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1 hour ago, MaxHugen said:

I have a slab of beer on TR.

  • Power.   I think they can muster a more low down power for the available RM. They can induce a lot of camber there in light air,  plus use the extra sail area to lower CE in stronger winds
  • Drag.     NZ have concentrated on minimising drag, not just on the foils but also the rudder, although that super skinny rudder may be why they've looking a touch skittish lately.

But I don't think it's a walk-over for NZ. 

  • Tacks/Gybes.  LR has a clear advantage in turns when TWS is in lower ranges, as TR has to build speed before turning on narrow foils, so losing a few metres every time.
  • Speed.    Whilst NZ may have the edge here, LR are no slouches either, esp in light air. And they've done a great job at getting god shape in the mainsail down to the deck.

If LR can force TR into a taking duel, that should neutralise any speed advantage TR may have. But if TR have enough of a speed edge, they could wriggle out of a duel downwind.

This doesn't take take into account which team has the best ability to spot and use gusts, wind shifts, etc. I've no idea which team is better at this.

I'm hoping for a hard fought 7-6 victory for NZ.  :D   (7-6 so we get to watch 13 races...)

Thanks for your insights, will be exciting sailing soon (I hope).

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Just a few interesting bits of the straight-line performances from today: Upwind /Downwind VMGs - race 1: Upwind /Downwind VMGs - race 2: Same story in both races actually.

Thanks to weta27's pics I have created an approximation of NZ's "BFB v2" foil. Main points: Foil area is almost the same, possibly even a smidge larger. Flaps have increased in area as

OK, it sounds like there's some interest in this topic, so here goes.   Any engineering effort starts by defining the requirements.  From this figure, it looks like the average foil area is 1.64

Posted Images

1 hour ago, MaxHugen said:

I have a slab of beer on TR.

  • Power.   I think they can muster a more low down power for the available RM. They can induce a lot of camber there in light air,  plus use the extra sail area to lower CE in stronger winds
  • Drag.     NZ have concentrated on minimising drag, not just on the foils but also the rudder, although that super skinny rudder may be why they've looking a touch skittish lately.

But I don't think it's a walk-over for NZ. 

  • Tacks/Gybes.  LR has a clear advantage in turns when TWS is in lower ranges, as TR has to build speed before turning on narrow foils, so losing a few metres every time.
  • Speed.    Whilst NZ may have the edge here, LR are no slouches either, esp in light air. And they've done a great job at getting god shape in the mainsail down to the deck.

If LR can force TR into a taking duel, that should neutralise any speed advantage TR may have. But if TR have enough of a speed edge, they could wriggle out of a duel downwind.

This doesn't take take into account which team has the best ability to spot and use gusts, wind shifts, etc. I've no idea which team is better at this.

I'm hoping for a hard fought 7-6 victory for NZ.  :D   (7-6 so we get to watch 13 races...)

You don't mention VMG...if TR can pull away upwind, and soak downhill, they gain a "Teflon get out of match racing card". There's been a lot of water under those foils since they last lined up. They won't show off the extra gear, just pop it in when needed

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2 minutes ago, barfy said:

You don't mention VMG...if TR can pull away upwind, and soak downhill, they gain a "Teflon get out of match racing card". There's been a lot of water under those foils since they last lined up. They won't show off the extra gear, just pop it in when needed

True... it's hard to factor in every variable. It will be very interesting to see if LR do have a VMG advantage - I don't think so, but that's purely a guess.

A few days ago I did a comparison of VMG between 2 boats - if one boat sails at 30 knots boat speed with 45° TWA, and the other sailed at 1° lower, but ~0.5 kn faster, VMG was the same.

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8 minutes ago, MaxHugen said:

True... it's hard to factor in every variable. It will be very interesting to see if LR do have a VMG advantage - I don't think so, but that's purely a guess.

A few days ago I did a comparison of VMG between 2 boats - if one boat sails at 30 knots boat speed with 45° TWA, and the other sailed at 1° lower, but ~0.5 kn faster, VMG was the same.

I saw that, interesting...although TR's speed is the "talk of the town" I reckon etnz will show a clean pair of heels upwind. Seemed to be their mo last cycle, and it makes sense to optimize the "work". Besides, it's another hard lesson from SF.

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5 hours ago, Filthy Phill said:

If it it comes down to one final race (6-6) I'm going have to be 8 beers in to handle the nerves.

Like Rugby World Cup 2011 Final  v France. My misses was almost throwing up she was so nervous.

me, well I was 12 beers in...........

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@MaxHugen @erdb

Just wondering guys, how would you optimise and improve the AC75 rule to both reduce costs and encourage more challengers for the next cup?

What could be done with the foils/flaps/tips to improve and optimise?

 More one design components? 

More motors and less grinders? 

Or do you think it is better now where its more open to design interpretation? 

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^ If the AC75 or a close derivative is chosen for AC37, any prospective team would have some advantages in having seen what worked, and what didn't.

Beyond that, the AC has always been about design, so it's unlikely that final costs would really be reduced in a meaningful manner.

IMO. :)

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1 hour ago, 45Roller said:

@MaxHugen @erdb

Just wondering guys, how would you optimise and improve the AC75 rule to both reduce costs and encourage more challengers for the next cup?

What could be done with the foils/flaps/tips to improve and optimise?

 More one design components? 

