34th America's Cup: multihulls!

[Doug Lord]

First Foiling America's Cup

Doug - The only two variables that can be used to control the AC72 foils in regard to pitch control is 1) The foil area eg if the AoA stays the same and the boat gains velocity then the boat must lift, the inboard tip of the foil breaks the water surface, the area reduces and the boat settles at that speed and height. There are many self adjusting foilers like this. But the AC72 rules limit the length and form of the board to enable this solution to be implemented entirely 2) The AoA is changed to match the required lift at the sailing speed. The question is can a person change the angle of attack (AoA) quick enough to keep a stable flight height? The answer is probably no. This is further complicated by the fact that the by changing the AoA of the daggerboard you also change the attitude of the boat, which changes the AoA and this can lead to instability. The aim is make a self stabilising system. This means the rudder elevators and wings (foils on the daggerboards) need to be coupled in a way that produces a stabilising condition not a destabilising condition. The type of system I drew earlier takes care of the wing trimming once a "stable" condition has been reached. The wing trimmer needs to ensure the wings AoA is correct for lift off at low speed becuase the boat is bow up so the rudder lifts as well (liftoff mode), then once at speed and attitude the wings need to be reset for the level flight mode. The SAS can then self stabilise the boat. The analogy of this is could you sail a Moth without a wand? Answer No... so without some sort of displacement control (wand) or force control (SAS) could someone control the flight of an AC72 by themselves ... probably not so an SAS is needed.An interesting comment in the final press conference by Larry was that they found the boat was better with a bow down attitude. This indicates that they found its sweet spot. If they had been trying to trim the boat level and faught the idea of having the boat bow down then they could have been chasing something that they could never acheive. But by giving in to the bow down condition they balanced all the boat dynamics and found the spot that gave it stability, I once built a 3wheeled tandem tricycle that initially was unridable. When you rode it by yourself it was "normal" but when you had a passenger and you turned a corner you fell off. This was due to severe oversteer in the system. After falling off so many times and nearly hurting myself and my passengers I nearly gave up. But then I noticed something and figured it out. All I had to do was lean right before I turned right and it behaved perfectly (you can lean steer a bike and handle bar steer a bike. If you get a bike and steer the handle bars you will notice the frame moves in the opposite direction then it is steered. Same thing happens with a powered trik with no differential) Then it became an easy thing to do. So Oracle probably went through a similiar thing. They chased something and toiled and toiled but it didn't want to work then someone said how about this???? and it all fell into place. . Peter

===============
Peter, I think the essence of the brilliance of the original TNZ single main foil system was that the foil would allow the boat to be relatively steady at a given speed-if it went faster or slower than the design range the angle of incidence of the foil had to be adjusted to the next "range". There is video of this happening as Oracle takes off and as soon as she is foiling the top of the lee foil was moved forward, reducing the angle of incidence for a "cruise" range. The foil moved extremely quickly.
The two video's I posted earlier show Oracle foiling with great pitch stability-and they were shot before the Cup started. I'm not at all sure they needed an SAS, but I think they improved by doing a lot of little things. At least thats where I am tonight.....

 

[Doug Lord]

First Foiling America's Cup

Coutts describes how they did it:

http://www.sfgate.com/sports/article/Coutts-says-strategy-change-key-to-comeback-4847578.php

 

[DCockey]

Russell Coutt's quote from the article Doug linked to http://www.sfgate.com/sports/article/Coutts-says-strategy-change-key-to-comeback-4847578.php:

A yachting expert named Peter Lester told a New Zealand TV network that Oracle was using a computer-automated system to get its boat up on the foils. He said skipper Jimmy Spithill merely had to press a button to put the boat on foils, thanks to something called the "stability-assistance system."

"That's complete baloney," Coutts said. "We weren't allowed to be automated. The measurers never would have allowed that." He added with a chuckle, "We were quite happy to have Team New Zealand believe that."​

On the other hand it appears that the NZ Herald is reporting as "fact" that Oracle had an "automatic foiling mechanism". http://www.nzherald.co.nz/yachting/news/article.cfm?c_id=106&objectid=11131614

And Grant Dalton said there would not be a legal challenge.

