Recon diary

Stingray~

Stingray~

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There is far more discussion on FB and even on YT comments about this video (again) than in this forum. C'mon guys! Most of us here have the longer perspectives than the newbies out there :)

edit: Bottom line, I think the answer to the main question posed, about the benefits of running and up-developing a legacy AC75 looks smarter than what the Q choice was. A lot more of the above-deck systems is where the action will be this time than last time, as said also by the Ineos sail and rig designer yesterday too. The Alinghi guy suggested much the same today. AM's late-April design decision will be for the hull shape and structure, their systems can go on being developed at full scale for forever and they are already deep into optimisizing the cycling power system and looking at what else the cyclers can do.
 
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erdb

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enigmatically2 said:
I don't think you could get much useful RM from the tip, because when it comes out of water (and it does) that RM would disappear, which would induce heel, which would mean that the RM would nit recover without control changes. And if you did those and it dug in again, the RM would suddenly increase. So you would be designing in an unstable system. Sometimes those are fast, but in this case I don't think so
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I agree, I don't think you could generate much RM. The angle of the foil is wrong for that, plus the profile is optimized to produce lift in the other direction. Maybe they could use the windward foil as a training wheel to keep the boat steady in waves, but that means giving up speed. If the other teams can get away without dragging an extra piece of foil, they'll be faster.
 
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enigmatically2

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You are missing the point a bit @erdb . With the AC75s everyone will be dragging the windward foil a bit because of the larger spans this time. The foil shape and angles are fixed so they will all be the same.
The question is only why Ineos have chosen to have more of that on their test boat than the others
 
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erdb

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What are the rules about messing with the auto pilot software in the AC40?
Is it open-source, available for all teams? Can they all manipulate that while still keeping the boat "one-design"? Or is it only NZL who can do that as part of developing the OD AC40?

I'm asking, because I think the NZL setup with their one-design plus modified AC40s allows them to optimize driving techniques. Let the one-design boat sail with the "standard" setup, compare it to an experimental AP setup on the other boat. Once the experimental setup is reliably faster, make that the new standard, upload that to the OD AC40, and start again. For testing, the AP is better than a human, because it's easier to replicate things. It can also be used to train the human sailors at the end in the same way.

I have a feeling that in this cycle, much more can be gained by fine-tuning flight control to deal with waves and optimize maneuvers than with a break-through foil shape that no one saw before.
 
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erdb

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enigmatically2 said:
You are missing the point a bit @erdb . With the AC75s everyone will be dragging the windward foil a bit because of the larger spans this time. The foil shape and angles are fixed so they will all be the same.
The question is only why Ineos have chosen to have more of that on their test boat than the others
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Maybe I missed that indeed. Are we sure they will all be dragging the windward foil?
 
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Dogfish

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I am not sure they will go for maximum span, if you can cant to windward to help get up you can get away with a smaller foil less drag = faster. Smaller rig less drag = faster. If you follow that philosophy through you are heading to the smallest most efficient you can get away with.
 
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enigmatically2

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Dogfish said:
I am not sure they will go for maximum span, if you can cant to windward to help get up you can get away with a smaller foil less drag = faster. Smaller rig less drag = faster. If you follow that philosophy through you are heading to the smallest most efficient you can get away with.
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But longer, thinner foil with higher aspect for the same lift gives lower drag and more RM. So why would you not do that?
 
Stingray~

Stingray~

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Dogfish said:
Yes but flex and twist are big issues higher aspect is not always the solution in the real world.
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I have a fantasy that we will see, somehow, flex and twist evolve this time around to shape-perform differently under different circumstances like water depth and water flow angles. Maybe even automatically through intelligent-flex and built-in smarts design. Even the little drone toy I am playing with is pretty amazing in how it reacts in different conditions and the regular firmware updates to its 'intelligent' battery makes it better and better at it.

It's even possible they could change chord aspect, right?
 
The_Alchemist

The_Alchemist

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enigmatically2 said:
@Mozzy Sails analysis suggests so assuming they all go for the max foil span (which seems likely). But we haven't seen the new foil arm spec so can't be sure. But whatever it is they will all be the same
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Not necessarily, the old rule limits the height the arm can be lifted. Like you said, The new rule ties it to the FCS control which is not yet specified.
 
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Dogfish

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Stingray~ said:
I have a fantasy that we will see, somehow, flex and twist evolve this time around to shape-perform differently under different circumstances like water depth and water flow angles. Maybe even automatically through intelligent-flex and built-in smarts design. Even the little drone toy I am playing with is pretty amazing in how it reacts in different conditions and the regular firmware updates to its 'intelligent' battery makes it better and better at it.

It's even possible they could change chord aspect, right?
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Nasa are playing with morphing wings with no flaps etc. I am playing with a flexing foil using the anhedral to control flex. I like the idea of Rob's no flaps just rudder angle boat. Might be a problem in Barcelona though due to the swell. Remember the water travels in a circular motion in waves which complicates the flow over the foils at times depending on wave height.
 
Sailbydate

Sailbydate

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This business of the V3 AC75's dragging their extended windward foil tips in the water is a croc.

If you review the racing footage from the 2021 Cup, the windward foils were no where near getting wet, unless the hulls touched down, IMO.
 
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Dogfish

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Stingray~ said:
So... Any conclusions yet about why Ineos at this late stage is dragging their windward foil around?
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I think it's slightly exaggerated by the fact they seem to be sailing with a bit of windward cant which is bringing the foil closer to the surface. I don't think it's anything more than that.
 
Stingray~

Stingray~

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Dogfish said:
I think it's slightly exaggerated by the fact they seem to be sailing with a bit of windward cant which is bringing the foil closer to the surface. I don't think it's anything more than that.
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Tend to agree, also think they will get braver with ride height starting soon.
 
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