34th America's Cup: multihulls!

Sorry I meant to Quote CT 279 for that first paragraph

 

34th AC

From Scuttlebutt tonight: read the whole thing here- http://www.sailingscuttlebutt.com/2...Email Newsletter&utm_term=Read more here#more

Once you begin sailing the new boat, what are the differences that will require the greatest focus?

Nathan: The new wing will be quite similar, so we will adjust to that quite easily, and have high confidence in its reliability. The main area that will be our focus is the board control system. Once you start foiling, the whole boat revolves around that system. How well you can control the board rake relates to how hard you can push the boat and how safely you can sail it.

We learned a lot on the AC45 with the foiling package, and are now testing the AC72 rake control system inside the shed to learn about the friction that is involved and the loads that are going through it. So though we are not currently sailing, we are recreating the sailing environment inside the shed to insure that by the time we hit the water the system is working well.
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I have watched all the other 72s sail, and when you watch on camera they appear to be gliding along quite nicely. It doesn’t appear that much is happening. There will be some guys grinding, but it’s hard to tell what they are grinding. And then you get onboard the boat yourself, and we got an idea of this on the foiling 45, that while it appears to be an easy smooth ride, you are kind of hanging on for dear life.

On the AC45, you’re sailing a boat that weighs nearly two tons, you are fully foiling going 35 knots, and you have two bits of carbon on the boards supporting you. There is a little push button and some oil that controls the board rake system, and if you get the controls slightly wrong it’s either going to stomp out of the water and skid sideways or it’ll do a messy dive and go bad then. You are literally on the edge the whole time, which is why the board control system is so crucial. Having a reliable board control system so that you’ll always have enough power to push the button to adjust the boat has become so important to sail safe and fast.

Part 2 of this interview here: http://www.sailingscuttlebutt.com/2...m_term=Artemis Racing Down But Not Out Part 2

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Note: see post1707, previous page, for video showing the head of Oracles lee main foil move forward as they just begin to foil. Also see the PDF from blunted where this movement is illustrated.

 

OK, thanks. I guess my ability to separate signal from noise in SA is atrophying (along with everything else ) In any case, the NA posting as "Hump101" over there pretty much answered my question.

Cheers,

Earl

 

What this excerpt depicts is an electronic control system in an infantile stage of implementation.

I have said, back in post #1460 (with no replies), that if the AC industry wants to keep big fast foiling cats racing in the future editions, this infantile stage will have to be overcome and automatic flight control systems will have to be implemented, for the sake of safety:

From the post #1460:
"In my opinion, if the AC organizators want to maintain this direction (rigid-wing multihull foilers), then the best way to keep the promise of racing in high wind-speeds and in variable sea conditions is to introduce the possibility to have an automatic flight-control system (yes, these vessels are essentially airplanes with sails) which will take care of fast aero-hydrodynamic corrections necessary to counteract effects of wind gusts and irregular waves, and which will maintain the vessel in a nearly constant flight attitude as external conditions change.
If you have recently flown on a modern jet liner, and if you bothered to look at the wings during the flight, you will have noticed that there are a range of fast-moving control surfaces (ailerons, spoilers) which keep moving, sometimes quite erratically, during the flight. They are controlled by the auto-pilot and serve to mantain the aircrat attitude against external disturbances. The reaction time of these control surfaces is very fast, making much faster corrections than a human pilot could perform.
That, imo, is a kind of system which fast foiling sailboats will need in the future, if the current trend to increasing speeds is to be maintained."

I believe that is the way which the AC will undertake in the future. More electronics and automatic control systems appear to become unavoidable at this level of boat speeds.
It means that several parts of AC Class Rule will have to be deeply modified, starting from the whole Section D, Art. 19, a good part of the Section B, and a brand new chapter will be introduced about on-board power electronics and hydraulics.

Opinions on this?

 

34th AC

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I'm not convinced that computer aided control is required. What is required is very fast control of the main foil angle of incidence controlled by a joystick ,perhaps.Definitely not a button as it's now done. From what I've read it seems the hydraulic power used to control the angle of incidence is limited as presently set up-if that was fixed and virtually instantaneous control of the foil was possible then the present system would work fine-and ,apparently, already does on at least one boat-TNZ.
Another possibility is using wands or electronic altitude control with the movable part being a flap and not the whole foil. That would be entirely automatic and the wand part is 100% proven.
I'm leaning towards wands because of their basic simplicity, though I haven't entirely given up on the foil system pioneered by TNZ assuming that instantaneous control of the foil was possible repeatedly. It's basically a very low wetted surface, low drag system(beating t-foils used with wands) but it requires excellent control force actuation which could be controlled manually as it is now but it would be faster and able to be used more often.

 

34th AC

From the San Fran Chronicle: ( whole article here-- http://www.sfgate.com/default/article/America-s-Cup-champs-cut-short-2-boat-testing-4622193.php )


"Among them were installing new rudder wings on both boats to give them more stability, particularly when they foil. Foiling is a recent advancement in which the hulls of the 7-ton boats skim across the top of the waves supported only by the two rudders and a daggerboard in the leeward hull. Foiling reduces the drag on the boat and increases the speed dramatically."

