3D Printed Hydrofoil Boat RC Flies

hydrofoil boat

[Wersy] has been trying out different designs for 3D printed RC boats — his latest is a hydrofoil!

He’s using a high power RC plane out-runner motor, which he found is simply… too powerful. It would cause his first boat to flip and sink if he opened the throttle up too much! To counter this — and make full use of his motor — he’s made new two boats; a hydrofoil, and a dual-hulled  air(?) boat.

He based the hydrofoil’s profile off of NACA 63-412, a typical profile for sailboat hydro foils like the Moth. What he found was it’s still extremely difficult to get the right balance between the pitch of the wings, and the throttle output to hit a steady condition for driving smoothly. It works, but it will still needs a few more iterations!

His other solution, a quasi-jet engine-dual-hulled-boat is pretty fun too — he’s 3D printed a large impeller for his motor, and strapped it in between two of his boats! It’s quite a bit more stable to drive, and looks pretty unique!

Stick around after the break to see both of them in action.

[Thanks Jotham!]

20 thoughts on “3D Printed Hydrofoil Boat RC Flies

  1. Even the simplest successful submerged hydrofoils have some kind of pitch/height feedback to adjust the lift of the foils. If he gets it working well with that design and no active stabilization, I’ll be *very* impressed indeed.
    In theory, it should be easier with U-shaped foils that break the surface, because they’ll produce less lift as they pull out of the water.

  2. I direct the interested reader to the World Cup yacht races last year. They were hydrofoil cats, with wing sails larger than a 747’s, and speeds well over 40mph. Stability systems were not allowed, making control very, very difficult.

    As I recall, Team Oracle had lost 7 races in a row and were one race away from losing the Cup. And then something changed. Just like that, they came back to win 7 or 8 races in a row. Their boat suddenly became incredibly stable. It was uncanny.

    Many believe they implemented in illegal stability augmentation system. It may have already been hidden on the boat and they decided they needed to use it.

    It is worth mentioning that Team Oracle had already been found guilty of cheating earlier in the series. Not minor rules infractions, but blanant secretive cheating.

    I think it was just dirty cheating.

    The people responsible for policing legality in the series have very few resources. They lack the manpower, expertise and budget necessary to police these incredibly complicated boats. That is by design, because the winner writes the rules for the next race.

  3. These boats look like they’ve been designed from first principles. I think this fellow should pay a visit to his local R/C model boat club where they know what works and what doesn’t plus he’ll gain an insight in how to build a more practical model, be it airboat, hydrofoil or plain old displacement hull.

  4. you guys are too harsh. If he wanted a functional ready to go boat, he could buy one. And presumably go back to printing Yoda heads on his printer. But that is not the spirit of hackaday. His twin hull airboat is a direct response to a single hull being unstable due to the large centrifugal forces. If he increases the cowling at the front of the impeller housing, it should prevent the wash from the hull being sucked into it.

    1. My comments weren’t meant to be negative or to take away from the guy’s fun, I just think this work shows some misunderstanding of the forces at work on a boat’s hull and trying to highlight a way forward: Tweaking the shape of the hull will probably do much more for him than adding wings or a second hull. These very round shapes he has going on aren’t doing him any good in the stability department.

      1. My aim was to replace or add – with little effort – only parts of a base model and see how far I come. It is clear that this can’t be always quite successful, especially if one try to morph a displacement hull to a speed boat ;-)

        But you are absolutely right. Today I made a little test of my very last version – with a broad stern part and spray rails to avoid water comming into the boat – and this is really fast :-)
        It will coming soon…

  5. Originally I just draw a hull to try out a free form surface method with three splines – freehand drawn by eye. What came out is a typical displacement hull. http://www.thingiverse.com/thing:272132
    Therefore of course, all my effort to make it faster than the hull speed can only be deficient. It was more experimenting for fun than serious designing. I love to design things from what I have hardly not a clue about it ;-) – like my printed airplane.
    Anyway it flies ;-) http://www.thingiverse.com/thing:86982
    And here with a save landing: http://www.thingiverse.com/thing:98954

    1. Yes, more freeboard would not be bad, The equipment is rather heavy.
      But it don’t need a bilge pump. If there is enough water the turning cylinder of the outrunner catapults the water outside again ;-)

  6. i seen a succesful model hydrofoil boat the foils it had where not as broad and a whent a little more to the sides of the boat , he could try to get the front wing to work and have the back ride on the bottom end of the prop like the older proprider / 3 point boats

    allso the story told about the model boat said that the foild are verry subseptible to cavitation so the surfaces need to be verry smooth
    the profile wasnt like and aircraft wing blunt in the front and sharp in the back it was sharp at both ends due to the waterrisistance being higher than the airresistance and to prevent cavitation , look at a boatprop and you see wat i mean

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