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First trial of horizontal fin drive
- Thread starter Skip Johnson
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Skip Johnson
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No not really, if I can't reduce the heave to a manageable amount (whatever that is) it's a lost cause. The idea of adding ballast to a human powered craft meant for speed just doesn't compute. But I think there were some early foil only craft that incorporated a flywheel to smooth out their operation.
Now that I think about it it might be possible to recover some of that power with fins on the hull. Time will tell.
It's not clear how much heave is involved at this point, some may be rocking motion since the foil isn't directly over the CG.
Now that I think about it it might be possible to recover some of that power with fins on the hull. Time will tell.
It's not clear how much heave is involved at this point, some may be rocking motion since the foil isn't directly over the CG.
fallguy
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The heave is caused by the AoA being too low and too much power wasted in the Y axis.
The dolphin’s body has a ball shaped vertebrae, from my cursory reading, but the ball is just part, the tendons and muscles allow the angle to be greater at the top of the stroke, and then the bottom. I think the fish varies it some, but that isn’t a big deal.
It seems to me the AoA can change in the simplest fashion by placing the vertical strut closer to the motion. But I think this oversimplifies the need.
Edit: what I meant to say was to make the motion mount move; if the motion mount is closer to the vertical strut; it would allow for some modification of the simple AoA, but it would not account for making the foil more angle at the top or bottom. Perhaps this was already tested for a sweet spot.
It may be possible to give the motion arm a custom joint so it is longer at the longer and shorter at the shorter ends of it’s throw, but there is a reason I’m not a mechanical engineer and can’t quite determine how to get the length with the foil at the top or motion arm bottom. These changes would probably not require significant changes to the current configuration; if attainable. But moving the motion arm closer to the fixed strut offers more angle and a joint in the motion arm or two? allows for more angle at the extremes somehow…
The dolphin’s body has a ball shaped vertebrae, from my cursory reading, but the ball is just part, the tendons and muscles allow the angle to be greater at the top of the stroke, and then the bottom. I think the fish varies it some, but that isn’t a big deal.
It seems to me the AoA can change in the simplest fashion by placing the vertical strut closer to the motion. But I think this oversimplifies the need.
Edit: what I meant to say was to make the motion mount move; if the motion mount is closer to the vertical strut; it would allow for some modification of the simple AoA, but it would not account for making the foil more angle at the top or bottom. Perhaps this was already tested for a sweet spot.
It may be possible to give the motion arm a custom joint so it is longer at the longer and shorter at the shorter ends of it’s throw, but there is a reason I’m not a mechanical engineer and can’t quite determine how to get the length with the foil at the top or motion arm bottom. These changes would probably not require significant changes to the current configuration; if attainable. But moving the motion arm closer to the fixed strut offers more angle and a joint in the motion arm or two? allows for more angle at the extremes somehow…
Last edited:
HelmutSheina
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******?
I thought they (O-foil) used such a thick profile to handle the loads.
It seems too thick to me relative to its chord.
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