Wind powered ground effect boat/craft

Discussion in 'Propulsion' started by Cloxxki, Jun 23, 2010.

  1. Cloxxki
    Joined: Jun 2010
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    Location: Netherlands

    Cloxxki Junior Member

    Alright then...

    It works on the cart, because the overhead air+rolling reistance (when passing wind speed) is smaller than the propellor's thrust, by a large margin. The cart travels (wheel turn) more distance than the propellor does through the air. As energy is taken from the wheels, there is enough of it to create a surplus of thrust, accelerate past wind speed (the prop is geared to always have nett thurst, at any speed) until things even out.
    Although wind has a given speed, it has plenty of force. Letting a wide open sailed vehicle reach (near) wind speed, is near effortless for the wind. Most of the air still moves at wind speed, thus little energy was harvested. the trick is to slow down the tail wind. Like in a bicyle race, pulling yourself forward on the alongside car. Car slows down a bit, cyclist accelerates more.
    Essential in the DDWFTTW concept, is a low-friction, high-traction interface between the surface and the vehicle, in order to exploit the speed difference between the vehicle and the air.
    The Blackbird's current runs are in the 2.5-3.0x windspeed ballpark. A 17ft propellor is pushing back at the wind, powered by it's ~290 sq. ft. spinning "sail". All the power in the wind is extracted.
    Anyway, imagine an efficiently build water vehicle would match the Blackbird's combined aerodynamic and rolling efficiency. In 25kph winds, a 50ph apparent headwind would be experienced. And as said, going upstream at the same time, would help some more.
    50kmph wind, that's something to try and get a lightweight crafts airborne with. If the air-vehicle interface holds up decently for traction vs. friction, the reduced friction from going to "rolling the water surface" to "rolling the ground effect air bubble" might mean that the flight could be sustained, or even accelerated.
    At this 75kph ground speed (using no water current), 50pkh apparent headwind (25kph tail wind), think of the aerodynamic properties as those of the vehicle moving as it does (tracks at ~water speed), hanging from a kite cord, stuck on the other end to a shadowing 50kph submarine. It just might work, you know...
     
  2. Cloxxki
    Joined: Jun 2010
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    Cloxxki Junior Member

    The Blackbird looks likely to be a awarded a >3 wind speed NALSA record, with runs up to 3.48 recorded.
    As well made as it is, their design is bound to be improved upon some day in the future. This lends more margin for an on-water vehicle to get into good values, despite the inevitably more draggy water interface.
    I cannot opver-empasie how light weight yet strong "my" craft will need to be, just to reach wind speed. Let alone created greater apparent headwind than actual tailwind, and get into realistic take-off speed. LET ALONE, remain powered through an airflow-to-track transmission.
     

  3. Cloxxki
    Joined: Jun 2010
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    Location: Netherlands

    Cloxxki Junior Member

    Great inspiration:

    http://www.youtube.com/watch?v=i9sHtVzdW8Q

    It will need to handle pretty low still speeds. Compare this one to your typical Cessna. It looks slower, doesn't it?
    http://www.youtube.com/watch?v=qk0HRShYbGU&feature=related

    Oh yes:
    http://www.youtube.com/watch?v=TYFEFekPzDM

    Imagine this, huge prop on back, track on belly, and all ultra-light (no engine or fuel):
    http://www.youtube.com/watch?v=i4QguO9ti1c&feature=related

    Hmm, see this one, I get the idea to use a rubberband or other wind-up system as a kick starter, to get the craft up to speed, after which it would cruise in flight, powered by the wind.
    http://www.youtube.com/watch?v=6R3zQ17VTck&feature=channel

    Ah, it's been done!
    http://www.youtube.com/watch?v=Om5MF0ZbujE
     
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