Just found this paper that seems highly relevant here:Thanks Mike, our SAS team is on the job! Couple of interesting things:
- The foil appears to have a quite a "sharp" Leading Edge, and a relatively thin section. That's "fast" - low drag - but it needs to be very carefully angled during flight so the AoA doesn't cause boundary layer separation starting right at the LE, destroying the foil's lift. LR will need to be precise.
- The "initial" AoA of the foil (to the perpendicular) appears to be much lower that I'd originally guessed - perhaps less than 1°. This suggests that LR have designed B2 to fly quite level at all wind strengths. It may also require them to deploy a quite a bit of draggy flap to take-of. Not using hull AoA to substantially set foil AoA also has CoE and weather/lee helm ramifications - flying "bow down" moves the CoE slightly forward.
- The 400kg or thereabouts of ballast weight is presumably mostly buried in the black lower portion of the foil arm. I don't think they would want too much extra weight in the foil wings, and there's probably not much volume available anyway after allowing for structural components.
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Ironically the foil arms themselves were the responsibility of LR who shopped it to Persico who totally fucked it up and ETNZ had to come in and redesign them.Heard a snippet on radio news this morning where Max Sirena accused ETNZ of supplying shoddy design foil arms which don't work as intended. What's the background to this? Haven't seen any rumblings reported before other than the early problems when they were being developed. Anyone got an inkling other than Max just starting the excuses for poor performance?
Not again - LR did the structural design (and evidently got it wrong) and Persico was only responsible for the execution. Is it too difficult to understand?the foil arms themselves were the responsibility of LR who shopped it to Persico who totally fucked it up and ETNZ had to come in and redesign them.
Interesting, thanks. After looking at my estimate of the foil shape, I guessed this:Just found this paper that seems highly relevant here:
In other words, because these foils operate close to surface, they may be less prone to stall even with the sharp leading edge.
This is all on ENTZ. They're running this cup and responsible for the design of the boat. Who let's Italians handle something this crucial?Ironically the foil arms themselves were the responsibility of LR who shopped it to Persico who totally fucked it up and ETNZ had to come in and redesign them.
This added extra work to ETNZ and caused a delay for all teams getting their arms.
Either Max is referring to FCS (in which case glass houses) or he is truly referring to the arms (in which case he is just trolling).
All four teams have been fanging it on the sparkling Waitemata with no evident foil arm failures looks pretty sorted to me.This is all on ENTZ. They're running this cup and responsible for the design of the boat. Who let's Italians handle something this crucial?
Has anyone heard what the actual issues are, that the teams are experiencing?Max is referring to the FCS:
Challenger of Record Luna Rossa is unhappy with a key design component provided by Team New Zealand for the upcoming America's Cup regatta - with skipper and CEO Max Sirena describing the foil cant system as something from a regular car being put into a Formula One car.
"I can tell you the two components are not on the same level - it's like putting in a component which is coming up from a Formula One car together with one from a car you use every day, so it doesn't really match. We are not happy because it doesn't work as we wish."
"It would be a shame if we're going to lose a race because the system doesn't work. We didn't complain in reality as much because we have made it work but I know the others are complaining quite a lot."