More motors and less grinders? 

Or do you think it is better now where its more open to design interpretation? 

It is a bit of a incoherent wish list question tbh.

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4 minutes ago, The Advocate said:

It is a bit of a incoherent wish list question tbh.

true, I was just spitballing, it's 4 different questions really

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6 minutes ago, 45Roller said:

@MaxHugen @erdb

Just wondering guys, how would you optimise and improve the AC75 rule to both reduce costs and encourage more challengers for the next cup?

More one design components? 

More motors and less grinders? 

Or do you think it is better now where its more open to design interpretation? 

 

Good question.

Would be interesting to know the breakdown of the $100M budgets. I'd guess that the real cost is in the majority is for the design team (50 people for 4 years probably costs > $40M), so any significant cut would probably need to come from that. One design might help (not sure it did for Bermuda) - but this would also make it less exciting.

I personally would like less motors and more grinders/cyclists as I do not think motors belong on a sailing boat. Perhaps that would be doable for a smaller version of the AC75, but that probably would make the boat less stable.

 

 

 

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You cannot make a rule against spending  money. No one has ever succeeded.  People will pay for an advantage, no matter how small.  The largest cost in the America’s Cup is just because it is the America’s Cup and they do things that no one else would do.  Imagine hauling a 75 foot yacht every time you go sailing and de-rigging it and putting it in a shed overnight.  I think this became the common practice in 2000.

 By comparison, 12 meters hung from travel lifts, with their rigs up. Seems spartan by comparison.  The 12 could go sailing in about an hour, the modern AC program requires about 6 hours to reassemble the yacht, launch it and boot the systems.

It may be that the huge budgets are part of the attraction.  

SHC

 

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14 hours ago, 45Roller said:

@MaxHugen @erdb

Just wondering guys, how would you optimise and improve the AC75 rule to both reduce costs and encourage more challengers for the next cup?

What could be done with the foils/flaps/tips to improve and optimise?

 More one design components? 

More motors and less grinders? 

Or do you think it is better now where its more open to design interpretation? 

Suggestions: Remove "built in country Rule" for legacy yachts. Maintain an open Rule with minimum OD components.

But my question is, "Why do you (and many others) want to encourage more, Challengers?"

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16 hours ago, 45Roller said:

@MaxHugen @erdb

Just wondering guys, how would you optimise and improve the AC75 rule to both reduce costs and encourage more challengers for the next cup?

Seems to me that should be a new thread.

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2 hours ago, Sailbydate said:

But my question is, "Why do you (and many others) want to encourage more, Challengers?"

One reason is to get greater diversity of challengers and hopefully more innovation, which should create a better spectacle. 

The current AC boats are irrelevant to most who aren't sailors, and of little relevance to those that are. The womens' match racing from the London 2012 Olympics was more entertaining than the current AC, and much more relatable despite the low tech broadcast.

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1 minute ago, RobG said:

One reason is to get greater diversity of challengers and hopefully more innovation, which should create a better spectacle. 

The current AC boats are irrelevant to most who aren't sailors, and of little relevance to those that are. The womens' match racing from the London 2012 Olympics was more entertaining than the current AC, and much more relatable despite the low tech broadcast.

Nothing beats the prolonged build up....the speculation of the designs being evolved....the politics and egos. ..all culminating at the first race of the AC. It's unique...thats why it will always be the pinnacle. Or just don't watch and go do something else. The AC will survive.

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I think the cost of winning will always be whatever people are willing to spend. Reducing amount of yachts to be constructed per cycle and a few equipment numbers can help a little. 

The major thing though is hanging on to the class for a few cycles. This massively lowers the cost, and risk to new 'also ran' teams. If they can pick up and race previous generation boats, or copy from previous cup, then it makes it much easier. Whilst I don't believe a team like this would ever win, these teams do breed talent, add to the variety of the competition, and some of them will upscale and become genuine contenders. 

The flip side is, you don't want to the class to turn stagnant, A few rule changes are required to spice up the design competition and ask new questions of design teams. Otherwise the teams will very quickly converge if a rule sticks around unchanged for a couple of cycles.  This is tricky though, you don't want to completely outdate previous generation boats. 

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4 hours ago, RobG said:

The current AC boats are irrelevant to most who aren't sailors, and of little relevance to those that are. The womens' match racing from the London 2012 Olympics was more entertaining than the current AC, and much more relatable despite the low tech broadcast.

There are any number of OD sailing competitions around the world, but few for truly open development classes.

No need to fuck with the AC. It's just fine the way it is, IMO.

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10 minutes ago, Mozzy Sails said:

Reducing amount of yachts to be constructed per cycle and a few equipment numbers can help a little. 

How is reducing the boats from 2 to 1 going to help. If a team builds a boat they realise is not competitive, they will be a no show to the cup.

15 minutes ago, Mozzy Sails said:

The major thing though is hanging on to the class for a few cycles. This massively lowers the cost, and risk to new 'also ran' teams. If they can pick up and race previous generation boats, or copy from previous cup, then it makes it much easier. Whilst I don't believe a team like this would ever win, these teams do breed talent, add to the variety of the competition, and some of them will upscale and become genuine contenders. 

Agreed. I think the best example we have seen of this is the AC Class, and I think AM had a bit to do with that. The problem with where we are now is that the package is so high tech, it is outdated so quickly.

