pacice

Foiling Monohull - what would it look like?

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I don't have an issue with stored energy being used for more than just foil control. I was lucky enough to get a tour though an AC base when in BER, was interesting that one of the 50's was almost fully electric with plug in battery packs which gave them about 2 hours sailing each so they could train and test foils etc all day. Without the batteries apparently they were limited to about 1.5 hours sailing before the energy stored in the grinders ran out.

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37 minutes ago, Rawhide said:

I don't have an issue with stored energy being used for more than just foil control. I was lucky enough to get a tour though an AC base when in BER, was interesting that one of the 50's was almost fully electric with plug in battery packs which gave them about 2 hours sailing each so they could train and test foils etc all day. Without the batteries apparently they were limited to about 1.5 hours sailing before the energy stored in the grinders ran out.

We also see it all the time in the Sydney Hobart, as well as other races in boats like Wild Oats XI, Perpetual Loyal (Infotrack) and Rambler 88. Doesn't make the racing any less exciting to watch.

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I'm with @Basiliscus, give me regenerative Hydraulics from foils any day over Engines &/or Battery powerboats.

SS+1988+bdef+Soft+&+hard_%C2%A9Marshall+

not

1455236570962.jpg

 

 

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4 hours ago, hoom said:

I'm with @Basiliscus, give me regenerative Hydraulics from foils any day over Engines &/or Battery powerboats.

Regenerarive electrics are more efficient than regenerative hydraulics.

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31 minutes ago, Terry Hollis said:

Regenerarive electrics are more efficient than regenerative hydraulics.

That's a very bold declaration!! ;)

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11 minutes ago, Indio said:

That's a very bold declaration!! ;)

The moth class use regenerative rubber. Simple shockcord pulls the wand down and water pushes it up again. Seems pretty efficient. But stupid ISAF rules required us to adapt the class rules to allow it. If classes change too many power related rules to suit themselves we will end up with unmanned power boats controlled by computers from somewhere on shore.

I'd be more happy with batteries if they are flat when the crew go on board and the only power available was what they put in to them.

Moving an appendage by stored power is not far remote from moving a propeller. Opens up plenty of cans of worms once the rule benders get hold of it.

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On 2/11/2018 at 9:59 PM, Terry Hollis said:

Regenerarive electrics are more efficient than regenerative hydraulics.

I don't have a problem with regenerative electrics.  You could use supercapacitors in place of the accumulators.  The class rules could specify the supercapacitors had to be discharged when the boat left the dock, leaving them to be charged by the crew and boat.  For that matter, I don't have an issue with batteries of limited size so they could get the boat through a maneuver but not a leg of the course.  Energy storage is fine, so long as the energy comes from the crew and the wind.  If you want to put up a wind turbine to power the systems, go for it.

What I wouldn't want to see are the engines that were used in the 33rd AC Match or battery powered systems like the AC45F that had enough energy to keep the systems running for the whole race.

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2 hours ago, Basiliscus said:

If you want to put up a wind turbine to power the systems, go for it.

Love that idea. 

But it obviously won’t work for the JC75, a power-hungry monster!

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1 hour ago, Stingray~~ said:

But it obviously won’t work for the JC75, a power-hungry monster!

I wish the JC75 was just wind power hungry.

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1 hour ago, Stingray~~ said:

Love that idea. 

But it obviously won’t work for the JC75, a power-hungry monster!

Exactly.  They should race with a class that doesn't require more power than can be generated by the crew and wind.  That is, after all, the whole point of a sailing competition.  

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6 hours ago, Basiliscus said:

The class rules could specify the supercapacitors had to be discharged when the boat left the dock, leaving them to be charged by the crew and boat.

This isn't going far enough, they'd charge from the tow to the course, have specialist charging gorillas who get off before the 10min signal or go out hours early to ensure plenty of time to charge & recover.

You'd need to mandate discharged until 10min signal, with tow dropped & only race crew onboard or something like that.

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doug has been so unusually quiet lately, did he finally get banned or something? 

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8 hours ago, frozenhawaiian said:

doug has been so unusually quiet lately, did he finally get banned or something? 

Don't jinks us, I'm just enjoying the quiet absence...

 

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^ Great read. Is it the first time they are getting a bit more specific about sails?

"The rig is still under development but will feature soft sails, including code zeros for downwind legs. The mainsail concept is likely to involve a twin-luff set-up, which creates a much more efficient wing-like transition from the mast to the sail."

