Rotary wing foiling, anyone?

Discussion in 'Boat Design' started by jakeeeef, Oct 26, 2021.

  1. jakeeeef
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    jakeeeef Senior Member

    This might be a very short thread, but while sorting through a box of lift blades for large RC helicopters (rescued from the FREE section of Facebook Marketplace!). I did wonder has anyone tried an unpowered rotary foil under a hull as a hydrofoil.

    I don't know much about forward motion powered rotary wings (autogyros), so I'm sure there's plenty of valid reasons not to bother. But what are these reasons?

    But don't they do useful and clever things like provide more roll stability than conventional wings and allow very short takeoff (more lift) for aircraft?

    And could some of these factors be of interest under a boat? Might the spinning mean they can clear weed by moving whichever blade had the weed on it to face backwards? Wouldn't help with a weeded foil mast of course.

    As I say, I don't know, but surely someone has had a go at it? Bet the Russians have. They loved this sort of caper back in the day!
     
  2. portacruise
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    portacruise Senior Member

    Unpowered rotating foils may have too much drag and other issues when used in water. There are some powered rotating foils of the "hydrocopter" invented by Frances Reynolds, which were demonstrated successfully, discussed in several threads, many years ago:

    https://foils.org/academic-papers/building-hydrofoils/

    4 Wheel Drive Boat - looking for builder https://www.boatdesign.net/threads/4-wheel-drive-boat-looking-for-builder.35641/page-2#post-424585

    The picture and video links showing working models have all disappeared on these Old Posts.
     
    Last edited: Oct 26, 2021
  3. jakeeeef
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    jakeeeef Senior Member

    Ah, thanks, I see one of the issues was cavitation caused by the tip speed of the forward rotating blade. Not a lot the designer can do about something like that.
     
  4. DogCavalry
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    DogCavalry Soy Soylent Green: I can't believe it's not people

    @jakeeeef , you certainly do like the weird ones.

    But no. A gyrocopter underwater is a terrible idea.
     
  5. upchurchmr
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    upchurchmr Senior Member

    My understanding is that lots of people have been killed in autogyros.
    Hence their lack of popularity.

    Just something I heard, not personal or professional knowledge.
     
  6. DogCavalry
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    DogCavalry Soy Soylent Green: I can't believe it's not people

    Lift to drag ratio of that would be awful. And that's before it picked up a bit of trash.
     
  7. portacruise
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    portacruise Senior Member

    The powered hydrocopter (is not a gyrocopter) model did seem to work quite well in the videos I have seen, but I have no idea about top speed or the efficiency. Presumably it at least partially uses drag friction to help propel itself forward, instead of drag friction being a detriment. It was not under water at all, while being powered, and the boat is lifted upward, just like with a traditional hydrofoil. It has some differences from a fixed hydrofoil in that the top surface is not immersed and whatever drag friction on the blades is being used as a positive factor propelling forward. The fan looking blades were bent upward about midway, and only the end part made contact with the water on the inside and under the boat. The axles and outer part of the blades facing away from the boat do not touch water -so any weeds, Etc would probably be flung away, behind the boat. Some of the prominent members of the human power boats Forum at the time seemed to think it was within the capacity of human power, but the concept may not be scalable or practical for large boats.
     
  8. jakeeeef
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    jakeeeef Senior Member

    Ha, yes. I do sometimes wish I could fill my mind with things other than rather niche small boat technologies!

    This is my favourite sort though: won't work, scrap idea, concentrate on something else! Its the ones that MIGHT work that have a tendency to become time consuming!

    I suppose in the final analysis, I think that very important discoveries are still to be made in vessel efficiency, with the decarbonisation agenda they are more important than ever, and (more qualified people on here may disagree) I think some of the technologies we need are still within the grasp of the amateur boatbuilder.
     
  9. philSweet
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    philSweet Senior Member

  10. Tedd McHenry
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    Tedd McHenry Junior Member

    One of the key
    At one time, there was a problem with amateur-designed autogyros that had the thrust line incorrectly located relative to the C of M, rather like a sailboat with too much lead, except with worse consequences. But properly designed autogyros actually have a good safety record, and enhanced safety in low speed flight is the main goal of autogyros in the first place.
     

  11. jakeeeef
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    jakeeeef Senior Member

    I note the Benson which appears to be a thrill seekers device for towing behind speedboat, a precursor to parascending.

    But what is the second picture? It's hard to make out but it looks like it might have been a Avro experimental craft, in which case it was probably developed a few yards from where I am now ( Hamble, UK).

    I know neither of them are what I was originally asking about, but I'd be grateful for any further info on the lower photo!
     
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