Steve Clark

Means of propulsion

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I just got schooled in a previous thread for not knowing that The defined "illegal actions" had been removed from Rule 42 in this event. Which pretty much opens the door for unlimited kinetics or human propulsion as long as it is attached to the wing, sails, rudders or daggerboards or is otherwise an "act of seamanship."  

This has completely changed my view of the event. Instead of viewing the athletes as providing power to "normally" adjust the sheets,  pull the boards up and down and provide enough juice to adjust the AoA of the main foil, it is now clear that the metabolic energy of the grinders can be used to propel the vessel by pumping the wing or other actions. Some have already poo pooed this, but I think it is significant and gives ETNZ a huge edge.  Previously, I believed that an efficient control system and forgiving foil design could compensate for the lack of pure horsepower. 

Earlier, 800  watts was sighted as the  power premium of 4 cyclist versus 4 hand grinders. What was not given is the duration and intensity of the pumping. It is clear from the videos that the grinders are not pumping  all the time and are not pumping hard all. Of the time. The cyclist, on the other hand, seem to be spinning the cranks 100% of the time. Does anyone want to hazard a guess what the difference in energy production during the course of a race is?

I expect this advantage to manifest itself most in marginal foiling conditions, where ETNZ will foil sooner and longer, and also on the down wind legs where they should be able to foil deeper at the same or better speed.  If they can trim faster, they will accelerate off the starting line faster.  Finally they should be able to tack and gybe  faster simply because the human power will buffer the loss of aerodynamic drive. One horsepower isn't much, except when it really matters.

Let me be absolutely clear, I do not regard this as cheating.  It is absolutely within the rules as written, but not within the rules as understood by fools like me who thought they knew the rules. I could believe the simplification was done to avoid another charge of cheating against Oracle by ETNZ.  I know how hard it is to police kinetics, and it has become customary in many classes to have a wind speed at which the Race Committee can declare "game on" but this is different. ETNZ deserves a golf clap for taking advantage of this opportunity. 

If anyone can quantify the difference between the arm grinders time producing x power and the cyclists producing y power, I think it would inform all of our appreciation of the events to come.

SHC

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2 hours ago, Steve Clark said:

I just got schooled in a previous thread for not knowing that The defined "illegal actions" had been removed from Rule 42 in this event. Which pretty much opens the door for unlimited kinetics or human propulsion as long as it is attached to the wing, sails, rudders or daggerboards or is otherwise an "act of seamanship."  

This has completely changed my view of the event. Instead of viewing the athletes as providing power to "normally" adjust the sheets,  pull the boards up and down and provide enough juice to adjust the AoA of the main foil, it is now clear that the metabolic energy of the grinders can be used to propel the vessel by pumping the wing or other actions. Some have already poo pooed this, but I think it is significant and gives ETNZ a huge edge.  Previously, I believed that an efficient control system and forgiving foil design could compensate for the lack of pure horsepower. 

Earlier, 800  watts was sighted as the  power premium of 4 cyclist versus 4 hand grinders. What was not given is the duration and intensity of the pumping. It is clear from the videos that the grinders are not pumping  all the time and are not pumping hard all. Of the time. The cyclist, on the other hand, seem to be spinning the cranks 100% of the time. Does anyone want to hazard a guess what the difference in energy production during the course of a race is?

I expect this advantage to manifest itself most in marginal foiling conditions, where ETNZ will foil sooner and longer, and also on the down wind legs where they should be able to foil deeper at the same or better speed.  If they can trim faster, they will accelerate off the starting line faster.  Finally they should be able to tack and gybe  faster simply because the human power will buffer the loss of aerodynamic drive. One horsepower isn't much, except when it really matters.

Let me be absolutely clear, I do not regard this as cheating.  It is absolutely within the rules as written, but not within the rules as understood by fools like me who thought they knew the rules. I could believe the simplification was done to avoid another charge of cheating against Oracle by ETNZ.  I know how hard it is to police kinetics, and it has become customary in many classes to have a wind speed at which the Race Committee can declare "game on" but this is different. ETNZ deserves a golf clap for taking advantage of this opportunity. 

If anyone can quantify the difference between the arm grinders time producing x power and the cyclists producing y power, I think it would inform all of our appreciation of the events to come.

SHC

I think trg stated (before he was banned) that the resistance the cyclists experience is probably variable so that they always crank the same speed but the power harnessed is constantly varying. 

I know very little about hydraulics so can only present what he said with a blank stare ;)

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Not long to find out how effective those cyclors will be, SHC. And how quickly OTUSA can convert, fully.

