34th America's Cup: multihulls!

There's a simple principle to minimize the drag due to negative lift at the head. The minimum induced drag for a given heeling moment is obtained when the induced velocity in the wake varies linearly along the span. The greater the slope to the wash distribution, the lower the center of effort will be.

It's also the case that the induced drag is inversely proportional to the square of of the apparent wind speed. One doesn't have to use reverse camber at the head unless the apparent wind speed is high, so the increased drag due to reduced effective span is offset by the reduction in drag due to high dynamic pressure.

The whole tradeoff is done at constant heeling moment, of course. Whether or not it pays depends on the hydrodynamic drag. More lift at a lower center of effort means more hydrodynamic lift to counter it, and if there's not too much increase in the hydrodynamic drag, the hydrodynamic lift/drag ratio can improve.

Although reverse camber at the head can reduce the steady-state heeling moment, the change in heeling moment due to a gust changing the apparent wind angle is the same as for the untwisted wing. So you really need to be on your toes when using the reverse camber technique.

 

Met some new fans of the flying cats, they enjoyed the show and are certain anything done by Oracle was certainly legal after that 2 race penalty. Most certainly true there so the Oracle funding founder should get a new moniker they say. "We'll call him Fairly Embellishin' Larry Ellison.

 

Yes, because the motor boat guys did what the canoe sailors, many of the dinghy sailors, the skiff sailors, the windsurfer sailors, the kitesurfers and other people did - they formed their own club rather than demanding that existing clubs be changed to suit a new type of craft. That seems to be the norm; when longboards came back into surfing, lots of people formed new clubs rather than demand entry into older clubs. When dragon boats came around, they formed new clubs rather than demanding entry into rowing or canoeing clubs. When mountainbikes arrived they made their own clubs. It seems to be a long-established pattern of human behaviour that when people bring in radically new gear (especially gear that they claim to be vastly superior) into a sport then they will form a new club.

The RMYCN have since allowed sailboats in but as far as I know it's not been a blessing for the powerboaties, but a forced response to the collapse in predicted log trials and small powerboat racing. The motor boat guys at the club are (in my experience) also given a hard time by some of the multihull sailors, in the same way that some of the multi sailors abuse the sailing monos.

That's the point - multihull sailors are complaining about people being biased against their craft and yet many multihull sailors are biased against other types in their turn. Multihull sailors want to be allowed to ban other types (and sometimes do) yet give clubs that ban them a hard time.

 

Goes both ways. I know several people who have finished 1st, 2nd, 5th etc in the world championships of famous high-performance "apparent wind" classes, who struggle to finish in the top half of the fleet in slow boats. They seem to find it hard to deal with the greater importance of things like surfing and the tactics of sailing closer to the rhumb line.

One would hazard a guess that Tom Slingsby, Sir Ben and Mr Spithill managed to adapt from slow boats like Etchells, Lasers and Finns fairly quickly to judge from the America's Cup results....... I am NOT knocking the skills of multi sailors as I respect the top guys greatly and in fact in some ways envy them more than I envy someone like Tom, because I can understand how Tom sails a Laser so well, whereas when I look at Gashby I can't analyse what he is doing to be so quick. It just seems to be magic (although logistics did mean that I could never train or analyse stuff as well in the cat as I can in monos).

As a matter of historical fact, by the way, leadbelly sailors were explicitly practising and writing about apparent wind, the effects of boatspeed and tacking downwind as early as the 1930s. It's noted in the writings of people like Uffa Fox and Sherman Hoyt. Dinghy sailors have long been aware of it too; around the '50s John Westell noted that 505s almost never went within 20 degrees of DDW.

 

CT 249 is CORRECT!

Everyone is prejudiced! Therefore the only solution is BAN THEM ALL.

IF THEY ARE NOT MULTIHULL, GET RID OF THE OLD TIMERS ....

Cmon, why is it multi hulls cost more to build, more to maintain, and more in fees, and

They are the only ones complaining?

I think it is a small portion of both multis and monos that do almost all of the complaining.

Maybe 5%?

I notice that in any group of people, a very small group does all the complaining, the rest of the group is too busy doing something to complain.

wayne

 

I like to think that a club can change and welcome people that share a common interest. If new people come in and make demands, that is just poor manners. OTOH I don't know of many clubs in North America that would not welcome 10-50 new members. If that means opening the doors to new experiences that should be a positive result for the club.

