Recon diary

[Dogfish]

I think the current TNZ Banana foil is a anhedral foil. It may actually become Gull winged when loaded but we currently cannot see whats happening underwater.

 

[Stingray~]

I think the current TNZ Banana foil is a anhedral foil. It may actually become Gull winged when loaded but we currently cannot see whats happening underwater.

Am curious if the outboard end of this and other foils may get actuated to flatten when unloaded and they surface, to act more like skimmers.

 

[Kiwing]

I think the current TNZ Banana foil is a anhedral foil. It may actually become Gull winged when loaded but we currently cannot see whats happening underwater.

I think also the built in seamless flaps are actuated by this flexing to accentuate the benefit?

 

[JALhazmat]

No bias, just facts. I spent my whole career doing research and product development.

It is much more accurate to measure the impact of changes if you do them one at a time instead of all in a handful. Having two ”identical“ AC40’s on autopilot is an ideal situation to minimize the noise and give the best comparison between changes. Having one boat that is significantly slower and with a completely different design adds several variable that have to be estimated out in order to measure any changes. This adds a lot of noise to the process and makes it very difficult to actually measure slight improvement.

There are already so many variables like sea state, wind variations and boat handling that make it very difficult to measure absolute changes. No need to throw in a test platform that can’t keep on the foil over 50% of the time in maneuvers. They will be able to measure large improvements using the T6 vs AC40, but the smaller incremental changes will be difficult.

By exactly the same metric LR have just as much chance of being in the same doom spiral as INEOS if their boat is slower, you couch the LR proposition as interesting, whereas is INEOS- doomed to fail

 

[Sailbydate]

Alinghi, bearing off first in R1 of AC33. You can hear Rennmaus saying 'Classic Start!'

You can see what happened when CZ was able to bear away much sooner than DZ.



On the water, pre-start, Race 1, America's Cup 33, Feb 12 2010, Valencia

So they weren't foiling then? ;-)

 

[enigmatically2]

Perhaps it's the exact opposite of wanting to back the sail.
An auto-tacking jib is pushed across by the jib backing, very slightly, but a bit. That slows the boat down a bit.

If they move it by hydraulics then if at exactly the right time and rate it would not slow the boat (as much).
Easy to get right with auto-control, but very hard to do manually. But possible by following the right instruments. It's even possible that the main traveller is set for the same.
I'm not asserting it, but it's another possibility that they might be testing. They will be going for small gains this time

 

[The_Alchemist]

By exactly the same metric LR have just as much chance of being in the same doom spiral as INEOS if their boat is slower, you couch the LR proposition as interesting, whereas is INEOS- doomed to fail

I have not made any such comparison of LR vs INEOS. LR will also have many of the same variables problems as INEOS, but LR LEQ12 is much faster and they have shown much better control of their test boat. I am not all doom and gloom on INEOS, it is just they have made some choices that make it a much tougher challenge.

 

[JALhazmat]

much faster? Given the recon teams aren’t actually allowed to take that data. I’d be interested as to how you would know what speed anybody’s doing actually doing, not old mate comes off the boat and says we did x

 

[Dogfish]

I think also the built in seamless flaps are actuated by this flexing to accentuate the benefit?

I think it is perfectly possible for the Banana foil to have a twisting trailing edge as apposed to a normal flap. If the outboard end is fixed and the inboard end moves you can achieve the desired twist for the flap effect. They have been talking about it been harder to control and than their normal foil and this is probably due to different response rates etc.
As to Ineos they are still building their data base, they have chosen simple straight forward foil design as their base design. They would have picked the span and cord to best suit the conditions where they were going to test it. Once they know they have a sound base to build on they can start playing around. TNZ and LR are miles further down the development curve, but once they can start computer modelling in earnest Ineos's can easily catch up on the design side they may struggle for time on the water.

 

[enigmatically2]

Rules committee asking COR/D for agreement to a new draft of the Tech Regs - #38.
But I can't see what has changed - unless it is just previous clarifications?

 

[buckdouger]

I think it is perfectly possible for the Banana foil to have a twisting trailing edge as apposed to a normal flap. If the outboard end is fixed and the inboard end moves you can achieve the desired twist for the flap effect. They have been talking about it been harder to control and than their normal foil and this is probably due to different response rates etc.
As to Ineos they are still building their data base, they have chosen simple straight forward foil design as their base design. They would have picked the span and cord to best suit the conditions where they were going to test it. Once they know they have a sound base to build on they can start playing around. TNZ and LR are miles further down the development curve, but once they can start computer modelling in earnest Ineos's can easily catch up on the design side they may struggle for time on the water.