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SHC, thanks for starting this thread. It links in with a question I have posed here before, which hasn't been answered- lower limb musculature will provide almost three times more energy than the upper limbs. Assuming ETNZ are providing at least twice as much more energy, where is it going? It hasn't translated into a obvious speed edge that I can see. So do people think that there is a 'sandbagging effect' where they don't use all the extra power produced to keep some cards up the sleeve for later or is this system much ado about nothing.

Logic suggests more power will allow micro adjustment of the foils and wing which should translate into better straightline speed, a longer time spent on foils and greater manoeuvrability. At least I'd like to hope so.

Thoughts?

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I don't know exactly, but the top portion of the flap is probably around 20 square meters.

100 m^2 total wing area, ~50% flap, a bit less than half of it being eased and trimmed.

How much energy to you think it takes to move the end of that control rib from neutral to +/- 20 degrees at an apparent wind of ~40 knots?  And they seem to be able to do it 30+ times a minute. My estimate is "quite a lot."

Perhaps one of our informed participants can tell us how big the  "approved" accumulators and what pressures they are allowed to  run at to get a handle on  how much energy the could harvest and store as a way of grounding this discussion.

Facts help.

SHC

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Two separate storage system one for raising and lowering of dagger boards with 2 pressure vessel and another for cant/rack with one.

Wing/sail is direct power!

Artimus have gone to great lengths to develop systems and methods to limit power on these two sub system. With what looks like pressure recovery with the double tackel board crains and curved vertical profile of the boards 

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@SHC

Now we are talking. This is an amazing development, breaking open a big innovation of both ETNZ and OR (and possibly TJ and Ar).

How much of the 100% more energy that ETNZ have will be translated into extra speed?

We have seen that more control of the wing seems to translate into more stability, of course trying to do tricky things with the wing might lead to less Stability.

30 times a minute, doing 40 knots is 20m/sec or 1200m/minute, so 30 times per minute is once every 40 metres. which is not fast if you are not travelling in a straight line.  It is only keeping the wing at optimum to the AW.

Now how much energy to do it ?  I don't know even where to start !

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3 hours ago, NZL5 said:

Logic suggests more power will allow micro adjustment of the foils and wing which should translate into better straightline speed, a longer time spent on foils and greater manoeuvrability. At least I'd like to hope so.

I think what Steve is saying is that the rules open the door for macro movements; essentially pumping. 

 

This is what windsurfing is to dinghy racing.

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^Ex-yachtie

Do you pump when you are going flat out or just when accelerating?

 

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2 minutes ago, Kiwing said:

^Ex-yachtie

Do you pump when you are going flat out or just when accelerating?

 

I sit on the couch pretending to know what I'm talking about. 

 

Windsurfers pump as much as they can but especially when the situation means that more speed can provide big tactical advantages. They also have planning to worry about = foiling?

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^Kiwing

Its not about about pumping in the traditional sense of generating power, but achieving  max power at minimum drag and given stable heeling moment

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21 minutes ago, justsomeone said:

^Kiwing

Its not about about pumping in the traditional sense of generating power, but achieving  max power at minimum drag and given stable heeling moment

I'm using pumping as the closest thing I can get my mind around and experienced to try to get into the head space were these wings are.

Sorry 1967 summer with a paper tiger is the limit of my cat experience. And while I do pump the laser sail to get home I don't usually do it.

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Don't have to be sorry. These machines are out of the experience of most of us.

The death of development classes in NZ just means even less people are exposed to thinking about sailing at hardware level.

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" it is now clear that the metabolic energy of the grinders can be used to propel the vessel by pumping the wing or other actions."

Sorry, I cannot follow your logic at all - you are not suggesting pumping in the accepted meaning of the term, given the speeds these things move at,  even pre-foiling, so what you are referring to is just rapid trimming.

So it's not pumping or propulsion in ANY sense that I understand?

 

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Some try to make this so simple, but it is not. While we know that the ETNZ grinders can produce more "power", we have no idea how much of that extra power  allows them to do more. The issue is the efficiency of the systems. By way of example, take BAR and Artemis in the informal racing in January. Both had hand grinders so five or take, their input was the same. BAR kept running out of hydro and had to stop racing while Artemis cruised around with the grinders not having to work all the time. Even after they moved to the AC50's, BAR started off having hydro issues and they have improved their systems so this is far less obvious.

This is a 2 sided equation. First there is how much power you can generate and ETNZ is leading that. Then there is how much power it takes to do the tasks and it seems pretty clear to me that some teams have systems that need less power to do the same things that other teams need more power. I guess that is what might be termed power efficiency of the systems. What are the chances that ETNZ have the most power efficient systems? I would suggest not high because statistically it can be no better than 1 in 5 but they have also spent less time on the water and it is clear that time on the water is a big factor in the hydro systems development. Therefore, I believe it is highly likely that some of the ETNZ extra grinding power is being used just to get level with the best out there.

