Jumping Foilboard Windsurfers : Technical Question

[frosh]

WA, quite right, what makes a sailboard great fun is largely the sensation of being in contact with the water just a few inches under the soles of your feet. Removal of this feeling by being hoisted up half a metre disconnecting your body from the feel of traversing the water moguls at high speed would be like building an airconditioned and soundproof capsule around your high performance motorcycle and trying to enjoy a blast through the canyons.
But I guess if you have not ridden a sailboard in gorge conditions, nor taken a Ducati through the canyons at 100 m.p.h without four wheel slugs (other cars) in the way, this will not mean anything to you.
What about 3D cinematic experiences for those who physically or for other reasons cannot do the real thing? I have witnessed some great ones at Disneyland Los Angeles.
Building something (the jumping foiler Moth clone) for perhaps 10 times the production cost of a modern shortboard, (if it can be technically done), seems plain stupid to me!

[BWD]

We windsurfers like being able to launch easily from the beach and sail in 12 inches or so of water.
safety notwithstanding.
We can jump plenty high already, and most don't want foils.
FWIW I think trying to jump with a T foil is silly.
High torque and shock loads, severe AOA and yaw problems, regardless of wand/no wand, etc.

With foilboards, the delta/lifting body shape, with wide tolerance of the problems above, helps.
PLUS, funny no one has mentioned yet,
it has a tail
that allows it to balance forces within itself and trim to AOA, free of some wildy varying lever arm a few meters aft
...

Originally Posted by BWD

We windsurfers

- You don't speak for me-and apparently not for Rush Randle and a fairly large number of other people who are windsurfers(me on and off since 1979).

Originally Posted by BWD

....that allows it to balance forces within itself and trim to AOA, free of some wildy varying lever arm a few meters aft
...

Could you elaborate on the "wildly" part?

[frosh]

You don't speak for me-and apparently not for Rush Randle and a fairly large number of other people who are windsurfers(me on and off since 1979).
...

Could you elaborate on the "wildly" part?
__________________
Doug Lord

Could it be possible that both you and Rush Randle have a vested interest, in that you both, are hoping to sell some derivative of the foiled windsurfer commercially? Who are the many other people who are windsurfers, who want to switch from a regular sailboard to a foiler one? Name two people then that are internationally known that have publically expressed this!

As far as elaborating on the " wildly" part: it is all wildly in the realms of fantasy, if you are only interested in buildling a successful prototype. There is not a term that I can think of ( and my vocabulary is at least 1000 words in length), to describe the chances of both building a successful prototype and then being able to turn it into a commercial success.

[nflutter]

gsus if you care that much just build one and prove to the world that its cool

[nflutter]

seriously

[water addict]

Your right Doug, nobody but you speaks for you.

I would hazard to guess, most windsurfers would not want to deal with some foiling mechanism on their boards, but I could be wrong. Maybe we'll see lots of boardsailors out there skimming along 2 feet above the water, and hopping up and down. I wouldn't want to particularly though.

You want to make a foiler board thingy, have at it! Maybe I'm wrong, post your videos and market the heck out of it. Maybe it's the next wave of windsurfing - who knows?

[nflutter]

werd!

I'm not particularly interested in foilboards at all.
The point of this thread was to discuss what would make a high lift foil(63412; 7/1 aspect ratio-for example) function as well as the foilboard(mainfoil) in re-entering.

[frosh]

Doug, why ask your question on this forum if possibly the only person in the world that might throw some light on your dilemma is Rush Randle. In case you don't already know it his email is: Rush@RushRandle.com

[BWD]

All I meant was to answer as best I could the general question without reference to a specific foil section. Here again is my answer:
1) a tail,
2) a robust connection to the strut or whatever attaches it to the hull,
3) and possibly a delta or lifting body design (which would facilitate no. 2)

I guess sometimes folks pick up the ball in your threads and run sideways off the field with it.
No offense intended.

As for the "wildy" varying input, I envision a typical t-foil rudder. If the front foil leaves the water, the whole boat can act upon the rudder to turn it on any axis, developing who-knows-what lift in who-knows-what direction.. Situation aggravated by chop etc.

Seen from the point of view of main foil re-entering, it may have to cope with sudden strong pitch/yaw inputs from rudder even as it tries to reestablish its flow/lift. Those little wingtips and the tail are crucial on the foilboard. Reducing degrees of freedom around the foil CE, or at least damping motion, at some drag cost....
I think stabilization features will be crucial on larger craft. http://www.youtube.com/watch?v=QoaZu8Ew_a4

As far as speaking for others, one accepts a risk in any generalization, such as "we windsurfers like ease of launching with our short fins," "we Americans are crass and like French Fries," etc. I am on safe ground here though. I don't speak for you, but I do speak for many. Just 25 years experience, don't know Rush Randle myself.
More power to him.
I am not much of a surfer but I also feel safe saying, "we surfers don't like it when hordes of tourists come in summer and hog the local break and pee in the water attracting sharks."

Anyway, attached is my idea-platform, a draggy bolt on solution but could help with main foil re-entry. Lot of optimization needed, maybe a bigger vertical tail, longer chords...

Very interesting response and illustration. I'd imagine you're not serious in suggesting two "air chair" foils instead of one main foil? Are you?
An arrangement like that would defeat the main advantages of a bi-foil arrangement particularly upwind.
I agree that kites have a lot to offer-including altitude.....

[BWD]

As a redneck solution, if you could obtain 2 such foils and bolt them on, it would be interesting to see what happened. Interesting as in spin or cartwheel once one popped out of the water...
One would probably be much, much better.
So far as my little brain can tell all these "advanced" craft from kiteboards to sailrocket ,et al are trying to solve the 2 fluids problem by evolving towrds airplane on a string designs.
So far the most elegant, commercially successful and versatile version is the kiteboard. It cracks me up; I make these in my kitchen! And Living room . Need a garage.
To the point, to find something that works like an underwater airplane, I would start with something that looks like one:
EDIT: crossref FWIW: http://boatdesign.net/forums/showthread.php?t=11497

[frosh]

BWD, just brilliant showing the kiteboard guy jumping what looks to be at least 10 meters off the water, on what? Simply a basic board even simpler than a standup surfboard that you can build for minimal cost in a room of your house.
Doug, have a REAL GOOD THINK if perhaps you are not on the right track.
The other hugely important fact (read fact* please) is that the commercial success of this kiteboard thing is greater that sailboards and Hobie cats combined, and shows no signs of abating in the near future.
Go on; ask yourself why this could be so. If you come up with an answer, please make a statement of that answer in no more than 50 words, and I will give you a score out of 10! for accuracy.
I applaud the aptness and logic in your illustration of the real world, BWD
Power to you man.