USA-Technical Details-Helium used

Discussion in 'Multihulls' started by Doug Lord, Mar 27, 2010.

  1. Doug Lord
    Joined: May 2009
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    Location: Cocoa, Florida

    Doug Lord Flight Ready

    From the BMW-Oracle site:
    -----

    Fact Sheet - "USA".
    Hull
    Boat Type: Trimaran of carbon composite construction
    Where Built: Core Builders, Anacortes, WA, USA
    Overall Length: 114-feet / 34 meters

    Waterline Length: 90-feet / 27 meters
    Beam: 90-feet / 27 meters

    Hours to build: 150,000 hours



    Mast
    Height
    : Up to 185-feet/55 meters
    Where Built: Hall Spars, Bristol, RI, USA; Core Builders, Anacortes, WA, USA



    Wing Sail
    Height: 223 ft / 68 m (compared to 102 ft / 31 m length of a Boeing 747 wing and 143 ft / 43.5 m length of an Airbus 380 wing)
    Chord: 10 to 45 ft / 3 to 14 m
    Width: 2 to 6 ft / 0.5 to 2.0 m
    Surface area: 7,000 sq. ft / 650 sq. m (profile)
    Weight: 7,700 lbs / 3,500 kg (approx)



    Design and R&D
    BMW ORACLE Racing Design Team
    Mike Drummond, Director; 30 designers and scientists
    Principal Naval Architects: VPLP (Van Peteghem and Lauriot Prévost)



    Sails Mainsail: 6,800 square feet; (630m2)
    Genoa: 6,700 square feet; (620m2)
    Gennaker: 8,400 square feet; (780m2)



    Notes on the wingThe 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."


    ==========================
    April 2010: Sailing World magazine article confirms that HELIUM was used on
    USA to help it fly a hull sooner!
    Sailing World,April 2010, page 51.
    ----------
    Just doing some rough calculations the "lift" from helium would be between a hundred + and a few hundred pounds depending on where the helium was put and how much weight it "cost" to contain it. Need more info......
     
  2. mark775

    mark775 Guest

    I'm goin' out on a limb here, Doug, but I got to thinking... If your numbers are correct (between one and a few hundred), then why not hydrogen, at half the weight of helium? Well, diminishing returns; filling a void with helium saves86% of the weight of the air that would be there, hydrogen, 93%. Hydrogen is expensive and more difficult to contain. Then, there is the flammability. Perhaps not a big concern in this application, but a concern. Then, I thot "vacuum". One could save all of the weight of the removed air (or any percentage of it) but this precludes using the pressure to assist in supporting some part of the boat - Then I really got to thinking... A pressurized area could support much more load than a volume of atmosphere. Maybe it is not the weight of air they were saving but the weight of a given section supported by a pressure - "then why not helium if we are pressurizing anyway?" they may have asked. It would require displacement of large volumes of air, at 1.25 grams per liter, for that to be the primary reason for helium use.
     
  3. marshmat
    Joined: Apr 2005
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    marshmat Senior Member

    Helium filled hulls.... oh, what have we come to....

    Re. vacuum: It's fairly easy to contain helium (or hydrogen) at zero pressure differential, as was the case in the old airships. Turning the same volume into a vacuum chamber, though, adds quite a lot of weight, and it's very hard to maintain vacuum.

    Re. pressurization: The only reason aircraft are pressurized is so that the occupants can breathe properly at 35,000 feet. Pressurization is much harder on the structure; it can stiffen the system (slightly) but, unless you're dealing with flexible cylinders (like a RIB's tubes), pressurization just adds structural stress (thus requiring a heavier structure). So I seriously doubt that any of the big race boats will have gone this route.
     
  4. Chris Ostlind

    Chris Ostlind Previous Member


    Geez... another list. It would be nice, though, if you had included the one statistic on a list of this type that really is germane to the argument you wish to stress... that being the helium and possible lifting of said boat.... Where is the all-up weight of the complete boat? I see the rig weight, but no weight figure for the boat itself.

    You indicate a possible savings of 100+ pounds due to helium use and have no idea as to how that would matter to a boat that obviously weighs-in with a likely double digit tonnage. You think that maybe the overall weight has a just a bit to do with the big picture here, especially when you have gone on the record as saying, and I quote,


    Doug, take a hard look at what you are pronouncing with the statement in the last paragraph. In the first post on this thread you indicate the hundred pound advantage and in the quote you say it is "...the most exciting, incredible developments in design and construction of high speed sailboats that I have run into in my 50+ years of studying design and sailing. Monumental is not too strong a word!!"

    Doug, really... in all 50+ years this is right up there for you?... The saving of 100 pounds from a boat that weighs in the teens of tonnage?

    All this excitement over something written in a publication for which no substantiation has been provided? Think maybe that's just a wee bit premature for such an earth-shaking proclamation?
     
  5. Doug Lord
    Joined: May 2009
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    Doug Lord Flight Ready

    USA Tech

    I have learned from someone involved that the helium was "in the hulls"-in that case a very rough calc(guesstimate) shows a potential of around 600lb. of lift. Thats based on 1kg per cubic meter lift. Will be interesting to find out the facts-if they release the details.
    Even if it was only one pound of lift the fact that they used helium gas at all "to make it easier to fly a hull" is an extraordinary development.
    I've wondered about a future wing designed for its "normal" purpose in addition to holding helium-lots of volume there but it might be impractical-I don't know. Before Thursday I would have thought using helium on a race boat was impractical period-too little benefit for too much cost(not just money). But obviously I was wrong-it did make a difference.......
     
