The WING is coming... Options

[cheapshacht]

How about cooking up a top for this wing which is able to hydraulically shift the top of the headsail windward/leeward, operating together with an (improved?) version of the infamous bowsprit to give the upwind/downwind slot that you describe... and, feel free to add tip vortex reducing design to said top of wing?
Too complicated?

Given the timeframe, I guess so - odd how nobody seems to consider how few days remain to the shipping deadline ..
Mind you, the slot would be desirable just downwind - upwind, you'd want the headsail as separate as possible.
But about the tip vortex reducing gadget, forget it: it's complicated enough with set airflow conditions/direction like with airplanes at cruising speed - not a chance here.

BTW, #2 son just e-mailed me mentioning he's having a meeting right now with Mark Drela (the creator of XFOIL as well as of MSES, for several airfoils operating together). I gave him this link, on the odd chance they might want to have a laugh on us (IMG:style_emoticons/default/ph34r.gif)

I work with your #2 son and I didn't know it until now. Would he be the good looking Italian aerodynamicist? I work at Aurora Flight Sciences and bumped into Drela at the coffee pot this morning. He is truly a genius!

cheap

[RHough]

Span is the name of the game. You get the same vortex control with the least drag penalty by adding span and using twist. Only in span limited designs are winglets and end plates a viable method of tip vortex control.

Not necessarily true, actually. Mother Nature did a beautiful job with vultures (got to see them up close when sharing thermals in Brazil): they need to soar with minimum effort, and yet their wings have to be short enough they can be folded when they work on a carrion. So they have a set of automatically adjusting end feathers that work infinitely better than man-made winglets ..

Land soaring birds are span limited designs ... (IMG:style_emoticons/default/smile.gif)

Efficient soaring/gliding performance requires high L/D ... dynamic soaring favours very high AR ... birds that soar over water tend to have high AR wings and relatively high area loading (higher soaring speed) to enable them to cover great distance. This also works for human carrying gliders.

Land based soaring birds that evolved to make use of small thermals close to the ground must have high L/D and the ability to circle at a very small radius relative to span ... tip stall becomes a problem and high AR does not work. Buzzard and Hawk wingtip "finger feathers" are dynamic tip vortex control that the low AR wings require to get high L/D. Some very interesting experiments along these lines were done in Germany (IIRC) 10-20 years ago. They built a RC glider with a "normal" high AR wing on one side and a low AR wing with tip fingers on the other ... and proved the theory that the L/D of both wings were equal ... the airplane flew well and soared as if both wings had the same, conventional, high AR planform.

This was very interesting to me as I was designing span limited RC gliders at the time. I never found enough information to allow me to try this design feature, it would have been a game changer if fixed tip fingers could have been used to give both high L/D for distance and high CL for minimum sink thermal soaring on a 1.5M span glider. I came to the conclusion that the tip fingers would require two or three axis control to give the wide flight envelope I needed and the added complexity and weight would have killed and performance gain ... low area loading and the resulting low flight speeds are needed to get minimum sink rates and at 1.5 to 3M spans the system was not workable.

Vulture Wings

[mdcf]

there are prople walking on the boat - things are starting to move in SD

[Radar]

there are prople walking on the boat - things are starting to move in SD

I'm gonna go make some popcorn and dim the lights as this all unfolds.

[luminary]

Forecast:
10am 1pm 4pm 7pm
Mainly sunny Mainly sunny Mainly clear Mainly clear
Mainly sunny Mainly sunny Mainly clear Mainly clear
Temp. 18°C 21°C 21°C 17°C
P.O.P. 0% 0% 0% 0%
Wind W 8 km/h W 15 km/h W 15 km/h NW 5 km/h

[Luiz S]

Just a few comments:

1) The fact that the gin pole is already raised is a strong indication that the mechanics of its use significantly differs from that used in smaller tris, like in the F33 trimaran seen here (scroll down to see the entire mast raising sequence with short comments).