IMO more people that love the water sharing a facility should be a goal of club management. Keeping an open mind to anything that floats and people having fun with should serve a club well. Unless your club assets are in use every weekend the idea of three narrow focus clubs all maintaining mark boats and race equipment is unneeded and redundant expense. The big mono guys can support other groups and the other groups can support them. The clubs gear gets used more often and there should be a larger active membership so share the costs.

Our club is doing Stand Up Paddle Boards, Kite, Sailboards, Opti's, Lasers, and we are adding Hobie 16's this season. The power guys can always join in as support boats and we try to offer crew experience to anyone that has the desire.

Clubs don't have to be single focus. There are other ways to enjoy the water if that is the club's goal.

I agree that when any narrow focus group starts demanding things it is time to start a new club.

Cheers,

R

 

adding Hobie 16's geez thats like adding non foiling Moths in the world of multis

 

RHough said :-
IMO more people that love the water sharing a facility should be a goal of club management. Keeping an open mind to anything that floats and people having fun with should serve a club well. Unless your club assets are in use every weekend the idea of three narrow focus clubs all maintaining mark boats and race equipment is unneeded and redundant expense. The big mono guys can support other groups and the other groups can support them. The clubs gear gets used more often and there should be a larger active membership so share the costs."

See my post #3920. The Cruising Yacht Racing Assoc:, in Toronto, Canada, did just that.

 

2 things you need to look at remembering the golden rule of yachts clubs;

"Young Men start them and Old Men Destroy them" and its usually the same group!

You have to look at what will attract new blood, not making a comfortable retirement home

 

Hobie 16's have 4 National level events in Mexico this year. It makes some sense to me to support an active Pan American class.

Having any multihull in the program is better than no multihull.

 

thats true
the asian games also use them as hobie gave them to all the poor countries ( without spinnakers )
Trouble is cant get any crew to commit to sail them...
well not any more as kids view then as front engined F1 cars..
The real problem with most small boats is their cost has climbed to where the car you tow your beach cat with cost less than the beach cat
There is no short cut to building them so they will cost what the labour costs

 

Here is a google translation from the French site Foilers; authors Daniel Charles and Fred Monsonnec, may be of interest to some:

Questions:

The Evaluation Committee has interpreted the hydraulic arrangement shown in PI_49 as conforming to class rule 19.2 , subject to the approval of the valve by the measurement committee . Below is a reproduction of the scheme PI_49 . There seems to be a component (unmarked in the original diagram) we called " X component " that connects the point Y ( the movable end of the linear actuator ) .

(1) Is the X component is part of the valve?

Answer: No

( 2 ) If the answer to question 1 is yes, complete valve , including the X component, must be commercially available as an element that can be approved by the evaluation committee ?

Response : Not applicable

( 3 ) If the answer to question 1 is no, the electric control valve allows it to perform an action on an element that is not a hydraulic valve or clutch system in a winch?

A. The electrical operation is authorized to provide the input information of the position of the valve or the clutch. In this example, the energy stored in the transaction is deemed to comply with Rule 19.2 ( a).

(4) Assuming that the X component is a spring system which can vary the length between the linear actuator and the valve element named " Hawe " and if the pump is not running, or the hydraulic pressure supplied to the cylinder double effect is insufficient to overcome the load, t is not it not move relative to the static part of the mounting ( NDT, or : from the ground). When the pivoting part is fixed and the piston "a" valve " Hawe " is pushed in an order to move the piece "Y" further to the right will have no effect on the position of the valve, but will change the extension of Component X. In this case the use of such a system meets the requirements of Rule 19.2 ( e) (i ) which states that " These operations must only provide input to the valve position "?

Answer: yes

(5 ) Is it possible for the actuator to perform work without changing the position of the valve?

Answer: the actuator only provides data for the position of the valve. In this example, the energy stored in the transaction is deemed to comply with rule 19.2 ( a)

This interpretation is issued pursuant to Article 3 of the class rules AC72 Version 1.1 February 22, 2011 .
Nick Nicholson,

President for the Measurement Committee

27th August 2013


Added on 10/13/13

If you read this translation, you will surely ask the following questions: "what consite this element X & could it be that this element is " Little Herbie "? ". During the implementation of this article I did not have enough evidence to go in this direction , even if this intrigued me (and it intrigued the committee ! ) . So I directed my ramblings to other ideas (see Part I) . Erwan found a document that evoke passionate " Little Herbie ", a system installed for the first time on the prototype XB -47 Boeing. I must say that the XB 47 suffered from problems of " stability." Erwan has heard many speculated that " X " was " Little Herbie ". On the proposed Erwan page , include the names of two designers of small " Herbie ." I 've done more research and I found the patent US2672307 A, which has the subject: " Airplane yaw damper ." Patented by William H. Jr. Cook , Calvin E. Pfafman , George S. Schairer Boeing March 16, 1954 !

