Kiwing

The new sailing twin skin setup

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7 minutes ago, Boybland said:

Well as legal as the hula at least... :D

And bow sprits...

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I think this is what we are talking about, where the lee side skin is more curved and the windward skin is more flat?1478022251_Fixedleaches.thumb.jpg.39c7b0b8cfc5c2fbef1aa435aee19b93.jpg

Maybe the leaches could be perpendicular to the boom?

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@Lickindip said on ETNZ thread386315537_rotatungleaches.thumb.jpg.94633e1b489911ea7150207283b171b8.jpg

You would have to have the same diameter leach "drum" as the mast to have equal skin distance between skin attachments.
If is "drum" is smaller the lee skin will be in a shorter distance between attachments and have more shape?

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24 minutes ago, Kiwing said:

@Lickindip said on ETNZ thread386315537_rotatungleaches.thumb.jpg.94633e1b489911ea7150207283b171b8.jpg

You would have to have the same diameter leach "drum" as the mast to have equal skin distance between skin attachments.
If is "drum" is smaller the lee skin will be in a shorter distance between attachments and have more shape?

no exactly, the aft 'drum' can be smaller but will have to go through more of an angle rotation to keep the skins the same

below ive got a 400mm wide mast ? (is this correct) rotated 20degrees each way which becomes a 137mm movement

the same movement can be made by a 200mm drum rotating 86 degrees

image.png.ac2d198350aaa66941f201d9f0b186ba.png

i suspect that the attachment points are slightly inside the mainsail and a smaller drum on/ drum off system rotating multiple times could achieve the desired finite control

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26 minutes ago, Lickindip said:

 

image.png.00bb96f8a46b4dcec95c0ca006f7c6e4.png

Thank you @Lickindip I understand your drawing. Interesting thoughts, I wonder what @Groucho Marx makes of it?Could it be advantageous to have more shape in the lee skin?
And could they control the relative shapes by the leach drum rotation?

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7 hours ago, Lickindip said:

image.png.00bb96f8a46b4dcec95c0ca006f7c6e4.png

If I was going to that much trouble, I'd use separate furlers so tension on each side of the sail is independent. Is this sufficient to control the offset all the way up the sail? Usually outhaul only affects the bottom 1/3rd of the sail, or am I really out of touch with the behaviour and properties of the materials in use?

I also can't see how this would auto–tack, it would need to be adjusted each time.  Maybe there's a setting for offset and they just press a button to reverse it when tacking/gybing.

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17 minutes ago, RobG said:

I also can't see how this would auto–tack, it would need to be adjusted each time.  Maybe there's a setting for offset and they just press a button to reverse it when tacking/gybing.

I think they just pull the windward side of the sail as it seems here, and the circular object rotates. I do think they have the same system on the top.

 

Capture.PNG

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They have a metre of height above the bottom of the skins, between the skins, in which to hide some clever stuff.  Of course the more simple the fewer problems?

They also have to quickly change the shape of the sails as they accelerate, to quickly change from power to minimum drag?  so simply rotating this drum will quickly change the relative shapes of the skins?

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2 hours ago, Tornado-Cat said:

I think they just pull the windward side of the sail as it seems here, and the circular object rotates. I do think they have the same system on the top.

Yes, that works for simple drum. A similar system at the top would need a boom–like structure at the head and should extend control to the whole leech. 4 m seems more than enough to fit it in.

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3 hours ago, RobG said:

also can't see how this would auto–tack, it would need to be adjusted each time.  Maybe there's a setting for offset and they just press a button to reverse it when tacking/gybing.

These guys have a track record of smart hydraulics. If you can imagine it, they've prolly evaluated it.

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11 hours ago, Tornado-Cat said:

 

 

Capture.PNG

Mentioned in another thread, but this is clearly the right place...

 

The attachments tell the story for me.

