## Post your polar and VMG

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alexrider
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### Re: Post your polar and VMG

I am not sure of that. To show apparent wind, you the value of the real wind must be fed. Will need to check if somewhere in the program you're supposed to give the wind speed. I wonder what assumption (in case you don't feed in the wind speed) the program makes to show the wind vectors. Good you pointed this, it would have escaped me.
bohme wrote:
Wed Apr 12, 2017 10:44 am
....
GpsAR can show apparent wind. Best AWA (Apparent Wind Angle is) were around 20° upwind, and 30° downwind.
...
Jacob

Slyde
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### Re: Post your polar and VMG

Can someone explain to me what the smaller linear "butterfly" is that is inside the outer "butterfly" on the polars. Also how come the polars also have a lot of info for square reaching. IMHO we almost never go square to the wind by choice. Is this recorded as the rider bears away??? or is it just a phenomenon of the averaging process of the program? Also does the outer butterfly plot max speed vs direction or is the speed taken over a period of time -say 5 seconds or something else. Gunnar's bursts past 30 knots are impressive but only so if sustained.

alexrider
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### Re: Post your polar and VMG

The inside dotted butterfly represents average VMG. The outside, maximum VMG. But confess I don't know the time span over which the max and average values are determined.
"A lot of info for square reaching"? I don't understand the question. VMG or speed info? You mean straight downwind?
"Also does the outer butterfly plot max speed vs direction or is the speed taken over a period of time -say 5 seconds or something else."
Good question. I don't know the answer (see above). The GPS unit's max speed should be determined with the shortest fix interval, which is usually one second. I don't know is GPS Action Replay uses that value, or it's own interval for max speed.
BTW if you look at the "speed results" menu you can set yourself the time (or distance) for various speed averages. It would be nice if the user could set the interval used for max speed and both VMGs in polar diagram.
Now there is another setting option which is "anti-aliasing" on (by default) or off. No idea what it does and have to consult the manual for that. Could be some smoothing process.
Slyde wrote:
Wed Apr 12, 2017 8:01 pm
Can someone explain to me what the smaller linear "butterfly" is that is inside the outer "butterfly" on the polars. Also how come the polars also have a lot of info for square reaching. IMHO we almost never go square to the wind by choice. Is this recorded as the rider bears away??? or is it just a phenomenon of the averaging process of the program? Also does the outer butterfly plot max speed vs direction or is the speed taken over a period of time -say 5 seconds or something else. Gunnar's bursts past 30 knots are impressive but only so if sustained.

ozchrisb
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### Re: Post your polar and VMG

alexrider wrote:
Wed Apr 12, 2017 7:53 pm
I am not sure of that. To show apparent wind, you the value of the real wind must be fed. Will need to check if somewhere in the program you're supposed to give the wind speed. I wonder what assumption (in case you don't feed in the wind speed) the program makes to show the wind vectors. Good you pointed this, it would have escaped me.
bohme wrote:
Wed Apr 12, 2017 10:44 am
....
GpsAR can show apparent wind. Best AWA (Apparent Wind Angle is) were around 20° upwind, and 30° downwind.
...
Jacob
You can tell GpsAR what the true wind angle was, there's a setting somewhere I used once. Thing it, it's still not going to give you totally accurate polars. To do that you'd need some kind of device measuring wind direction on the kite, or at least on you. Boats do this, America's Cup boats spend a lot of money and have instrumentation all over the masts to try and work this out.

gmb13
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### Re: Post your polar and VMG

Or kite at a spot with no windshifts and nice laminar winds, like me

stefmoris
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### Re: Post your polar and VMG

Here is my very first session on my homemade 11m2 foil kite.

- Wind: nice ( I don't know the numeric amount but felt powered up)
- Hydrofoil: Mikeslab 2014 prototype
- Kite: Homemade 11m2 (lecca-lecca MINIMA) viewtopic.php?f=197&t=2391006
- Distance covered 16 km in 45 minutes.
- Top speed: 24.29 knots (1 second) and 23.76 knots over 500 meters
- Upwind VMG was 48º @ 15 knots (I used virtual runs in GPS action replay) but will read the thread authors blog to learn more.
- Rider HF experience: I too still consider myself a beginner. I have almost 3 years since the beginning but I only get about 25 sessions a year. Still figuring out how to gybe and tack.

I'm posting this now and will repost once I've tuned the kite and performance improves.

-stef

gmb13
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### Re: Post your polar and VMG

Here is the Polar from yesterdays Moses Comet video shoot:

23-25 Knots

1m heavy chop

Foil: Moses Comet 111

Kite: Ozone R1V2 9m 12m lines
Click to play video:
phpBB [video]

--
Gunnar

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### Re: Post your polar and VMG

gmb13 wrote:
Mon Apr 24, 2017 9:51 pm
Here is the Polar from yesterdays Moses Comet video shoot:

23-25 Knots

1m heavy chop

Foil: Moses Comet 111

Kite: Ozone R1V2 9m 12m lines

Screen Shot 2017-04-24 at 21.48.29.jpg

Click to play video:
phpBB [video]

--
Gunnar

Granted these numbers are from a choppy day with a smallish kite, but they seem to be...how shall we say..."not as good" as other foils for which you've posted results.

Would you attribute this performance more to the conditions or to the foil? I remember you seemed very shocked in your unboxing video when you found out that the front wing is drastically smaller than foils like ML or Banga...is there something worth taking away?

gmb13
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### Re: Post your polar and VMG

Well you have to take the conditions into account. It was very choppy and as we where filming for the review, I was spending more time doing tacks, gybes and jumps.

The upwind VMG is still around 16.5to 17 knots range which is pretty much where my Banga VMG was that I posted, that is pretty good considering the conditions. Downwind I tend to not push that hard in these type of conditions without a vest on. In that regard I am a chicken.

The Comet is actually easier to handle (for me) in these type of conditions than the Banga. It resists ventilation a lot better than the Banga too, so the chop affects it less.

Another factor is that I have not sanded the Comet wing that I used here. The Front wing is straight out of the box with a satin finish. It will probably be faster if painted and sanded properly.

The only drawback of the smaller wing, is in the really light winds (19m kite), where I have problems tacking 10/10 with my weight (85kg).

--
Gunnar

gmb13
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### Re: Post your polar and VMG

Just in case anyone is interested. This is a polar of a Go Foil "Kai" foil

Wind: 10-12 Knots
Water: Flat
Foil: Go Foil "Kai"
Kite: 8m ReoV4 20m Lines