Note that the gin pole remains perpendicular to mast during the manouver:
(IMG:http://www.f-boat.com/media/F-33floridalaunch/mastraising.jpg)
(IMG:http://www.f-boat.com/media/F-33floridalaunch/mastraising3.jpg)


2) I think the size of the wing will not be the one published. Chances are that it can be enlarged or shortened by means of adding or removing a section or two. Personally, I'd expect it to be larger than the largest mast, and also that it will be used alone for upwind sailing but together with a genoa for downwind sailing.

3) Since a wing stresses the boat's structure a lot less than a conventional rig, it is conceivable that the big stick broke while the crew was performing structural tests that can't be done with the wing, such as measuring longitudinal stiffness under high mainsheet tension. If this is true, it would follow that something minor gave before they reached the target (max safe) tension.

4) Right now BMWO has an edge:

BMWO:
Tri beats Cat
Rigid wing beats Soft sails
More time in the water beats Less time in the water

Alinghi:
Light beats heavy

5) The big question now is if Alinghi will also show up with a wing.

Luiz

[A Guirri]

Span is the name of the game. You get the same vortex control with the least drag penalty by adding span and using twist. Only in span limited designs are winglets and end plates a viable method of tip vortex control.

Not necessarily true, actually. Mother Nature did a beautiful job with vultures (got to see them up close when sharing thermals in Brazil): they need to soar with minimum effort, and yet their wings have to be short enough they can be folded when they work on a carrion. So they have a set of automatically adjusting end feathers that work infinitely better than man-made winglets ..

Land soaring birds are span limited designs ... (IMG:style_emoticons/default/smile.gif)

Efficient soaring/gliding performance requires high L/D ... dynamic soaring favours very high AR ... birds that soar over water tend to have high AR wings and relatively high area loading (higher soaring speed) to enable them to cover great distance. This also works for human carrying gliders.

Land based soaring birds that evolved to make use of small thermals close to the ground must have high L/D and the ability to circle at a very small radius relative to span ... tip stall becomes a problem and high AR does not work. Buzzard and Hawk wingtip "finger feathers" are dynamic tip vortex control that the low AR wings require to get high L/D. Some very interesting experiments along these lines were done in Germany (IIRC) 10-20 years ago. They built a RC glider with a "normal" high AR wing on one side and a low AR wing with tip fingers on the other ... and proved the theory that the L/D of both wings were equal ... the airplane flew well and soared as if both wings had the same, conventional, high AR planform.

This was very interesting to me as I was designing span limited RC gliders at the time. I never found enough information to allow me to try this design feature, it would have been a game changer if fixed tip fingers could have been used to give both high L/D for distance and high CL for minimum sink thermal soaring on a 1.5M span glider. I came to the conclusion that the tip fingers would require two or three axis control to give the wide flight envelope I needed and the added complexity and weight would have killed and performance gain ... low area loading and the resulting low flight speeds are needed to get minimum sink rates and at 1.5 to 3M spans the system was not workable.

Vulture Wings

Here ya go.

Video here

[Xlot]

I work with your #2 son and I didn't know it until now. Would he be the good looking Italian aerodynamicist? I work at Aurora Flight Sciences and bumped into Drela at the coffee pot this morning. He is truly a genius!

cheap

Small world, ain't it? I wouldn't be objective about the "good looking" bit, but Francesco is indeed in hog heaven at Aurora - and I got the Odysseus T-shirt .. (IMG:style_emoticons/default/smile.gif)

This was very interesting to me as I was designing span limited RC gliders at the time. I never found enough information to allow me to try this design feature, it would have been a game changer if fixed tip fingers could have been used to give both high L/D for distance and high CL for minimum sink thermal soaring on a 1.5M span glider. I came to the conclusion that the tip fingers would require two or three axis control to give the wide flight envelope I needed and the added complexity and weight would have killed and performance gain ...

Rather humbling, don't you think? Reminds me of the old, ignorant bumblebee story ..

[tmouton]

Luiz: the gin pole in your example also starts oriented vertically. Whats the difference?