17 minutes ago, Mozzy Sails said:

The flip side is, you don't want to the class to turn stagnant, A few rule changes are required to spice up the design competition and ask new questions of design teams.

Agreed, I think the AC class didn't develop well but it was a good concept. Rules to ensure a decent lifespan of a boat would also be key. 2 cup cycles would be reasonable in my book.

17 minutes ago, Mozzy Sails said:

Otherwise the teams will very quickly converge if a rule sticks around unchanged for a couple of cycles.  This is tricky though, you don't want to completely outdate previous generation boats. 

I think if the mentality is not to outdate the previous generation of boat, but beyond that is fair game, we would see a sensible level of development.

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1 minute ago, The Advocate said:

How is reducing the boats from 2 to 1 going to help. If a team builds a boat they realise is not competitive, they will be a no show to the cup.

Sorry I wasn't clear. I'm not saying they should reduce to from 2-1. Just saying generally reducing the amount of boats teams can build through a limit is an effective way to reduce costs (like they already are). 

It'll be interesting to see what they do with the rules and 'loopholes' as this will affect the second hand value of the boats from this cup. The stuff around deck height is quite hard to retrofit! 

This is a conversation that is common in all development classes though. Existing owners have capital tied up in boats they want to protect. But that can sometimes stifle those wanting to invest in new equipment and new ideas. Opening up the rules encourage fewer, but more financially committed entrants who have ambitions to win. Closing down the rules encourages new blood with less capital but fancy having a go with slightly old but fundamentally the same equipment. 

The AC75 is new enough that the above won't be  massive issue just yet as I think they're still room for significant innovation in this current rule without changing anything.  

 

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9 minutes ago, Mozzy Sails said:

Sorry I wasn't clear. I'm not saying they should reduce to from 2-1. Just saying generally reducing the amount of boats teams can build through a limit is an effective way to reduce costs (like they already are). 

It'll be interesting to see what they do with the rules and 'loopholes' as this will affect the second hand value of the boats from this cup. The stuff around deck height is quite hard to retrofit! 

This is a conversation that is common in all development classes though. Existing owners have capital tied up in boats they want to protect. But that can sometimes stifle those wanting to invest in new equipment and new ideas. Opening up the rules encourage fewer, but more financially committed entrants who have ambitions to win. Closing down the rules encourages new blood with less capital but fancy having a go with slightly old but fundamentally the same equipment. 

The AC75 is new enough that the above won't be  massive issue just yet as I think they're still room for significant innovation in this current rule without changing anything.  

 

If I remember correctly Il moro de Venezia built five boats and had a budget of $43M (in 1992), not sure anyone would do that today even if it was allowed as computer simulations have got so much better. I guess the biggest cost-savings for newcomers would be to have access to the software used by the current teams. But how that would be enforced I have no idea.

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3 minutes ago, arneelof said:

If I remember correctly Il moro de Venezia built five boats and had a budget of $43M (in 1992), not sure anyone would do that today even if it was allowed as computer simulations have got so much better. I guess the biggest cost-savings for newcomers would be to have access to the software used by the current teams. But how that would be enforced I have no idea.

That is an interesting idea, but the biggest cost centre, in my opinion, is not being addressed anywhere. That is the cost of team design and support staff. Perhaps a pay cap needs to be introduced as so many pro sports have done.

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If ETNZ had wanted to they could have flogged off their simulator to the other teams this go around, they didn't because its one of their proprietary advances. (You could argue that LR has the same base simulator and so as a pair, COR/D, they didn't want to give up their advantage).

I like the idea of keeping the AC75, and allowing teams to purchase old boats bypassing the constructed in country rule. (e.g. you can buy anyones boat, but if you build the rule still applies). If the teams can agree to a multi cycle deal (oh the irony), that would encourage teams to buy boats to develop talent for future cup efforts (knowing that this generation of boat likely wouldn't win against the next generation of boat).

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A class with a roadmap for development over three cycles, and ability for new reams to buy old boats ex another team?

So the class evolves, but teams have an eye on development for the next cycle.

Existing teams advance, development not wasted. New teams have a good idea of where it's heading.

A shake up every three cycles with the winner getting to dictate the start of next cycle.

Or let current chaos reign - it's kept the event going thus far...

 

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7 minutes ago, Nutta said:

A class with a roadmap for development over three cycles, and ability for new reams to buy old boats ex another team?

So the class evolves, but teams have an eye on development for the next cycle.

Existing teams advance, development not wasted. New teams have a good idea of where it's heading.

A shake up every three cycles with the winner getting to dictate the start of next cycle.

Or let current chaos reign - it's kept the event going thus far...

 

 

Exactly what all teams (except TNZ) agreed to at AC35.

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1 minute ago, arneelof said:

 

Exactly what all teams (except TNZ) agreed to at AC35.

I'd more meant the class laid out in cycle 1 included a roadmap. Others could pick it up and run with it.

Locking in everyone contractually would be a step too far and kill the random changes of direction that the AC has offered. Making it sail GP is not what's needed.

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9 minutes ago, Nutta said:

A class with a roadmap for development over three cycles, and ability for new reams to buy old boats ex another team?

So the class evolves, but teams have an eye on development for the next cycle.

Existing teams advance, development not wasted. New teams have a good idea of where it's heading.

A shake up every three cycles with the winner getting to dictate the start of next cycle.