 

[oceancruiser]

winner-takes-all match

Seen this referred to in three different articles.


The final day of the 34th America's Cup brought only the third in Cup history (previous such matches had occurred in 1920 and 1983).

Where can I find the terms and references to what is the extra the winner gains compared to other cup races.

Is it the winner takes the race and the cup. Meaning there has only been two previous occasions in the history of the cup that both challenger and defender have been tied equal on the won races numbers before the final race.

Can't find it on Google only the term.

 

[DCockey]

Here's my guess on the function of the system shown in the schematic Oracle submitted to the measurement committee:

"Component X" is passive and contains a spring and a dampner in parallel.

The linear actuator is adjusted to a setting corresponding to the desired daggerboard angle.

The valve then opens so that the double acting cylinder moves the top of the daggerboard (called "pivoting part" in the schematic) fore/aft until the top of the daggerboard is at the desired position.

So the system allows the person controlling the daggerboard to set the desired daggerboard angle without having to watch the angle of the daggerboard and stop at the desired angle. Once the desired angle is set the system moves the daggerboard to the desired angle without overshoot.

 

[andybrnr]

David,

Good find, that makes perfect sense. Very KISS-principle compliant... and certainly far from "a computer flying the boat."

 

[daiquiri]

So the system allows the person controlling the daggerboard to set the desired daggerboard angle without having to watch the angle of the daggerboard and stop at the desired angle. Once the desired angle is set the system moves the daggerboard to the desired angle without overshoot.

Good find, that makes perfect sense. Very KISS-principle compliant... and certainly far from "a computer flying the boat."

What we see in the schematic of the actuating system is the electromechanical part. It allows, as David said, to set the daggerboard (or wing) angle at a preset value. A sailboat-version of servo-assisted steering we have in every modern car.

But what is the best angle? Who decides the shut-off presure of the hydraulic circuit, and based on what? That is the missing info. The electronics and software part are not shown in the schematics. Perhaps there is no electronic part, perhaps the choice of the daggerboard angle is taken fully by the human trimmer. But in a situation where 0.1 knot Vmg or 1° closer hauling angle makes a difference between winning or losing the AC, I doubt it is so. After all, we are talking about high-tech boats, and about teams funded by high-tech sponsors.

There are many instantly changing variables which determine the optimum daggerboard and wing angle. A human operator can get the ballpark, but it is impossible for him to continuously monitor all of them at once and decide the best setup for the moment. And, given the boat's great reactivity to changes, that's an operation which has to be done several times in a minute, with great precision.

So, while the schematics of the system helps understanding what the arm does, the brain which commands the arm is not shown in it. I find the story about a computerized system which visually indicates to the skipper the instantaneous best setup (leaving to the system in the schematics, perfectly legal, the task of actuation) a very plausible one. It is actually a minimum of automation which I would expect to find on board of vessels of this type and size.

Cheers

 

[xarax]

[1] The main thrust of this was could they use servo systems to control the component vs direct control by a sailor. The answer was yes. Reasoning was that the servo did not contribute to the propulsion of the boat only the control of the boat.
[2] It could be argued there is no difference between a block and tackle and a servo.
[3] The leap is in the use of batteries to enable/disable the servo device. Electric servos make logistics and packaging sense.

[1] So, we are allowed to control = "steer" the boat with the help of a whatever complex automatic mechanism ? ? ? Provided we do not use "stored energy", or "electric energy", but we use any other form of energy generated on board ( by the grinding action of the grinders ), we can use any automatic mechanism we wish to control the boat, and make it go faster ? ? ? ( This is NOT a rhetoric question. )
[2] A block and tackle is a "simple machine", a servo, or a relay, is something more complex. I myself can not pinpoint or define the difference, and I also doubt that it can be defined theoretically - but nevertheless I feel that there is some...
[3] THAT is the easy, but wrong way to address the issue - and I have no doubt that the measurers and US Oracle will hide themselves behind this... An automatic mechanism that controls the sailboat, is an automatic mechanism that controls the sailboat, is an automatic mechanism that controls the sailboat - either it uses "stored energy" or not, electric energy from a battery or not, or any other form of energy, as the energy generated on board by the grinders !
A complex enough mechanical automatic device, a sort of mechanical computer, can do exactly the same job an electronic computer, that uses electric energy, can do. The use of "stored" or "electric" energy is not something that can make something more automatic, "computing", or "intelligent" than something else !

