Kiwing

The new sailing twin skin setup

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23 minutes ago, RobG said:

Here's a map of the airspace in the area from AirShare (I think the blue circles are aerodromes/heliports). You can sign up for free if you have an NZ phone number and check out restrictions for wherever you want to fly a drone in NZ.

Seems to me most of the race areas are open slather. The chance of anyone being booked for being closer than 150 m horizontally from a marine mammal would be pretty remote I expect, especially if there are no whales. Dolphins might be an issue, but only if someone in authority wanted to be a prick.

65890229_Aucklandairspace.thumb.png.2dc0696b1039b478e602b6e348d675f0.png

here are the race courses:

image.thumb.png.6b617de58c9e436cf40c2180acd7b99d.png

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That big purple area over the Bays looks like RNZAF Whenuapai circuit? They might not be so keen on drone traffic.

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Encouraging at first glance ........ except that Standard Operating Procedure for Cup regattas has been special Notices to Mariners and published civil aviation notices prohibiting public activities on and above race courses. It was SOP through the 12-Metre era,  And probably before that but I don't have direct knowledge stretching back that far

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4 minutes ago, KiwiJoker said:

Encouraging at first glance ........ except that Standard Operating Procedure for Cup regattas has been special Notices to Mariners and published civil aviation notices prohibiting public activities on and above race courses. It was SOP through the 12-Metre era,  And probably before that but I don't have direct knowledge stretching back that far

Not racing yet. :-)

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7 hours ago, phill_nz said:

and the heliport at northshore hospital would kill most of the rest

 

surprisingly the regs covering the proximity to controlled airspace are not the stupid ones

you can fly shielded operations within that zone 

some countries also have a gradient from a certain range ( ht v distance from port )

 

the sub 400 meter airspace is becoming a shit fight between model flyers and multi national corps who want it for uav deliveries and can afford to buy the regs ( politicians / snivel servants ) that suit them .....  they want to remove the model air enthusiasts .. hence you get so many hate drone stories on the media .. when in reality they are still one of the safest hobbyists around and thats by no means just an nz thing

 

 

No other country as far as I know has shielded operations,a boon to me and my mates who fly low and fast, with only the occasional victory loop. 

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Courses c is out. And problem is to access b from north head is impossible. And you can't fly from doc land ie rangi or browns so d is problematic

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2 hours ago, barfy said:

a boon to me and my mates who fly low and fast, with only the occasional victory loop. 

im a learner

 i have drone ( cfly faith ) and a few fixed wings i have to to learn to fly

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Good view of gap and concave windward shape, courtesy of @airflownz's latest excellent video

gap-1.jpg

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On 9/11/2020 at 3:40 PM, The_Alchemist said:

might be an issue, but only if someone in authority wanted to be a prick.

 there's a planet that has alternatives ?

 

i keep forgetting to send them notice they need to put out a notam

im flying one of my kites today

1,000 mtr string on a large delta form

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10 hours ago, weta27 said:

Good view of gap and concave windward shape, courtesy of @airflownz's latest excellent video

gap-1.jpg

It almost looks like they are trying to simulate the shape of the two parts in a wing.

510336860_F50wing.jpg.f1943a20f4c65ca822d611bb29cd9128.jpg

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I guess the mechanism inside is the part that will be hard to copy?  A boom which curves in one dimension and is straight in the other?  But the top of the rig is another guessing game.

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On 9/9/2020 at 4:42 AM, Kiwing said:

Sail shape from Mule.1620288912_Mulesailshape.thumb.jpg.7c21202f57313e7086b9bcdc81311999.jpg

The only factual picture of early sail shape.  Sorry it is not very good and certainly has no "S" in it!?

@KiwingDo not use or confuse a still photograph from a long time ago as being representative of what we are seeing now. I posted that to quickly illustrate how the twin skins have assymmetry across the two invidual surface to create a wing shape. It clarified for many what was not being explained well in writing. As to how Two shots - neither of which show the windward skin in the area that any "S" Bend might occur, is in anyway helpful, to establish your clearly one-eyed opinion is however, useful.

Your attempt to "Yellow Line" is also very misleading. The actual Draft Stripe is there to show what sort of camber/profile the leeward skin is creating.

I have put a Red Line over this in the photo below to show a more representative profile.

417184533_RedVsYellow.png.740a3290cb7cbdb43aec77ccedfc0bde.png

A very different take from your effort......

Worth noting that the shape of the profile is not what is carried through the body of the sail. 

Which raises the age old topic of using just one still photograph to prove or disapprove the evidence of something as well as the much lampooned use of yellow lines........

So @weta27 posts his usual good work, and you respond:

On 9/13/2020 at 2:01 PM, weta27 said:

Good view of gap and concave windward shape, courtesy of @airflownz's latest excellent video

gap-1.jpg

On 9/13/2020 at 2:04 PM, Kiwing said:

No evidence of "S" there!

So you are seeing a frozen moment in time and trying to beat the lack of "S" as being an open and closed case. Because, as I have written before, mainsail shapes are just set and forget, to one predefined shape - regardless of wind conditions, chop, or even direction being sailed in........ Or at least they maybe in your world.