Or let current chaos reign - it's kept the event going thus far...

 

I agree, but the DoG prevents such a thing. Remember what happened in Bermuda. All teams except ETNZ agreed on developing the cats etc... ETNZ won and here we are.

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13 minutes ago, arneelof said:

 

Exactly what all teams (except TNZ) agreed to at AC35.

Yep, because someone, not always ETNZ, but someone, always wants to fuck the apple pie.

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10 minutes ago, strider470 said:

I agree, but the DoG prevents such a thing. Remember what happened in Bermuda. All teams except ETNZ agreed on developing the cats etc... ETNZ won and here we are.

Perhaps if ETNZ lose the cup this time that table could be set up in a boat park again.

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1 minute ago, The Advocate said:

Perhaps if ETNZ lose the cup this time that table could be set up in a boat park again.

But LR was not at that table as well. They were completely supporting ETNZ (from the outside)

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23 minutes ago, strider470 said:

But LR was not at that table as well. They were completely supporting ETNZ (from the outside)

Different times now. Italians in general are one of the guilty ones, I think, hope, they see it differently now.

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Yeah right, sell off more old boats, have a new "whatever happened to"thread, have more lovely frenchlike teams that you know aren't going anywhere...even room for s&s..while two or three teams are the contenders...why tf would you want to serve that table again? Bigger press conferences? More round robin days? :huh:

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16 minutes ago, The Advocate said:

Different times now. Italians in general are one of the guilty ones, I think, hope, they see it differently now.

Guilty of what? Ffs.

Edit: not having Larry vision on their subscription list?

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Personally, I think the weight in the foils is a bit of a red herring, and in fact ETNZ are using their lower T section to remove weight from below the water line. Agree?

 

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On 3/5/2021 at 12:28 AM, barfy said:

Yeah right, sell off more old boats, have a new "whatever happened to"thread, have more lovely frenchlike teams that you know aren't going anywhere...even room for s&s..while two or three teams are the contenders...why tf would you want to serve that table again? Bigger press conferences? More round robin days? :huh:

Bigger better parties? :P

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On 3/4/2021 at 5:29 PM, Mozzy Sails said:

Personally, I think the weight in the foils is a bit of a red herring, and in fact ETNZ are using their lower T section to remove weight from below the water line. Agree?

 

I just watched part 2 and i think you guys are assuming that both flaps on a foil are set equally. LR has the ability to set the flaps differently, so the center off lift can be moved out by differential flap settings.

Down wind, when you want negative leeway, then this is probably the default setting.

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1 hour ago, sfigone said:

I just watched part 2 and i think you guys are assuming that both flaps on a foil are set equally. LR has the ability to set the flaps differently, so the center off lift can be moved out by differential flap settings.

Down wind, when you want negative leeway, then this is probably the default setting.

Not at all. I hint at the end of the video! Just for this discussion to isolate a single factor we kept it with equal total lift on each foil.  

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1 hour ago, Xlot said:

NZ's foil doesn't look quite right... it's more of a BFB.   Also not the latest foil, which has a bit of curved anhedral.

Nice diagrams though.

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The drawings certainly illustrate the differences in approach. I just have to admire the engineering ingenuity and how we all see things differently. One massive round of applause to all concerned. 

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48 minutes ago, MaxHugen said:

NZ's foil doesn't look quite right... it's more of a BFB.   Also not the latest foil, which has a bit of curved anhedral.

Nice diagrams though.

But do you think that anhedral will flex to flat under load?

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2 minutes ago, Flags said:

But do you think that anhedral will flex to flat under load?

It might.

The boat data from ACWS indicated that the median NZ foil cant angle was 22°.  This was a bit less than I'd expected, and may have been due to generally flying a bit higher than I thought they would.  However it could also be due to the foils flexing, thus reducing the amount of cant without breaching too much of the foil.

The fact that the foils are curved also suggests to me that they may be designed to flatten out under load.

Very much guesswork though.

 

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A major consequence of end plating he mainsail is that the Vertical Center of Effort is more responsive to changes in twist. 

SHC

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30 minutes ago, MaxHugen said:

It might.

The boat data from ACWS indicated that the median NZ foil cant angle was 22°.  This was a bit less than I'd expected, and may have been due to generally flying a bit higher than I thought they would.  However it could also be due to the foils flexing, thus reducing the amount of cant without breaching too much of the foil.

The fact that the foils are curved also suggests to me that they may be designed to flatten out under load.

Very much guesswork though.

 

Silly question Max, but I know you won’t shoot me ..... is there any give in the foil like suspension? I ask because aircraft wings move a lot at the tips. 

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On 3/3/2021 at 7:53 PM, Steve Clark said:

You cannot make a rule against spending  money. No one has ever succeeded.  People will pay for an advantage, no matter how small.  The largest cost in the America’s Cup is just because it is the America’s Cup and they do things that no one else would do.  Imagine hauling a 75 foot yacht every time you go sailing and de-rigging it and putting it in a shed overnight.  I think this became the common practice in 2000.

 By comparison, 12 meters hung from travel lifts, with their rigs up. Seems spartan by comparison.  The 12 could go sailing in about an hour, the modern AC program requires about 6 hours to reassemble the yacht, launch it and boot the systems.

It may be that the huge budgets are part of the attraction.  