 

34th AC

Not too good an interview-not technical enough-but here it is:
http://www.youtube.com/watch?feature=player_embedded&v=_N0nM2maxZc

 

34th AC

Pictures below of the two Oracle boats testing-click--note different sails in the right picture:

 

^^^

Two boats!

I can't tell which is which!

but one appears to have more roach on the the wing, it also has a black band on the clear portion above the Puma logo, and the top lip of the trophy symbol is a little below the line of telltales, and doesn't have telltales immediately below the flag...

And it has a white doohickey on the end of the windex.

Other than that, I've preferred to pay attention to boats that are actually racing, as of late.

 

34th AC

AC boats are racing from the day of the challenge. You may not think so but those two boats are racing a third boat......

 

34th AC

A slightly biased review of the status of the rudder elevator issue. The International jury will meet July 3rd to decide what happens.

http://www.sail-world.com/USA/Ameri...-as-Oracle-sails-with-rudder-elevators/111255

 

Daiquiri - the sailing sport fraternitry has to decide what sailing is. If we use electronic controls then is it a sport? Electronics remove skill from the sport so this is not a good thing. But electronics are a key feature of auto sport, aircraft, radio controlled models etc etc. Its even debatable whether the mechanical control on moths is "sailing". If we could use elevators and other trim devices and use electronics then we don't need sailors. We just need a Nintendo controller on shore and we have the biggest best RC boat out. The military regularly fly planes totally pilotless into skirmishes all over the world. So we are not technicaly limited in what you say. So where do we draw the line? I'm happy if technology is introduced in various classes as Sailing needs to become contemporay. You can't drive a F1 car without the technology so why not a boat? But being a sailor I would miss the feel of a sheet, the stall of a rudder etc. Its a great discussion and it will happen in the future. Peter

 

USA 17-A and USA17-B - Initially the pods where diferent but I think they have been upgraded so both are very similiar. One wing has more telltales on it then the other. But then I expect they will be swapping wings to detect differences. eg a two wing program like a two boat programme. I also thought that the deck under the wing was different from VA to VB. Cheers Peter S

 

I agree, this problem will arise in the future - especially if we see further speed increase with the new class of sailboats. It is almost of philosophical nature. The technology, as you said, is already there. Has been there for the last 50 years, but the sailing world has always preferred human power for controlling the boat.
Well, with this level of forces and speeds in play the required reaction time for corrective actions shrinks to a small fraction of reaction time required by classical monohulls. Humans can be part of the control system when it comes to controlling large-scale events, both in timewise and in spacial sense. But they are ineffective controllers of boat's reactions to big forces acting in a very short time. Remember that time is distance/speed, so the required reaction time is inversely proportional to speed. There is a whole branch of science (developed for military purposes, by a USAF colonel J. Boyde) which deals with decision-making process. Check the subject of OODA loop.
In complex scenarios a human brain can take up to about 2-3 seconds to analyse the input from it's sensors (eyes, ears, tactile nerves, balance sensors), comprehend that something is going wrong, take a decision about corrective action and perform the corrective action.

So, even if we give humans the instant-reacting tools for correcting boat's attitude after it was disturbed by an external force, there still remains this 2-3 seconds lag between the moment a disturbing force has started acting on the boat and the corrective action. Actually, the lag is even bigger, because the human sensors do not feel the disturbing force in the moment when it happens. They feel the boat's reaction to that force, hence the process is already well under way when the human operator starts to react.

I am pretty sure that if we analysed the recent boats' pitchpoles or capsizes with the OODA method, there would be indications that many of them could be related to the out-of-phase sailors' reaction to the external disturbances (wind gust, waves, unbalanced external forces). An automatic control system reduces the reaction time to the same disturbances to a fraction of a second. And while it is no warranty against accidents, it would certainly reduce the probability of accidents. That's the reason for the considerations in my previous post.

Cheers

 

34 th AC

I was privileged to spend some time working with Dr. Sam Bradfield. I was interested in building a 16' monofoiler using manual control of the main foil flap. He said it would never work because the reactions of a human were too slow for proper control system response. Well, I foiled my boat and it had several problems, but the manual control system wasn't one of them (other than a bent control rod!).
And, at about the same time, two guys out of Gainesville ,Florida modified two Rave multifoilers to fly them manually, eliminating the wands. Now that is something on a 16' Rave because it uses two independent wand altitude control systems-one on each side. The Rave system controls not only altitude but also RM for the whole boat. So these guys used two joysticks too control lift and roll(RM) and not only did it work ,but it was faster than the wand controlled boats.
So while ,theoretically, the required reactions were beyond the scope of a humans' reation time- according to the boats designer, the sailors proved that that assesment was wrong. And a small Rave requires much quicker reaction time(at over 30 knots) than does a manual system on a 72. The current problem(such as there is one) with a 72 is not human reaction time, it is being able to translate those reactions quickly enough and often enough to foil movement.