We should decide how far we should go along this road :

Oracle had push button automated control over foils: similar to an autopilot. The crew need not anything aside form keep up hydraulic pressure. I cannot see that surviving another cup.

The problem is that a complex enough level mechanism can function like a mechanical computer, and a complex enough mechanical computer can function like an electronic computer... Theoretically, anything an electronic computer can accomplish can be simulated by a mechanical computer, and vice versa - provided that the complex mechanism uses a small only amount of the energy provided by the grinders.
So, where do we draw the line ? Where does the mechanisms make the humans obsolete ? Where does the technology eliminate the sailors ?
Just a few grinders grinding, and one helmsman ( much like a drone pilot/operator ) pushing buttons and turning the wheel or the joystick, siting comfortably on an armchair ...

In a sense, any "automaton" ( a self-operating machine, or robot ) is a kind of a computing device...It does not matter if this computer is electronic or mechanical, digital or analogue, a linear series of simple mechanical relays, the one after the other, or a 3D grid of supercomputers
I would nt be surprized if, in the next America s Cup, the faster boat would be the boat with the faster on board computer ..

 

[Jim Caldwell]

This is far enough!!!
Bye

 

[petereng]

Xarax - A servo is just something that turns things off and on remotely. A servo is quite different to a computer controlled sytem. These (computer controlled sysytems) are currently not allowed in any form of sailing under the RRS. But in a "Mutual Consent" AC race they could be. Last race and in many superyachts there is a motor of which if you turn it off, the boat cannot function. All these things are debates that need to happen as sailing "progresses" we probably need to have corinthian classes and technology classes, then both sides of the coin can exist. Same as we have one design classes and development classes. I could build a very automated boat using computer controls etc and call it a class and we would be OK. Cheers Peter S

 

[xarax]

Here's my guess on the function of the system shown in the schematic Oracle submitted to the measurement committee:

"Component X" is passive and contains a spring and a dampner in parallel.

The linear actuator is adjusted to a setting corresponding to the desired daggerboard angle.

The valve then opens so that the double acting cylinder moves the top of the daggerboard (called "pivoting part" in the schematic) fore/aft until the top of the daggerboard is at the desired position.

So the system allows the person controlling the daggerboard to set the desired daggerboard angle without having to watch the angle of the daggerboard and stop at the desired angle. Once the desired angle is set the system moves the daggerboard to the desired angle without overshoot.

To me this is a nice description of a semi-automatic mechanism. It is up to an interpretation if we are going to call it a SAS mechanism or not, but it is some sort of automation. The question is how much automation we wish to incorporate into sailboats - which are already LOADED with more or less automatic devices, albeit simpler ones.

Coutts said. "We weren't allowed to be automated. The measurers never would have allowed that."

Yeah... The measurers had to follow the rules word by word, and there is nothing in the AC72 rule that prohibits automatic mechanisms, in general. As I have repeated a number of times, an automatic mechanism does not cease to be automatic because it does not use "stored energy" or "electric energy", but only energy provided by the grinders.
So, there is no "legal" issue, but this does not mean that there in no issue whatsoever - to burry our heads in the sand, will not solve anything...

 

[xarax]

A servo is just something that turns things off and on remotely. A servo is quite different to a computer controlled system.