SHC

 

Great comments.  Any idea how the 75s compare in cost to the AC 50s and AC 72s in terms of cost and setup times?

Does each iteration end up costing more than previous, no matter the boat?

What has been the most expensive Cup to date?

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A thought just occurred to me: Is a split flap permitted?

Various-operational-configurations-of-th

Closed you can have effectively normal non-cavitating profile, opened out you can potentially get a decent approximation of a ventilated/cavitating profile.

If you could get the engineering right...

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19 minutes ago, hoom said:

A thought just occurred to me: Is a split flap permitted?

Various-operational-configurations-of-th

Closed you can have effectively normal non-cavitating profile, opened out you can potentially get a decent approximation of a ventilated/cavitating profile.

If you could get the engineering right...

Very interesting thought.

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On 2/15/2020 at 2:54 PM, Lickindip said:

9.34% more RM from you windward foil

and an additional 5.37%  from hull weight in this particular orientation if the foil arm stock isn't vertical

the blue line is just an arbitrary water line when foiling

image.png.7f938e4f895279e14aef07e0ee67b9c2.png

geez Mozzy creating a video of something that was discussed here 13 months ago :P

I'm curious as to why your video uses the term 'diddly squat' ... yes the pic I have above is based on the extremes of top / bottom  of foil weight positions but I would suggest the benefit of 0.5% that you state is under exaggerated

if I'm correct you ignored the COG of the hull being the different distance from the lever point? in your video its 123mm so about 2.18% difference in lever/moment just from Hull/rig/crew weight

maybe we agree to meet somewhere in the middle? ... if I was an AC designer id be happy with a 2% more righting moment then the other team with an overpowered boat

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55 minutes ago, hoom said:

A thought just occurred to me: Is a split flap permitted?

Various-operational-configurations-of-th

Closed you can have effectively normal non-cavitating profile, opened out you can potentially get a decent approximation of a ventilated/cavitating profile.

If you could get the engineering right...

I knew a girl once who had ...

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3 hours ago, Mozzy Sails said:

Not at all. I hint at the end of the video! Just for this discussion to isolate a single factor we kept it with equal total lift on each foil.  

Great videos again Mozzy. I was the same - but what about the differential flap settings?!:huh: until you said that's (I assume) will be in the next one.

One thing though that kind of connects Part 1 and 2 of your vids is what I've been harping about for awhile. You can only cant the foil out more, if you lower the CoE of the sail. The two are connected, especially for ETNZ with the T foils. So the ability to lower the CoE is a double win in roll balance.

What did Tom use to make his VPP?

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50 minutes ago, Mozzy Sails said:

Single flap must be linear. And rotate about a single fixed point of rotation. So effectively no. 

I think you could get them both rotating around the same axis but yeah probably not a linear object.

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56 minutes ago, Mozzy Sails said:

Single flap must be linear. And rotate about a single fixed point of rotation. So effectively no. 

What about a split flaps encased in a single somewhat flexible flap made from unobtainium? 

 

edit: Would be funny if one of the teams asked for a ruling on this with no intention of implementing... probs a bit late for those sort of shenanigans unfortunately :)

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ha - just watching your episode 2 so might have spoken too soon

I have an observation I don't think you have taken into account regarding combined vertical lift (your red arrow position)

(let's ignore foil tip out of water for a second)

image.png.a4bbe592c2376a43b1ea4642bafe42eb.png

 

image.png.57def1c9030ce59f7e0cf80c895be44f.png

LR with the more vertical lift coming off the outside half of the foil there will be a ratio someone can SohCahToa between the 2 halves ... this will move your red arrow outboard which would close the gap with the ETNZ flat foil centre. yes/no???

 

what gets more complicated is if LR are using different actuators for flaps and if ETNZ has only 1 actuator :lol:

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4 minutes ago, Lickindip said:

ha - just watching your episode 2 so might have spoken too soon

I have an observation I don't think you have taken into account regarding combined vertical lift (your red arrow position)

(let's ignore foil tip out of water for a second)

image.png.a4bbe592c2376a43b1ea4642bafe42eb.png

 

image.png.57def1c9030ce59f7e0cf80c895be44f.png

LR with the more vertical lift coming off the outside half of the foil there will be a ratio someone can SohCahToa between the 2 halves ... this will move your red arrow outboard which would close the gap with the ETNZ flat foil centre. yes/no???

 

what gets more complicated is if LR are using different actuators for flaps and if ETNZ has only 1 actuator :lol:

Yes, placing the lift potentially further from the hull than ETNZ.

Indeed. I think this is probably where the high mode is coming from.

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1 minute ago, The Advocate said:

Yes, placing the lift potentially further from the hull than ETNZ.

Indeed. I think this is probably where the high mode is coming from.

I would like to see the numbers before saying 'further'

it does leave LR more susceptible to coming off there foils in choppy conditions and they would have to be more accurate with rideheight being so dependant on the vertical lift from the outer half of the foil while the tip is continually coming out of the water

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1 minute ago, Lickindip said:

I would like to see the numbers before saying 'further'

it does leave LR more susceptible to coming off there foils in choppy conditions and they would have to be more accurate with rideheight being so dependant on the vertical lift from the outer half of the foil while the tip is continually coming out of the water

Why I said "potentially".

Why does it, would that not be why they have the foil size they do? Surely ETNZ venting a foil tip would be more so?

