twin tip hydrofoil

[wil]

Thanks for that information revhed. It was my intention right from the start to have a flexible fuselage set up. It will be a lot quicker for me to make 3 wings for a twin tip than making a complete new board. I will try to take my twin tip board out this weekend and take the screws out of the foot straps on the inside. Maybe having a strap just fastened on the outside could be enough for a hold. I have not been able to find out where to buy the NSI foot hook. I also found it hard to purchase a bigger block of high density foam. Could only find a square piece of 15mm thick that I would have to laminate to build a foot hook out off. Have you got any other easy solutions.

[wil]

Today I got some aluminium wings made up. the central one has a modest amount of anhedral. I left the outer wings flat. The central wing is 5mm and is a bit springy. I have decided to put a big of carbon around it. Since I never worked with epoxy it will be interesting. Once I am working with the carbon cloth I am considering to wrap some around the mast as well. The mast has a bit of give. I am just a bit concerned about the total weight of the foil.

The mast and fuselage are 2.9 kg and the weight of the wings is 1.5 kg. If you add the bolts and nuts and carbon for the centre wing it start to add up a bit. What weight is still acceptable. My plan is to make some carbon wings in the future. Do I just go ahead now and add one strip of carbon to the mast for safety?

I am going to bolt the hydrofoil to a twin tip board with quite a bit of rocker.

[Hawaiis]

Placing Carbon fiber on Aluminum may cause Galvanic corrosion, you may want to use Fiberglass first.

[wil]

How long before it will weaken the strut. I don'r really want to get more stuff and make it complicated.

So far this has been a low cost project.

[Hawaiis]

It depends on how thick your aluminum and how long it contacts salt water. The original Airchair/Skyski was made of solid aluminum on the strut, fuselage and wings, not hollow.

[revhed]

. I have decided to put a big of carbon around it. Since I never worked with epoxy it will be interesting. Once I am working with the carbon cloth I am considering to wrap some around the mast as well. Do I just go ahead now and add one strip of carbon to the mast for safety?
.

WIL,
Bonding to alu requires considerable know how and toxic expensive products to be good.
You can read up on this on line easy.
You will think that a simple epoxy carbon lay up will work, it will not.
And as H said and L F knows even when just mechanicaly mating carbon to alu a barrier should be used.
The tests we have done give us the impression, as with DIR KBHFs that flat wings are not the best, way to go, yaw and roll stability issues. See almost all of the designs available for sale.
This seems to be more important on a Bi Di set up.
R H

[wil]

H and revhed, Thanks for your advice. this project for me is all about learning and trying. I take on board that carbon to alu will not work well.

Would it work if the aluminium was powder coated first?

Perhaps I don't even need to strengthen the mast. the profile seems pretty sturdy. We are just before Christmas now and all the businesses are shutting down till the second week in january.

I'll take a photo of the alu wings so you can see what anhedral there is in the centre wing. I can perhaps bend the tips of the outer wings myself. The centre wing was rolled by an engineer today. I decided not to put too much anhedral in. I can put in more later if the foil does not go well.

[Hawaiis]

Carbon epoxy might have difficulty adhering to powder coat. I have tried using a layer of fiberglass between the aluminum and carbon with good results.

[wil]

stop putting adds on this topic. This is now the second time.

[Peter_Frank]

stop putting adds on this topic. This is now the second time.

Ads, where ?

What are we talking about - confused

Or is it something we can not see anymore ?

PF