The other thing that surprises me about the ETNZ grinding is that they are always pedalling. There doesn't seem to me to be any free wheeling at all from 3 of the 4. Again, contrast that with Artemis and you see periods when none of their grinders are in action. Artemis grind less than any other team and it certainly doesn't hurt their speed. Again, this points to differences in efficiency of systems.

The other thing the ETNZ fanboys seem determined to ignore is that Artemis is also "flapping" the wing in the same way (I prefer "flapping to "pumping"!). I wouldn't have noticed because for some reason, there is far less video taken from the right angle, but having read Bora Gulari's report on this, I watched some videos and I am pretty sure he is correct. Maybe ETNZ is "flapping" a bit more, but they aren't the only one that is using up hydro for that. I have yet to see any evidence that ETNZ can do things with their hydro that another team cannot, although what nobody knows is if their extra power allows them to do things more often.

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I'm sure we'd all love to know what ETNZ is doing with all that extra power/hydro, and as you say, the evidence is that some teams think they would benefit from more. But going back to the title of this thread, I guarantee they want it for better control, not propulsion.

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21 minutes ago, weta27 said:

" it is now clear that the metabolic energy of the grinders can be used to propel the vessel by pumping the wing or other actions."

Sorry, I cannot follow your logic at all - you are not suggesting pumping in the accepted meaning of the term, given the speeds these things move at,  even pre-foiling, so what you are referring to is just rapid trimming.

So it's not pumping or propulsion in ANY sense that I understand?

 

Correct, its not about generating power its about using it! The wing generate a lot of power.

Stable flight  is a pre-requisite  for speed

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4 minutes ago, weta27 said:

I'm sure we'd all love to know what ETNZ is doing with all that extra power/hydro, and as you say, the evidence is that some teams think they would benefit from more. But going back to the title of this thread, I guarantee they want it for better control, not propulsion.

Agreed. Any gain in propulsion would be infinitesimal compared to loss of efficiency. 

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Why does it have to be so black and white? - yeah I know it's SA, there is no compromise. 

I think it's a potential to be 'pumping', 'flapping', 'trimming' and 'depowering' options all in the same solution. 

Hard to engineer into a typical soft rig, as the mast and sail need to be different stiffness, yield and optimal draft/twist to achieve all these.  But with a wing, these options all become variables that can be fine tuned at will - if you have the systems and power. 

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Hey everyone, I'm sorry I used the idea "pumping" it does not seem to be that and in my post about a trim every 40 metres I was sort of saying it is not pumping.

Once again sorry for PUMPING.

My first trip Sydney to Auckland took 5 days on the fastest thing available. I remember the 12 hours Sunderland flight as amazingly fast !!

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Yes, it's not black and white, but shades of gray, with different teams advancing or ignoring various areas of development according to their designs.

The team that creates a rainbow from their shades of gray will win... 8)

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When there is no news poetry - wow

better than shit !!!

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Yeah, some fucker had better put a boat on the water before haikus start appearing...

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27 minutes ago, Kiwing said:

All fanboys are dreaming all the time ...

Ain't that the truth.

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36 minutes ago, Nutta said:

Yeah, some fucker had better put a boat on the water before haikus start appearing...

 

32 minutes ago, Ex-yachtie said:

Win at any cost. Aye.
Skip a race, lie, or sandbag.
We are diminished.

Credit: http://www.apparent-wind.com/haikus.html

Team New Zealand Will

Win The Americas Cup 

With Their Foiling Boat

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1 hour ago, Team_GBR said:

I have yet to see any evidence that ETNZ can do things with their hydro that another team cannot, although what nobody knows is if their extra power allows them to do things more often.

Exactly......yet to see.

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9 minutes ago, Nutta said:

 

Team New Zealand Will

Win The Americas Cup 

With Their Foiling Boat

2019?

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Twenty Nineteen Will

Be the second time that the

New Zealand Boat Wins

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28 minutes ago, Nutta said:

Twenty Nineteen Will

Be the second time that the

New Zealand Boat Wins

I doubt that. Are you trying to tell me GD will join the cartel, after an AC35 win?

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"

16 hours ago, Steve Clark said:

The cyclist, on the other hand, seem to be spinning the cranks 100% of the time

Lets try to get this back on track, a discourse on technologies.

One reason for the full time cranking is its easier to load up than start up. they could be not much more than free wheeling for part of the time

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I'm really hoping that TNZ win by cheating that is somehow untouchable by the jury.  Payback fucking time.

