33rd America's Cup

[voluptuary_manque]

OK guys. Perhaps someone would explain how the damned aerofoil sail works? - in slow motion ?.

I have sufficient basics of a wing, but that usually has one side (the top) slightly longer than the other (the better to get lift).

I cannot see how a shape supposedly getting lift on one side can drive the boat faster, unless it is purely for pulling the mast into the direction of travel.

Yes, exactly! That's how a fore and aft sail works. It pulls the mast (which is attached to the boat) in the direction of travel. I couldn't have put it better.

 

[Handley_Page]

Yes, exactly! That's how a fore and aft sail works. It pulls the mast (which is attached to the boat) in the direction of travel. I couldn't have put it better.

I don't think I got that right.
As I understand it, wind blows from a particular direction and the sail/s is/are aligned to capture the largest volume of air thus propelling the boat in the desired direction. The snag is that wind is'nt always from where you want it, so the mast bends the boat over (pictures of beefy blokes hanging on for dear life of the high gunwale).
The only thing I can see a wing doing is tending to oppose that lateral motion. If so, how then does one achieve forward thrust from it ?

 

[voluptuary_manque]

The airfoil rotates around the mast just like a sail does. The air flows over the cambered surface and creates lift that pulls the foil "upward". The rudder and keel(s) keep the hull going in the desired direction whether the wind is actually blowing that way or not.

This might help. http://www.sheridanhouse.com/catalog/boatgeneral/physicsofsailing.html

 

[jomar]

.....

 

[trysail]

I don't think I got that right.
As I understand it, wind blows from a particular direction and the sail/s is/are aligned to capture the largest volume of air thus propelling the boat in the desired direction. The snag is that wind is'nt always from where you want it, so the mast bends the boat over (pictures of beefy blokes hanging on for dear life of the high gunwale).
The only thing I can see a wing doing is tending to oppose that lateral motion. If so, how then does one achieve forward thrust from it ?

HP,
It's the Bernoulli Effect:
http://en.wikipedia.org/wiki/Airfoil

It's the same principle that kept Handley Page aircraft airborne 'cept in this case the wing is vertical rather than horizontal!

Vector mathematics are used to solve for the various forces. Lateral resistance ( akin to drag and gravity being opposed and overcome by the lift and thrust provided by the airfoil ) comes from the hull(s) and keel(s).

http://upload.wikimedia.org/wikipedia/commons/thumb/1/17/Airfoil.svg/500px-Airfoil.svg.png

 

[Weird Harold]

As I understand it, wind blows from a particular direction and the sail/s is/are aligned to capture the largest volume of air thus propelling the boat in the desired direction.

Actually, except for the most primitive of sails, it isn't the wind the is "captured" by the sail that provides propulsion, but the shape that captured air gives to the sail and the wind going past the sail that provides the propulsive force.

Rigid sails simply use all of the wind to create the bernouli effect instead of using part of it to shape the sail into an airfoil.

 

[trysail]

.....

Jo,
I know you've done some messin' about in boats. Size doesn't much matter ( well, except for speed! ); the essential principles remain the same.

 

[trysail]

Ellison Uses ‘Techie’ Approach to Regain America’s Cup for U.S.
By Alex Duff

Feb. 15 (Bloomberg) -- Larry Ellison turned America’s Cup boat design on its head to take the 159-year-old sailing trophy back to the U.S.

Software billionaire Ellison’s BMW-Oracle team, with a motorized 68-meter (223-foot) carbon fiber wing sail, yesterday beat Ernesto Bertarelli’s defending-champion Alinghi of Switzerland off Valencia, Spain, to take a winning 2-0 lead in the best-of-three series.

“Ellison has taken the America’s Cup into the third millennium,” Jacques Taglang, who has written a history of the boats used since 1851, said in an interview. “It may never be the same again.”

One of the world’s oldest sporting contests became more about technology than sailing after a New York judge rejected Alinghi’s rules and ordered a head-to-head match that gave teams a free rein on design, according to BMW-Oracle chief executive Russell Coutts. Alinghi and BMW-Oracle couldn’t agree on rules for the challenge trophy during 30 months of legal wrangling.

Ellison, 65, co-founded Oracle Corp., the second-biggest software maker, 32 years ago. The world’s fourth-richest person, according to Forbes magazine, he bankrolled unsuccessful America’s Cup campaigns by BMW-Oracle in 2003 and 2007, when his team lost in qualifying.

Employing dozens of designers, Ellison’s team this time outfoxed Alinghi with its wing sail, which is bigger than that of any passenger jet. The structure, whose airline-style flaps were controlled by remote, had less drag than Alinghi’s traditional sail and powered ahead. The hulls on its trimaran lifted as much as 12 meters into the air as it skimmed the water...

*****​

More at: http://www.bloomberg.com/apps/news?pid=20601079&sid=avjs0MnLK6sM

 

[R. Richard]

Actually, except for the most primitive of sails, it isn't the wind the is "captured" by the sail that provides propulsion, but the shape that captured air gives to the sail and the wind going past the sail that provides the propulsive force.

Generally true, however a spinnaker more or less 'captures the wind' on a run.

 

[voluptuary_manque]

Generally true, however a spinnaker more or less 'captures the wind' on a run.

And yet even the spinnaker can be used as a wing on broad reach. Some spectacular speeds have been reached in the pre-wing days using that technique.