1/ a ram attached to the traveller with a purchase (hydraulic lines internal to the skins).The ram pushed down on or eases up on the black disk which is attached to the leech of each of the 2 skins above. The disk allows them to move relative to each other but doesn't control their fore and aft movement. That control either comes simply from rotating the mast - or some other hidden device. (The disk gives no impression of being powered 'rotationally' and also does not appear to have any direct attachments that would facilitate moving the skins fore and aft relative to each other as a 'furler' would need to)

2/ an outhaul purchase that attaches to the end of the two deck sweeper battens to control the tension in the foot (feet!?) of the sails

3/ between these two points of tension then is a 'crumple-zone', loser or tighter depending on the settings. It's not designed to look pretty - but to give maximum control/modes while gaining full benefit from deck end-plating.

 

Something like that anyway....need clearer photos.

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I.e

yysw283981.jpg

ETNZ_Sailfoot_detail_28112019.jpg?w=800

This also has the 'disk' at the bottom of the ram, again attached at the first set of battens above to control the leeches - not sure what else is going on though...

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14 hours ago, barfy said:

These guys have a track record of smart hydraulics. If you can imagine it, they've prolly evaluated it.

I have no doubt it can be automated, but I don't think that's legal on an AC75. They aren't allowed to have sensors for yacht state, so it would need a human to tell it to do something (which might just be throw a lever or push a port/starboard button). Even a simple drum mechanism still needs a human to tell it to tack for the same reason, it's just simpler. Tacking might be fully automated on a test boat for testing, but not for training.

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6 hours ago, nav said:

yysw283981.jpg

Quite a bit was said about the LR test boat (launched before their B1) having a forward driving position. Now we know that was just for the test boat. In retrospect it makes a lot of sense—automate everything and just have driver and flight controller for testing and training.

Seems ETNZ had the same idea. There are also a lot of similarities between the aft shapes of the two boats, so while the relationship between the two teams seems to be miles apart now, clearly there was quite a bit of common ground on design early on.

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24 minutes ago, RobG said:

I have no doubt it can be automated, but I don't think that's legal on an AC75. They aren't allowed to have sensors for yacht state, so it would need a human to tell it to do something (which might just be throw a lever or push a port/starboard button). Even a simple drum mechanism still needs a human to tell it to tack for the same reason, it's just simpler. Tacking might be fully automated on a test boat for testing, but not for training.

I don't see where sequenced inputs are banned tho? 

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they can do what they want with the test boats and with the race yachts outside racing. from memory etnz ac50 B1 was fully controllable from the chase boat and the hydro was powered by batteries while the fake grinders did nothing. they just need to get the illegal gear off the boats for measuring and racing

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4 hours ago, barfy said:

I don't see where sequenced inputs are banned tho? 

As I understand it, §24 Electronic control circuits (ECCs) bans input from anything that can measure yacht state other than the specific sensors mentioned (mostly related to foils and flaps which is reasonable since they're hidden when operating underwater), which they'd need to do for an automated outhaul system to know the boat just tacked. Event sensors that estimate yacht state based on some component within an ECC are banned as inputs (§24.1 (d)), so linking outhaul tacking to say the position of the hydraulic ram that raises or lowers a foil arm, or discharge of the accumulator, is not allowed.

So there is probably an ECC that controls, say, a hydraulic valve and ram to cause the drum to rotate, but it can't be connected to a sensor that detects when the boat tacks, even simple contacts on the mast that activate different circuits if the boom is on port or starboard would likely be out (that's the simplest system I can think of, maybe there are simpler ones).

PS. there is clause 24.1 (a) that allows "passive input devices", but they're defined in §35.87 as requiring the crew to do something such as push a button, move a slider, etc. There's a caveat that yacht movements that cause a crew member to fall onto a passive device causing it to activate is not "measuring yacht state". Someone has a sense of humour.

But of course it's a free for all on the training boat so likely it has fully automated and manual modes. For training a flight controller and helm, you'd want them doing everything manually that they need to do on the real thing, so if one of them is controlling outhaul tacking, they'd want to do that in the training boat. The automated system might be used to find the best settings, sequences, etc. then they're imprinted into human brains through manual training.

