Kiwing

The new sailing twin skin setup

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Another scene grab from @Boink's find.

NYYC sail 2.jpg

Note.
1) the guy pushing the sail over
2) boom over second helm head - no deck sweeper!

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from https://www.sailingworld.com/intel-on-ac75s-twin-skin-main/

 

<<The one big challenge with this type of boat will be the ­takeoffs. In 7 knots of breeze, if you sheeted the sails on, the boat would capsize because there’s so little righting moment available at that speed. With so little righting moment, both sails are almost luffing and it feels wrong. You’re trying to accelerate, but you have to ease the sails so the boat doesn’t heel over.

The way the foil geometry works, as soon as you heel over, you lose a lot of righting moment very fast. So it’s about trying to accelerate with a flat boat, and this is where the big top-panel inversion and the deeper cambers to start the acceleration come in. >>

 

Hents independent control ov top ov main.

Also for roll tacking? Eg to lode new leeward foil ahed of need.

Like sno skeeing. Erly wate transfer.

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5 hours ago, snaerk said:

from https://www.sailingworld.com/intel-on-ac75s-twin-skin-main/

 

<<The one big challenge with this type of boat will be the ­takeoffs. In 7 knots of breeze, if you sheeted the sails on, the boat would capsize because there’s so little righting moment available at that speed. With so little righting moment, both sails are almost luffing and it feels wrong. You’re trying to accelerate, but you have to ease the sails so the boat doesn’t heel over.

The way the foil geometry works, as soon as you heel over, you lose a lot of righting moment very fast. So it’s about trying to accelerate with a flat boat, and this is where the big top-panel inversion and the deeper cambers to start the acceleration come in. >>

 

Hents independent control ov top ov main.

Also for roll tacking? Eg to lode new leeward foil ahed of need.

Like sno skeeing. Erly wate transfer.

Only TNZ knows if takeoff in 7 kts will be necessary, it could be in 6 kts, 12, 15. All other teams trying to work on it do it without knowing if it's a key point.

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14 minutes ago, Tornado-Cat said:

Only TNZ knows if takeoff in 7 kts will be necessary, it could be in 6 kts, 12, 15. All other teams trying to work on it do it without knowing if it's a key point.

The starting wind limit might be up for debate, that doesn't mean the wind during racing won't fall below that.

Safe to say the lower limit is extremely unlikely to be over 10 knots so you better be ready for lulls well be low that.

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7 hours ago, Boybland said:

The starting wind limit might be up for debate, that doesn't mean the wind during racing won't fall below that.

Safe to say the lower limit is extremely unlikely to be over 10 knots so you better be ready for lulls well be low that.

The only one that can know that is TNZ, the minimum could be 12, 14, 16 and we don't know what the max will be either, 20, 22, 26, 28 ?

You  have to prepare for the conditions that will happen most often in a race within the wind limits at the start.

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On 10/12/2019 at 8:46 AM, Tornado-Cat said:

The only one that can know that is TNZ, the minimum could be 12, 14, 16 and we don't know what the max will be either, 20, 22, 26, 28 ?

You  have to prepare for the conditions that will happen most often in a race within the wind limits at the start.

Nature will provide the wind limits.  Maybe there will be a time limit to complete races?

Anyway I think all teams will have an equal say if there is any type of limit it will be unanimous. 

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Realistically, cannot see a minimum windspeed being as high as 12 knots.

Nor can I see them going off in sub 5 knots.

I know that at these speeds it is as much about how you define or determine that measurement. I.e. height of measurement or mean over gust etc.

The change between 5-8 knots is truly transformative to any sailor who knows their stuff. 

I think this is the ball park that those who determine the limits will be looking, and possibly made following or in conjunction with the experiences of the sailing team.

They have earned the right to be Defenders after all...... 

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8 minutes ago, Boink said:

They have earned the right to be Defenders after all......

Runs and ducks

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Worth revisiting this to see if the parentage is there. Boomless

 

Edited by buckdouger
Boomless

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1 hour ago, Boink said:

Realistically, cannot see a minimum windspeed being as high as 12 knots.

Nor can I see them going off in sub 5 knots.

I know that at these speeds it is as much about how you define or determine that measurement. I.e. height of measurement or mean over gust etc.

The change between 5-8 knots is truly transformative to any sailor who knows their stuff. 

I think this is the ball park that those who determine the limits will be looking, and possibly made following or in conjunction with the experiences of the sailing team.

