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#369700
Hi all,

Recently I bought a Flytec 6030 and I now have a new toy to play with :)

In order to make the Speed-To-Fly function and all other air-speed dependent functions workable, I entered the Wills Wing U2 polar data as it is published here:

willswing site at page polar-data-for-wills-wing-hang-gliders
(sorry I am not allowed to post HTTP links)

Namely,
V1: 175fpm@23mph
V2: 530fpm@44mph
as it appears in the right-side of the graph.

However, after several flights I noticed that:
1) the Indicated Air Speed is reported too low
2) the Netto Vario is increasing as the Indicated Air Speed decreases

After looking more carefully on the graphs published by Wills Wing, it appears that Vms is at 25mph although on the side it appears as 23mph.

Also in the WW U2 User Manual it is written that the Stall Speed at Maximum Wing Load is at 25mph.

My hook-in-weight is ~180 lbs, which is what WW state they have used to generate their polar graphs.

When I am flying at trim speed the Indicated Air Speed reported by my Flytec 6030 is 23 mph.

Anyone tried to calibrate this instrument for the U2?
Please advise,
Adrian.
User avatar
By Lucky_Chevy
#369701
You can check the stall speed of your glider by stalling it. :) Remember it will stall at a much slower speed in ground effect.

The polar is meaningless except when having theoretical discussions. But you don't have to take my word for it. Answer this: What glide angle are you getting at trim?

It's probably somewhere between 2:1 and infinity. In fact, there is not a single point on the polar that is consistently repeatable outside a wind tunnel. It may be of some statistical value to know that the glide angle of a U2 is slightly better than a Sport2 but the practical applications are limited.

Good luck,

Dan
By adrian.herscu
#369705
Dan hi, and thanks for your fast reply.

I did all the things you described in your answer.

Still I don't have the numbers that I should type into the device :(

When I bought it, I just thought that there are other U2 pilots out there which managed to calibrate it to a *reasonable* accuracy level. I am trying to find one of these by publishing this post.

BR,
Adrian.
User avatar
By haddieman
#369709
Hi Adrian,

I fly a U2 160 with a "dirty" harness (an LMFP GT XC) and I use different numbers for my polar. Specifically, I use the numbers that are posted at the bottom of the same page you referenced: https://www.willswing.com/polar-data-fo ... g-gliders/ These are slightly more conservative numbers than are posted in the graphic on the article.

The numbers from the page that i use:
V1: 176fpm @ 23mph
V2: 530fpm @ 44mph

If you fly a clean harness you should add six percent to the V2 speed.

First, I don't think that Indicated Air Speed has anything to do with your polar. If you think that it is off then I think there may be another problem going on.

Second, I do not use the NETTO vario at all but I have successfully used my 6030 for making final glides as long as 20km in competition. I use the "Alt a WP" field which uses MacCready speeds and the polar in it's calculations. I've found it to be pretty accurate for my purposes. I am usually a little on the conservative side when it comes to final glides though.

All in all, I'm pretty happy with my polar though I may play around with it more in the future.
By smokenjoe50
#369710
the wills wing polars are just starting points. I fly the U2 145 hooking in around 195lbs. I can tell you the polars from wills wing are not perfect. As for stall speed mine stalls arround 18mph. I have mine haing point in the front hole and VG off it trims around 20 to 21. Full VG I see around 30 Hands off.
By blindrodie
#369711
:ditto:

8)
#369716
adrian.herscu wrote:
Also in the WW U2 User Manual it is written that the Stall Speed at Maximum Wing Load is at 25mph.
Actually, it says "The stall speed of the U2 at maximum recommended wing loading is 25 m.p.h. or less."

I flew a U2 160 yesterday hooking in at 235 lbs. and the stall speed was about 20 MPH.
User avatar
By pjwings
#369725
Interesting idea to use the netto vals to spot check your polar settings. I'll have to try that. I fly a U2 160 with a hook in (harness, bags, water, etc) of between 230 and 240. I haven't really done any calibration. To the best of my knowledge it will be different for every glider/pilot/harness combination. Therefor the only option is to tow up on a perfectly calm morning and do a series of straight line glides at various air speeds. Measure the mean sink rate at each speed and those become the points on your polar.

In my case I took the WW published numbers and degraded them. I'm near the upper end of the weight range for one. Also I reason that the main thing the polar gives me is altitude at a given point. Basically calculating glides like Haddieman mentioned. In that case I'd rather have my polar be a little too pessimistic (getting me to my point with extra altitude) than for it to be too optimistic (getting me to my point with less altitude).

I use
-197 @ 23
- 551 @ 44
By adrian.herscu
#369770
Thank you all for the inputs :)

I forgot to mention that I am flying a U2 145. As far as I understand it should not have a different polar than the U2 160.
The instrument is hosted in a carbon pod on the basebar. Hence I believe that it is properly aligned to air stream.

Do you apply some correction factor or offset to the Air Speed Sensor?

Thanks in advance,
Adrian.
By smokenjoe50
#369778
The best way to calibrate the airspeed is to mount it to your car or motorcycle. Go out early morning when there is no wind. Your gps ground speed should match your indicated air speed.
User avatar
By tizon
#397110
I thought I'd revive this thread.

On the 6030 when you are in Settings and entering the polar data what does the
"Alt i" field represent?