I guess it was a matter of time ...

[finnkc]

I just wanted to say hello and that I will probably be lurking around ...
So to make a long story very short.

You may or may not know of my great grandfather's work on hydrofoils. His name was F.W. Baldwin and he was one of a few men that worked with Alexander G. Bell on various ideas and machines. More to the topic, Hydrofoils were one of the last things Bell and Baldwin worked on before Bell passed away. The pinnacle of this being the HD-4.

I have been sketching drawings every so often and more and more I find I am sketching twin tip foil designs as well as some split board ideas but really I am getting close to maybe taking a shot a fabricating some of these ideas.


I guess my first question would be:

1. Has anyone tried or thought about the J foil type yet? Perhaps a double J type of configuration? Has anyone tried any of the self trimming foils?

cheers,
Casey

[finnkc]

Self trimming foils being the 'Acute L' Foil. Not the J.

[ChristoffM]

I do not know of anyone that has tried a J-type foil, but it could be interesting. I almost think an active height control like the moth boat magic wand would be better than a passive height control like a J-foil simply because the foils are small for a single person (kite boarder). On a boat, the J-foils are big and much larger than the expected chop height. Whereas on a kite, the foils are much smaller than the typical chop height, especially where I ride so the J-foils might not work too well unless they are very long and thin.

But that is just my opinion, what ideas have you got in mind?

[Toby]

Can you post a picture of a J foil?
No idea what that is!

[finnkc]

http://dlo9dp2r69urx.cloudfront.net/wp- ... /foil3.jpg

[BWD]

Looks like a the letter, "j" from head on, approximately.
The acute angle of the J combined with boat heeling to leeward means if too much lift develops, the tip of the J surfaces, reducing lift and avoiding a crash.
The boats have huge beam and ability to raise and lower foils working in their favor.
Neither of these things are available in kiting, and in themselves they would add so much disadvantage that the result might not be fun, or fast.
The concept has major challenges to adapt to kiting.
It still has appeal though, seeing the AC cats flying with these, and now smaller cats.

[ozchrisb]

AC boats originally used this to get past the rule that disallowed appendages (i.e. a moth style wand) Others boats have started using is because the have similar restrictions, or they don't want a control system to deal with. The downside of these foils is the leeway they induce (i.e. they're a lot less efficient that a moth style foil because they slip sideways), which also helps with ride height. I'd love,love, love to try a wand style, or electronic ride height control on a kite foil. The J style is very appealing for its simplicity though. One thought would be to have a W shaped main foil for us. As you heal one side of the W would pop out and reduce lift. I asked Remee from Taaroa about it and he said they tried it but it wasn't so successful. Some kind of help with leveling is bound to increase a lot of people performance around a race course though (even if the foil is less efficient you're faster if you don't crash!) so it's worth pursuing.

[finnkc]

Interesting.

Right now I am focusing on the TT ... it is what I ride and so far from what I have seen the only TT foils that have worked are echoed designs to the currently standard excepted foil being used. They work and I think they are great as well ...

However my main goal would be... Make a Twin Tip board with a shallow draft foil(s) that can self trim but also still maintain a good or better VMG vs. a non foil TT.
I ride in shallow (6"-24") water and on a TT. The main drawback to the current foils right now is that they draw much deeper than any of the spots I like to ride would allow. Also they are active foils, and require the user to keep the angle of attack (if you will) at the right spot. These foils work don't get me wrong and I am not looking to challenge that.

So ... am I barking up a tree at an imaginary squirrel or do you guys think it can be done?

[windfreak74]

hello Finnkc,
welcome to the fórum!
any specific sites we can get more info about these foil shapes and its design atribbutes?
Pedro

[finnkc]

Been following this site however most of it applies to multi hull setups.

http://carbonicboats.blogspot.ca/2013/0 ... -soup.html