 

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Team New Zealand's breakthrough sail design for next America's Cup

Team New Zealand's design geniuses are at it again, producing a ground-breaking soft wingsail for the revolutionary foiling monohull to be used in the next America's Cup.

And they have proven true to their edict to produce state-of-the-art technology that can trickle down to the average yachtie.

Last week they secretly tested a scaled down version of the new sail, popping the rig into a 22-foot non-foiling trimaran and ripping around Auckland's Waitemata Harbour.

... (Includes a video)

https://i.stuff.co.nz/sport/other-sports/101711195/team-new-zealands-breakthrough-sail-design-for-next-americas-cup

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Thanks SR - but meh, not impressed. IMVeryHO, the only advantage of such a sail would be adding a few knots at extremely low AWAs (upwind foiling) due to its reduced section drag coefficient. But the AC75's Achilles' heel is its high take-off speed, and there it's the lift coefficient that comes into play, implying a slotted section.

I do hope Basiliscus will comment. And needless to say, if teams will have to develop everything independently other than the mandated spar section, this will add a lot to design activities and cost: just what's needed if somebody was hesitating on joining in ...

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I wonder if Tarkus III is this boat? https://www.yachtingnz.org.nz/boat/tarkus-iii

Neil Wilkinson is the designer who did the deep-dive presentation in NZ of OR’s AC72 after AC34. Before that he was with ETNZ (AC32), OneWorld (AC31), probably ETNZ before that. So, good chance, small world. Basiliscus has, iirc, a similar boat.

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28 minutes ago, Xlot said:

Thanks SR - but meh, not impressed. IMVeryHO, the only advantage of such a sail would be adding a few knots at extremely low AWAs (upwind foiling) due to its reduced section drag coefficient. But the AC75's Achilles' heel is its high take-off speed, and there it's the lift coefficient that comes into play, implying a slotted section.

I do hope Basiliscus will comment. And needless to say, if teams will have to develop everything independently other than the mandated spar section, this will add a lot to design activities and cost: just what's needed if somebody was hesitating on joining in ...

Is the control arm at the top a novel idea?

7E70FDD4-FE33-4085-B6A6-7139F36CB668.jpeg.7216e3612932b86ebf46f8d2d52fd6ed.jpeg

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1 hour ago, Stingray~ said:

This is nothing like a wingsail - it's just a double-surface soft sail.  What makes a wingsail superior to a soft sail is not the fact that it is thick.  From an aerodynamic point of view, it would be better to make a wingsail thin, but the structure won't support it.

What makes a wingsail so maneuverable is the torsion loads are reacted internally through the ribs and D-tube structure.  The sheet only has to carry the loads needed to rotate the entire wing, and even those can be reduced by appropriate choice of the pivot axis, providing some aerodynamic balance.  In contrast, a soft sail controls twist through leech tension.  This requires very high sheet or vang loads, which affects the structure of the entire boat.  It significantly increases the energy from the crew needed to trim the sail.  And it is impossible to reduce the heeling moments by using negative lift at the head, as was done by the AC72 and AC50 wingsails.  

The mainsail shown is a single element section that won't have anywhere near the high-lift capability of the slotted flap sections used in the  AC and C-class wingsails.  

The surface texture of the soft sails is also much rougher than the smooth film, increasing the profile drag and decreasing the maximum lift.  Granted, profile drag is not a large component of the total drag, but it isn't negligible, either.

About the only aerodynamic benefit I can see for this rig over a rotating wingmast/single surface sail combination is a reduction in the windward separation bubble that forms at the mast/sail junction.  It can be reefed, which is an advantage over the hard wingsail, although I'd be very surprised to see them using reefed sails in an America's Cup race.  It would be more likely to have different sized sails for different conditions.

Cost is another interesting factor.  The wingsails were expensive to build, but once built they weren't that expensive to operate - Clysar film is cheap.  They were long term investments, like the hulls, and could (with a stable Design Rule) be used for multiple campaigns.  Sails in an America's Cup campaign are disposable items, good for only a few races at most.  The sail budget for an AC campaign is at least as much as the cost of building a wingsail.

The double-surface sail shown in the video may be an advance over conventional soft sails, but it's no wingsail.