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As a former windsurfer with previous posts about this, pumping is mainly used to accelarate and get the board on the plane in higher winds, however in lower winds you can virtually generate your own wind by pumping and achieve a considerable speed in windless conditions = critical advantage for ETNZ - I for one cannot help think that OTAUS will try and copy and that the first effort was merely deception to try and ensure the other teams think that a simple add on with a cyclor without handlebars can do the job - fortunately and as alluded to ETNZ have this time left the reveal too late for easy copying....

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I'm curious has anyone trolled patents filed by any of the teams? That would be an interesting revelation .

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Request for Drawing Question / Interpretation No. 9A 

Gas  return springs greater than 50J acting on one control surface. Jib positioning, wing flapping?

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10 hours ago, Nutta said:

Yeah, some fucker had better put a boat on the water before haikus start appearing...

I wrote this limerick in a boring spell during the AC34 LV series, in reply to a post by snaerk (o wearfour art thow snaerk?!):

Tucker Thompson was once heard to say

Andy there's TWO 72's on the bay!

Better fetch for yourself

Something from the top shelf

While we figure out just what to say

 

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Moving the entire wing to get up on the foils early or in marginal conditions, like the windsurfer examples ^ seems reasonable, likely even. It may even be an added advantage to those teams with adequate power if they are set up to do it - but has there been any sign of it yet by anyone (not counting OTUSA in AC34 - as you no longer have to 'restart' after each manoeuvre)?

 

The movement of the ETNZ top flap, as per the OP, is a different (and smaller) kettle of fish and seems like part of normal trimming to me, especially given when and where it occurs.

 

I very much doubt they have predicated their system on pumping their way around the course in light winds - and with the just released change in the wind measurement protocol really sticky conditions are less likely now than ever.

 

 

 

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Rather than helping in marginal conditions, wouldn't you run a less cambered (lower drag) foil than the others, with the pumping/fanning getting you airborne at the same wind speed as others on fatter foils?

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^ or that - but one takes the whole wing and uses the sheet/traveller (any sign of it yet?), the other, (just the top flap as per OP), is not going to achieve the same thing - nor is there any sign of it being used in that way so far AFAIK??

 

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I believe the research shows that it always pays to pump.  The effect is due to hysteresis, where you can stretch the operating conditions by oscillating the surfaces such that the foil is generating more lift than it would in a steady state. Think fish swimming, birds flying and those guys pumping hydrofoil surfboards around by just bending their knees in the right ways.   Birds with their wing still sink like sailplanes, when they flap, their wings generate enough more force that they can climb.  Usually in sailing, it gets too hard when the wind gets up and the loads become large, but it always faster.  

No doubt the aerodymanisits on the forum will correct this, but I am very confident. 

Beast mode was not physically sustainable in AC 34, and according to the Oracle are cheaters brigade, exceeded what was permissible under Rule 42.  Having removed the prohibited actions from Rule 42 for AC 35, the Kiwi may well have devised a way to sustainably flap the flap all the time.  It may be that the top of the flap is the most they can sustainably pump given the limits of power.  I am sure they studied the opportunities and developed the most promising option.

Artimis may have a very active flap as well, but I think this is probably more passive and relies on the springiness of materials. artimis seems to spend less time spinning the handles than the other teams, and this suggests that they have some very refined design of the various elements, or really sophisticated control systems that sip oil where other guzzle.

 

SHC

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1 hour ago, Happie Jack said:

Lolz... do you sail or sit on leadmines?

If you have anything to add  feel free....

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1 hour ago, Steve Clark said:

I believe the research shows that it always pays to pump.  The effect is due to hysteresis, where you can stretch the operating conditions by oscillating the surfaces such that the foil is generating more lift than it would in a steady state. Think fish swimming, birds flying and those guys pumping hydrofoil surfboards around by just bending their knees in the right ways.   Birds with their wing still sink like sailplanes, when they flap, their wings generate enough more force that they can climb.  Usually in sailing, it gets too hard when the wind gets up and the loads become large, but it always faster.  

No doubt the aerodymanisits on the forum will correct this, but I am very confident. 

Beast mode was not physically sustainable in AC 34, and according to the Oracle are cheaters brigade, exceeded what was permissible under Rule 42.  Having removed the prohibited actions from Rule 42 for AC 35, the Kiwi may well have devised a way to sustainably flap the flap all the time.  It may be that the top of the flap is the most they can sustainably pump given the limits of power.  I am sure they studied the opportunities and developed the most promising option.

Artimis may have a very active flap as well, but I think this is probably more passive and relies on the springiness of materials. artimis seems to spend less time spinning the handles than the other teams, and this suggests that they have some very refined design of the various elements, or really sophisticated control systems that sip oil where other guzzle.