They have earned the right to be Defenders after all...... 

Lower windspeed will simply be a function of can they complete the races in my opinion.

But yeah extremely unlikely to be anywhere near as high as 12 knots given the boats can clearly lift out in less and all the talk has been that none foiling aspects to some races is not considered a negative.

The real interest is the upper wind limits, however relative performance is likely to be mostly theoretical by the time that decision is made given there will likely be very few testing days above 20 knots for most of the teams.

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6 hours ago, Kiwing said:

Nature will provide the wind limits.  Maybe there will be a time limit to complete races?

Anyway I think all teams will have an equal say if there is any type of limit it will be unanimous. 

A time limit to complete races is not nature, it's a way to impose a minimal wind limit.

Teams have no say whatsoever in the wind limits, the CoR/D have all the rights.

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1 hour ago, Tornado-Cat said:

Teams have no say whatsoever in the wind limits, the CoR/D have all the rights.

Firstly - COR is a Team

Secondly - Both COR and Defender have both launched hull shapes that would be considered more aligned than the the two Flat scow like hulls of the other teams.

QED

:lol:

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9 hours ago, Boink said:

1) Firstly - COR is a Team

2) Secondly - Both COR and Defender have both launched hull shapes that would be considered more aligned than the the two Flat scow like hulls of the other teams.

QED

:lol:

1) I wrote the 2 exceptions

2) So what ?

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Does ETNZ have two bendable booms one for each skin?

Looking at the gap between skins of the Mule there is a big gap at boom level at the widest part of the wing.

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8 hours ago, Kiwing said:

Does ETNZ have two bendable booms one for each skin?

Looking at the gap between skins of the Mule there is a big gap at boom level at the widest part of the wing.

Nope it looks like one single articulating boom with the articulating point pretty close to the luff

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On 10/13/2019 at 10:32 PM, Tornado-Cat said:

1) I wrote the 2 exceptions

2) So what ?

Thanks for this.... 

This confirms everything I needed to know (about you).

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12 hours ago, 17mika said:

Nope it looks like one single articulating boom with the articulating point pretty close to the luff

1548668029_Boom1.thumb.jpg.05b7a88537ec2e1d26a510e7a6e4b5b8.jpg

@17mika Looking something like this, skins thin lines boom thick line?

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2046130638_Boometnz2.jpg.741594b21116f747e248df665e67777e.jpg404560150_Boometnz3.jpg.a8751682c2363d7d9216711600739a7a.jpg

Looks fairly smooth curve on the inner skin.  But could be achieved as you say.

They are allowed a metre of "mechanism" at the bottom of the sail (must be pretty transparent?)

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617175376_Boometnz5.thumb.jpg.c5fc1da3226b09b4e07c614f25ad418b.jpg

two booms ^

463267054_Boometnz4.thumb.jpg.a538459164956f2f0376da76b8125542.jpg

Two flexible booms

It's is a push to think they are still using this setup but I think they are.

 

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22 hours ago, Kiwing said:

2046130638_Boometnz2.jpg.741594b21116f747e248df665e67777e.jpg404560150_Boometnz3.jpg.a8751682c2363d7d9216711600739a7a.jpg

Looks fairly smooth curve on the inner skin.  But could be achieved as you say.

They are allowed a metre of "mechanism" at the bottom of the sail (must be pretty transparent?)

Air boom

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3 hours ago, Varan said:

Air boom

I like the idea of air booms if they are vertically strong using some vertical titanium sheet and something stopping twist

OR Twin air booms?

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Frog has an angled down boom between the two mains but I get distortion near the clew areas. Originally the boom cross section was circular but in attempt to reduce the ugly clew/leech area I shaped down the boom to a thin I shape and laid in carbon ... but the sail shape in that area, although improved, is still annoyingly distorted. And I snapped the thin carbon but beefed up area so had to lay in yet more reinforcement. No boom sounds like a good solution? The AC blokes are way ahead of me.

double_main.jpg

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Hi, 

Regarding the type of "morphing boom"  ETNZ seems to have at the bottom of their mainsail, on each side, or for each skin.

I would suggest to Googlize the following Key Words (Biomimetics + fishbone gripper+ FESTO)

FESTO is a German company specialized in bringing to the industry, news ideas borrowed from Nature.

The "Fishbone Gripper is at least a 15 years old story, so not new, but for morphing boom.

