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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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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

Data from yesterday's races - no big surprise, but there are some interesting things. I've excluded the first few minutes from Race-1 when INEOS was off the foils. As was obvious during broadcast

Posted Images

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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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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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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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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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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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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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 would be great to see a trend line for each boat on these charts if possible. What would also be very interesting to see is a plot of ETNZ with and without speculated sandbagging as two different colours - i.e. Christmas regatta vs cup match

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10 minutes ago, Regular Swimmer said:

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.

Unfortunately all 6DoFs need to be balanced at the same point in time, which is what makes the calculations so complex. And every one of them is tied to the force on the sails.

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11 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 ;-)

yes and no. you are trying to balance leeway. I'm trying to balance RM

in the simplistic (ignore the rudder etc) try Zero the force moments around the red dot. the leeway provided by the foils (ignore the upright pretty much cancel each other out (etnz style) so all you are left with is to balance weights vs sail force to keep in balance. more weight / distance = more sail force

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1 hour 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!

Very nice work.  It does get you wondering about how AM would have done without crashing...  So far LR has shown the best boat handling and that has gone a long way.

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15 minutes ago, The Advocate said:

Question.

If the flap AoA is unequal, would it shift the CoL? Could that be a technique LR is using to move the CoL further outboard?

Assuming you mean the Vertical force (Fz), yes.  A certain amount of Fz is required - too much and the boat rises and vice versa. Increasing flap angle on the leeward wing increases the combined wing/flap AOA, thus increases the Resultant force (Fr) and Fz, and to compensate, the windward foil needs to reduce flap angle to maintain the same required Fz.

But as always there is a tradeoff, as the windward wing produces more Lateral force (Fy) when flaps are at the same angle. Reducing flap there thus reduces Fy, so more leeway.

"No such thing as a free lunch" in these boats either!  :D

 

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Thanks Erdb.

This supports my observations that  GBR were the slow boat (but sailed well in the RR's). I think overall their campaign lacked the finesse you would expect from a winning campaign. Really not much better than Bermuda!

Also it doesn't really paint LR in a good light. LR is not really performing well in any category. Even without performance figures the history and sheer capability of ETNZ would be a daunting target. These figures make it just that much harder. The constant view that LR is setup for light air races I do not think will be shown to be correct. When they line up against ETNZ in the light I still see an advantage (and a reasonable one) for ETNZ.

As for AM - what may have been if they didn't have their off! They could have given LR a good test in the semi's with some more time for crew work and development rather than fixing the hole.

 

 

 

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11 minutes ago, Barnyb said:

Thanks Erdb.

This supports my observations that  GBR were the slow boat (but sailed well in the RR's). I think overall their campaign lacked the finesse you would expect from a winning campaign. Really not much better than Bermuda!

Also it doesn't really paint LR in a good light. LR is not really performing well in any category. Even without performance figures the history and sheer capability of ETNZ would be a daunting target. These figures make it just that much harder. The constant view that LR is setup for light air races I do not think will be shown to be correct. When they line up against ETNZ in the light I still see an advantage (and a reasonable one) for ETNZ.

As for AM - what may have been if they didn't have their off! They could have given LR a good test in the semi's with some more time for crew work and development rather than fixing the hole.

 

 

 

I think you're unfair to INEOS. They aren't great, but a lot better than Bermuda and not that far behind LR.

I agree that the whole myth about LR being shit hot in light airs will only be HALF right, in that they will be shit but not hot.

To think ETNZ will not be prepared for light airs is absurd. LR are going to receive a king sized reaming.

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11 hours ago, Xlot said:

Does anyone know what the extension jutting out from the trailing edge on ETNZ foil is for? Been meaning to ask for ages..

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5 hours 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.

Very true. 

We also didn't take in to consideration that each semi wings CoL will be nearer the root than the tip. This makes no difference for the T foil, but again recues righting moment for the anhedral. But alas, there is only so much time!

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7 minutes ago, Mozzy Sails said:

Very true. 