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7 minutes ago, Mozzy Sails said:

The whole wing CoL IS shifted to outboard. Look at the red arrow, it is.closer to the out board CoL than the inboard CoL in the X horizontal axis. 

It is closer to the outboard side CoL in the X axis, in proportion to its y component. But, in X and Y it in equidistant (to reflect that the X component will be greater on the inboard wing).

Those black arrows are the vertical component (y) of the resultant lift from each side (perpendicular to foil surface). 

Notice the outboard arrow is larger, reflecting that it has a larger vertical (y) component and a not shown smaller horizontal component (x). In hindsight, we should have drawn X,y and resultant. 

What we purposefully dont discuss in this video is flap differential. But I do drop a hefty hint at the end. 

I'm agreeing with the method of splitting the vertical and horizontal forces as you have with the black arrows

I'm not agreeing with how you have added the 2 LR vertical forces together and place them halfway between (still on the mirror line) and called that your equivalent

the effective Red arrow should be outboard from the foil mirror line (green) for the LR.

this would bring the centre of vertical lift from Center of the boat dimension closer to ETNZ's so would tighten up the advantage in knots as you also describe

the mirror image of this is the leeway horizontal force. LR would be deeper in the water and a smaller distance to the CL of the boat (maybe they are able to turn a tighter circle?)

image.png.07c3d829423cdfd2e7caddfeec2eb485.png

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17 minutes ago, Lickindip said:

I'm agreeing with the method of splitting the vertical and horizontal forces as you have with the black arrows

I'm not agreeing with how you have added the 2 LR vertical forces together and place them halfway between (still on the mirror line) and called that your equivalent

the effective Red arrow should be outboard from the foil mirror line (green) for the LR.

this would bring the centre of vertical lift from Center of the boat dimension closer to ETNZ's so would tighten up the advantage in knots as you also describe

the mirror image of this is the leeway horizontal force. LR would be deeper in the water and a smaller distance to the CL of the boat (maybe they are able to turn a tighter circle?)

image.png.07c3d829423cdfd2e7caddfeec2eb485.png

This.

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1 hour ago, Mozzy Sails said:

mmm. let me think and re draw

 

haha sounds good, sorry if it comes across as criticism. just trying to get a clear understanding of the principles/application/benefits of the T vs V foil.

we make enough assumptions from our armchairs I think its healthy debate to challenge each other's theories and schematics.

if I was an AC designer / sailer i would have probably gone for Max RM  ... but with independent actuators as I see times when a moment control (ailerons on an aircraft) would be beneficial when rounding marks for example

 

 

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7 hours ago, sfigone said:

I just watched part 2 and i think you guys are assuming that both flaps on a foil are set equally. LR has the ability to set the flaps differently, so the center off lift can be moved out by differential flap settings.

Down wind, when you want negative leeway, then this is probably the default setting.

 

5 hours ago, Mozzy Sails said:

Not at all. I hint at the end of the video! Just for this discussion to isolate a single factor we kept it with equal total lift on each foil.  

Also you did not take into account the fact that foils give less lift as they approach the water surface, this has a greater affect with the anhedral foils than with the tee foils.

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2 minutes ago, Terry Hollis said:

 

Also you did not take into account the fact that foils give less lift as they approach the water surface, this has a greater affect with the anhedral foils than with the tee foils.

How so?

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3 minutes ago, jaysper said:

I think ventilation introduces entrained air, reducing the density of the water.

There is that, but I think @Terry Hollis is referring to the pressure gradient.

My question is about why would affect one foil arrangement over a different one.

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4 minutes ago, The Advocate said:

There is that, but I think @Terry Hollis is referring to the pressure gradient.

My question is about why would affect one foil arrangement over a different one.

The flat foil offers a more acute angle to the surface than the anhedral foil so that the flat foil can have a discrete portion of the leeward end breaking the surface, the anhedral foil is almost parallel to the surface so a larger portion at the leeward end is closer to the surface than with the flat foil.

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Just now, Terry Hollis said:

The flat foil offers a more acute angle to the surface than the anhedral foil so that the flat foil can have a discrete portion of the leeward end breaking the surface, the anhedral foil is almost parallel to the surface so a larger portion at the leeward end is closer to the surface than with the flat foil.

Copy that. I imaging that surface ventilation as @jaysper mention would screw with it though. I was thinking the other way in the the anhedral foil would have more area at a higher water pressure. I could very well be pissing into the wind though.

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4 hours ago, Paddywackery said:

Silly question Max, but I know you won’t shoot me ..... is there any give in the foil like suspension? I ask because aircraft wings move a lot at the tips. 

"No such thing as a silly question, only silly answers." :)

The foils are made from steel, and with up to 7.8 tonnes riding on them, they must have some flex on them I think!   Not being an engineer I don't know how much though.

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3 hours ago, Lickindip said:

ha - just watching your episode 2 so might have spoken too soon

I have an observation I don't think you have taken into account regarding combined vertical lift (your red arrow position)

(let's ignore foil tip out of water for a second)

image.png.a4bbe592c2376a43b1ea4642bafe42eb.png

 

image.png.57def1c9030ce59f7e0cf80c895be44f.png

LR with the more vertical lift coming off the outside half of the foil there will be a ratio someone can SohCahToa between the 2 halves ... this will move your red arrow outboard which would close the gap with the ETNZ flat foil centre. yes/no???