Cheers

 

EK

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13 minutes ago, Erwankerauzen said:

Hi, 

Regarding the type of "morphing boom"  ETNZ seems to have at the bottom of their mainsail, on each side, or for each skin.

I would suggest to Googlize the following Key Words (Biomimetics + fishbone gripper+ FESTO)

FESTO is a German company specialized in bringing to the industry, news ideas borrowed from Nature.

The "Fishbone Gripper is at least a 15 years old story, so not new, but for morphing boom.

Cheers

 

EK

Interesting. Thanks for the post.

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Wow yes that gripper could be adapted to make a very controllable boom, but does it have the vertical strength?

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On 10/16/2019 at 4:48 AM, Kiwing said:

1548668029_Boom1.thumb.jpg.05b7a88537ec2e1d26a510e7a6e4b5b8.jpg

@17mika Looking something like this, skins thin lines boom thick line?

That was my understanding, from some old photos published here

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43 minutes ago, 17mika said:

That was my understanding, from some old photos published here

Can you comment on the photos above which is where I am coming from on the twin booms?

there are some interesting ideas how shape-able booms might be built to control the bottom and hence the greater part of the twin skin.  I believe this shape-able twin skin is the secret to it being more powerful at low speed and less drag at high speed.

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A nicely-zoomed above-deck boom photo posted recently by a poster here revealed what looks like a boom with 2 articulating joints (three angles), was it ETNZ? 

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Not that I have seen and I am always looking for details of the twin skin setup.

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A combination of tubular booms (square, round or deep section rectangular) morphing into Batten style booms which would give smooth sail shape towards the leeches is highly probable. This is old but highly transferable........ I have mentioned this group before here.

 

soft-wing2.jpg

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Thanks for the pic Boink,

AFAIR, there is a patent for this morphing wing, the name of the author is  Huges de Rosnay ?? not sure!

and there is a video somewhere where they tested this wing on a foiler and the comment from Mr de Rosnay was that windward the performances were better than expected.

Cannot remenber the name of the boat to find the related website sorry!

 

Cheers

 

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This video, that was on the ETNZ Thread, shows the boom pretty well.

from my understanding there is definitely some kind of a pivot at 1/4th from the mast, where there is the tapering, and maybe something at the back as well.

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1 hour ago, Boybland said:

Timestamp from above, there really is some serious hardware hanging off the back of that boom at about 1:24 in.

here

15303766_Boometnz6.thumb.jpg.7fd09644a8092685e394429dc42e78e7.jpg

Wow That will set the speculation on fire!  Thanks @Boybland

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Taking a wild guess: looks like they can pivot the two clews with that mechanism to gain differing windward/leeward mainsail fullness/flatness?

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Looking at the dolphin's performance so far I'd guess that we are not too short of the AC50 wing performances.

Is greater than 52 knots possible with this Beast?

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Hi Everybody,

For the Wingsail geeks, please find attached a workpaper, describing another application of the fishbone concept to a morphing airfoil.

For our topic, it is a bit more illustrative than a gripper.

Cheers

EK

Fish_Bone_Concept.pdf

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@Erwankerauzen That is really interesting we will never know if they are going to use something like this for the foil but,

What about he booms?  This is much more possible and well These clever guys might have something like this?

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19 minutes ago, Erwankerauzen said:

Hi Everybody,

a morphing airfoil.

Interesting,

Wondering if it could be modified to adjust both depth and location of draft.

Seems like it may be possible with more complex tendon arrangement 

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2001987786_Boom1Britiania.thumb.jpg.c3533f322be8041c1913c0267dd655e5.jpg

There looks to be little development of the lower part of the wing?

Maybe an 2 section internal boom?
 

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On 10/23/2019 at 1:59 AM, Kiwing said:

Looking at the dolphin's performance so far I'd guess that we are not too short of the AC50 wing performances.

Is greater than 52 knots possible with this Beast?

A lot of folks will be laughing their asses off if the AC75s hit 52+ before you-know-who's fleet does. Especially if they are faster in sustained speed, not blink and it's over speed.

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2 hours ago, Kiwing said:

2001987786_Boom1Britiania.thumb.jpg.c3533f322be8041c1913c0267dd655e5.jpg

There looks to be little development of the lower part of the wing?

Maybe an 2 section internal boom?
 

So a double surface sail with no boom and twin clews and different shape on each sail surface and that’s “little development”? 
 

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All the wrinkles, poor shape to the bottom most important part of the whole twin skin wing, is why I say little development?

