America's Cup

[JumbleDuck]

You keep yer clever for the classroom. This is t'internet, where having once done a two-week charter in Corfu carriers far greater weight than all your book learnin'.

I am duly chastised, and will keep my fancy-pants edumication to myself in future. Or at least for as long as I can, which on past form is about three and a half minutes.

 

[JumbleDuck]

I vaguely remember that skin drag is much higher in hydrofoils than on aerofoils. Something to do with Reynold's number and density, IIRC. Then there's that velocity squared bit and the reference area. Maybe why ship propellers don't look like aircraft propellers.

You're right that skin friction drag matters more on hydrofoils because the sea is - please forgive a technical term - stickier than the air. Propeller design isn't really my thing, but a colleague pointed out (in some stuff we wrote together) that aircraft and ship propellers tend to be of quite similar sizes for similar powers, though of course the blades look very different and the airscrews turn a lot faster.

 

[JumbleDuck]

Yes! Three and a half minutes on the dot.

 

[bedouin]

High drag aircraft:

Low drag aircraft of similar weight:

Basially, drag in wings and foils arises in three way. There is skin friction (or viscous) drag which matters at low speeds much more than high speeds, there is pressure (or profile) drag from the pressure distribution and there is induced drag which is much more complicated but basically arises from the production of lift by a vortex around the wing.

The longer the wing the smaller that vortex needs to be and so the smaller the induced drag. In general the longer and thinner you make a wing the better its lift to drag ratio is.

The TNZ foil are much thinner - looking more like the wings of the glider while the LR wings are much fatter, more like those on your high drag aircraft. Since the maximum width of the foils is fixed by the rules that makes the TNZ foils much smaller

 

[LONG_KEELER]

Seems to be a bit odd not being able to race yachts in 6-7 knots of wind but that is the technology at the moment.

I enjoyed the highlights of day 3 , but the results are based on whether you can get it up
or not at the pre start so a bit of a lottery. Personally, I would still like to see them race in
displacement mode on a shortened course, with the expectation that they may be able to get up on the foils at any time. Would be fun to watch. Probably highly unlikely though.

 

[Frogmogman]

It's looking difficult for Luna Rossa now.

 

[bedouin]

TNZ are looking strong. They made the right sail choice in the first race today and were much faster

The 2nd race was a bit of a lottery and should perhaps have been called off. It seemed to be pure luck.

 

[Frogmogman]

It could be all over by tomorrow, but I don't think I'll be dragging myself out of bed at 4 in the morning (French time) to watch it live.

 

[Bathdave]

I’m finding getting up a a sensible time and watching ‘live‘ on YouTube makes it live enough

 

[DavidonMersea]

the results are based on whether you can get it up
or not at the pre start so a bit of a lottery.

You obviously have not seen to days race. Both boats had a 2km lead at one time or another

 

[LONG_KEELER]

You obviously have not seen to days race. Both boats had a 2km lead at one time or another

Just watched the highlights . Great viewing . The kind of racing probably not envisaged
by the designers, organisers , or racing purists.

I think it was suggested before the Cup started by Flaming, who said the AC is really about rich men todger swinging. If the racing had to pay for itself more, a bit like F1 cars, there would be pit stops , sail changes, flying an extra sail if within two boat lengths etc.

I hope it stays as it is . Mostly free of big commercial pressures like all other sports. I can't
believe we have been watching it on Youtube . Lets hope the rich men don't sell out . Difficult to see how the trickle down will affect Wednesday evening racing , but It's not guaranteed that the AC 75's will be seen again next time. It's mad , lets make the most of it.

 

[TLouth7]

I thought the shortening course yesterday was a shame, it gave the Kiwis one fewer legs to fall back off their foils and let the Italians through. I guess it was based on race time limits?

Today's race was great, tight racing that all came down to a windshift. I wonder if the favoured side of the course was as obvious to the boats as it apparently was to the commentators? I felt that both teams gave that side up voluntarily at several points.

 

[Bobc]

Race 9 - OMG.

You want to see some match racing?

 

[Nimrod18]

So having posted (#10) that I thought it was getting a bit dull, along came race 9. Humble pie...

Marvellous viewing.

 

[Daydream believer]

Pedants? Haven't seen any around. I'm just someone who teaches fluid dynamics for a living.

And which pub would that be?

 

[Daydream believer]

deleted

 

[JumbleDuck]

And which pub would that be?

I'm teetotal.

 

[Frogmogman]

Congratulations to team New Zealand. A thoroughly deserved result.

I had hoped we would see the cup returning to Europe, for purely selfish reasons. I suppose it might yet happen if there’s any truth in the rumours that the kiwis are keen to see it staged elsewhere because of the expense.

 

[davidej]

IMHO the Defenders grip over the formula and venue makes it unreasonably difficult to dislodge them.

In the early days the NYYC insisted that the Challenger crossed the Atlantic under sail so it had the be much more heavily built then the Defender. They got more sophisticated bur nothing has really changed

 

[newtothis]

Congratulations to team New Zealand. A thoroughly deserved result.

I had hoped we would see the cup returning to Europe, for purely selfish reasons. I suppose it might yet happen if there’s any truth in the rumours that the kiwis are keen to see it staged elsewhere because of the expense.

Is there a significant cost to the host country? It's not like you have to build an Olympic park to host an America's Cup. Surely the revenue from sponsors and rights makes up for any expenses. And the marketing oppo for the host nation is pretty big; post-Covid, it will even encourage visitors and tourism.