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7 kn of wind, who will win AC45F (America's cup boat) or kite foil?

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Slyde
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Re: 7 kn of wind, who will win AC45F (America's cup boat) or kite foil?

Postby Slyde » Wed Jun 14, 2017 8:36 pm

i sat on the beach a few times last summer when there was not enough wind to launch and fly a 15m R1V1 and watched team NZ train at speeds that well exceeded 25 knots.The low end on those boats is pretty impressive, they probably were testing light wind foils. IMHO I think there is no contest. They are waaaaaay faster than a foiling kite at almost any windspeed when on optimised configurations. Game over guys.

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edt
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Re: 7 kn of wind, who will win AC45F (America's cup boat) or kite foil?

Postby edt » Wed Jun 14, 2017 9:48 pm

first of all this would be a fantastic race and I think it all depends on the conditions and the course. I would call it 50/50 for the kite or the ac45f.

But I think people who think the kite is better light wind have it backwards. the ac45f will foil in nothing and reach top speed quickly. Kites at least how they are made now need a little bit of wind to get on their foils and start going fast. Upwind the ac45f has a much harder time staying on the foil, there the kites will have the edge as kites have a much easier time staying on the foil upwind. Downwind, the ac45f foils better than kites and can go faster at a bigger angle.

Top speed, the kites have the ac45f absolutely crushed. These 100% carbon fiber boats are built right at the edge of the specifications. They can get up to somewhere around 30 knots, maybe a little bit more and then if the wind increases, they are still stuck somewhere around 30-35 knots, the reason being that if they try to go even a little bit faster the entire craft will disintegrate into a cloud of dust. They cut the weight so low and the specs are so high for this craft that they can simply not "go faster" they can't exceed the red line on these ac45fs or they will explode. The only limit kite foilers have is a cavitation limit on their hydrofoils, and of course how large the kiters balls are. It's scary as f--- going at high way speeds, 4 feet up in the air with those sharp blades under you.

So who wins? I think it's a pretty even match (if you choose the right conditions) and would be fantastic to watch.

In 7 knots it's interesting. Downwind the ac45f should be faster, but upwind the kite will be able to get on foil easier. I don't think this particular boat can get on a foil in 7 knots upwind, while the kite certainly can. You know what they say about sailboat races? It's all about the upwind leg. It does no good for the ac45f to go 30 knots downwind 3x wind speed if you are slogging it 1x wind speed on the upwind leg.
Last edited by edt on Wed Jun 14, 2017 10:05 pm, edited 5 times in total.

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Re: 7 kn of wind, who will win AC45F (America's cup boat) or kite foil?

Postby james » Wed Jun 14, 2017 9:58 pm

A couple of things...

Poster above is an idiot and factually wrong on so many counts

AC45 is a basic wing sailed foiling cat used in the World Series, would get dicked by a top 5 in the world kite foiler, strictly one design class very very basic compared to...

AC50, full blown bat shit crazy would wipe the floor with anyone, exception might possibly be in the 6 KT range but even then it's unlikely, unless the kite boys are crushing 30-35 kts upwind in 14-16 kts and able to maintain 44-47 kts downwind it's a one way fight

Neither class of boat races I've 24kt wind speed so saying in 30 kts a race might happen is stupid

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Re: 7 kn of wind, who will win AC45F (America's cup boat) or kite foil?

Postby Eltreato » Tue Jun 20, 2017 5:30 am

james wrote:
Wed Jun 14, 2017 9:58 pm
A couple of things...

Poster above is an idiot and factually wrong on so many counts

AC45 is a basic wing sailed foiling cat used in the World Series, would get dicked by a top 5 in the world kite foiler, strictly one design class very very basic compared to...

AC50, full blown bat shit crazy would wipe the floor with anyone, exception might possibly be in the 6 KT range but even then it's unlikely, unless the kite boys are crushing 30-35 kts upwind in 14-16 kts and able to maintain 44-47 kts downwind it's a one way fight

Neither class of boat races I've 24kt wind speed so saying in 30 kts a race might happen is stupid
Stay classy Slingshot brand manager...

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Re: 7 kn of wind, who will win AC45F (America's cup boat) or kite foil?

Postby james » Tue Jun 20, 2017 7:04 am

Haha!

Not disputing you were wrong then?

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Re: 7 kn of wind, who will win AC45F (America's cup boat) or kite foil?

Postby bigcane » Sun Jun 25, 2017 8:56 pm

Been watching the AC races, looks like Kiwis are on fire. But I notice that in 9 to 10 knots of wind that the AC cats tacking angle upwind looks pretty shit compared to kiters plus they sail pretty low after each tack to get back up to speed. Anyone have the cat's VMG numbers upwind and downwind? I am thinking that the kiters might be have better vmg on the upwind leg but not sure about downwind where the cats seem to be able to go quite deep. Would be really cool to get a matchup before they put the boats away. I think what makes the kite hydrofoil unique in the foiling world, besides low cost, is the ability to get the wing cranked way over when going upwind. You can see the effect in the kite vs moth vs cat videos. The kiter has way more height on the upwind leg.

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Re: 7 kn of wind, who will win AC45F (America's cup boat) or kite foil?

Postby gbrungra » Sun Jun 25, 2017 9:20 pm

Ok, so both craft are highly capable from 7-25kts wind. AC50 by changing foils, kitefoils by changing kit sizes.

I found the polars for the AC45s from a few years back and they were unimpressive.

Everyone has opinions, but I don't see this getting settled without either:
A: a match race (which would be awesome).oe
B: comparing polars

Does anyone have AC50 polars, or top kitefoil racer polars?

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Re: 7 kn of wind, who will win AC45F (America's cup boat) or kite foil?

Postby evan » Sun Jun 25, 2017 9:53 pm

Are there polars that account for the amount of wind shift? Otherwise the vmg on the polars are not comparable at all.

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Re: 7 kn of wind, who will win AC45F (America's cup boat) or kite foil?

Postby bigcane » Mon Jun 26, 2017 8:20 am

Some more speculation: I think the top kiters are getting 15 knots vmg upwind based on 45degrees to true wind and 21 knots speed. Looking at the AC tracks yesterday in 9 to 10 knots of wind i think they are closer to 60degrees to true so the cosine of 60 is .5 times speed of 25knots gives vmg of 12.5 knots.

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Re: 7 kn of wind, who will win AC45F (America's cup boat) or kite foil?

Postby gbrungra » Mon Jun 26, 2017 8:55 am

I'm beginning to think we should just be comparing two numbers: upwind VMG and downwind VMG.

Ideally they would be taken with similar wind speeds (7knts if we go off the title of this thread).

I'm beginning to think breaking down the race videos might be the only way we get our two numbers.


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