Sustainable Human powered foiling

Discussion in 'Boat Design' started by jakeeeef, Oct 2, 2021.

  1. clmanges
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    clmanges Senior Member

    @jakeeeef
    One of the problems no one else here has addressed (unless I missed it) is in your having to operate a long lever to deploy the foils. I think this could affect your power output just at the most critical moment.

    I think it's possible to have the foils in their un-deployed position being in tension against a spring arrangement, so to deploy them you'd only need to pull a trigger to release them.
     
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  2. Skyak
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    Skyak Senior Member

    IMHO Ray's book is way oversimplified. It's Ray's way to make a few bucks by telling people they will be able to build craft as good as people way smarter than they are.

    If you have 500W you can get on foil and 200W can sustain a high quality build in my estimation. AR 8 does not sound like that high quality though.

    Foiling moths have very high quality foils and a broad Cl range with excellent height control. Compare to Wazp to see how performance drops going to merely excellent foils and controls.

    "I wonder if my system of keeping the foils within the perimeter of the craft and folding them down when needed could be a worthwhile development or not." If you could do that you would address the hugely awkward takeoff stage by using boat momentum to reduce the takeoff power peak.
     
  3. fallguy
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    fallguy Senior Member

    can you show the math that says you can operate at 40% once up??

    I have zero intuition, but this would be better than planing vessels.
     
  4. Robert Biegler
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    Robert Biegler Junior Member

    He may not even need the spring. As long as the resultant force from the lifting part of the L-foils is inboard of the hinge, there will be torque rotating them down as soon as they hit the water.
     
  5. philSweet
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    philSweet Senior Member

    UT2 - no lactic acid buildup. Endurance is basically unlimited until you quit from boredom. Can talk normally while working and do not sweat much at pleasant temps. Power less than 60% of TR.

    UT1 slight lactic acid buildup - less than 4 mmol. Moderate sweating. Endurance measured in hours. Power 60-70% of TR. Pulse 150s for fit athlete

    AT Hard workout at aerobic limit. Lactic acid more than 4mmol. Endurance typically 20-30 minutes. Power 70-80% of TR. Heart rate 160s.

    Heart rates are highly variable at the high end. At altitude, I could sustain 212bpm for 20 minutes after several hours of UT1. 204 for 1 hour. Resting rate was 28. I was something of a spinner because you end up coordinating heart rate, respiration, and pedal rate on hard cruises and hill climbs, and my heart rate was higher than most. Typical climbing pedal rate for me was 93/min on a 172.5mm crank.

    Has the target moved? You were talking about sustainable power levels for non-elite athletes. Sustainable as in 4 hours?
     
    Last edited: Oct 3, 2021
  6. Skyak
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    Skyak Senior Member

    I have nothing to support the notion that you can operate at 40% once up and that is not what I was saying.
    Jakeee... said that 500w is a conservative sprint power estimate -I can't do that and I think it is too high. But it is true that if this 85 kg pilot can do 500w he can get foiling.
    200w is what I estimated an excellent low speed foiling craft would need to sustain flight in post 12 (as opposed to the 170w and 124w in his post).
    A 40% drop in power getting up on foils just indicates to me that the design has a terrible takeoff drag hump.
     
  7. philSweet
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    philSweet Senior Member

    The point is to address the question and issues that were asked by the OP. Nice pun, though;)
     
    Last edited: Oct 4, 2021
  8. Skyak
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    Skyak Senior Member

    Your analysis was spot on (as usual) but the selection of values is more argumentative. I am glad you appreciate the pun, but I have no interest in arguing about what someone can do and a mild interest in what I could do with a human powered hydrofoil. It seems like something I should know and my sister and brother in law just bought a lake house far from any gym so I have a place for a workout boat.

    For a start I was thinking we could check the viability of the Shutt patent's surface piecing foil version because it doesn't need a flap. It has three factors controlling fly height -area reduction, surface proximity, and the rotation about the forward ski. First try would be a constant cross-section with an ellipse center and 45 deg. extensions to each side piecing the surface. I was thinking I would just assume an excellent lift distribution and go back after it is sized to check how far off it was.
     
  9. BlueBell
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    BlueBell WOT

    You missed the chapter you've obsessed about for 25 years but then forgot about it.
    How can you forget what you didn't see?

    Ray's book is very basic and hugely lacking in foundation.
    Clearly you lack the fundamentals to reason this out.
    It now appears you've abandon your thread.
    Fickle?
     
  10. Skyak
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    Skyak Senior Member

  11. BMcF
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    BMcF Senior Member

    Based on that power ratio, it would be more accurately an electric-powered pedal-assist bike. I like it though..as a hydrofoil designer/advocate for almost 40 years now, that kind of thing is very cool to see realized.
     
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  12. Skyak
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    Skyak Senior Member

    Before I saw it I was thinking that if I made a human powered craft with a large enough span on the main foil I could achieve sustained foiling with ~200w. I was thinking 1.5m span and 3 to 4 m/s. This Manta5 has a 2m span main, ~1.5m forward, two stage foil skimmer and even with a larger cord than I planned the speed is 5-6m/s. I don't see much opportunity for improvement. Not looking good for human powered foiling.
     
  13. clmanges
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    clmanges Senior Member

  14. BMcF
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    BMcF Senior Member


  15. clmanges
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    clmanges Senior Member

    Nope. Watch the video; when the thing slows down below a certain speed it begins to sink and ultimately goes straight down. What you're seeing isn't buoyancy, it's an impressive amount of lift.
     
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