(The usual caveat applies: I am not a rules expert!!)

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4 hours ago, Lickindip said:

they can do what they want with the test boats and with the race yachts outside racing. 

They'd have to be careful not to create a surrogate, for which the definition is very open.

Surrogate Yacht means any yacht exceeding 12m LOA which is capable of producing meaningful design or performance information for use either directly or indirectly in the design, construction or sailing of an AC75 yacht and as further provided in the AC75 Class Rule…

So a modified AC75 might be a surrogate if it's not an AC75, which the protocol defines as:

AC75 Class Yacht means a yacht that complies with or could comply with the AC75 Class Rule;

The "or could" part is very loose, so maybe they can do pretty much anything with B1. But there is also "…whether a yacht is a Surrogate Yacht or not shall be the sole responsibility of the Rules Committee whose decision shall be final."

Glad that's cleared up.

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6 hours ago, RobG said:

As I understand it, §24 Electronic control circuits (ECCs) bans input from anything that can measure yacht state other than the specific sensors mentioned (mostly related to foils and flaps which is reasonable since they're hidden when operating underwater), which they'd need to do for an automated outhaul system to know the boat just tacked. Event sensors that estimate yacht state based on some component within an ECC are banned as inputs (§24.1 (d)), so linking outhaul tacking to say the position of the hydraulic ram that raises or lowers a foil arm, or discharge of the accumulator, is not allowed.

So there is probably an ECC that controls, say, a hydraulic valve and ram to cause the drum to rotate, but it can't be connected to a sensor that detects when the boat tacks, even simple contacts on the mast that activate different circuits if the boom is on port or starboard would likely be out (that's the simplest system I can think of, maybe there are simpler ones).

PS. there is clause 24.1 (a) that allows "passive input devices", but they're defined in §35.87 as requiring the crew to do something such as push a button, move a slider, etc. There's a caveat that yacht movements that cause a crew member to fall onto a passive device causing it to activate is not "measuring yacht state". Someone has a sense of humour.

But of course it's a free for all on the training boat so likely it has fully automated and manual modes. For training a flight controller and helm, you'd want them doing everything manually that they need to do on the real thing, so if one of them is controlling outhaul tacking, they'd want to do that in the training boat. The automated system might be used to find the best settings, sequences, etc. then they're imprinted into human brains through manual training.

(The usual caveat applies: I am not a rules expert!!)

But as in ac35, a button push could sequence say 3 events: like bring traveller to center, change outhaul or leech tension from one skin to the other, then pull the traveller to it's far stop. No sensor needed, all controls just hit a stop and finish. Completely hypothetical example of course, but I think control can stop a ram when it hits the end of travel. 

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On 3/31/2020 at 2:59 PM, Tornado-Cat said:

I think they just pull the windward side of the sail as it seems here, and the circular object rotates. I do think they have the same system on the top.

 

Capture.PNG

If the disc is free to rotate perhaps the sail shape is controlled by mast rotation only

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3 hours ago, barfy said:

But as in ac35, a button push could sequence say 3 events: like bring traveller to center, change outhaul or leech tension from one skin to the other, then pull the traveller to it's far stop. No sensor needed, all controls just hit a stop and finish. Completely hypothetical example of course, but I think control can stop a ram when it hits the end of travel. 

That seems like a grey area to me. Something like "bring traveller to center, change outhaul… then…" sounds like doing things when parts of the yacht are in certain positions, which is measuring or at least estimating yacht state.

An ECC can only use the state of parts within the ECC itself, e.g. when a ram has reached a certain position to stop moving it. Using the fact that you've stopped moving it to then do something else (e.g. turn a drum) is estimating yacht state based on some component within an ECC—"we're stopped the traveller half way, so must be half way through a tack, lets swap the skin tension…".