I believe you understand very well that a "computer" - be it a mechanical or electronic one - is but a series of servos and relays connected together. The fact that, at some point of this series, the output of this complex automatic device has to be "seen" and "approved" by a sailor, who will then push the button and will allow the system to re-adjust itself and move from one state to another, does not mean that this sailor plays any "intelligent" role in the whole process. The general public will be satisfied by this naïve BS, that if a system does not use "stored energy" or "electric energy", it is not automatic enough to be considered as "computing"... A mechanical / hydraulic SAS mechanism will not need "electronic" input devices, that use "electric" "stored energy", to function !
One could argue that there is no computer ( the hardware part of a computer ) because there is no program ( the software part of the computer ). However, the instructions given to the puppet-sailor / foil trimmer that pushes the button if, say, a pointer points above or below an already drawn line on a "chart" like the one described below, play the role of a program that tries to achieve an already defined target.

The trimmer would have a chart in front of him generated by training data. It would have speed and AoA ranges. So he can read his speedo and adjust the trim to the chart or by feel and anticipation.

When a control system has a target that it is trying to achieve, as opposed to just responding to inputs, those are two very different things. And if the target is supplied by automation instead of by direct input from a crew, that is different again.
Not only should stored energy not be employed by the boat for control, stored information should not be employed by the boat either.

 

[markdrela]

Here's my guess on the function of the system shown in the schematic Oracle submitted to the measurement committee

A simpler description: It's a "power steering" system for moving the foils.
1) The button pusher decides on a foil movement.
2) The valves and piston move it using the grinders' mechanical power.
Nothing more.

 

[xarax]

It's a "power steering" system for moving the foils..

Noope ! It s a power-driven semi-automatic system to control the movement of the foils. This system has to be fed not only with "power" from the grinders, but also with "information" from the other movable parts of the boat ( the wing, the rudder ) and from its environment ( wind speed and direction, acceleration and inclination of the sailing platform ) - and we should not forget that all those things have to be "inserted" into the semi-automatic servo-mechanism in real-time, while their values change more than once per second !
However, I have to say that I admire this carefully chosen, politically correct expression : " power steering system for moving the foils" ! I hope Coutts will use it the next time he will make some statement !

1) The button pusher decides on a foil movement. ..

Ooops ! The trimmer has became the "button pusher " ? I am afraid you have to polish this expression a little bid !
"Decides" ? How does he decide ? Does he have to think, or just to "copy" what the pointer tells him, and to "paste" this information into the button ? You seem to use the word "decision" too lightly... Decision demands judging, thinking, taking risks, etc - when you just adjust the movement of your finger that pushes a button to something an automatic mechanism dictates to you, you do not decide !

I had hoped that it would be the markdrela wearing the hat of the scientist that would reply, not the markdrela trying to catch one of the hats of the US Oracle team flying on the air !
Don't get me wrong, I am still undecided about how much of "computing", in the broader sense of the word, we should allow in sailboats - and I certainly do not believe that US Oracle cheated by incorporating a SAS mechanism on board, if this is what they did. I am sure that TNZ would had used it, too, had they realized its great potential. I just wish to tell things by their proper names, and an automatic mechanism that controls the movement of the foils far faster than the eye-brain-hand coordination of any human can, is an automatic mechanism, regardless of the source or the kind of the power it utilizes.
I do not believe that computers are "inhuman", so we should prohibit their use in sailing - but the extend this will be allowed is something debatable, which should be decided only after we know all the details of what had happened during those last 8 races of AC34, and only after we imagine the implications of what we will decide for AC35. Any attempt to hide the issue under the rug will fail and backfire, sooner or layer.

 

[daiquiri]

But, Xarax, technically the schematics shows just that - a power-assisted foil (or wing) positioning system. It shows nothing more, so Mr. Drela is right on that point. No info is given about the decisioning process which leads to the value of the desired foil angle, which is the input to the mechanism. Just as I said in my last post.

And please, please don't be so harsh with prof. Mark Drela. He is discussing it here with us with no agenda to defend, just for the sake of discussion. And he is entitled to have an opinion, even if someone might not like it. I am actually very glad to see that he comes to the forum from time to time and shares with us some of his great knowledge of aerodynamics.

Cheers