What you conveniently forget is that It was myself who highlighted the picture that clearly showed the S-bending of the windward skin in the first place - but  - it was also myself who cast doubt over over its long term use or usefulness.

But re-read my comments over implications on Drag, AOA and how this will change how the leech tips present as to why I floated the idea in the first place.

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Thank you @Boink Guilty as charged!  I am just putting it out there in the hope someone will correct me so I can understand better myself.
What % of the sailing time will there be an "S" in the windward skin? only during maximum speed to reduce drag?
If someone were to reveal a new shape of wing how long would it take to copy it?

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Is "S" the new wing twist?

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This new engine room - powerhouse is so interesting but no one will discuss it.
Will they be able to reverse the top like they did the AC35 wing?
Will there be teardrop shape in the twin skin?
Will the new twin skin soft wing be only 60% as powerful as the AC35 wing?

There does not seem to be a consensus?

@Sailbydate what do you think?

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Yes - there have been pics of this

no - an aerofoil shape

no - more powerful - higher RM avaiable ... heaveier boat going the same if not more speed

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35 minutes ago, Kiwing said:

This new engine room - powerhouse is so interesting but no one will discuss it.
Will they be able to reverse the top like they did the AC35 wing?
Will there be teardrop shape in the twin skin?
Will the new twin skin soft wing be only 60% as powerful as the AC35 wing?

There does not seem to be a consensus?

@Sailbydate what do you think?

To be honest mate, I'm a skeptic. I think they have their hands full just maintaining a fast shape with this double skin set-up, without all this inside out voodoo. I think if they're trying to de-power the rig, they'd be better off with less sail area. It would certainly help to decrease drag. But, as I said before, what the fuck would I know?

A lot of this stuff is waaaay past my pay grade. ;-)

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58 minutes ago, Sailbydate said:

To be honest mate, I'm a skeptic. I think they have their hands full just maintaining a fast shape with this double skin set-up, without all this inside out voodoo. I think if they're trying to de-power the rig, they'd be better off with less sail area. It would certainly help to decrease drag. But, as I said before, what the fuck would I know?

A lot of this stuff is waaaay past my pay grade. ;-)

Isn't the problem with less sail area that you need it to get up on foils, but after that you need to depower and minimise drag?

 

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1 minute ago, arneelof said:

Isn't the problem with less sail area that you need it to get up on foils, but after that you need to depower and minimise drag?

 

As I understand it, Arne, yes.

But I doubt if they can actually invert the top third of the main, that that would actually reduce drag. Surely it would just increase drag?

Better to go for a smaller sail in the first place, no?

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1 hour ago, Lickindip said:

Yes - there have been pics of this

no - an aerofoil shape

no - more powerful - higher RM avaiable ... heaveier boat going the same if not more speed

I'm with you on reversing the top to move the COE down, help steady the ship during maneuvers, just going symmetrical for less drag?
I'm also with you on Aerofoil shape (the "S" is a crude way of contrasting a fully windward concave shape with the aerofoil shape).
Mmmm more powerful is a stretch for me but at least equal over all!

But you give me hope that what I guess at is not so far off, after all.

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1 hour ago, Sailbydate said:

To be honest mate, .......That's what I like about you @Sailbydate you are honest

A lot of this stuff is waaaay past my pay grade. ;-)

It is even further past mine, but it is so much fun observing these little glimpses of odd things that make you wander.  Like the quiver of ETNZ's wing last time.  Still don't know what was for!

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2 minutes ago, Sailbydate said:

As I understand it, Arne, yes.

But I doubt if they can actually invert the top third of the main, that that would actually reduce drag. Surely it would just increase drag?

Better to go for a smaller sail in the first place, no?

This is the nut they are trying to crack.

As you ask SBD, do you go for additional RM by inverting the wing (but at the expense of significant additional drag) or do you go for less drag and more efficient shapes that allow shallower AOA (thereby improving VMG) and better drag characteristics ?

We have seen that AM are inverting the top of the mainsail. Don't believe we have seen ETNZ do the same. It would be fair to say that if you were to go down this route - then you will only chase such mainsail manipulation when using the Low aspect jib - otherwise you are asking the air to bend one way (by the jib) then entirely another way (by the main) - and these contrary goals will only add drag and complexity. 

If that is the case then do we see a different approach for the lower wind range?

I personally believe that the S-Bend is only seen at that moment of manoeuvre (tack or gybe) where the wind pressure has reduced but the sail has not yet inverted.

But the reson that this may be worth chasing is the uncanny way that the sail resembled those Eppler profiles which are used in sail planes and ultra lights - so are already in a speed range that is much more similar to that which these boats are also operating. If you can manipulate the windward skin to not just permanently fall to leeward then surely that is more flexible and ultimately more desirable solution than a concave only wing?

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16 minutes ago, Sailbydate said:

...
But I doubt if they can actually invert the top third of the main, that that would actually reduce drag. Surely it would just increase drag?
Better to go for a smaller sail in the first place, no

If they can make it symmetrical and point it at the apparent wind it will give stability with little drag and then they can use it to get onto the foils quicker which should be a winning advantage?
Smaller sail area reduces power jumping up on to foils after a battle in the start box or other mistake?