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1 hour ago, Kiwing said:

All the wrinkles, poor shape to the bottom most important part of the whole twin skin wing, is why I say little development?

It does look a bit out of sorts compared to the latest pic of LR, I won'tcross post but no baggys evident on their main

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In the Italian thread @Boink said
"This is where you will never see or witness the internal manipulation that is going on inside the twin skins. We will be left speculating how a simple mainsheet can exert such varying degrees of control. Simple answer - the mainsheet isn't......

But - Batten technology, with electro, hyrdraulic or mechanical (string) manipulation, 3Di skins, D-section mast and independant mainsheets will be more than enough to give a good mainsail trimmer a headache........ Yes the zones of manipulation are only the bottom 1.0m and top 3.0m but that will do.

The shots from directly astern showing the foil shape they create and depth between skins is where they simultaneously create power at low drag. Keeping both sides fully energised without stalling either side will be the key ( and hence why we are seeing tell tales everywhere).

Remember the apparent is only moving 13 degrees( I believe I have read this number somewhere - but don't quote me) aft between upwind to downwind angles when on the foils..... So large rotation of the D mast or setting the mainsail uber deep and wide is not on the agenda. They will be seeking low drag shapes as much as max power shapes. So aero treatments to deck, foot and crew hideouts will matter. "

Lots to talk about;-
26 degrees side to side or 13 side to side?
Electro, hydro, and mechanical , 3Di independent main skins......
ETNZ up and foiling in 7 knots .......
This new twin skin system, lowerable will be great I am sure.

 

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6 hours ago, Kiwing said:

In the Italian thread @Boink said
"This is where you will never see or witness the internal manipulation that is going on inside the twin skins. We will be left speculating how a simple mainsheet can exert such varying degrees of control. Simple answer - the mainsheet isn't......

But - Batten technology, with electro, hyrdraulic or mechanical (string) manipulation, 3Di skins, D-section mast and independant mainsheets will be more than enough to give a good mainsail trimmer a headache........ Yes the zones of manipulation are only the bottom 1.0m and top 3.0m but that will do.

The shots from directly astern showing the foil shape they create and depth between skins is where they simultaneously create power at low drag. Keeping both sides fully energised without stalling either side will be the key ( and hence why we are seeing tell tales everywhere).

Remember the apparent is only moving 13 degrees( I believe I have read this number somewhere - but don't quote me) aft between upwind to downwind angles when on the foils..... So large rotation of the D mast or setting the mainsail uber deep and wide is not on the agenda. They will be seeking low drag shapes as much as max power shapes. So aero treatments to deck, foot and crew hideouts will matter. "

Lots to talk about;-
26 degrees side to side or 13 side to side?
Electro, hydro, and mechanical , 3Di independent main skins......
ETNZ up and foiling in 7 knots .......
This new twin skin system, lowerable will be great I am sure.

 

The 13 degrees is the difference in angle of apparent wind when going to windward compared to the apparent when running off the wind.  The logical conclusion being that trimmed hard to go to windward and eased to go off the wind will only require moving the main by a similarly small amount.

I must say I'm pretty impressed with the light wind performance, we haven't got any angles, but with the code zero up they just looks amazing foiling in very light conditions!

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On 10/23/2019 at 3:59 PM, Kiwing said:

Looking at the dolphin's performance so far I'd guess that we are not too short of the AC50 wing performances.

Is greater than 52 knots possible with this Beast?

I think top speed is more about the foils than the sails, the limit seems to be cavitation.

An AC75 main is a lot smaller than that of an AC72 (145 m2 vs 260 m2). If speed was about power from the sail, the rule could have allowed a bigger sail.

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4 hours ago, RobG said:

I think top speed is more about the foils than the sails, the limit seems to be cavitation.

An AC75 main is a lot smaller than that of an AC72 (145 m2 vs 260 m2). If speed was about power from the sail, the rule could have allowed a bigger sail.

I think cavitation for top end, and parasitic drag up to there are limiting factors. Perhaps the deep camber the mains are developing are crucial to early lift off and this will be their edge over the wing sail.

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7 hours ago, RobG said:

I think top speed is more about the foils than the sails, the limit seems to be cavitation.

An AC75 main is a lot smaller than that of an AC72 (145 m2 vs 260 m2). If speed was about power from the sail, the rule could have allowed a bigger sail.

Less area less drag QED !

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1 hour ago, Kiwing said:

Less area less drag QED !

The code 0 ö generate a lot of drag.