 

what gets more complicated is if LR are using different actuators for flaps and if ETNZ has only 1 actuator :lol:

Surely it's the horizontal forces (against the sail power) that we're trying to maximise, rather than the verticals which are only compensating for the (fixed) boat weight.  Which by this reasoning would make the anhedral dynamic even worse. 

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Since there is nothing new to analyze, I went back and combined data from (almost) all the previous races to make a bunch of scatter plots with pretty dots :D.

For every race, I averaged parameters for each boat from all segments of each race, when the boat was sailing relatively steady and in straight line (less than 2 kts speed change and less than 10 deg course change in 6 sec). Also, the speed had to be above 20 kts, so any non-foiling is cut out.

This time I calculated VMG, TWA and AWA using the GPS track, not the compass heading. This way, the leeway effect is included. Called them "Real" VMG, TWA etc. All parameters are plotted against wind speed on the horizontal axis.

VMG:

r_vmg.thumb.png.00be0ae946a90621910332dffaaf88f3.png

ETNZ showing good numbers in those few races, but LR and AM had some outstanding numbers, too. INEOS on the other hand tended to be on the wrong side of the trend line.

What's interesting is that LR didn't actually show good VMG numbers in the light, but like I said, this is all foiling at steady speed, so their ability to start foiling and accelerate better in light wind is cut out from this analysis. However, it seems that once the boats are up to speed, the ETNZ/AM concept is faster even in the light.

Speed:

bs.thumb.png.bdf61d79998f98d66d5fa747a316313b.png

TWA:

r_twa.thumb.png.262796aabd1632ab95d7bd2e363ca707.png

LR and ETNZ can both point high upwind. Sometimes AM, too, but INEOS was once again always on the wrong side of the line.

We talked a lot about AWA, and how close the boats can sail to the apparent, and I realized, I've never analyzed that before. So here it is, average AWA (once again using GPS track, so leeway is accounted for):

r_awa.thumb.png.80acd59c0a0f0ee7fc273636dded5fec.png

They can get down to ~ 11-12 degrees AWA between 10-15 kts wind. Again, ETNZ is always on the right side of the line, INEOS is always on the wrong side. The others are in between.

Some other interesting stuff - foil cant angle vs wind speed:

cant.thumb.png.7198bece3bcd890beca59c03ee01f1f5.png

Most interesting is how ETNZ and AM tended to use the highest cant angles upwind, and the lowest cant angles downwind. Showing the similarities between their approaches.

Pitch angle vs wind speed (positive is forward pitch)

pitch.thumb.png.00049464af9761d73235886399cbeace.png

Again, ETNZ and AM in one group, most bow-down. LR in the middle, and INEOS pitching forward the least.

Leeway:

leew.thumb.png.9c6517e3f9747431d2e47f56104ca3bd.png

Look how rapidly upwind leeway of INEOS increased with wind speed. The others didn't show a trend like that. I wonder why - foil issues?

Heel angle (negative is windward):

heel.thumb.png.2de5f8910d1b989e4f18515405926457.png

Some interesting differences. AM always heeling windward a lot, LR not so much. It's also surprising how the boats heel less to windward as the wind picks up. I thought it would go the other way. Using windward heel for roll stability.

There are of course potential errors in TWS readings, current, sea state etc, but this is what we have. It's like staring at the stars. Eventually you begin to see constellations:D. One thing seems obvious though - among the four boats, INEOS was the worst. They sailed very well in the RRs and looked much better than they were, but overall their boat performed the worst. AM could have achieved a lot more with if they had sailed better.

I wonder when F1 teams will start to brag about having AC engineers working for them!

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1 minute ago, Regular Swimmer said:

Surely it's the horizontal forces (against the sail power) that we're trying to maximise, rather than the verticals which are only compensating for the (fixed) boat weight.  Which by this reasoning would make the anhedral dynamic even worse. 

yes and no

we are taking the simplistic model of ...

image.png.40d6cae9af3ef1b5fa97e1ddcf81ed32.png

and trying to balance forces around the red dot.

the original discussion was to do with RM (hull, windward foil weight multiplied by the distance from leaver)

as above we were debating where that relative leaver (red dot) is ... quite clear its fairly central on the etnz T foil ... on LR, my pick is it's outside the symmetry plane due to geometry

 

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On 2/1/2021 at 10:58 PM, MaxHugen said:

Mozzie, I did the following diagram quite a while ago to convince myself that the net vertical and horizontal forces were the same for "equivalent" T and Y foils - they are of course.  I'm not sure about the torque you mention, but from the bottom right diagram, the Y foil appears to have net horizontal force a bit further outboard than the T foil, no flap differential used though.

image.png.b855cf783a3a41d5f175040c0025d09f.png

this guy is onto it with the angles and forces in the X/y

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3 minutes ago, Lickindip said:

yes and no

we are taking the simplistic model of ...

image.png.40d6cae9af3ef1b5fa97e1ddcf81ed32.png

and trying to balance forces around the red dot.

the original discussion was to do with RM (hull, windward foil weight multiplied by the distance from leaver)

as above we were debating where that relative leaver (red dot) is ... quite clear its fairly central on the etnz T foil ... on LR, my pick is it's outside the symmetry plane due to geometry

 

So... in your model, what's stopping the boat from going sideways (there's no keel remember).  I know that the discussion talked about righting moment but the real discussion was about how much wind power could be harnessed and turned into speed.  

