Cup Experience

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Wing design – simulations vs wind tunnel

 

USA17 9 flap wing USA17 9 flap wing

9 flap wing on USA 17 trimaran

From a January 2010 article on the website of software maker CD-adapco:

On February 8th 2010, in the picturesque Spanish port of Valencia, BMW ORACLE Racing’s skipper Russell Coutts will take the helm of one of the most technologically advanced – and hopefully fastest – boats ever built, in a bid to capture the 33rd America’s Cup.  The most remarkable feature of the trimaran – named “USA” – is that it will be powered by an enormous wing, rather than a conventional sail.

As Mike Drummond, BMW Oracle’s Racing Design Director explains: “A wing of this scale has never been built for a boat. In terms of size, it dwarfs those on modern aircraft. Towering nearly 190ft (57m) above the deck, it is 80 per cent bigger than a wing on a 747 airplane.”

In an exclusive interview (with CD-adapco’s Anthony Massobrio) BMW Oracle’s CFD Manager Mario Caponnetto explains how STAR-CCM+ was used to optimize the aerodynamic wing design, at the expense of traditional wind tunnel testing.

 

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Mike Drummond interview: USA 17 wing – Jan’10

 

So how tall was the wing on USA 17?  In an

interview

published in January 2010, Mike Drummond, BOR Design Director, said:

“A wing of this scale has never been built for a boat. In terms of size, it dwarfs those on modern aircraft. Towering nearly 190ft (57m) above the deck, it is 80 per cent bigger than a wing on a 747 airplane.”

So, was it 57 m (190 ft), or, as later info said, 68 m (223 ft).  I’ll go find out when the top section was added to the wing on USA 17, and I’ll post some photos from the 33rd AC Match in Valencia in February 2010.

Have a look at these pics and give me your answer in a comment!

USA17 8 flap wing USA17 8 flap wing

USA17 9 flap wing

9 (?) flap wing on USA 17

 

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Artemis wing details – how many elements & slots?

 

And why are “elements” and “slots” important?

Since we got the first photos of Artemis’s AC72 wing there have been many questions about the wing’s configuration – how many elements? How many slots?  (For the basics, see this short video explaining wing stucture and controls here.)

Wing AR 2 slots? jjga Wing AR 2 slots? jjga

Artemis wingsail: 3 elements. How many slots? Copyright ? Annotations: Jack Griffin 365 x 260 Artemis Racing 365 x 260 Artemis Racing

First sail of the Artemis Racing AC72 wing. Valencia, 15 March 2012. Photo copyright Sander van der Borch / Artemis Racing

Let’s compare with the two element wing on USA 17 in race 1 of the 33rd America’s Cup Match against Alinghi 5 in Valencia in February 2010.  Look at the dimensions of the leading and trailing elements of Artemis’s wing and USA 17’s. Quite a difference!

USA17 camber-TM jjga USA17 camber-TM jjga

Two element wingsail of USA 17 in race 1, 33rd America’s Cup. Annotations: Jack Griffin

Camber is the angle between the leading and trailing elements. (You knew that, right?) By the way, here’s how camber is controlled on an AC45:

Wing AC45 camber control jjga Wing AC45 camber control jjga

AC45 wingsail camber control – Copyright Jack Griffin

It will be interesting to learn about the control systems for Artemis’s wing.  Kimball Livingston quoted Artemis CEO Paul Cayard  last November as saying the wing would have 38 hydraulic cylinders.  True? Or disinformation to throw off the competition?

In the same article, Kimball wrote:

The Artemis approach to efficiency, Cayard says, uses a three-element, two-slot wing. No surprise. Any wing is much more efficient than a mast and soft sail—for many reasons, not the least of which is that mid-leech tension becomes a non-issue—and C Class catamarans long ago demonstrated that three elements, two slots, are faster than two elements, one slot. I expect every AC72 to have a three-element wing.

 But that might not be quite right…   Here’s a picture of a C Class catamaran’s wing.  An aeronautical designer would say it has two elements, one of which has a flap.  In aeronautical terminology, the number of elements = number of slots + 1.

595x446-Wing-C-class-detail-3-el-2-slot-jjgb 595×446-Wing-C-class-detail-3-el-2-slot-jjgb

Wingsail design: C-Class catamaran wing with 2 elements + 1 tab

Do you think the Artemis wing has one or two slots?Comments? Questions? Answers?

What are the advantages of two slots?

How will the control systems work on AC72 wings?

 

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New plan for using Piers 30-32 for team bases

 

Piers 30-32 Renovation Idea Piers 30-32 Renovation Idea

Piers 30-32 Renovation Idea - room for 5 America's Cup team bases

Someone has finally come up with a Plan B for Piers 30-32!

Here’s a diagram showing five team bases on Piers 30-32 for the America’s Cup in San Francisco in 2013. These piers would be a much better location for the fans and media than Pier 80 – much closer to the AC Village at Piers 27-29.

Estimated cost? $7-8 million. Much lower than a full restoration of the piers, and a lot better idea than letting them crumble into the Bay!

What do you think of this plan?  Members of the media – wouldn’t this make it easier to do interviews?  If you know the area, please add your comments – what’s good / bad about this idea?

 

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Surrogate yacht

 

Under the Protocol for the 34th America’s Cup, the number of sailing days in an AC72 or a surrogate is restricted.  But a team can sail as much as they want in yachts that are not catamarans over 40 feet long, unless it is an AC45.
Team New Zealand uses two “SL33” catamarans (less than 40 feet long) and tests wing designs on them.

Artemis has found a more clever (and expensive) solution:  they use a 60 feet long trimaran, big enough to test their full-size AC72 wing, which they first installed on 14 March 2012.  How much will this help Artemis?  Is the sailing performance of the trimaran close enough to a lighter AC72 catamaran? Share your opinion with a comment!