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Downwind Faster Than The Wind - update

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Re: Downwind Faster Than The Wind - update

Postby Peter_Frank » Mon Jul 16, 2012 4:06 pm

spork wrote:I just got word that our upwind record of 2.1X wind speed has been ratified. It feels good to close that chapter.
Awesome - nice feat and well done :thumb:

:D Peter

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Re: Downwind Faster Than The Wind - update

Postby alexrider » Thu Aug 17, 2017 5:50 am

Evidence theory and practice concur.
From the polar and VMG thread.
viewtopic.php?f=196&t=2395866&p=985409#p985409
Horst Sergio wrote:
Tue Aug 08, 2017 7:04 pm
...
... I just can present another way to measure at least my downwind vmg:

overtaking-Ballon.jpg

The wind in the picture comes from the right side as the masthead fly showes. In the moment of the picture I (on the right corner) was around 600 m directly upwind of the ballon which was always around 40 m above ground (20 m diameter).
Medium wind was metered by movement of the ballon at its height to be around 14 knts, 15 m² Chrono V1, 16 m lines, Bionic back wing.

It tooks me 3 km to overtake the ballon :D

So my downwind VMG was around 18 knts. If the factor of being faster than the wind was 1,25 is not that clear as the wind is a katabatic one with sometimes pretty high gradient, anyway for sure I was a bit faster than the wind and had a nice private race and demonstration. :)

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Re: Downwind Faster Than The Wind - update

Postby abel » Thu Aug 17, 2017 8:47 am

spork wrote:
Mon Jul 16, 2012 1:43 pm
I just got word that our upwind record of 2.1X wind speed has been ratified. It feels good to close that chapter.
:claps: :cooltext:

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Re: Downwind Faster Than The Wind - update

Postby Horst Sergio » Thu Aug 17, 2017 11:14 am

Hi Spork,

even if some years ago: GREATEST RESPECT and honour for your project. :thumb:

I am also fascinated by what is possible and even if it is not something new that also a foil can have a faster downwind VMG than wind. It's always nice to show in reality as visible as possible:

Somebody linked this threat so I do the same with my own comment:
Horst Sergio wrote:
Tue Aug 08, 2017 7:04 pm

...My words and as I haven't got such a VMG polar-Rorschachtest-maker :D I just can present another way to measure at least my downwind vmg:


Image

The wind in the picture comes from the right side as the masthead fly showes. In the moment of the picture I (on the right corner) was around 600 m directly upwind of the ballon which was always around 40 m above ground (20 m diameter).
Medium wind was metered by movement of the ballon at its height to be around 14 knts, 15 m² Chrono V1, 16 m lines, Bionic back wing.

It tooks me 3 km to overtake the ballon :D

So my downwind VMG was around 18 knts. If the factor of being faster than the wind was 1,25 is not that clear as the wind is a katabatic one with sometimes pretty high gradient, anyway for sure I was a bit faster than the wind and had a nice private race and demonstration. :)


Maybe once I ask the guys from the ballon to come even more down, take myself longer lines and let them do a nice video.
Imagine to be cool to see a guy in the ballon maybe producing some smoke with a cigarette to show the absolute zero relativ wind situation at ballon level, while a kite passes with full speed at same height. :D

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Re: Downwind Faster Than The Wind - update

Postby dave1986 » Wed Jun 26, 2019 3:17 pm

I've been following this forum thread with a lot of interest since the very beginning... (even the previous forum thread).

The recent surge in popularity of hydrofoils on the water has made me wonder whether "downwind faster than the wind" is possible with a hydrofoil given their very low drag? I would imagine that it would not work with a kite, but perhaps some other concept?

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Re: Downwind Faster Than The Wind - update

Postby evan » Wed Jun 26, 2019 4:15 pm

dave1986 wrote:
Wed Jun 26, 2019 3:17 pm
I've been following this forum thread with a lot of interest since the very beginning... (even the previous forum thread).

The recent surge in popularity of hydrofoils on the water has made me wonder whether "downwind faster than the wind" is possible with a hydrofoil given their very low drag? I would imagine that it would not work with a kite, but perhaps some other concept?
Not straight Downwind, but very close.

On race gear overpowerd with a 21m, say 13kn gusting 15kn it is possible to ride at an angle close to 155deg where 180deg is dead Downwind. Speeds a little over 30kn so the vmg will be more than twice the actual wind speed.

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Re: Downwind Faster Than The Wind - update

Postby dave1986 » Wed Jun 26, 2019 4:53 pm

evan wrote:
Wed Jun 26, 2019 4:15 pm
dave1986 wrote:
Wed Jun 26, 2019 3:17 pm
I've been following this forum thread with a lot of interest since the very beginning... (even the previous forum thread).

The recent surge in popularity of hydrofoils on the water has made me wonder whether "downwind faster than the wind" is possible with a hydrofoil given their very low drag? I would imagine that it would not work with a kite, but perhaps some other concept?
Not straight Downwind, but very close.

On race gear overpowerd with a 21m, say 13kn gusting 15kn it is possible to ride at an angle close to 155deg where 180deg is dead Downwind. Speeds a little over 30kn so the vmg will be more than twice the actual wind speed.

So you are saying that if you were to release a helium balloon in those winds, and set-off at the same time on race hydrofoil gear, then in theory you could arrive directly downwind on a zig-zag path before the balloon?

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Re: Downwind Faster Than The Wind - update

Postby evan » Wed Jun 26, 2019 5:17 pm

dave1986 wrote:
Wed Jun 26, 2019 4:53 pm

So you are saying that if you were to release a helium balloon in those winds, and set-off at the same time on race hydrofoil gear, then in theory you could arrive directly downwind on a zig-zag path before the balloon?
Yes, and not only in theory. We sometimes get floating tree-seeds in the air and it is easy to overtake them Downwind if they clump together to make them easy to spot.

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Re: Downwind Faster Than The Wind - update

Postby Bille » Thu Jun 27, 2019 4:35 pm

evan wrote:
Wed Jun 26, 2019 4:15 pm

...
Not straight Downwind, but very close.

On race gear overpowerd with a 21m, say 13kn gusting 15kn it is possible to ride at an angle close to 155deg where 180deg is dead Downwind. Speeds a little over 30kn so the vmg will be more than twice the actual wind speed.
A Dumb question , coming you way , (evan) : ------- :lol:

How about if Ya had really Long lines , (50m +) ; would that compensate for your
155- deg angle , and make it possible to go straight down wind , if ya kept the kite
flying Really fast , with up and down motion ?

Bille

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Re: Downwind Faster Than The Wind - update

Postby spork » Thu Jun 27, 2019 5:01 pm

Long lines won't solve the straight downwind problem. The problem is that, to go directly downwind faster than the wind, you have to make the wind work against the water in the downwind direction.


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