Foils, Foiling & stuff..

Originally posted by tgruitt Originally posted by hum3 AFAIK The AC72 have two methods of controlling height:   1) Self control - this is via the V shape main foil. As it lifts out of the water, the lifting surface reduces. They look L shaped when retracted, but that's down to the curved board shape.   2) Manual control - there are guys on eack boat who can manually adjust the rake of the main foils, thus changing lift. They do this through manouvers.   The rudders are a fixed rake for racing, but can but adjusted up to 5 mins before the race, to suit conditions.   EDIT - there is probably a whole load of aero stuff going on as well which helps control lift (just look at the rear beams of both boats) but I'm not expert. Yep that's how they seem to do it.Don't forget GRF, 3 times the foil size and 3 times the drag, your rig is probably pretty dragtastic too. I think you will need it down to Cherub weight to foil, one of them is using a RS600 hydrofoil kit... Might be a good starter? Or are you going down the AC72 route and having one on each side?

Well I guess that was what illuminated the bulb, instead of having one in the middle the layout of the VT would accommodate one on each side like the AC's it could also have twin rear foils given it does 'fly' one side of the hull if you give it enough welly.

I had this idea (flux capacitor style must have hit my head) for a self levelling foil with a sub surface wand pointing forward and connected to the trailing edge to operate the flap according to the angle of flow via a pulley system, but those curved things that go up and down on each tack, I could fit those I would have thought.

And I'd definitely have to rethink the rig, the kite would go and some sort of wing system like theirs looks like the best route forward, could it work? Hell what a blast if it did, it's so stable you wouldn't have the landing problems (other than being chucked in forward).

Who could you get to do it?

Edited by iGRF - 18 Sep 13 at 12:58pm

id like to see a moth try a c foil on the bottom of the vertical foil instead of the standard flat wing type.  has the self leveling and ability for veal heal. 

Graeme

Ah, I've met that guy, he has a workshop down at Weymouth that was almost a surface running foil as I recall, all in one thing, I've got a pic of it somewhere, too much drag I thought.

I was trying to get him to make me a set for a windsurfing race board, but the costs became prohibitive and it was around the time of lehmans when we all pretty much lost our mojo..

I wonder if he's still there, funny I was thinking of having a jolly down at speedweek with the Twin just to see what she'd top out at in her current form for a lark.

I so want to do this, it hurts, it's built for it I can vary the angle of the centreboard foil manually like those AC craft do, I could have one either side and twin rudders, it's got endless scope to be foiled.

According to tonight's programme the AC72s weigh about 7 tons all-up, but the foils get loaded up to about double that during manoeuvres.

They do seem to have to work hard to keep the ride height stable, it must be especially difficult given that the rudder foil angle of attack is fixed. You can clearly seem them pitching bow down on the bear away as they accelerate and the rudder lift increases; and similarly waving their bows in the air when they round up at the leeward mark.

Also interesting to see what they are doing with the wing trim to have effects you wouldn't normally consider when sailing. Watching the other night Oracle seemed to have the new windward hull out of the water before they were even head to wind during their so called "roll tacks". I'm assuming they keep the wing over-rotated as they head up so it produces a windward heeling moment to pop the boat onto the inside hull, but they must have to be pretty smart getting it turned back again to stop it from capsizing the boat as they get onto the new tack!