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1 minute ago, arneelof said:

The code 0 ö generate a lot of drag.

That is why they will roll (and drop?) it after getting foiling and being sure they can stay on foils.

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1 hour ago, arneelof said:

The code 0 ö generate a lot of drag.

52 knots would be when the wind speed is approaching 20 knots, code zero is only for less than 10 knots.

Most likely the code zero is not even going to be on the boat on a day they are likely to crack 52 knots.  Just the smallest available possible headsail.

 

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On 10/29/2019 at 7:08 AM, Kiwing said:

That is why they will roll (and drop?) it after getting foiling and being sure they can stay on foils.

Yes, they can drop the CZ, but it must be stowed above deck (rule 19.16). So it won't be aboard unless they really need it.

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6 hours ago, RobG said:

Yes, they can drop the CZ, but it must be stowed above deck (rule 19.16). So it won't be aboard unless they really need it.

We might see some cool storage solutions on b2's if b1 proves the validity of the cz.

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@Tornado-Cat Do you think a twin skin main sail will be used on one or any of these amazingly fast ocean going multis?

Is any of them trying a wing like AC35?

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14 minutes ago, Kiwing said:

@Tornado-Cat Do you think a twin skin main sail will be used on one or any of these amazingly fast ocean going multis?

Is any of them trying a wing like AC35?

For the twin there are still some questions:

First, I don't know what is the value added of the twin skin main, we should know within the next month.

Second, I don't know how much more cost and difficulty vs a regular main

Third, I don't know how much more weight it will add

If we have a positive answer for the 3 questions, yes it will be applied on the ocean racers and some fast dinghies

 

No, there is wing on ocean racers now, the difficulty of reefing present wing is IMO, the main reason. Some technical solutions exist though.

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@Tornado-Cat Thank you for your ideas.  I am not sure we will know any time soon the answers to your (and mine) questions.

Trying to hide mechanisms during hoisting and a bit of sand bagging will hide a lot.  I wonder if we will see one reefed in the next year?

I don't see cost as a problem as much as weight.  I see reduction of drag in the low to mid wind ranges as the main advantage with a conventional main for the very high wind.

I also see an improvement in boom design towards a curved boom, giving more control of the foot of the sail?

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Just now, Kiwing said:

@Tornado-Cat Thank you for your ideas.  I am not sure we will know any time soon the answers to your (and mine) questions.

Trying to hide mechanisms during hoisting and a bit of sand bagging will hide a lot.  I wonder if we will see one reefed in the next year?

I don't see cost as a problem as much as weight.  I see reduction of drag in the low to mid wind ranges as the main advantage with a conventional main for the very high wind.

I also see an improvement in boom design towards a curved boom, giving more control of the foot of the sail?

Thanks Kiwing. Teams have seemingly very different approach, one will be better, it will be good to know, we are all in a learning curve !

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On 11/8/2019 at 5:58 AM, Kiwing said:

 I wonder if we will see one reefed in the next year?

I don't see cost as a problem as much as weight.  I see reduction of drag in the low to mid wind ranges as the main advantage with a conventional main for the very high wind.

I also see an improvement in boom design towards a curved boom, giving more control of the foot of the sail?

The AC rule permits enough sails so that you will not see a set reefed - just a smaller set of sails flown. The smaller set will also have battens tailored to the stiffness and curvature sought, rather than a full size set that would have different characteristics.

Too much drag from both reefed material and the now exposed and unfaired D section mast with flat back wall will kill that approach. 

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Regarding the reduction in drag, Imho, it will be a true all along the apparent wind range but in different proportions. To make it simple

As the (section + friction drag) is proportional to AWS^2 

and the induced drag is prop to (1/AWS^2)

it means in low wind the induced drag is dominant while in high wind it is the section+friction drag.

The twin skins sail is likely to decrease the friction & section drag, because the induced drag would not change between a single or double skins sail.

Of course I can be wrong so do not hesitate to throw a few stones it will make this interesting thread even more interesting

Fair Winds

EK 

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1 hour ago, Erwankerauzen said:

Regarding the reduction in drag, Imho, it will be a true all along the apparent wind range but in different proportions. To make it simple

As the (section + friction drag) is proportional to AWS^2 

and the induced drag is prop to (1/AWS^2)

it means in low wind the induced drag is dominant while in high wind it is the section+friction drag.

The twin skins sail is likely to decrease the friction & section drag, because the induced drag would not change between a single or double skins sail.