[cheapshacht]

I work with your #2 son and I didn't know it until now. Would he be the good looking Italian aerodynamicist? I work at Aurora Flight Sciences and bumped into Drela at the coffee pot this morning. He is truly a genius!

cheap

Small world, ain't it? I wouldn't be objective about the "good looking" bit, but Francesco is indeed in hog heaven at Aurora - and I got the Odysseus T-shirt .. (IMG:style_emoticons/default/smile.gif)

Yes, indeed, a very small world. Francesco is one of our engineering "rock stars" - I love wondering into his office to see what his mind has cooked up this week! He is working on some truly bizarre stuff .... Odysseus is one of them. He'd be right at home working the BMW-Oracle wing.

cheap

[cheapshacht]

I work with your #2 son and I didn't know it until now. Would he be the good looking Italian aerodynamicist? I work at Aurora Flight Sciences and bumped into Drela at the coffee pot this morning. He is truly a genius!

cheap

Small world, ain't it? I wouldn't be objective about the "good looking" bit, but Francesco is indeed in hog heaven at Aurora - and I got the Odysseus T-shirt .. (IMG:style_emoticons/default/smile.gif)

Yes, indeed, a very small world. Francesco is one of our engineering "rock stars" - I love wondering into his office to see what his mind has cooked up this week! He is working on some truly bizarre stuff .... Odysseus is one of them. He'd be right at home working the BMW-Oracle wing.

cheap

[RHough]

Span is the name of the game. You get the same vortex control with the least drag penalty by adding span and using twist. Only in span limited designs are winglets and end plates a viable method of tip vortex control.

Not necessarily true, actually. Mother Nature did a beautiful job with vultures (got to see them up close when sharing thermals in Brazil): they need to soar with minimum effort, and yet their wings have to be short enough they can be folded when they work on a carrion. So they have a set of automatically adjusting end feathers that work infinitely better than man-made winglets ..

Land soaring birds are span limited designs ... (IMG:style_emoticons/default/smile.gif)

Efficient soaring/gliding performance requires high L/D ... dynamic soaring favours very high AR ... birds that soar over water tend to have high AR wings and relatively high area loading (higher soaring speed) to enable them to cover great distance. This also works for human carrying gliders.

Land based soaring birds that evolved to make use of small thermals close to the ground must have high L/D and the ability to circle at a very small radius relative to span ... tip stall becomes a problem and high AR does not work. Buzzard and Hawk wingtip "finger feathers" are dynamic tip vortex control that the low AR wings require to get high L/D. Some very interesting experiments along these lines were done in Germany (IIRC) 10-20 years ago. They built a RC glider with a "normal" high AR wing on one side and a low AR wing with tip fingers on the other ... and proved the theory that the L/D of both wings were equal ... the airplane flew well and soared as if both wings had the same, conventional, high AR planform.

This was very interesting to me as I was designing span limited RC gliders at the time. I never found enough information to allow me to try this design feature, it would have been a game changer if fixed tip fingers could have been used to give both high L/D for distance and high CL for minimum sink thermal soaring on a 1.5M span glider. I came to the conclusion that the tip fingers would require two or three axis control to give the wide flight envelope I needed and the added complexity and weight would have killed and performance gain ... low area loading and the resulting low flight speeds are needed to get minimum sink rates and at 1.5 to 3M spans the system was not workable.

Vulture Wings

Here ya go.

Video here

Left, the lead feather is set at negative 27 degrees (this is not a typo), the second is at -19 degrees, the third at -15 degress and, the remaining stationary feathers are reduced 4-5 degrees per feather until the aft one is at zero. Other combintions of angles have not worked as well as this one.

Link

[Blackburn]

Milking away; The Oracle blog website tells of a ceremony held this morning, the construction crew handing the wing over to the sailors.

http://bmworacleracingblog.blogspot.com/

Hopefully we'll get some finished wing pictures soon - we've been strung along with all this PR stuff about long enough, or what?

[Luiz S]

Luiz: the gin pole in your example also starts oriented vertically. Whats the difference?

Usually we start by fixing the mast to the mast base and then we rig the gin pole. If the gin pole is rigged as a short mast with a pulley at the top, to be used as a fixed crane, there will be no way to take it from under the mast/wing after raising, unless the pole is stepped on a second ball.

There is a reason to rig the gin pole as we do: when the gin pole remains perpendicular to the mast it is under compression only and under less stress, meaning you work less to raise the mast.