I think a legal timed sequence would be something like at 0 seconds start moving the traveller, at 0.75 seconds swap skin tension, at 3 seconds lift the foil. The actions are based on timed delays that are manually initiated and just run to completion without reference to whether or not some other action has started or finished, avoiding measurements or estimates of yacht state.

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16 hours ago, RobG said:

They'd have to be careful not to create a surrogate, for which the definition is very open.

Surrogate Yacht means any yacht exceeding 12m LOA which is capable of producing meaningful design or performance information for use either directly or indirectly in the design, construction or sailing of an AC75 yacht and as further provided in the AC75 Class Rule…

So a modified AC75 might be a surrogate if it's not an AC75, which the protocol defines as:

AC75 Class Yacht means a yacht that complies with or could comply with the AC75 Class Rule;

The "or could" part is very loose, so maybe they can do pretty much anything with B1. But there is also "…whether a yacht is a Surrogate Yacht or not shall be the sole responsibility of the Rules Committee whose decision shall be final."

Glad that's cleared up.

sorry I should have said, they can put whatever equipment/controls on B1 and B2 to test sail, if the equipment does not comply with the class rule it must be taken off for measuring /racing ... they cannot build an additional hull over 12m (lets call it B1.5) to test. I think the teams are not allowed to build a 'similar' style of boat where they could gain knowledge for the AC75 except for current racing classes like TP52 and sailgp

for example: the team will have more weather input devices on B1, they will have radio equipment to talk to chase boats, they may have additional electric pumps to make sure they have hydro while evaluating the systems ... all of that would be illegal under the class rule and will be removed for measuring/ official races

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8 hours ago, RobG said:

That seems like a grey area to me. Something like "bring traveller to center, change outhaul… then…" sounds like doing things when parts of the yacht are in certain positions, which is measuring or at least estimating yacht state.

An ECC can only use the state of parts within the ECC itself, e.g. when a ram has reached a certain position to stop moving it. Using the fact that you've stopped moving it to then do something else (e.g. turn a drum) is estimating yacht state based on some component within an ECC—"we're stopped the traveller half way, so must be half way through a tack, lets swap the skin tension…".

I think a legal timed sequence would be something like at 0 seconds start moving the traveller, at 0.75 seconds swap skin tension, at 3 seconds lift the foil. The actions are based on timed delays that are manually initiated and just run to completion without reference to whether or not some other action has started or finished, avoiding measurements or estimates of yacht state.

 

Yes, that's exactly what I was thinking. The timed sequence never knows when you are head to wind, but the overall timing is music that the helmsman and trimmer are dancing to. I believe from below any trimming move can be carried through to completion, or a preset position. There is also some words in the HCC section about manual stops that may be interesting, like a peg board for different modes?

Lovely grey areas.

 

24.1 (e) sensors measuring the internal geometric state of a drive clutch or HCC component, so long as those
sensors do not directly measure yacht state information, and are not used to estimate yacht state
information, for example:
(i) a sensor measuring the orientation of a cam in a hydraulic valve can be measured in order
to drive that cam to a desired position, as long as the orientation of the cam is not used to
estimate pressure or flow; and
(ii) current in a servo motor can be measured as part of a position control loop within the servo
motor circuit, as long as the current is not used to estimate any part of the yacht state, such
as control surface load; but
(iii) a sensor measuring the position of a plunger in a pressure relief valve cannot be measur. 

 

35.108 Yacht state
The specific condition of the yacht, comprising all of the following:
(a) the position and orientation of the yacht in space;
(b) the position and orientation of any control surface;
(c) the position and orientation of a foil;
(d) the position and orientation of any force input device or part thereof;
(e) the stress, strain, tension and force in any part of the yacht, except in passive input devices;
(f) other force-related quantities in any part of the yacht;
(g) the volume, velocity, flow rate or pressure of fluid within, or acting on, any part of the yacht;
(h) all absolute measures of the above and quantities measured relative to each other;
(i) the water or wave height or velocity relative to the yacht;
(j) all time derivatives of the above;
(k) all quantities derived from any of the above; and
(l) all quantities from which the above can be derived or approximated.