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12 minutes ago, Basiliscus said:

This is nothing like a wingsail - it's just a double-surface soft sail.  What makes a wingsail superior to a soft sail is not the fact that it is thick.  From an aerodynamic point of view, it would be better to make a wingsail thin, but the structure won't support it.

What makes a wingsail so maneuverable is the torsion loads are reacted internally through the ribs and D-tube structure.  The sheet only has to carry the loads needed to rotate the entire wing, and even those can be reduced by appropriate choice of the pivot axis, providing some aerodynamic balance.  In contrast, a soft sail controls twist through leech tension.  This requires very high sheet or vang loads, which affects the structure of the entire boat.  It significantly increases the energy from the crew needed to trim the sail.  And it is impossible to reduce the heeling moments by using negative lift at the head, as was done by the AC72 and AC50 wingsails.  

The mainsail shown is a single element section that won't have anywhere near the high-lift capability of the slotted flap sections used in the  AC and C-class wingsails.  

The surface texture of the soft sails is also much rougher than the smooth film, increasing the profile drag and decreasing the maximum lift.  Granted, profile drag is not a large component of the total drag, but it isn't negligible, either.

About the only aerodynamic benefit I can see for this rig over a rotating wingmast/single surface sail combination is a reduction in the windward separation bubble that forms at the mast/sail junction.  It can be reefed, which is an advantage over the hard wingsail, although I'd be very surprised to see them using reefed sails in an America's Cup race.  It would be more likely to have different sized sails for different conditions.

Cost is another interesting factor.  The wingsails were expensive to build, but once built they weren't that expensive to operate - Clysar film is cheap.  They were long term investments, like the hulls, and could (with a stable Design Rule) be used for multiple campaigns.  Sails in an America's Cup campaign are disposable items, good for only a few races at most.  The sail budget for an AC campaign is at least as much as the cost of building a wingsail.

The double-surface sail shown in the video may be an advance over conventional soft sails, but it's no wingsail.

Serious question - what would a soft wingsail be given it's obvious need for rigidity? Is it a simply a wingsail that can be unpacked, and then hoisted and made rigid on the boat?  

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looks like 2 sails instead of 1 sail with a double luff.  mounted on a special mast that is flat at the back.

i wonder if the added weight is worth the benefit.  will it hold it's shape better than a regular full battened main?

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3 minutes ago, rh2600 said:

Serious question - what would a soft wingsail be given it's obvious need for rigidity? Is it a simply a wingsail that can be unpacked, and then hoisted and made rigid on the boat?  

A soft wingsail is something of an oxymoron.  I suppose in the future it may be possible to have materials that act as you propose, but they're not available now.

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42 minutes ago, Stingray~ said:

Is the control arm at the top a novel idea?

No, I could swear having seen something similar over the years - someone over at the MH forum would know. I definitely saw it in another field more than 40 years ago: on a wind turbine, with a round spar/leading edge and soft, roller reefing sail - the control arm was used to set twist

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8 minutes ago, Xlot said:

No, I could swear having seen something similar over the years - someone over at the MH forum would know. I definitely saw it in another field more than 40 years ago: on a wind turbine, with a round spar/leading edge and soft, roller reefing sail - the control arm was used to set twist

This link is not working for me but maybe there are more photos to be had somewhere there: http://emirates-team-new-zealand.americascup.com/

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22 minutes ago, Basiliscus said:

A soft wingsail is something of an oxymoron. 

Thats what I was thinking too... if you think about rigid wing and soft wing flyers, you compare hang gliders to paramotors, the later of which does not provide the control we expect of a 'soft-wing-sail'
s338505810942120584_p55_i2_w968.jpeg

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1 hour ago, Stingray~ said:

Is the control arm at the top a novel idea?

7E70FDD4-FE33-4085-B6A6-7139F36CB668.jpeg.7216e3612932b86ebf46f8d2d52fd6ed.jpeg

I am sure to have seen that before, can't find where. Coming from RC boats ? allowing negative lift at the head in order to decrease heeling moment ?

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37 minutes ago, Tornado-Cat said:

I am sure to have seen that before, can't find where. Coming from RC boats ? allowing negative lift at the head in order to decrease heeling moment ?

Yes, maybe.