Luiz

Attached File(s)

 Mast_raising_2.jpg ( 96.31K ) Number of downloads: 21
 Mast_raising_3.jpg ( 83.43K ) Number of downloads: 19

 

[Jeffhorn]

Time for a really dumb question... Wings don't luff, and you cant take the thing down all that quickly, so how does one account for this? Just keep her pointed dead into the breeze at all times when shes on the pier? Piviot the wing round and round to keep it in line with the breeze? If one kept the sail up on DZ all day you would think that there would be some problems, do they just put it up and pull it down when they want to use it like a regular sail? Or will the wing stay up for the next few days (once it goes up)?

Sorry I have no experience with this kind of sailing, and it doesnt really add up to me. Can someone with some wing experience help me out here?

Sorry for my noobidness :/

( . ) ( . )

.

\/

-Radar

From a pilot's point of view, wings don't luff but they do stall. My simple, feeble brain tells me that a sail luffing is much the same as a wing stalling. Am I very far off?

[hoom]

Yes.

[spencerogden]

From a pilot's point of view, wings don't luff but they do stall. My simple, feeble brain tells me that a sail luffing is much the same as a wing stalling. Am I very far off?

Yes, Sails luff at 0 degrees AOA. Both sails and wings stall above some maximum AOA. A sail at 0 AOA is a very high drag structure, while a wing at 0 AOA is very low drag.

Stalling is an issue for wings downwind, solved by flaps, just like planes landing.

[Windy6327]

http://www.sail-world.com/Australia/Steve-...-wingmast/63118

Nice writeup of a Steve Clark interview about the BOR90 Wing.

[Smiget]

wing going up?


i lied, just moving the crane..

Attached File(s)

 wing.jpg ( 30.57K ) Number of downloads: 25

 

[Luiz S]

http://www.sail-world.com/Australia/Steve-...-wingmast/63118
Nice writeup of a Steve Clark interview about the BOR90 Wing.

And worth reproducing here:

Steve Clark is widely acknowledged as one of the most astute and most experienced inshore multihull technologists and sailors on the planet. His is a family pedigree with his father Van Alan Clark being heavily involved C-class catamaran development in the early days of the Little America's Cup.

From that upbringing, Steve has continued and led the team that developed the C-Class challenger Cogito, which broke the Australian domination of the Little America's Cup in 1996 at Macrae, in Australia, breaking the dominance of the Lindsay Cunningham designed succession of C-Class Yellow Pages.

For reasons best known to others, Steve has not been involved in the multihull America's Cup. His co-designer and helmsman in 1996, Duncan Maclane works as part of the Alinghi design team.

With the release of the first images of the wing mast for BOR90, Sail-World asked Steve Clark for his analysis of the largest wing mast ever built.


(As we noted yesterday, the BOR90 is a two element wing mast which essentially just has a tail section rotating off a front section, a little like an aeroplane rudder. The more sophisticated three element wings, used on Cogito, comprise a smaller third section which sits between the other two for greater efficiency and control. Wing sails are two to three times more efficient than a conventional spar and soft sail rig).

Steve Clark:' The rig on BOR90 is a two element single slotted wing. This is a 'cleaner' configuration instead of a 'more powerful' configuration. You will not get the high lift coefficients without the #2 element ( the flap in the slot that directs the flow through the slot.) This is probably not a big deal because they have the ability to set head sails for down wind work.

'It may or may no have twist capabilities. For one thing, the use of head sails makes this less necessary. For another, the majority of the wind gradient is in the first 30' off the deck, so given the scale of this wing, it may not be as big a deal as it is for the smaller C Class wings.

(Sail-World: One of the features of the Cogito three element wing mast was that it gave the crew the ability to adjust the twist in the wing, meaning that leech tension was a thing of the past, as the sail 'leech' was completely controllable.)

'The control system seems to be the tried and true Patient Lady (the predecessor to Cogito) system, which is self tacking and very well worked out.

'This system scales well and can accommodate as many control arms as needed.


'Stretch in the control cables is a big deal, but given the super low stretch lines available it is less of a problem than it was even 10 years ago. The exact function of the short control arms is not entirely clear. It may be necessary to reduce the stress on the longer ones and thus reduce the stretch on the control cables.