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1 minute ago, Kiwing said:

Smaller sail area reduces power jumping up on to foils after a battle in the start box or other mistake?

I guess that is the trade-off, Kiwing. My own experience with apparent wind sailing is zero. But I keep hearing drag is a big factor at these high speeds. When I look at the cut of Defiant's sails, they look bigger and certainly fuller than Te Aihe's. It seems to me that ETNZ has gone to the smaller, flatter end of the sail design box.

I would guess you only need enough sail area to get flying and not more than you need to maximum speed. Maybe that's why ETNZ's boat has a bustle (to help launch her) in the absence of more power in the sails?

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59 minutes ago, Sailbydate said:

As I understand it, Arne, yes.

But I doubt if they can actually invert the top third of the main, that that would actually reduce drag. Surely it would just increase drag?

Better to go for a smaller sail in the first place, no?

Would it really be that significant though, it is still an airfoil shape producing maybe 15-20 times more force than drag but doing it at mast head height equaling lots of righting moment. Profile drag in either case would be similar. Cool stuff regardless. 
 

edit. Also will do wonders to the tip vortex. Just killing spanwise flow dead. 

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Has anyone noticed the twist profile of mainsails with upper control "device" is bow-like? Also the AM is constantly sailing with more twist than NZ: that could be punishing in light winds, I guess.

twist.png

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On 9/22/2020 at 2:18 PM, dorox said:

Has anyone noticed the twist profile of mainsails with upper control "device" is bow-like? Also the AM is constantly sailing with more twist than NZ: that could be punishing in light winds, I guess.

twist.png

I get the same impression with AM's headsails too.  They always seem to be more open.

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3 hours ago, Ex-yachtie said:

I get the same impression with AM's headsails too.  They always seem to be more open.

The obvious conclusion is it's simply correct trim and they are not going as fast or perhaps pointing as high (or some combination of both).

Of course it might also be largely optical given the much lighter colour of their rig, black makes you slimmer and all that!

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On 9/22/2020 at 12:18 PM, dorox said:

AM is constantly sailing with more twist than NZ: that could be punishing in light winds, I guess.

Yeah I've noticed this. I think their main is cut bigger and they're having to depower it up top.

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They could have the traveler further up with more twist at the top, this would give the impression of being more open but really just a different set up.

The picks above do seem to show this.

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On 9/17/2020 at 6:39 PM, Sailbydate said:

I would guess you only need enough sail area to get flying and not more than you need to maximum speed. Maybe that's why ETNZ's boat has a bustle (to help launch her) in the absence of more power in the sails?

At 35 knots all that extra sail is going to generate a lot of drag.

i suspect more drag than the extra power. At high speed any deficiencies in sail shape are going to be glaring in regards to turbulence. 

 

 

 

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The kiwis appear to be sheeted wider and harder, the midleeches in very similar position?

Mako, the inverted or more twisted drag might be less than you think, the skins just hanging in the onset flow.

 

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50 minutes ago, Frogman56 said:

The kiwis appear to be sheeted wider and harder, the midleeches in very similar position?

Mako, the inverted or more twisted drag might be less than you think, the skins just hanging in the onset flow.

 

You may be correct, I’m being biased and assumed TNZ have the correct solution in a smaller jib.  It’s an assumption based on stupid Patriotism and TNZ  longer history. They have more experience than any one else using a jib on these sort of boats. Also I’ve Seen AM starting to use more this sort of jib. It’s also based on these jibs seem to hold there shape better, they really look wing like. The problem seems to me with a full length jib is there no way to control the leech. The taller the jib the less control you have

to be honest I’m no expert in this area and will happily accept input from people who who no more. 

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1 hour ago, mako23 said:

You may be correct, I’m being biased and assumed TNZ have the correct solution in a smaller jib.  It’s an assumption based on stupid Patriotism and TNZ  longer history. They have more experience than any one else using a jib on these sort of boats.

And of course it is not that long ago that lots of people were lauding the inverted shape at the top of NZ wings as being a reason for their success. Which is really just taking lots of twist further.

Which is correct we cannot of course tell without shit loads more data, It is even possible that both are correct for the different design philosophies of the respective boats (or small differences in conditions at that point and time).

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9 hours ago, enigmatically2 said:

And of course it is not that long ago that lots of people were lauding the inverted shape at the top of NZ wings as being a reason for their success. Which is really just taking lots of twist further.

I don't think the inverted twist was "lauded" as a reason for success, its existence was debated longtime. It's pretty obvious to everyone the etnz main controls were superior to the rest of the pack in bda, and had the best control over twist..and that may have been one of the reasons the cup resides in NZ.

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16 minutes ago, OldWoodenShip said:

Each of the teams in BDA were capable of inverting the top camber arm, FWIW. What differed were the various compromises made in relation to how this was achieved.

Right...

Some with cables, quadrants, and winches.

One with a custom built hand held low latency hydraulic controller. Edit:.big compromise wtf

;)

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