Nice:

 

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1 hour ago, Stingray~ said:

This link is not working for me but maybe there are more photos to be had somewhere there: http://emirates-team-new-zealand.americascup.com/

This works, lots of pics too

http://emirates-team-new-zealand.americascup.com/en/preview-news/269_INNOVATION-CONTINUES-IN-THE-CLASS-RULE-DEVELOPMENT-AT-EMIRATES-TEAM-NEW-ZEALAND.html

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40 minutes ago, Stingray~ said:

Yes, maybe.

Nice:

 

Yes, that is what I think he says at 1:35: it twist her off

As for thew double sail around the mast, nothing really new either, it's pretty much what we had on sailbords, decades ago.

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Insiders are saying the JC75 will have a battery-electric system for the foils, with ‘some cool shit coming down the pike on that front’ - I wonder if that power system will extend to some of the rig controls?

From the ETNZ link,

“In addition to conventional mainsail trimming controls, this concept allows for twist and camber control at the head of the mainsail through a control arm on top of the rig which will be very interesting for us sailors especially transitioning back from the AC50 hard wing sails.” said Glenn Ashby.

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6 minutes ago, Tornado-Cat said:

Interesting that they chose a multi for the test, the easy way to go...:)

And they made sure it is less than 40 ft :D

Yep, they may have made the recent Rules Change to prevent others from doing the same thing with multi’s - but on a bigger scale. Multi’s are a good platform for it without risking your life :D

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L. Francis Herreshoff patented a double luff, rotating mast rig in 1927 (US Patent 1, 613, 890, attached.) The fitting he used to enable a rigid jib stay to work with a rotating mast is worth study.

I would be very interested in Basiliscus' opinion on the aerodynamic advantages and disadvantages of each.

Cheers,

Earl

PS. I apologize for the low res PDF due to SA's attachment limit; PM me if you want a high res version.

US1613890Low.pdf

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2 minutes ago, Earl Boebert said:

L. Francis Herreshoff patented a double luff, rotating mast rig in 1927 (US Patent 1, 613, 890, attached.) The fitting he used to enable a rigid jib stay to work with a rotating mast is worth study.

I would be very interested in Basiliscus' opinion on the aerodynamic advantages and disadvantages of each.

Cheers,

Earl

 

US1613890Low.pdf

Impressive find - cool

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Another significant problem with double skin sails is getting the camber of the windward skin different to the leeward skin. Basically to simulate a true aerofoil the windward sail needs to be much flatter than the leeward sail. We can not vary the batten stiffness as we need to tack and reverse the responsibility.

Usually the windward side simply sags against the leeward side, except near the luff, effectively matching what can be achieved with a pocket luff.

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Frog, placed in water early last year with D mast, twin tracks, central down angled boom (and proposed double luff soft sail) - except I've been occupied with other nutty projects so I haven't finished or sailed the Frog. Just think of the "invaluable" information I could have passed to ETNZ? That's a joke, you blokes. My thoughts for the twin leech batten ends was to have a sliding peg in slots - so the two sails would set correctly for windward or leeward sail shapes. Better get my act together now that ETNZ have leapt ahead?.

frog7copy.jpg

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3 hours ago, Tornado-Cat said:

Interesting that they chose a multi for the test, the easy way to go...:)

And they made sure it is less than 40 ft :D

Maybe they are scared of tipping?...lol

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1 minute ago, oobilly said:

Maybe they are scared of tipping?...lol

You mean, to windward, imagine the future heavy ballasted windward foils in a lull, or even better, when luffed by a faster boat. The first falling to ww is out :)

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3 hours ago, Phil S said:

Another significant problem with double skin sails is getting the camber of the windward skin different to the leeward skin. Basically to simulate a true aerofoil the windward sail needs to be much flatter than the leeward sail. We can not vary the batten stiffness as we need to tack and reverse the responsibility.

Indeed. And obviously the clew of the windward skin goes aft of the leeward one - which means you need a boom with separate tracks, not the common sheeting arrangement shown

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4 hours ago, Stingray~ said:

One of them

m2476_crop169014_1024x576_proportional_1

Oh jebus wait till DrugLord sees this :unsure:

He's gonna splurge PeoplesFoiler model pics for days :rolleyes:

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4 hours ago, Earl Boebert said:

L. Francis Herreshoff patented a double luff, rotating mast rig in 1927 (US Patent 1, 613, 890, attached.) The fitting he used to enable a rigid jib stay to work with a rotating mast is worth study.

I would be very interested in Basiliscus' opinion on the aerodynamic advantages and disadvantages of each....