 

SHC

You are slowly catching up with the RRS AC Steve....but not quite

Here is Ver 1 from 2011 on Propulsion

 

42 PROPULSION
42.1 A yacht shall compete only by using the wind and water to increase, maintain or decrease her speed.
Her crew may adjust the trim of the wing, sails, rudders, daggerboards and hulls, and perform other acts of seamanship
 
42.2 (a bit about towing)
 
So no important changes between AC34&35
 
You seem very invested in proving that the use of the ETNZ flap is for more than trim. Why is that?

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2 minutes ago, nav said:

You are slowly catching up with the RRS AC Steve....but not quite

Here is Ver 1 from 2011 on Propulsion

 

42PROPULSION
42.1
A yacht shall compete only by using the wind and water to increase, maintain or decrease her speed.
Her crew may adjust the trim of the wing, sails, rudders, daggerboards and hulls, and perform other acts of seamanship
 
plus a bit about towing
 
So no important changes between AC34&35
 
You seem very invested in proving that the use of the ETNZ flap is for more than trim. Why?
42

I fail to see how you draw that conclusion from what SC has said in this thread.

Maybe in other threads, I don't know.

It sure seems that if certain teams can flap (verb) their wings, it should transfer human energy into propulsion  in a way cunning way. It does seem a perhaps unintended consequence of the change to the racing rules but thats how you win in a technical competition.

Find an advantage and exploit it.

Oracle did that quite well in the last go round.

Go ETNZ.

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8 hours ago, random said:

I'm really hoping that TNZ win by cheating that is somehow untouchable by the jury.  Payback fucking time.

By NOT cheating, then. 

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If there was no difference between A C34 &AC35 what was all that bitching about Oracle pumping their wing? I understood it if the conventional RRS had been in place, but as they weren't, what was the point? Just to throw another turd on the Oracle sucks flaming dung heap.

SHC

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7 hours ago, Steve Clark said:

If there was no difference between A C34 &AC35 what was all that bitching about Oracle pumping their wing? I understood it if the conventional RRS had been in place, but as they weren't, what was the point? Just to throw another turd on the Oracle sucks flaming dung heap.

SHC

You got it, Steve. If they weren't cheating by pumping, they were cheating with "herbie" or they had hidden parts or they had hidden code or, or, or. Some simply refuse to believe that OR could improve as much as they did, even though they ignore that ETNZ also improved a lot during the racing, but not by as much as OR. People ignore that ETNZ was foiling upwind by the end of the racing yet nobody questions how they managed it despite not changing anything on their boat. OR added lots of new gear and people are surprised they improved.

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^^ ^ Straw man much? One sets it up and then together you knock it over. ;)

At least steve is getting to grips with AC history - another couple of threads and he'll get it.

Others have insisted nothing new was added!? But sure have it both ways, whatever suits the argument eh?

The book containing the accusation was written by an American IIRC but carry on with this baseless attacks guys or maybe teamgbr can find us something positive and post it in the team uk thread?

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11 hours ago, Steve Clark said:

If there was no difference between A C34 &AC35 what was all that bitching about Oracle pumping their wing?

 

can-stock-photo_csp11820651.jpg

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2 hours ago, dogwatch said:

can-stock-photo_csp11820651.jpg

You missed lawyers in there, this is the AC, there are always lawyers in there!

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18 hours ago, Steve Clark said:

I believe the research shows that it always pays to pump.  The effect is due to hysteresis, where you can stretch the operating conditions by oscillating the surfaces such that the foil is generating more lift than it would in a steady state. Think fish swimming, birds flying and those guys pumping hydrofoil surfboards around by just bending their knees in the right ways.   Birds with their wing still sink like sailplanes, when they flap, their wings generate enough more force that they can climb.  Usually in sailing, it gets too hard when the wind gets up and the loads become large, but it always faster.  

No doubt the aerodymanisits on the forum will correct this, but I am very confident. 

Beast mode was not physically sustainable in AC 34, and according to the Oracle are cheaters brigade, exceeded what was permissible under Rule 42.  Having removed the prohibited actions from Rule 42 for AC 35, the Kiwi may well have devised a way to sustainably flap the flap all the time.  It may be that the top of the flap is the most they can sustainably pump given the limits of power.  I am sure they studied the opportunities and developed the most promising option.

Artimis may have a very active flap as well, but I think this is probably more passive and relies on the springiness of materials. artimis seems to spend less time spinning the handles than the other teams, and this suggests that they have some very refined design of the various elements, or really sophisticated control systems that sip oil where other guzzle.