During these "research" , I also came across a document summarizing the different stages of the development of control systems for aircraft stability . In the list of those who have worked on this subject, there was Robert R. Gilruth (it was one of the first studies to NACA will become NASA ) . R. R. Gilruth is none other than the designer Catafoil , "the first flying boat " as my father of American space exploration !

A sample of the patent US2672307

A sample of the patent US2672307
Here are some excerpts from the text of the patent U.S. 2672307 A:

... The mechanism is particularly suitable for incorporation in a control of a steering control comprising a power actuator , such as a hydraulic piston cylinder , which is controlled by the pilot. The control of the present invention may be superimposed on the control of a hydraulic actuator, for example , by acting on the elongation or shortening of the control linkage ...

... The detecting device 3 can incorporate a mechanism called gyroscope, that detects the yaw angular velocity and is arranged to develop a signal proportional to the yaw rate of the aircraft electrical signal ...
And now:

I guess like me you wonder if the famous extra crew , mister " Herbie " had its place on board. Does the committee rolled in flour ? I do not control enough measurement rules , and the science of interpretation of this gauge , for a clear position ! But once again (see previous article) , I think the gauge should be reviewed to take into account the implementation of such tools ...

9 Comments | Catamaran , Physics | Tagged: America's Cup | Permalink
Posted by Fred Monsonnec
America's Cup, " is someone who told me !"
October 4, 2013

This goes back to four years , I was talking with friends of many breaks the Vendée Globe ( mats, bowling ... ) . During our discussion I repeated , without mentioning his name, an architect friend told me . This is a " big names " present said, " and this is the son of your concierge who told you ? " Or something of that ilk . This meant that as I was only peddle stories as a simple parrot. And wham, take it !

Well, I admit, this article will be 100% , or almost the same barrel ! Nothing official that " they say " or almost! Anyway, the official America's Cup does not reflect reality! Why not quote my sources? They are numerous and often themselves take this information to others. Passing from one person to another there must transformation (especially if one of the players had a drink in hand ) . It would therefore not respect those with whom I could share that mention ! Well, there are still some links already verified and verifiable data. Finally, I give my opinion on some issues and I did not want to link my contacts with my ideas!

Anyway, I am sharing the sounds of pontoons, you bring it or not , your attention and respond to support these ideas , however , proving the opposite ...
1 - Rigging

The next gauge you will it run on AC72 ? If so , hope the wing section will be reviewed . Initially, when the gauge was only status "draft" , two rigs were provided, one for light winds , one for the " fight ." But for various reasons, including price rigging , a single surface has been retained : the breakfast time ! Where problems overkill . Crews are using , always after radio dock , a small portion of the available power. Besides the danger of sailing on a high-powered vehicle, it is never good to use a system in the lower part of its capabilities.
2 - Misuse gauge
Fly or not!

ETNZ would be the first to want to fly, and did what it took to get there , wavering in the heart of the limits set by the gauge. Oracle would not initially planned to take off. In fact at the beginning of this section , before the Louis Vuitton Cup when we were talking about foilers (see Oracle 17 , the hut on the dog) , we did not understand how Oracle was well able to fly and especially control . And he was not flying !
Energy

The gauge prohibits the storage of energy . To allow for the rig, several team members must constantly crunching to provide hydraulic power needed! ETNZ have hijacked this gauge using expandable tubing to act as a reserve of energy ! I suppose that by integrating the gauge parts for hydraulics, the goal was to avoid the presence of such engines on Alinguy 5 in 2009, but then to make dangerous boats prohibiting energy storage I'm missing something ...
3 - Regulation
Need for regulation ?

AC72 design rule prohibits moving surfaces on the drift and rudder (see paragraphs 8.6 and 9.6). In addition, the dimensional limitations of the appendages do not allow the use of foil in "V". The design teams have opted for foils that can be categorized foils "L" . Logically foils equipped with a control system "standard" ( complete rotation of the lifting surface or of a shutter , usually controlled by a feeler or saddle ) . And yet , the AC72 does not have followers, and they fly !
Self !