 

[jomar]

Jo,
I know you've done some messin' about in boats. Size doesn't much matter ( well, except for speed! ); the essential principles remain the same.

Sorry, decided not to walk down memory lane in your thread.

 

[Weird Harold]

Generally true, however a spinnaker more or less 'captures the wind' on a run.

And yet even the spinnaker can be used as a wing on broad reach. Some spectacular speeds have been reached in the pre-wing days using that technique.

A spinnaker is about the "most primitive of sails" still in regular use. A spinnaker is almost never used by itself, either; it's generally only one element of a more complicated modern sail plan.

 

[voluptuary_manque]

Yup. Sailboats are like fine, well-bred horses. They are an exquisite blend of the art of God with the art of man. That doesn't mean I necessarily want one. Any boat I own will be a platform to fish off. One must keep one's priorities in order, after all.


http://i264.photobucket.com/albums/ii177/1volupturary_manque/905949820_eb8e5294d7.jpg

 

[trysail]

http://bmworacleracing.com/en/yacht/index.html

Notes on the wing:

The wing sail consists of two main components: the main element and the flap element. The main element is one single piece that rotates around the mast step. Nine flaps rotate around the trailing edge of the main element. Both elements are separated by a small gap and linked together by hinges.

The wing sail is primarily constructed from carbon fibre and kevlar with a light, shrinkable aeronautical film material used as an overall skin over the frame.

According to Joseph Ozanne, an aeronautical specialist with the BMW ORACLE Racing design team, the ability to trim the wing sail easily is one of its big advantages over a soft sail.

"With a soft sail, it's so big, it's difficult to shape as you only have control over three points (head, tack, clew). You need massive tension to trim the soft sail," he says. "With a wing sail, you can get the shape you want much more easily."

The main trim parameters are: master wing rotation (similar to mast rotation on a conventional rig); master camber control (general rotation of the flap element); flap twist control (each flap can have a specific angle of rotation).

"On paper, it's a clear advantage over the soft sail," Ozanne says. "It’s on such a different scale to what has been done before, it was hard not to have some uncertainty. But we are more and more confident... I think it's going to be a strong addition for us."

 

[oggbashan]

There are yachts and yachts.

Since the J-class, racing yachts have been completely different from yachts for cruising and long-distance sailing.

The difference is as marked as that between a Formula One Racing car and a SUV.

Racing yachts, particularly for the America's Cup, are finely tuned machines designed for one racing environment only.

In the 19th and early 20th Century, a gentleman's yacht would have a professional crew, a cook, a butler and be equipped with comfortable living accommodation and a wine cellar.

A racing yacht might not even have a toilet! (Even for those crew members scared shitless)

Og

 

[voluptuary_manque]

There are yachts and yachts.

Since the J-class, racing yachts have been completely different from yachts for cruising and long-distance sailing.

The difference is as marked as that between a Formula One Racing car and a SUV.

Racing yachts, particularly for the America's Cup, are finely tuned machines designed for one racing environment only.

In the 19th and early 20th Century, a gentleman's yacht would have a professional crew, a cook, a butler and be equipped with comfortable living accommodation and a wine cellar.

A racing yacht might not even have a toilet! (Even for those crew members scared shitless)

Og

In those days, the rich knew how to live. Now they only know how to make and spend money.

 

[trysail]

There are yachts and yachts.

Since the J-class, racing yachts have been completely different from yachts for cruising and long-distance sailing.

The difference is as marked as that between a Formula One Racing car and a SUV.

Racing yachts, particularly for the America's Cup, are finely tuned machines designed for one racing environment only.

In the 19th and early 20th Century, a gentleman's yacht would have a professional crew, a cook, a butler and be equipped with comfortable living accommodation and a wine cellar.

A racing yacht might not even have a toilet! (Even for those crew members scared shitless)

Og

All well and true, Og.

The world is full of analogues of one-off vessels designed for single purposes that are superb at narrow functions yet miserable failures at others. An American NASCAR vehicle would fare poorly at Brands Hatch or Le Mans.

Like human evolution, the common ancestors of all sailing vessels recede further and further into the past. I am well acquainted with one staysail schooner of the last century that was not only a scratch boat but also managed two circumnavigations.

Nevertheless, over the years many of the advances made in racing have migrated to cruising vessels. Everything from hull materials to roller furling to hull shapes to sails to running rigging to multihulls to self-tailing winches have all had their genesis in racing.

The design tradeoff of safety ( and comfort ) versus speed is a sure-fire topic for stimulating a lively discussion 'mongst sailorfolk. Is a seaworthy vessel one built to survive Force 12 storms or one that sails so fast that she's unlikely to ever encounter one? Is the truly well found vessel one that can absorb enormous punishment from a grounding or one with the ability to claw her way off a lee shore?

 

[R. Richard]

And, that's the reason for racing!

 

[voluptuary_manque]

No, that's the utility of racing. The reason for racing is adrenaline.

 

[trysail]

No, that's the utility of racing. The reason for racing is adrenaline.

The reason for racing is a Greek trireme or a Viking longship or a Turkish galley or a Spanish felucca or Sir Francis Drake or a British 74 in pursuit of you. Adrenaline is the result.

http://upload.wikimedia.org/wikipedia/en/8/8f/The_Hundred_Days_cover.jpg​