US1613890Low.pdf

I like Herreshoff's configuration.  This figure shows the principal aerodynamic features of a wingmast/sail section:
image002.gif

What you'd like is for the sail be just outside of the separation bubble on the windward side, because then you don't get the separation, recirculation, and losses associated with the separation bubble.  That's exactly what the Herreshoff patent was designed to do.  Mark Pivac used a sail very much like Herreshoff's on his Spitfire hydrofoil catamaran.
sail1.jpg

The ETNZ double surface sail also avoids the separation bubble, but it also adds thickness to the section further back where you don't want it.  It would be possible to tension the leeward sheet on the ETNZ more than the windward sheet and let the windward sail be supported by the leeward sail.  Of course, that also means both surfaces have to be strong enough to carry the leech tension, so the weight would be a lot more than for a single sail.

Putting a control arm at the head is helpful, but what about mid leech sag?  It is still going to take a lot of leech tension to control that twist. 

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ETNZ's dual blade main could be a boon for sailmakers. Two mains now required at twice the price. :P

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Maybe that fat head gantry set up will provide some useful reverse twist?  :P

Screen Shot 2018-02-25 at 3.12.05 PM.png

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19 minutes ago, Sailbydate said:

Maybe that fat head gantry set up will provide some useful reverse twist?  :P

Uh huh, and it'll make reefing good fun... What is the point of this again?

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Goofy boat design and now they expect to get it up to takeoff speed with this re-baked idea for the sail? Is it April yet?

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6 hours ago, Phil S said:

Another significant problem with double skin sails is getting the camber of the windward skin different to the leeward skin. Basically to simulate a true aerofoil the windward sail needs to be much flatter than the leeward sail. We can not vary the batten stiffness as we need to tack and reverse the responsibility.

Usually the windward side simply sags against the leeward side, except near the luff, effectively matching what can be achieved with a pocket luff.

We made a series of double surface windsurf sails in the 90s (back when we had big budgets and perhaps too much free time). In the end, a properly tuned wide-sleeve cambered sail was far superior - based on observation, a large part of that was the much greater skin tension on the leeward side of the single surface sail, plus the huge weight advantage.

The one really clever (to my mind) concept we came up with was rigid ‘tacking’ hinged links that connected some of the battens on the windward surface to those on the leeward surface at the point of maximum camber  - for the sail to assume its 3D shape, the windward leech moves aft of the leeward leech, and we decided to control that internally rather than use 2 separate outhauls that would need to be adjusted every time you tacked/jibed. Our system meant the sail jibed with an audible ‘clunk’ and went right to it’s designed camber - functionally, it was a sort of midspan camber inducer.

The one innovative thing I see is the gantry at the top and the possibility of inducing reversed camber at the head, but I’m sure a serious look under the hood would reveal more.

I have a hard time seeing how the performance advantages would be worth the additional complexity and weight, especially at the speeds we are talking about where skin tension is SO important, but shoots - I’ve been wrong before.

 

 

 

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I sort of hosted our local pros and semi (I AM A PRO) pros on one of the wonderful events known as the HIHO. I entered the event myself and hired a buddy to run my boat while I beat myself into a pulp trying to keep up with those guys on the course. We got a visit from the founder of F2, the innovative German sailboard manufacturer to spy on what sail my crew had tied into the nets of my trimaran. By the end of the regatta I bought for a good price a F2 carbon race board with a double luff camber induced sail that was a wonder. 

All this stuff you see here proposed for the AC boat is about 30,40,50 years late. I loved that sail (and board) but if it layed in the water for more that a couple minutes you couldn't uphaul it as the luff pocket would fill up. This sail experiment with the double sails on the D-sect spar seems to be more of a distraction taking away the feasibility of the 'monohull' lizard that really needs to be shown as achievable NOW!

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^ The HIHO was awesome - what a great era. We played with a long chord D section mast concept that I think would be far superior for this application, but who knows - maybe there is some sort of control innovation that we’re not seeing that will mitigate the issues with double surface sails at high speeds.

You know who is going to love this? North sails - those mains will cost more than twice as much as a normal 3Di raw for a 75’, and because it’s an entirely new class, there will be lots of design iteration. I’m thinking 20 million plus sail budgets.

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One thing on little boats, but weight overhead on any decent sized boat is high - two sails, two sets of battens although maybe could get clever with one.

