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hydrofoil at max speed limit

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james
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Re: hydrofoil at max speed limit

Postby james » Sun Dec 03, 2017 12:51 pm

revhed wrote:
Sat Dec 02, 2017 10:16 pm
Peter_Frank wrote:
Sat Dec 02, 2017 6:59 pm
even draggy low performing kites can go unlimited fast, when it blows sufficiently and you ride on a downwind course.
We have actually seen this quite often when talking speed records - crazy high winds and a normal low aspect kite, has been used for many of these - riding a deep downwind course.
8) PF
https://video.search.yahoo.com/yhs/sear ... ction=view
This sure does NOT look like and is NOT a deep downwind course!
So you are wrong AGAIN!
No such thing as "unlimited fast"!
As for the gods, they must be crazy!
R H
Rev head

I respect your opinions hugely when it comes to foiling BUT!

How can you possibly say that the luderitz speed canal isn’t a deep down wind course?

It’s been built specifically to be deep off the wind, ask any of your fellow frenchies that have been there and fired themselves around that corner onto that very deep course.

It’s got nothing to do with hydrofoils or this topic but both luderitz and the canal Alex used to set his record on are both deep angles

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edt
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Re: hydrofoil at max speed limit

Postby edt » Sun Dec 03, 2017 3:17 pm

I think there is a practical limit to every foil and it's different for each one. Yeah, sure theoretical you can get it to go faster, but it's more like the hull speed of a sailboat. You can go a tiny bit faster than the top speed but it costs an enormous amount and realistically just get a smaller higher aspect foil if you want to go faster. I think the top speed if it's done would be done in a channel like at luderitz. Ventilated at 50 knots is no joke on a hydrofoil, so you want the water to be as flat as possible. They have made the channel a lot deeper than it was 5 years ago, there's some sort of speed rule that requires the water deeper than they used to have it, so you can definitely foil at luderitz or maybe france at the salt flats. Nobody is doing it yet, I think mainly because of the huge risks. It's gonna happen tho one day and then we'll see the limits.

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Re: hydrofoil at max speed limit

Postby revhed » Sun Dec 03, 2017 4:14 pm

james wrote:
Sun Dec 03, 2017 12:51 pm
revhed wrote:
Sat Dec 02, 2017 10:16 pm
Peter_Frank wrote:
Sat Dec 02, 2017 6:59 pm
even draggy low performing kites can go unlimited fast, when it blows sufficiently and you ride on a downwind course.
We have actually seen this quite often when talking speed records - crazy high winds and a normal low aspect kite, has been used for many of these - riding a deep downwind course.
8) PF
https://video.search.yahoo.com/yhs/sear ... ction=view
This sure does NOT look like and is NOT a deep downwind course!
So you are wrong AGAIN!
No such thing as "unlimited fast"!
As for the gods, they must be crazy!
R H
Rev head

I respect your opinions hugely when it comes to foiling BUT!

How can you possibly say that the luderitz speed canal isn’t a deep down wind course?

It’s been built specifically to be deep off the wind, ask any of your fellow frenchies that have been there and fired themselves around that corner onto that very deep course.

It’s got nothing to do with hydrofoils or this topic but both luderitz and the canal Alex used to set his record on are both deep angles
Good question, I guess we need to define what angle is considered "deep down wind"?
How much down wind angle do you think an average speed course has?
Luderitz?
And while on this subject, what is optimum?
I have my thoughts but do not want to sway opinions.
R H

revhed
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Re: hydrofoil at max speed limit

Postby revhed » Sun Dec 03, 2017 4:44 pm

slowboat wrote:
Fri Dec 01, 2017 11:39 am
What happens when you push a foil beyond its maximum speed?
Then you have determined its new higher maximum speed!
Enough said!
As for the misleading false post comments, "unlimited fast" and "no maximum speed" so sad that it in the world today
even all out lies often go unchallenged and even believed!
R H

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Re: hydrofoil at max speed limit

Postby BWD » Sun Dec 03, 2017 4:51 pm

Isn’t the standard course for speed a 90-110 lead in leg to build apparent and then a bear away over a curve to 140-150 or so?
Is this ok for foils also?

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Re: hydrofoil at max speed limit

Postby james » Sun Dec 03, 2017 11:25 pm

Pretty sure luderitz is at 145 off the wind maybe a touch more

By the time they are half way down there are running directly off the back of the wind blown chop indicating that they are so far off the wind that the “upwind” bank isn’t actually providing any protection and sheltered water

I have gps tracks of speed events from this year where given the wind direction you would be supprised where you were heading

This is on foil with foil kite, big slalom board with foil and Lei and then speed asymmetric with lei

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Re: hydrofoil at max speed limit

Postby revhed » Mon Dec 04, 2017 7:01 pm

I always think of wind angles simply like this.
Exact perp is 90°
Exact downwind is 0°
I would think that anything more than 45° is deep down wind.
Have never been to luderitz but looks to me like from flag direction that may well be that.
R H

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Re: hydrofoil at max speed limit

Postby lovethepirk » Mon Dec 04, 2017 9:41 pm

slowboat wrote:
Fri Dec 01, 2017 11:39 am
Obvious beginner question: What happens when you push a foil beyond its maximum speed?
Slowboat,

The wind speed and breaking strength of the foil will determine the max speed. I'd recon the foil, board, or human bones break at the max speed.

I think what you are asking is what gives out first after you are overpowered and on a downwind death tack scared out of your mind. Answer is you most certainly are giving out first before your board, foil or bones break. Your weight inputs will eventually fail and you are going to hit the water hard. I learned this riding a 14m kite in 25knots on a race foil with the kite about 10 ft above the water line. I couldn't get the kite to move, it was pinned low near the water and I just kept accelerating and it may seem that the simple answer is to bear off straight downwind, but it's not that easy when you are locked in going 35-40 knots and one wrong move could be epic pain. My goal was to get the kite up in the air and I inevitably failed before I could accomplish that.

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Re: hydrofoil at max speed limit

Postby edt » Tue Dec 05, 2017 2:24 am

revhed wrote:
Mon Dec 04, 2017 7:01 pm
I always think of wind angles simply like this.
Exact perp is 90°
Exact downwind is 0°
I would think that anything more than 45° is deep down wind.
Have never been to luderitz but looks to me like from flag direction that may well be that.
R H
rev if you can, try using direct upwind as 0 and direct downwind as 180. That's the standard that's been used for hundreds (thousands?) of years in sailing, so it makes it a little easier to communicate using those coordinates. 45 is close hauled, 90 is a beam reach, 135 is a broad reach, and 180 is running.

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Re: hydrofoil at max speed limit

Postby plummet » Tue Dec 05, 2017 10:36 am

What I find interesting about the luderitz trench is that its straight broadreach. Why? the fastest speeds are achieved with a arcing downwind run. The faster you go the further back the wind window shifts and the further you can point down wind. With a high aspect kite you can point even further down wind at speed.


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