Means of propulsion

Steve Clark

Super Anarchist
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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jaysper

Super Anarchist
10,172
1,295
Wellington
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 ;)

 

NZL5

Member
230
1
Auckland
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?

 

Steve Clark

Super Anarchist
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

 

justsomeone

Member
203
58
Australia
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 

 

Kiwing

Super Anarchist
3,523
592
Bay of Islands
@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 !

 

Ex-yachtie

Super Anarchist
2,998
1,342
Auckland, NZ
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.

 

Ex-yachtie

Super Anarchist
2,998
1,342
Auckland, NZ
^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?

 

justsomeone

Member
203
58
Australia
^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

 

Kiwing

Super Anarchist
3,523
592
Bay of Islands
^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.

 

justsomeone

Member
203
58
Australia
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.

 

weta27

Super Anarchist
1,573
4,516
" 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?

 

Team_GBR

Super Anarchist
1,025
29
The Medal Race
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.

 

weta27

Super Anarchist
1,573
4,516
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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justsomeone

Member
203
58
Australia
" 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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