We also didn't take in to consideration that each semi wings CoL will be nearer the root than the tip. This makes no difference for the T foil, but again recues righting moment for the anhedral. But alas, there is only so much time!

Not really, there is no time limit on YouTube videos.

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7 hours 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

You can't just draw balance the vertical component though. Truth is the foils have no idea which direction is X and Y. Add in the X component and then balance.  

The way you have drawn it the CoL would constantly change depending on how you orientated the foil on your page!

I mean, draw a foil with a right angle? What could possibly be the conclusion there? 

 

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10 minutes ago, Mozzy Sails said:

You can't just draw balance the vertical component though. Truth is the foils have no idea which direction is X and Y. Add in the X component and then balance.  

I mean, draw a foil with a right angle? What could possibly be the conclusion there? 

 

The point of the diagram was CoL though?

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4 minutes ago, The Advocate said:

The point of the diagram was CoL though?

Yes, but those aren't the lift. Those are not the resultant forces. If they were, yes, but they're not.  Those are Y components of the lift. 

I mean, rotate the foil on the piece of paper and the CoL would change relative to the foil. Despite all geometry saying the same. 

The foil does not know what you are defined the X-Y refence frame as. 

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1 minute ago, Mozzy Sails said:

Yes, but those aren't the lift. Those are Y components of the lift. 

I mean, rotate the foil on the piece of paper and the CoL would change relative to the foil. Despite all geometry saying the same. 

The foil does not know what you are defined the X-Y refence frame as. 

Ok.

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On 2/1/2021 at 9:58 AM, 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

And all this is correct in how the forces are drawn, but the conclusion that "the Y foil appears to have net horizontal force a bit further outboard than the T foil" is very misleading. That is not shown here. 

The vertical component is greater on the outboard wing. But that is a force component. 

I mean, otherwise just rotating the foil on your piece of paper changes the CoL. 

How can tilting the foil on your piece of paper change where the CoL is?

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Imagine roll stability in a plane. 
Anhedral is unstable, in that as the plane rolls the gravitational force start pulling the mass further over to the side inducing more roll. But is is not the CoL which is changing position relative to the wings and fuselage, but that the gravity is pulling in a different direction once the plane starts to roll (relative to aircraft). 

Now, people draw this as gravity staying a fixed direction and the plane rotation on the diagram. But it would show up the same if you fixed the rotation of the plane on the diagram and rotated gravity. The result is not dependent on what you label X and Y. You could fix the plane as your reference frame, or the direction of gravity and still come to the same conclusion. 

You should be able to orientate you X-Y reference frame in any direction you like and get the same result. 

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29 minutes ago, Mozzy Sails said:

How can tilting the foil on your piece of paper change where the CoL is?

I'm unsure of your question... are you referring to the Vertical force  (FZ)?

As there's obviously some interest in force CEs and Flap factors in Y foils, I've done a few calcs.  LR's foil has been used as the example, and the required Vertical Force (FZ) for balance of forces in the y plane is set at 70,000 Newtons (about 6.8 tonnes-force).

Diagram 1 shows an approximation of the Centroid of the foil, although strictly speaking this is probably not quite the CE - but it will have to do.

image.png.8bf822b5f3a34e217b1aa52ae73daf58.png

Diagram 2 shows the foil at 20° cant. LR data during the Challenger Finals indicated a range of 18-20° - notably less than TR during the ACWS (median = 22°).

Both flaps are at equal angle. The Resultant (Lift) Force (FR) is therefor equal for each wing, and is perpendicular to the foil cant angle.

The CE of both FZ (vertical force) and FY (lateral force) have also been calculated, and if we were to use the FR (or the foil/bulb intersection) as the "axis of rotation" for the calculation of moments, both FZ and FY should be included for somewhat greater precision.

image.thumb.png.f1dc71c26fb4c93e102f9cad67f16758.png

Coming to a forum near you, "in the fullness of time", ... maybe... will be an attempt to quantify the effects of using differential flaps to increase the CE-FZ offset. This will again be calculated on the basis of requiring a total FZ = 70,000 N.  :)

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