'Or it may be that given the need to set head sails, the lower arms have to be shorter than the upper ones to facilitate sheeting head sails to the proper angles. These are both pretty good reasons, and I doubt there is much more in it than that.

'If this were a C Class wing, I would have believe it was part of a super light program in order to be frightened by it, but that is completely driven by the sail area limitations, which, once again, don't apply here.

'I expect the raising and lowering procedure will be very much like what we do with the C Cats except it will be rotated 90 degrees. The wing will approach the vessel lying flat on its side, with the leading edge 90 degrees to centerline. The leeward ( down side ) shroud will be connected, the fore stay will be connected and the running back stays will be connected. I expect the leeward shroud will be positioned such that the hydraulic cylinder is completely drawn.


'There will be a pivot at the base of the mast such that as the mast is raised, the ball will mate with the socket.

'There is a gin pole to which the weather shroud will be attached. They will then winch the wing up. The vessel may need to be allowed to swing such that it is close to head the wind, but not allowed to tack. As the wing becomes upright, one may expect the leeward hydraulics to be eased and the running backs to be ease such that the wing can feather as soon as possible. A temporary shroud, or halyard will be used to enable the lifting shroud to be disconnected from the gin pole and attached to the hydraulic ram. The rig will then be stable and can be tensioned as per normal.

'At this point it is probably imperative that the vessel get underway as soon as possible. So I would expect the entire sailing crew to be on board and ready to go before the wing starts to rise. If flow attaches to the wing when they aren't ready for it they will have a large problem on their hands.

(IMG:http://www.sail-world.com/photos/std_29LAC.jpg) 'Once again this is just speculation based on what little I have seen on the Internet. There are people who know much more about the specifics of this particular rig than I do.'

The new wingsail on BOR90 is expected to be sailing off San Diego in two or three days, and will obviously be watched with great interest.

For some some other thoughts on the C-Class and wingsail development click here

For an earlier analysis fro Steve Clark of the respective America's cup multihull campaigns click here

[Luiz S]

From a pilot's point of view, wings don't luff but they do stall. My simple, feeble brain tells me that a sail luffing is much the same as a wing stalling. Am I very far off?

You got that wrong.
Luffing is the opposite of stalling.
Luffing happens at zero angle of attack, when lift goes to zero. The equivalent with a wing would be when it is free to rotate.
Stalling happens at high angles of attack when lift is near its maximum.

[williwaw]

Funny to see all the BMWO fans being in winning mode again after the unveiling of the wing. They still have that heavy pos boat and probably Alinghi have a wing available also so that will leave bmwo where it was: very much behind!

[Windy6327]

Funny to see all the BMWO fans being in winning mode again after the unveiling of the wing. They still have that heavy pos boat and probably Alinghi have a wing available also so that will leave bmwo where it was: very much behind!

Proof of the Alinghi wing or it didnt happen.

[sabarry]

Funny to see all the BMWO fans being in winning mode again after the unveiling of the wing. They still have that heavy pos boat and probably Alinghi have a wing available also so that will leave bmwo where it was: very much behind!

I too wondered why we had heard little about an Alinghi wing when they clearly would have known about DZ's and blackburn posted an answer earlier today which I paste below

Brad Butterworth to Stuart Streuli (during the recent Alinghi media day event):

excerpts:

SS: ...they're going to be unveiling a wingsail soon... is that something you would have an issue with?
BB: No. I'm totally encouraged by that, I think that's great.... I think it's probably great for both of us. I really think that if they can build a wingsail and make that work on that boat, and they win the America's Cup here, good on them. That really shows some innovation - Those guys are trying hard, a lot of respect for the sailing team... and the way that they have taken it on...

SS: Any chance you'll be trying a wingsail?
BB: Well thats a huge committment in time and effort and logistics, it's like building a boat. ..so they would have had that in mind for a long time. Obviously we've looked at it, and right now, I can tell you right now; no, we won't have a wingsail.

http://www.sailingworld.com/americas-cup/r...1000068251.html

[cbags]

Certainly look like the wing is hooked up now.