Of course I can be wrong so do not hesitate to throw a few stones it will make this interesting thread even more interesting

Fair Winds

EK 

Thanks for making it simple!  Does this mean:-

Induced drag decreases as AWS increases - seems counter intutitive? 

when AWS = 1,   Drag = constant plus 1/1^2 => drag = constant plus 1
when AWS = 10 Drag = constant plus 1/10^2 => drag = constant plus 1/100  less than when AWS = 1?

Or are you saying the difference between the two sail types the induced drag gets smaller?
And are you saying the difference between the two sail types The (s +f) drag increases as the square of the AWS?

@Erwankerauzen So at relatively high AWS (as in the AC) there is a relatively high difference?

In the Ocean races the AWS must be quite high too but can the make the twin skin strong enough?
If they could reef the skins inside the wing This should apply too?

 

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3 hours ago, Kiwing said:

...

Induced drag decreases as AWS increases - seems counter intutitive? 

..

That is indeed true when the lift is held constant.  At higher speed, more air is flowing past the rig, and to create the same lift one needs to deflect it less.  It is always more efficient to move a lot of air a little than to move a little air a lot.  The lift is approximately constant because it is dictated by the righting moment available from the hull.

Induced drag is also inversely proportional to span squared.  It is another reason why tall rigs are more efficient in light winds, besides being able to generate the righting moment to get the windward hull out of the water or being able to extend up to higher true winds.

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Thank you Mr Speer  I neglected to present the constant righting moment and constant lift, otherwise, it would not be understandable.

Not exactly the twin skins sail  topic but not that far

In the foiling tack video of INEOS team UK (SA Front Page)one can see a hudge gap between the deck and the footsail of the jib.

Initially I thought this special rounded deck shape ahead of the mast, was designed so to minimize flow separation before the "flow" arrives at the slot between jib and mast/mainsail.

I don't know if there is a trade-off here, or if this deck design is driven by other considerations?

Not sure it deserves a special thread that is why I post it here.

Fair wind

EK 

 

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Kiwing,

The formulaS I use come from a 30 years old, R/C Gliders Magazine for teenagers.

I am sure you can get that on Wikipedia, look for Lift coefficient, Drag coefficient, Moment Coef, Induced drag coef, Aspect ratio, Effective Lift coefficient is very important too, and a more subtil parameter:  the Oswald Coefficient, you can find it in a workpaper especially written to adress the gap between the mainsail and the deck and only available on tspeer.com (Probably in "Optimun PlanForms" workpaper)

You should also have a look on all the other workpapers available on this website You will not waist your time.

Soon you will be happy to be able to have your own independent judgment regarding these matters.

Cheers

EK

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Good chance I have missed it up thread, but can't be arsed to read all 7 pages.

But does it strike anyone else that with the deck sweeping mainsails these guys are going to be absolutely blind to what is going on behind the sails unless they have very good communication between sides and retain someone to leeward at all times? I see the chance of running into a competitor or spectator as extremely high. And I wouldn't like to see the consequences.

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First;        most boats will have crew both sides.
Second;  there will be a 5g boat location referee who will be monitoring any danger and deciding right of way etc.  He will probably have sophisticated prediction software to help his deliberations.

I can not see any probability of near collisions the results are too bad to contemplate.

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2 hours ago, Kiwing said:

First;        most boats will have crew both sides.
Second;  there will be a 5g boat location referee who will be monitoring any danger and deciding right of way etc.  He will probably have sophisticated prediction software to help his deliberations.

I can not see any probability of near collisions the results are too bad to contemplate.

I take it you didnt watch the RWC on spark?

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1 hour ago, kenergy said:

I take it you didnt watch the RWC on spark?

Well said and I take your point.

let's hope Grant can have a long cat-a-nine-tails.

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4 hours ago, Kiwing said:

First;        most boats will have crew both sides.
Second;  there will be a 5g boat location referee who will be monitoring any danger and deciding right of way etc.  He will probably have sophisticated prediction software to help his deliberations.

I can not see any probability of near collisions the results are too bad to contemplate.

Imagine that at 40 kts with razor sharp foils.

 

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54 minutes ago, Tornado-Cat said:

Imagine that at 40 kts with razor sharp foils.

 

Imagine the carnage Sir Ben could achieved amongst the 18's fleet.

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1 hour ago, Sailbydate said:

Imagine the carnage Sir Ben could achieved amongst the 18's fleet.

Sir Russ didn't do so bad himself!

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