• 8th September 2015 - By greg

    Holy Flying Stabilizer Batman!

    I finally succeeded in getting a foil to controllably lift one stabilizer out of the water and ‘fly’ it a couple of inches above the water without either of the stabilizer floats touching the water surface with a new high-lift foil. The foil was mounted to my control arm, and I found it pretty easy to use the control arm to make minor adjustments to the angle of attack to fly at a consistent height above the water surface.

    I know I can easily exchange the manual control lever for a float skimming the water to make that AoA adjustment automatic, but I don’t think there is really any point. The drag from that high-lift foil is way higher than the drag from the stabilizer float skimming through the water. Even if I were to swap out my heavy but aerodynamically efficient stabilizers for some super-light weight foam blobs, the weight savings plus float drag savings still don’t justify using the foil.

    Essentially, this is a very small experiment that shows how flying the entire boat with a very large hydrofoil just doesn’t make sense. If I am unable to achieve better efficiency with a very small foil lifting up only 10 pounds of stabilizer, then it is highly doubtful I will be able to lift the weight of the entire boat + me with a much larger foil.

    To make the new foil, I used a section of old chromoly aero bike tubing and cut it in half length-wise. Then I filled the inside with micro / epoxy, and sanded flat. I ground the leading edge round, and the trailing edge sharp, then welded a strut onto it. I was pretty happy with the aero profile.

  • 3 Comments to “Holy Flying Stabilizer Batman!”

    • Chris Pollard on October 8, 2015

      There is a world of difference between what you have made and a correct foil section. A huge difference. The same is true of your prop and the flexible tube you have to drive it.

      A round tube has a drag coefficient close to 1 and can be replaced by a much larger rigid airfoil section tube with less length and drag.

      With all the effort you have put into training and the boat design I think you should find somebody to help you with the foil and prop design.

    • David on February 16, 2016

      A circular arc … of maybe 12% thickness … does not make a good hydrofoil section.

      Anyhow, I’m late to the party. I did bring beer: https://www.facebook.com/sordomuti/videos/720504444750448/


    • Ivan John Kuljis on May 30, 2016

      Hey Greg,

      Wrote to you a while ago when l also sent a picture of a recumbent built by Paul Sims called ‘xevon’. I was also lucky to have the chance many years ago to try out
      Rick’s early aluminium out-rigger boats, where from memory l pedalled it to around 16 knots or it may have been 16kph….time and memory! You know what l mean!

      Meanwhile, l have been composing and recording with some of Australia’s great
      for an album release…thought l might send you a song called ‘Destiny’ if you’d like to hear it?

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