The son of my concierge told me that someone very close to the team of ETNZ would have explained that these foils "L" would regulate themselves by losing the lift to approach the surface. So , as some Russian hydrofoils engines! This is true , why bother with followers ? Does it mean that the drivers are deliberately Moth crash by dropping their main foil yet equipped with a sensor and a component?
manual control

ETNZ is equipped with foils "S" solution which allows you to play on the inclination of the lower part of Appendix varying depth. Appendix lowered, the foil 'S' , which ends in foil "L" ( today , revision of the alphabet) , becomes a kind of foil "V" , which is closer to the surface loses its efficiency by reducing the wet surface. But a teammate would still have been seconded to adjust the depth of the fin / foil and thus lift.

Oracle, it was equipped with a foil in "The classic". The regulation was therefore even more vital. The angle of the carrying surface is not , like on ETNZ regulated depth but the inclination of the appendix. Tilt made ​​possible by playing a slight displacement of the entrance to the "drift" and its output must accept the gauge (see here) . At first the skipper was flying height control (in addition to the path ) by manipulating levers positioned inside the bar. When the Oracle team realized that it was more difficult to successfully do a teammate has been delegated to the regulation of foil (as ETNZ ) .

To facilitate its work the team has used for the last meeting , a system called " Little Herbie " developed for the Boeing 747. Equipped with accelerometers , gyroscopes and computers , Herbie can detect variations in attitude and make corrections stability. This with a speed and precision that exceeds the ability of pilots ! This system was not directly connected to the foil, it is of course forbidden by the gauge. Little Herbie pointed only to the person in charge of regulating the adjustment to be made (source).

So, is it normal to use a tool that is beyond human capacity , whether connected or not to foil ? This reminds me of my questions , when Hydrofoil trying to develop a system for regulating the angle of the rear bearing plane ( see Ptites News 26 "Question" and 28 Ptites news , see " Rules "). Some felt that this was an autopilot that does not regulate the trajectory but the height of flight . Why not, but it should not limit this type of systems at the races and records alone (since it is now an indispensable tool that replaces the old weathervanes and participating in safety ) , and prohibit a crew ?
4 - Responding or not?

One of the last "records" of the Cup would be the use of an aid to regulation. ETNZ Why does not claim ? Already , it would bad player especially after Oracle performance and fantastic comeback . Of course, ETNZ could argue that the rise of 8-1 to 9-8 is related to the use of " Little Herbie ". But it would undermine the work of gauges . And then the ETNZ team might not be " white white " too!
5 - The start

It seems that when Oracle is not going to dip, the team would have heavily modified the boat, reducing the length of the bowsprit , looking dull and even greater change in the form of shells to take back of rebalancing the masses ! Finally, implementation of the famous crew trained by Boeing , the little " Herbie " ( a guy ) .

While the Oracle team has responded brilliantly, the ETNZ team seems you did not make much change their AC72 . It is true that he had crushed the competition in the Louis Vuitton Cup. And the fact align wins ( up to 8-1 ) should not encourage them to make changes !
6 - The sequel

I think ( perhaps wrongly ) that the designers of this gauge does not have enough experience in creating multihulls tips.

Above all, they were not vicious enough to imagine the possible misuse of the gauge. While it is true that to exploit the loopholes of the gauge can give rise to different gear, which is also the salt of the competition.

 

Honeywell will sell 3 axis laser ring gyros to anyone theses days
They package into to box half the size of a shoebox
We use them offshore plugged into DP systems and still call them INS systems although they cant navigate just tell you acceleration
I played with one set up on a guys desk and it would read movement as you started to press your finger on it before you would think you had moved it. Impressive

 

First Foiling Americas Cup: Property of the USA!

Still on your cheating kick, eh Gary! Dredging up more ******** speculation that has been repeatedly disproved as has the conspiracy that would have had to exist.
You're an exceedingly poor sport as is anyone that pushes this BS. You and TNZ lost fair and square and you just can't take it so you try everything you can to besmirch the Team the whuped your ***. Pitiful.

 

Doug, those Oracle guys are big boys.....how does it go? "methinks the lady doth protest over loud and long for it to be true..."

Right or wrong it is an interesting avenue to explore and might lead to developments across the board so the world should scratch its heads and come up with a better mouse trap. When teams have to have lawyers to wrangle the fine print to be legal, the Spirit of the rules isn't really considered so it shouldn't surprise that the post race dissections are conducted similarly. Lets keep looking at the angles or gyros measuring them, because we can all learn from some of these ideas.