There have been many attempts at these sort of rigs, and a lot of them worked IF you took weight out of the equation - and then of course practicalities in use.  I guess that's one aspect you don't have to care about in AC world though.

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13 hours ago, Basiliscus said:

I like Herreshoff's configuration.  This figure shows the principal aerodynamic features of a wingmast/sail section:
image002.gif

What you'd like is for the sail be just outside of the separation bubble on the windward side, because then you don't get the separation, recirculation, and losses associated with the separation bubble.  That's exactly what the Herreshoff patent was designed to do.  Mark Pivac used a sail very much like Herreshoff's on his Spitfire hydrofoil catamaran.
sail1.jpg

The ETNZ double surface sail also avoids the separation bubble, but it also adds thickness to the section further back where you don't want it.  It would be possible to tension the leeward sheet on the ETNZ more than the windward sheet and let the windward sail be supported by the leeward sail.  Of course, that also means both surfaces have to be strong enough to carry the leech tension, so the weight would be a lot more than for a single sail.

Putting a control arm at the head is helpful, but what about mid leech sag?  It is still going to take a lot of leech tension to control that twist. 

Thanks for the comments. Do you think the rigid jib stay is a significant advantage? 

BTW, after Herreshoff came up with this, the New York Yacht Club banned  "revolving masts, double luffed sails, and similar contrivances."  The ban is supposedly still in effect  --  I wonder if this affects the NYYC challenge (just kidding).

Cheers,

Earl

 

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15 hours ago, Basiliscus said:

.Putting a control arm at the head is helpful, but what about mid leech sag?  It is still going to take a lot of leech tension to control that twist. 

What about leveraging the structural rigidity of the D-section mast with a series of internal control arms (4 or 5)? The control arms could be diagonally braced against the longitudinal axis of the mast to control the vertical position as well as AoA. The double surface would hoist right over them, and they could connect to the battens.

This would provide much better leech control, while still having relatively little windage when the ‘sails’ (really just removable skins at this point) were down.

Weight would probably be an issue, tho.

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Wouldn't the hybrid hard / soft sail Randy Smythe is pushing solve a lot of the problems you are talking about and be cheaper.

Also if you over rotate the mast it shortens the distance between the mast and the main sheet position giving a near wing shape between the two, allowing a lot of shape control just on the mast rotation position. 

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A D section mast with double luff sails does not have to rotate as much (in fact only around 20 degrees or so side to side) compared to a conventional tear drop shaped wing mast with one sail, (which turns 70 sts or more off wind to gain correct mast/sail shape) - therefore on the D there is less movement of the double leeches and battens rubbing against each other. That is a plus and provides cleaner, less turbulence on windward side of the sail/rig. There is the weight problem of the two sails, however.

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2 hours ago, Groucho Marx said:

A D section mast with double luff sails does not have to rotate as much (in fact only around 20 degrees or so side to side) compared to a conventional tear drop shaped wing mast with one sail, (which turns 70 sts or more off wind to gain correct mast/sail shape) - therefore on the D there is less movement of the double leeches and battens rubbing against each other. That is a plus and provides cleaner, less turbulence on windward side of the sail/rig. There is the weight problem of the two sails, however.

I’d think you’d need a lot more than 40 degrees (+/- 20) even with the advantages of a D over a teardrop - especially if these boats need to bear way off in lighter winds to get onto the foils.

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Could be some very cool shit come out with asymmetric battens, 3D printing, managing the relative elastic modulus of the materials, maybe ram air inflation with internal soft battens to drive shapes etc.  

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^ The 3D printing of structural materials has amazing potential because you can create ‘impossible’ geometries.

Inflatable battens are another possibility without a huge weight penalty that would also mitigate some of the risk of capsizes going catastrophic. We've played around with this in windsurfing world. 

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You may be right, Surfsailor, about D mast rotation - I need to get my a into g and build the double luff main for Frog; reality is often very different to theories and BS talk with friends..

Incidentally here are a couple of double luff French mains from the early 1980s.

