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Speeding things up...
http://www.hobie.com/forums/viewtopic.php?f=69&t=13887
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Author:  IkosTri [ Wed Aug 19, 2009 11:13 pm ]
Post subject:  Speeding things up...

I just came across the following tube video
http://www.youtube.com/watch?v=bQRtgEIs--k

and I remember the Hobie Trifoiler. I don't think it would be too hard to make some changes/add-ons to the AI to take advantage of physics:

First off, there are 2 distinct ideas:

(1) use 3 small hydrofoil belt-ons to lift the bow and the the amas to keep them from submerging.
Image

(2) Hydrofoil upgrade kit that lifts the entire kayak out of the water. This would go through the mirage drive shaft:
Image

and of course you would have to replace the rudder with a hydrofoil rudder.

Hobie has a lot of experience with the trifoiler so I hope they will pick up this post and set my crazy head straight

Or else we'll soon be flying AI's across the seas ... ;-)

Author:  rokraider [ Thu Aug 20, 2009 3:30 am ]
Post subject:  Re: Speeding things up...

Interesting concept. How will you trim the ride height? Having a foil on the rudder will change the angle of attack some, but you will need an a aileron of some sort on the main wing to determine the height that it will ultimately ride at.

Author:  IkosTri [ Thu Aug 20, 2009 12:29 pm ]
Post subject:  Re: Speeding things up...

I am not sure you would need an aileron. The rudder could look somethink like this:

Image

This way, even when the hydrofoil is all the way up, just under the surface, you still have enough rudder under water. The angle of attack for the front hydrofoils would not differ that greatly between the rudder fully submerged and fully up. There are two forces at work here: the weight of the boat and the amount of lift created by the foils. The lift depends on the size and shape of the foils and on the speed with which the boat is moving. Most of the weight is close to where the drive shaft is, so the rudder hydrofoil can be smaller...

What do you think? Shall we build one ;-)

Author:  rokraider [ Thu Aug 20, 2009 1:37 pm ]
Post subject:  Re: Speeding things up...

I believe It will need to be somewhat more complicated than that. You will still need to be able to adjust the angle of attack and the ride height. I don't think the rudder pin will be very happy with these developments. :wink:

Author:  IkosTri [ Thu Aug 20, 2009 3:46 pm ]
Post subject:  Re: Speeding things up...

Oh the good old rudder-pin... forgot...my bad. You are right, this needs a bit more professional approach. But maybe Hobie is willing to look into it. I guess for now I will leave the boat in the water and just lift the bow and amas a little, to reduce the drag they produce... Back to option 1. Later...

Author:  IkosTri [ Thu Aug 20, 2009 4:28 pm ]
Post subject:  Re: Speeding things up...

Now here is another crazy video of a windsurfer on 1 foil !
http://www.youtube.com/watch?v=1oyWMusaDTI

Another thought... how about attaching the second foil through the wheel shaft - same construction as the wheels just with a foil instead ;-). You would have one before the rider and one behind. The rudder still needs to be longer, and maybe that already creates an issue... don't know....

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