 

SHC

I'm not sure exactly what the research shows, but you only mention generating more lift. So, what about conditions where the boat is fully powered up & they need to trim to minimize drag?

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20 hours ago, Steve Clark said:

I believe the research shows that it always pays to pump.  The effect is due to hysteresis, where you can stretch the operating conditions by oscillating the surfaces such that the foil is generating more lift than it would in a steady state. Think fish swimming, birds flying and those guys pumping hydrofoil surfboards around by just bending their knees in the right ways.   Birds with their wing still sink like sailplanes, when they flap, their wings generate enough more force that they can climb.  Usually in sailing, it gets too hard when the wind gets up and the loads become large, but it always faster.  

No doubt the aerodymanisits on the forum will correct this, but I am very confident. 

Beast mode was not physically sustainable in AC 34, and according to the Oracle are cheaters brigade, exceeded what was permissible under Rule 42.  Having removed the prohibited actions from Rule 42 for AC 35, the Kiwi may well have devised a way to sustainably flap the flap all the time.  It may be that the top of the flap is the most they can sustainably pump given the limits of power.  I am sure they studied the opportunities and developed the most promising option.

Artimis may have a very active flap as well, but I think this is probably more passive and relies on the springiness of materials. artimis seems to spend less time spinning the handles than the other teams, and this suggests that they have some very refined design of the various elements, or really sophisticated control systems that sip oil where other guzzle.

 

SHC

   The comparison to fish, birds and windsurfers is valid minus one important element,  you can clearly SEE them pumping.  We are not seeing obvious pumping w ETNZ or any of the other teams. 

  I think to have any meaningful effect, the pumping would be pretty dramatic and clearly visible.

 

  Watch ETNZ go through various maneuver and straight lining it,  aside from some subtle wing trimming, there is no evidence of dramatic flapping or pumping of the wing...

 

 

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I guess people just don't see what I see. I see a wing which has a much more active upper flap than the other wings sailing at the same time in the same conditions. This would take additional power, which explains the cyclors.

SHC

 

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9 minutes ago, Steve Clark said:

I guess people just don't see what I see. I see a wing which has a much more active upper flap than the other wings sailing at the same time in the same conditions. This would take additional power, which explains the cyclors.

SHC

 

Agree

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One of prerequisite  for speed is stable flight about all axis. Sail trim and small adjustments to the stabilisers is the most effective way of maintaining that balance

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52 minutes ago, FinnFish said:

This taking on shades of DL in the foiling thread.

I am not surfe who you think is being DL on this thread. I hope you aren't suggesting it is Steve Clark, because outside of the AC, he is the most experienced wing designer/builder in the world. The wings he and his team designed and built 20 years ago literally "wrote the book" on the subject. He has probably built and/or rebuilt more wings than most of the AC teams have. He not only knows what he is talking about, but he has "been there, seen it, done it".

Steve is correct regarding the active upper flap. I would argue that Artemis does it as well, but slightly less frequently while with others, you cannot see it going on.

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I agree SHC.  I see ETNZ moving the top of the wing much more than others.  On a regular cat, it would be as if someone could play the cunningham through an enormous range in rapid cycles beyond what the gear we have is capable of.

The articles about the team say Glenn has become an excellent hydraulic operator and may do construction if sailing stops working out.  It appears much more sophisticated than the the old sheet on a winch. 

 

 

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On 5/22/2017 at 5:21 AM, Steve Clark said:

I believe the research shows that it always pays to pump.  The effect is due to hysteresis, where you can stretch the operating conditions by oscillating the surfaces such that the foil is generating more lift than it would in a steady state. Think fish swimming, birds flying and those guys pumping hydrofoil surfboards around by just bending their knees in the right ways.   Birds with their wing still sink like sailplanes, when they flap, their wings generate enough more force that they can climb.  Usually in sailing, it gets too hard when the wind gets up and the loads become large, but it always faster.  

No doubt the aerodymanisits on the forum will correct this, but I am very confident. 

Beast mode was not physically sustainable in AC 34, and according to the Oracle are cheaters brigade, exceeded what was permissible under Rule 42.  Having removed the prohibited actions from Rule 42 for AC 35, the Kiwi may well have devised a way to sustainably flap the flap all the time.  It may be that the top of the flap is the most they can sustainably pump given the limits of power.  I am sure they studied the opportunities and developed the most promising option.

Artimis may have a very active flap as well, but I think this is probably more passive and relies on the springiness of materials. artimis seems to spend less time spinning the handles than the other teams, and this suggests that they have some very refined design of the various elements, or really sophisticated control systems that sip oil where other guzzle.