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On 3/31/2020 at 11:05 AM, nav said:

Mentioned in another thread, but this is clearly the right place...

 

The attachments tell the story for me.

1/ a ram attached to the traveller with a purchase (hydraulic lines internal to the skins).The ram pushed down on or eases up on the black disk which is attached to the leech of each of the 2 skins above. The disk allows them to move relative to each other but doesn't control their fore and aft movement. That control either comes simply from rotating the mast - or some other hidden device. (The disk gives no impression of being powered 'rotationally' and also does not appear to have any direct attachments that would facilitate moving the skins fore and aft relative to each other as a 'furler' would need to)

2/ an outhaul purchase that attaches to the end of the two deck sweeper battens to control the tension in the foot (feet!?) of the sails

3/ between these two points of tension then is a 'crumple-zone', loser or tighter depending on the settings. It's not designed to look pretty - but to give maximum control/modes while gaining full benefit from deck end-plating.

 

Something like that anyway....need clearer photos.

Agreed, we would need better photos and pretty much on your post

I my opinion the ram controls the leach tension while the separated skin are controlled by both the rotation of the mast and the line in the bottom. When the windward line is tensioned it pulls the winward sail and the mast rotates.

However I do not exclude a forced rotation of the black disk which has two lines (rods ?) going toward the top that would control the leach of each sail.

 

Capture.PNG

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2 hours ago, barfy said:

The timed sequence never knows when you are head to wind, but the overall timing is music that the helmsman and trimmer are dancing to. I believe from below any trimming move can be carried through to completion, or a preset position. There is also some words in the HCC section about manual stops that may be interesting, like a peg board for different modes?

Yes, I think that would be OK. There could be sequences for tack, gybe, upwind rounding, downwind rounding, etc. but it's a dangerous gamble if you've been using timed mode all week and suddenly you have to do it all manually, e.g. crash tack to avoid a collision or big gust near a boundary when trying to squeeze the last few metres out of a favourable shift. You also don't want to trigger the wrong sequence!

Maybe not such an issue in a match race where there's only one other boat, but a concern in fleet racing (though maybe there won't be any anyway).

3 hours ago, Lickindip said:

sorry I should have said, they can put whatever equipment/controls on B1 and B2 to test sail, if the equipment does not comply with the class rule it must be taken off for measuring /racing ... they cannot build an additional hull over 12m (lets call it B1.5) to test.

Yes, agree with that.

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  ^ I disagree with their statement that the top control mechanism stays up (and the skins fit into it as they are hoisted). I seem to remember the Rule says it has to come down

 

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9 hours ago, barfy said:

Some observations from the Italian Guy(s).

 

Who are these guys? Are they professionals or just random guys pulling shit out of their asses like the rest of us. Wish Barfy and SClarke had a show like this.

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2 minutes ago, pusslicker said:

Wish Barfy and SClarke had a show like this.

:D :D :D 

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9 minutes ago, pusslicker said:

Who are these guys? Are they professionals or just random guys pulling shit out of their asses like the rest of us. Wish Barfy and SClarke had a show like this.

Well, Vittorio is Quantum Italy - plus a passionate 12’ Dinghy owner. Don’t recall about the other guy

 

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11 minutes ago, Xlot said:

Well, Vittorio is Quantum Italy - plus a passionate 12’ Dinghy owner. Don’t recall about the other guy

 

Thanks!

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4 hours ago, pusslicker said:

Who are these guys? Are they professionals or just random guys pulling shit out of their asses like the rest of us. Wish Barfy and SClarke had a show like this.

Google is your friend...or let me guess...you're one of those who don't Google up shit you see on YouTube...

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2 hours ago, barfy said:

Google is your friend...or let me guess...you're one of those who don't Google up shit you see on YouTube...

I thought you ignored me? It would be a kiwi thing to just keep threatening to ignore  and then continuing the whine forever.

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