I agree it's possible, but I think we are overestimating how radical those curved foils really are...

...I wouldn't say that's a given, it's an area they probably have a resource advantage but there are limits, as has been discussed last cycle, in parallelization, simplification of real geometry and systems for CFD, and you still need to come up with good ideas to simulate, etc.

 

[enigmatically2]

I think we have a way to go on foils yet. AFAIK LR, Ineos and Nz have only uses one of their LEQ12 allowance. And the others have not yet been allowed to use anything except last gen. One would expect the starting foils to be fairly conservative whilst they test out other systems.
One could argue that the AC40 OD has given them a freebie conservative foil and so this first LEQ one is a move away from that, but I still expect to see a lit more to come on the LEQs

 

[enigmatically2]

Perhaps it's the exact opposite of wanting to back the sail.
An auto-tacking jib is pushed across by the jib backing, very slightly, but a bit. That slows the boat down a bit.

If they move it by hydraulics then if at exactly the right time and rate it would not slow the boat (as much).
Easy to get right with auto-control, but very hard to do manually. But possible by following the right instruments. It's even possible that the main traveller is set for the same.
I'm not asserting it, but it's another possibility that they might be testing. They will be going for small gains this time

I meant to point out that whilst this may seem minor, with the AWS these boats get it's more significant than most people are used to. I know from sailing with much smaller sails in higher TWS that it's quite a lot of force.

Furthermore it occurred to me that it's not just drag, but also turning the boat with so much force that it might make it harder to stop the turn, hence more rudder angle.

Anyone have any views? @Mozzy Sails ?

I must admit it's an idea I have blown hot and cold on overnight, but it would seem like a bigger potential gain than a pre-start duel

 

[Stingray~]

it would seem like a bigger potential gain than a pre-start duel

Agree

 

[Dogfish]

I agree speed of triming is more important. If you watch the jib trimming it's very smooth, I just used the pre-start as a quick lazy example I could think of at the time.

 

[Mozzy Sails]

I meant to point out that whilst this may seem minor, with the AWS these boats get it's more significant than most people are used to. I know from sailing with much smaller sails in higher TWS that it's quite a lot of force.

Furthermore it occurred to me that it's not just drag, but also turning the boat with so much force that it might make it harder to stop the turn, hence more rudder angle.

Anyone have any views? @Mozzy Sails ?

I must admit it's an idea I have blown hot and cold on overnight, but it would seem like a bigger potential gain than a pre-start duel

Not sure. I get what you're saying, but also I've seen a couple clips where it appears to come over later in tacks. Although Bleddynn also said they've had a few teething issues with it in his last interview.

The traditional style of self tacking jib you need the jib sheet to originate from the tack of the jib and the track to follow a radius roughly around centre at the jib tack (with some deviation to encourage it to slide out).

The above all puts constraints on the geometry of the bow. INEOS system doesn't have those restrictions, which is a benefit i proabably should have mentioned in the video.

But it will also be interesting to see if they have some link so that as the jib moves out it eases or sheeting angle steepens to accomdate for that straight tack.

 

[Stingray~]

I just used the pre-start as a quick lazy example I could think of at the time.

Me too, the very obvious one from the R1 start of AC33 that I posted (there are better vids of all that whole thing...) where the boat that peeled out of the dialup first gained an absolutely huge advantage. The Alinghi cat may or may not have used some windward jib sheeting to accomplish that, but it's certainly possible.

I wonder what camera or probably other instrumentation may be being used or developed, to continuously optimize slot flow?

 

[Stingray~]

I forgot, DogZilla actually furled the jib for some reason in that start.

 

[Stingray~]

Some forum posts about that start

Did Dogzilla ever practice starts??

Got into a bit of a bar discussion about the DZ/CZ starts and have a clear memory that Jimmy Spihill once said that BMWO had never actually practiced a match race start or even sailed an AC race course before the gun for Race 1 in Valencia. I"ve found an interview where he says they had never...

forums.sailinganarchy.com

 

[Stingray~]

Some forum posts about that start

Did Dogzilla ever practice starts??

Got into a bit of a bar discussion about the DZ/CZ starts and have a clear memory that Jimmy Spihill once said that BMWO had never actually practiced a match race start or even sailed an AC race course before the gun for Race 1 in Valencia. I"ve found an interview where he says they had never...

forums.sailinganarchy.com

^ from a link there.. dialups can matter!