 

SHC

I see subtle changes in the top elements, normally can see small changes in heel just before the trim; ie GA is trimming out gusts, changes in AWA, balance due to crew.

Having dabbled in high performance paragliding, the norm for the best glide was not to flap but to trim constantly and subtly using a "speed bar", device to change all lines proportionately to alter angle of attack, or by "sweating" rear lines to minutely change profile. Using the actual "brakes" controls is inefficient, and Flapping causes such disruption in flow it's only used in landings to micro stall the wing and reduce lift at low speeds.

Oh and beast mode, well you probly know my beliefs based on the video I made of high frequency changes on OR in 34 with no apparent attention by Jimmmmy whilst sailing upwind with very low, *very* stable ride height to reduce leeway. ETNZ foiled upwind, but did not have the consistent low height resulting in hull kiss at the lower limit of ride height. DB needed more redbull i guess.

EDIT: thx again sc for showing up here and leading some interesting informed tech discussion

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Late to the party and won't post much. Fascinating thread.

 

This answers my questions as to why ETNZ would want constant cycle power.  I notice that the ETNZ guys are not always pedaling at high cadences, so I would think that the wattage is not always very high.  That said one of my cycling team mates who is a strong cat 3, posted his wattage results from a recent win.  He could sustain between 500 and 700 watts for 15 to 18 second periods.  Generally backing off for each upcoming corner, then get back on it for a similar period of time on each straight.  He peaked at just over 1000 watts in one acceleration.

So, four guys putting out maybe 400-500 watts every other 15 second period?

Has anyone edited some footage to present side by side views of ETNZ, vs Groupama Vs Artemis, et al?

I'll admit I am struggling to see the top elements moving repeatedly in the above video.  Probably just me, I certainly don't mean to come across as a doubter! 

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@ Hitchhiker

Steve said > 30 per minute every 2 seconds. Only minor not pumping but trimming every 40metres or so at 40 knots. So just very quick micro trimming.

If you read about fluttering above you might understand something that is too hard for me! 

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@ Hitchhiker

peak power is only one factor in the power load

As sail trimming is not allowed to use stored energy sustainable power is the key to flapping, bringing the flap on again requires energy from the crew. I'm assume any other way of bringing the flap on again would fall foul of the stored energy rules.

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on a low wind day in say 5 knts of breeze could you do one massive wing flap, to provide sufficient thrust to get up on foils?

Once up on foils you are fine and you sail away.

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1 hour ago, Barnyb said:

on a low wind day in say 5 knts of breeze could you do one massive wing flap, to provide sufficient thrust to get up on foils?

Once up on foils you are fine and you sail away.

This came up in the practice Video thread with Artemis pumping their wing.. mgibbs01 spotted it

Check out the video from 30 seconds in.. The best example of pumping I've seen so far

 

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Now a days all the sailors are pro athletes, they can adapt quickly and are paid to do so.  If OR suddenly changes to bikes at this point in the cycle, can the team adapt quickly enough?

If ETNZ has trained their team for a long period on the bikes then they may just have the advantage because the physiology of a grinder and a cyclist is quite different.  The grinders would be built way bigger up top and have the ability to stay aerobic and switch to anaerobic from the waist up and the opposite is true for the bikers (down below).

Spinning the handles or the cranks takes time to develop - speed vs. power or speed plus power.  You don't create muscle memory overnight...  To do this and switch effectively takes months of preparation.  Not weeks.  This is gonna be very interesting to watch!

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@ Rusto

That's the first time I've seen it so obviously.  That was like pumping to get themselves accelerating and up on their foils.

Thank you Rusto

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6 minutes ago, Kiwing said:

@ Rusto

That's the first time I've seen it so obviously.  That was like pumping to get themselves accelerating and up on their foils.

Thank you Rusto

Yes.  The most graphic display I have seen.

Just as an aesthetic aside, I don't like the whole bow down trim under foiling.  Looks like they'll pitch it at the first hint of a wave! 

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Hi guys, 

I have been a long time follower  / never poster to the forums. Could this be what ETNZ is doing with all their extra power? 

https://aviation.stackexchange.com/questions/17406/could-a-blown-wing-ever-be-powerful-enough-to-lift-an-aircraft-at-zero-forward

in light wind and at low speed ( coming out of gybes or taks) this would work. 

Now, would the rule allow this? or is the wing too " one design" for this to happen? 

 

 

 

 

 

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Kiwing - looks that way to me too - a little like a dinghy pumping a few times in marginal planing conditions to catch a wave and plane. Wind was only 10kt in that video - they'll all have tricks for getting on foils in marginal conditions.

