member

    Whoops, that's another good reason. I got the impression from the pics that it was a mid '80s boat.
     
  10. CT249
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    CT249 Senior Member

    That seems to be incredibly common when people are making claims about inclined rigs, wing masts and wing sails. Obviously they can work, but there seems to be something about such rigs that causes people to make grossly exaggerated claims.
     
  11. Konstanty
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    Konstanty Junior Member

    Canting keel and canting wing sali.

    It was supposed to be kasperwing sail, but done the slot - wing - flap sail.
     

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  12. Petros
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    Petros Senior Member

    I worked in aircraft aerodynamics for 8 years in a previous life. I have actually studied Dr. Withold Kaspers original paper (I think I have a copy of it a box of documents somewhere), I also knew Steve Grossruck who owned the Kasperwing UL company that built them, and was the pilot that did a flight demonstration inside the old Seattle Kingdom (see video) in 1981. And I also happen to own a Kaserpwing UL I got used cheap.

    https://www.youtube.com/watch?v=dRqteDXb3Yk

    I can say categorically there is no advantage to the wing design on a sailboat. There are almost no advantages for it in any commercial or private aircraft. All the design does is capture a large stable vortex when in mush mode to allow a controlled decent, which is slowed by the amount of energy it takes to form the vortex. You still have to have a very low wing loading to allow the mush mode it be safe to perform, which pretty much makes its features useless for any long range or useful cargo/payload aircraft of any size. The formation of the vortex BTW, also increased drag significantly, which allows the controlled sink rate, but is not good for efficiency in normal horizontal flight.

    There is no magic in it, it is just a matter of physics. the benefits on a modern aircraft are so tiny they are not even worth considering because of the major disadvantages. All it does is create a trapped vortex on the top of the wing, which generates a lot of lift, but with a lot of drag. The control surfaces are large enough to maintain control at low speeds (there is no magic there either since this is common on aerobatic aircraft). None of this is useful for improving cursing speed, payload, or range, which dominates the priorities in aircraft design.

    Nor are any of this high lift but high drag capability useful on a sailboat. Why would you use it? It is not efficient, it dose not have good L/D, it is not simple (required LE flaps and warpable wing surface). It has not "caught on" for aircraft because it is more a curiosity, but does nothing to benefit the desirable performance of aircraft. The high lift could conceivably contribute to going down wind faster, but the high drag would cause the boat to heel over so far the benefit would be lost. A well designed spinnaker is more useful, less complex and far lighter than a Kasperwing for goging down wind.

    It is just an oversold curiosity, a stunt that serves no purpose. the low wing loading makes for a good STOL type aircraft, but that is not unique to Kaperwing. the stable mush mode does allow you to control the decent when dropping into a field or grass strip with trees or terrain around it, but that would not be safe if there was any cross wind with such a lightweight and low wing loaded aircraft, and there are other flying methods and use of conventional controls that can accomplish the same thing.

    Do not waste any mental effort on thinking it would be useful, it is just a bad idea on a sail boat.
     
  13. Konstanty
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    Konstanty Junior Member

    Sails at last drawings not caming from kasperwing. That is tradicional STOLD type slot - wing - flap.
     

  14. Petros
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    Petros Senior Member

    yes that is true, and it appears to be a wing shape designed to be used as a sail. Something like that can be made to work reasonably well.

    The title of the thread is to use a Kasperwing as a sail, that would be a wasted of time and effort.
     
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