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I'm amazed how these relatively complex discussions get ludicrously more complex.

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5 minutes ago, Lickindip said:

this guy is onto it with the angles and forces in the X/y

You are both talking about the same things, the resultant force vector.

That diagram supports your opinion on the shift of the CoL, which I agree with.

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32 minutes ago, Regular Swimmer said:

Surely it's the horizontal forces (against the sail power) that we're trying to maximise, rather than the verticals which are only compensating for the (fixed) boat weight.  Which by this reasoning would make the anhedral dynamic even worse. 

I think you are mixing the 3 degrees of "directional" forces, with the 3 degrees of "turning" forces called moments. Collectively they are called the 6 degrees of Freedom (6DoF):

image.png.ee7b4f1a94150866c8ecf8969245cd4c.png

https://en.wikipedia.org/wiki/Six_degrees_of_freedom

 

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33 minutes ago, Regular Swimmer said:

So... in your model, what's stopping the boat from going sideways (there's no keel remember).  I know that the discussion talked about righting moment but the real discussion was about how much wind power could be harnessed and turned into speed.  

image.png.6ac75e738efcbccf4e456c1588ede8fd.png

better?

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23 minutes ago, MaxHugen said:

I think you are mixing the 3 degrees of "directional" forces, with the 3 degrees of "turning" forces called moments. Collectively they are called the 6 degrees of Freedom (6DoF):

image.png.ee7b4f1a94150866c8ecf8969245cd4c.png

https://en.wikipedia.org/wiki/Six_degrees_of_freedom

 

No... I'm just saying that "roll" forces (or pitch or yaw) can be simplified out of the "how to handle the maximum force from the sails" analysis.

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2 minutes ago, Regular Swimmer said:

Yes. And if you want to harness more top green arrow you need more bottom green arrow.  That's all I'm pointing out ;-)

No, too simplistic.

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54 minutes ago, erdb said:

Since there is nothing new to analyze, I went back and combined data from (almost) all the previous races to make a bunch of scatter plots with pretty dots :D.

For every race, I averaged parameters for each boat from all segments of each race, when the boat was sailing relatively steady and in straight line (less than 2 kts speed change and less than 10 deg course change in 6 sec). Also, the speed had to be above 20 kts, so any non-foiling is cut out.

This time I calculated VMG, TWA and AWA using the GPS track, not the compass heading. This way, the leeway effect is included. Called them "Real" VMG, TWA etc. All parameters are plotted against wind speed on the horizontal axis.

VMG:

r_vmg.thumb.png.00be0ae946a90621910332dffaaf88f3.png

ETNZ showing good numbers in those few races, but LR and AM had some outstanding numbers, too. INEOS on the other hand tended to be on the wrong side of the trend line.

What's interesting is that LR didn't actually show good VMG numbers in the light, but like I said, this is all foiling at steady speed, so their ability to start foiling and accelerate better in light wind is cut out from this analysis. However, it seems that once the boats are up to speed, the ETNZ/AM concept is faster even in the light.

Speed:

bs.thumb.png.bdf61d79998f98d66d5fa747a316313b.png

TWA:

r_twa.thumb.png.262796aabd1632ab95d7bd2e363ca707.png

LR and ETNZ can both point high upwind. Sometimes AM, too, but INEOS was once again always on the wrong side of the line.

We talked a lot about AWA, and how close the boats can sail to the apparent, and I realized, I've never analyzed that before. So here it is, average AWA (once again using GPS track, so leeway is accounted for):

r_awa.thumb.png.80acd59c0a0f0ee7fc273636dded5fec.png

They can get down to ~ 11-12 degrees AWA between 10-15 kts wind. Again, ETNZ is always on the right side of the line, INEOS is always on the wrong side. The others are in between.

Some other interesting stuff - foil cant angle vs wind speed:

cant.thumb.png.7198bece3bcd890beca59c03ee01f1f5.png

Most interesting is how ETNZ and AM tended to use the highest cant angles upwind, and the lowest cant angles downwind. Showing the similarities between their approaches.

Pitch angle vs wind speed (positive is forward pitch)

pitch.thumb.png.00049464af9761d73235886399cbeace.png

Again, ETNZ and AM in one group, most bow-down. LR in the middle, and INEOS pitching forward the least.

Leeway:

leew.thumb.png.9c6517e3f9747431d2e47f56104ca3bd.png

Look how rapidly upwind leeway of INEOS increased with wind speed. The others didn't show a trend like that. I wonder why - foil issues?

Heel angle (negative is windward):

heel.thumb.png.2de5f8910d1b989e4f18515405926457.png

Some interesting differences. AM always heeling windward a lot, LR not so much. It's also surprising how the boats heel less to windward as the wind picks up. I thought it would go the other way. Using windward heel for roll stability.

There are of course potential errors in TWS readings, current, sea state etc, but this is what we have. It's like staring at the stars. Eventually you begin to see constellations:D. One thing seems obvious though - among the four boats, INEOS was the worst. They sailed very well in the RRs and looked much better than they were, but overall their boat performed the worst. AM could have achieved a lot more with if they had sailed better.

I wonder when F1 teams will start to brag about having AC engineers working for them!

Excellent analysis thanks! It woul