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Interesting stuff.  A couple of thoughts.. when I've been riding, going from full power to stopped isn't always a pleasant feeling, whereas spinning the pedals at no load helps keep your legs warm and the lactic acid moving along.

Also, a quick (very rough) calculation, based on the power output table above.. if each cyclist can momentarily put out 1200w (20w/kg @ 80kg), x4 = 5000W (5kW)

The mass of the boat say 2500kg + 500kg wing + 500kg crew = 3500kg = 34300N

Power = force x velocity => Velocity = Power/Force = 5000/34300 = approx. 0.15m/sec.

So they have the power to lift the boat vertically at 0.15m/sec.  Not fast, but interesting nevertheless as in combination with an accumulator etc. it could be enough energy to affect the hull kinetics and bounce it up or some such, a co-ordinated movement with the wing, or good dynamics to provide that little extra during a roll tack.

For example, if a tack takes 1 second, 5kW input means you could theoretically be 0.15cm higher on the exit of the tack (assuming you've worked out a way of physically doing this )

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1 hour ago, Ben G said:

Interesting stuff.  A couple of thoughts.. when I've been riding, going from full power to stopped isn't always a pleasant feeling, whereas spinning the pedals at no load helps keep your legs warm and the lactic acid moving along.

Also, a quick (very rough) calculation, based on the power output table above.. if each cyclist can momentarily put out 1200w (20w/kg @ 80kg), x4 = 5000W (5kW)

The mass of the boat say 2500kg + 500kg wing + 500kg crew = 3500kg = 34300N

Power = force x velocity => Velocity = Power/Force = 5000/34300 = approx. 0.15m/sec.

So they have the power to lift the boat vertically at 0.15m/sec.  Not fast, but interesting nevertheless as in combination with an accumulator etc. it could be enough energy to affect the hull kinetics and bounce it up or some such, a co-ordinated movement with the wing, or good dynamics to provide that little extra during a roll tack.

For example, if a tack takes 1 second, 5kW input means you could theoretically be 0.15cm higher on the exit of the tack (assuming you've worked out a way of physically doing this )

There is no accumulator allowed for sail trim.

Much thanks for doing some math for us dummies.

Edited by rustylaru
sail wing trim

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1 hour ago, Hitchhiker said:

Yes.  The most graphic display I have seen.

Just as an aesthetic aside, I don't like the whole bow down trim under foiling.  Looks like they'll pitch it at the first hint of a wave! 

Wave? From where, Larrys motorpalace?

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@ Matt2000

Keep those posts coming.

That vid of the little plane taking off made me think of my 2m glider which I get up there on a tow line like a kite then dive to loose the tow string and then it's off using gravity.

It can go much faster than the wind speed.   This is not a good analogy but it springs to mind.

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1 hour ago, rustylaru said:

There is no accumulator allowed for sail trim.

Much thanks for doing some math for us dummies.

Sorry I wasn't clear, I was referring to the foils.  Pumping the foils may be more effective than pumping sails if you have an accumulator to store the energy lost on the return cycle, as a spring would.  Cyclists only need to supply the energy lost per pump cycle as opposed to the wing, which is a total loss system with no accumulator

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Pretty sure OTUSA was pumping up wind last time, and they are all pumping this time. The amplitude doesn't need to be large. And the frequency would be something on the order of tens of seconds per cycle, and it would be coordinated with wind, wave and boat movement, so we wouldn't always be able to pick it out. I think power and fitness were paramount last time and will be again this time.

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Like this thing.  First seen on South Park?

 

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I'm going to ask this here 'cos it seems to be propulsion related.

After two days of watching these teams, who does what?

Four guys generating hydaulic power to run systems?

One wing trimmer, does he trim the jib too, or is that just an advertising platform?

Driver with lots of buttons or twisty things on the wheel.  Is he also trimming foils?

Who controls foils up and down?

 

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^ Different teams have different systems. Jib only needs to be trimmed an inch or two in or out depending on whether they are upwind, downwind, or reach, and then it tacks itself. Trim is done by the trimmer. Most boats have helm trimming foils, but ETNZ has one of the cyclists doing it.

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when is it trimming and not pumping when your boat ( foil) is only a 1' long so it sees lots of little waves at 30kts

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An example of how much things are being moved and how often comes from the onboard mic on BAR. Boat is established on port tack, foiling. In the normal course of affairs, you settle down and drive for a minute or two. However, Ben is heard encouraging the grinders to maintain pace so they can continue to make adjustments at a rate that he believes will close the gap with the boat ahead of him. Like the now famous " work your asses off" quote from the last Cup.  Clearly there is a link between the effort the crews put into the hydraulic system and the speed of the boat.

SHC

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