  6. Chris Ostlind

    Chris Ostlind Previous Member


    Please tell us that this isn't going to be another one of those situations where there's no photos, no named attribution, and essentially no proof. You know, something like the claims of foiling made by the builder of the AeroSKIFF.

    Come on, man, this isn't kindergarten where kids with big eyes sit around the teacher and believe everything they are told. Produce the name of the mysterious, "someone involved", along with photos of the installed gas container showing its size and the process of filling said container... or put a halt to the effervescence.

    The world is filled with crazy levels of disinformation. Until you can produce the asked-for material, we really have no choice but to look at all this as another one of those things where one competitor is attempting to get in the head of the opponent. It's easy to prove that you're not functioning as a dupe.

    Bring forth the substance.
     
  7. CT 249
    Joined: Dec 2004
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    Location: Sydney Australia

    CT 249 Senior Member

    Does it really matter, anyway?

    Is there any sailor on the planet who has not joked about helium-filled hulls several times before? Years ago a bunch of us were laughing over drinks about the prospect of grabbing an old set of Laser moulds, building a bunch of Nomex/carbon Lasers, and filling them with helium. It's the sort of silly thing everyone says over a drink or two.

    It's not hard to dream up, it's just something that's probably enormously impractical. So, in a typical (say) 16' cat you may gain a couple of kilos lift, at the cost of having to cart around heavy cylinders of helium every time you go sailing. That would add (and this is a very vague memory) about $300 in cost every race, plus all the messing around.

    Yep, wow, it's really going to happen. As Chris O says, why not just go to a fully lighter-than-air craft. Manned long-distance balloons have reached over 100 knots, crossed the Atlantic and gone on to Italy in three days, and gone around the world in 19.

    So why not just go for a balloon with a tiny foil trailing down thousands of feet in the water, and call that a sailboat? Surely no one would be small-minded enough to find a difference between two craft that had their displacement reduced by helium??
     
  8. daiquiri
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    daiquiri Engineering and Design

    More than filling the hull with helium (I really wouldn't bet on that one untill I see official claims), I would see some advantage in filling the WING with helium...
     
  9. Doug Lord
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    Doug Lord Flight Ready

    ============
    Bet on it----
     
  10. daiquiri
    Joined: May 2004
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    Location: Italy (Garda Lake) and Croatia (Istria)

    daiquiri Engineering and Design

    Ok. :)
     
  11. Paul B

    Paul B Previous Member

    It has been tried before, 20+ years ago, and was not something that led to any significant success.
     
  12. Doug Lord
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    Doug Lord Flight Ready

    I think that the use of helium, for whatever reason, in an Americas Cup is significant. But, remember the article said it was used to make the hull fly earlier.
    So lets look at a few guesstimates:
    -est. max lift of the helium in 3 hulls= 500lb.
    -est. boat+ rig weight= 25,000lb.
    -----
    Now, just for the heck of it a 175lb crewman moved from the lee hull to the windward hull would generate about(87 X 175) 15,225 ft. lb. of RM.
    The helium would reduce RM by approx.( 42 X 500) 21,000 ft.lb..
    Now lets compare that to the approx. RM of the whole boat( 25,000 X 42) which is 1,050,000 ft. lb.(!) So the helium would reduce RM by 2 %. Is that enough for a serious gain? Maybe.
    ----
    Lets look at it from another angle. Lets say you had a hull that absolutely,unequivocally had to measure in at exactly 90' or less. The approximate pounds per inch immersion on that hull would be ([90 X 9] X .65) X .083=43.65 cu. ft.=2796lb. Now, lets say that the hull was floating just a few milimeters too deep, how would you lighten it assuming, for the sake of discussion, that everything that could be removed had been removed. Well, its very interesting that the approximately 500lb of lift from the helium in three hulls would change the immersion of the boat by .179" or 4.5mm......
    Could the helium have been a measurement device with somewhat minor, but positive, side effects?
    Just an idea....
     
  13. Paul B

    Paul B Previous Member

    Wow, for someone with a pipeline to the inside info it seems you should not have to guess about the purpose. Why didn't your source just tell you what it was for?

    By the way, reducing RM is not a gain. In fact, during the 2nd race Cam Lewis said it looked like USA needed more RM. Since Cam Lewis said it, how can you argue with him?

    On the other hand, during the same race Cam talked about Bruno sailing in the Louis Vuitton Cup in '77 and '80. Since the LVC didn't begin until '83 that sounds wrong, but again it is Cam Lewis saying it, so surely no one on this board can argue with it.
     
  14. mark775

    mark775 Guest

    Compare a section (or an entire hull) to a liter plastic bottle of coke - atmosphere inside and one can crush it like a... liter plastic bottle. Pressurise it, and it is as hard (stiff) as a rock. You guys are the engineers but, to me, it seems not only possible but likely that hulls be pressurised. I could build a like-sized vessel that weighs less than the BMWO that could survive thirteen knot winds as long as nobody had to enter. My skills don't lead to a proper shape or strong enough attachment points but if amas or other specific vessels (contained areas) are not being designed this way, why not?
    I might add, you sailboat types seem to be a mean spirited bunch. I appreciate the discussion and tossing about of ideas - perhaps being very constrained by a requisite for substance leads to stagnation. Sailboats don't work very well in stagnation, I reckon - Design, neither.
     

  15. Doug Lord
    Joined: May 2009
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    Doug Lord Flight Ready

    -------------
    No guess-fact.(approximately)
     
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