Gautier 11 copy.jpg

Gautier 111 copy.jpg

Gautier 111 main copy.jpg

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6D0310A7-56E9-4668-8494-260104D1F954.jpegt

 

Again, with thanks to F15 AUS: our Miss Lancia C-Cat, circa 1978. Twin battens at each level (about 10) were joined by two tie rods, with pulleys for criss-cross tensioning wires for each tack. Wires were led below to "mixing beams" that could be raised/lowered for camber or raked for twist - I suspect the OR AC72 may have had something similar. The whole thing worked readonably well going to weather, but of course overall it didn't have a prayer against the Patient Ladies' slotted wings. As pointed out above, the arrangement was wrong in that it introduced aft thickness in the section, and when we tried out a thinner spar in the subsequent Signor G forces on the tensioning wires became excessive

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At around 20:30

The inflatable wing sail – The future?

Wingsails may not be commonplace in the sailing scene but the last two America's Cups have demonstrated how much more efficient a wing sail can be. The trouble is handling them – few amateur sailors have a crane and a shore crew at hand to lift the rig in and out each day.

But a Swiss engineer has come up with an ingenious and innovative design that could provide an answer to the problems of handling a wing sail. And it's based on air.

 

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Regarding these hybrid wing-sails, I have a workpaper somewhere written by the designers after the Little Cup, and they mentionned that the "symetrisation" of the leading edge has created some issues on aerodynamic performance.

I ll try to scan this old paper and post it asap.

Regards

 

Erwan

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that D mast looks strong, no spreaders needed. maybe they will find some cool solutions for the full sized version.

 

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What’s the point of a fully foiling monohull?   Seriously?  Besides the AC protocol mandating it?   It doesn’t look as efficient as a multihull based on animations, it’s going to cost a shit load of money to design and build it and it looks like it will be an awkward pain in the ass to match race.  

I prefer monos in the AC but right now I am having a hard time accepting the JC75.  Hopefully it will make sense when I see real one foil and maneuver, but probably not.  

Not trolling just honestly don’t get it.

WetHog  :ph34r:

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5 hours ago, WetHog said:

What’s the point of a fully foiling monohull?   Seriously?  Besides the AC protocol mandating it?   It doesn’t look as efficient as a multihull based on animations, it’s going to cost a shit load of money to design and build it and it looks like it will be an awkward pain in the ass to match race.  

I prefer monos in the AC but right now I am having a hard time accepting the JC75.  Hopefully it will make sense when I see real one foil and maneuver, but probably not.  

Not trolling just honestly don’t get it.

WetHog  :ph34r:

I would think if/when you see in person a fully flying JC75 in all its glory it will be as awesome if not more than the AC72s, of which let's be honest the AC50s were always the poor cousin to.

We have ETNZ to thank for the AC72s (non foiling = lame) and as a consequence the AC50s, so let's see what they cook up with this time.

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On 2/8/2018 at 8:37 PM, surfsailor said:

^ Some more than others. Flight control was done by the driver on all of the boats except one - using hydraulic power to be sure, but still an essentially 'manual' operation like steering.

unlike the ac72s, where one was fully auto leveling...

Why the fuck do you keep beating this drum

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7 hours ago, WetHog said:

What’s the point of a fully foiling monohull?   Seriously?  Besides the AC protocol mandating it?   It doesn’t look as efficient as a multihull based on animations, it’s going to cost a shit load of money to design and build it and it looks like it will be an awkward pain in the ass to match race.  

I prefer monos in the AC but right now I am having a hard time accepting the JC75.  Hopefully it will make sense when I see real one foil and maneuver, but probably not.  

Not trolling just honestly don’t get it.

WetHog  :ph34r:

I'm sceptical too hoggie, but you never know - we could be 100% totally fucking wrong.

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41 minutes ago, barfy said:

unlike the ac72s, where one was fully auto leveling...

Why the fuck do you keep beating this drum

You certainly trigger easily. Making up things about ac34 doesn’t make you seem any brighter - no AC72 was ‘auto leveling’ ever - they simply did not have either the hydro or the tech. You - not me - have been beating the same tired, broken drum since 2013. It’s 2018 now - time to move on.

:)

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44 minutes ago, surfsailor said:

You certainly trigger easily. Making up things about ac34 doesn’t make you seem any brighter - no AC72 was ‘auto leveling’ ever - they simply did not have either the hydro or the tech. You - not me - have been beating the same tired, broken drum since 2013. It’s 2018 now - time to move on.

:)

Actually you got triggered here mate... stop taking the bait... you're like a fucking Ethiopian goldfish  ;-)

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36 minutes ago, Stingray~ said:

Anything interested being said? Italian

 

"My junk looks huge in a silver catwoman suit"?

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