AIR Glide S

On Tuesday, October 20, 2015 at 8:12:13 AM UTC-7, krasw wrote:
I recently found some interesting articles concerning AIR Glide S and it's inertial platform in particular. Enjoy:

http://www.how2soar.de/index.php/584...ut-frustration

http://www.how2soar.de/images/H2S_me...sch%20V2.1.pdf

http://www.asl.ethz.ch/people/lestef...l/icra2012.pdf

Latter one has some heavy math in it, but worth reading anyway (incl. references for further study). They measured AIR Glide ISU accuracy with GPS signal switched off. Position error was 600 meter after 30 mins flight. Not bad.

Regarding the description of wind accuracy in the first link: This was my impression also: that the instantaneous wind indication could not be accurate, as it was so dynamic. However after two years of use I have come to believe it is accurate, and the wind field really is that dynamic, you just had no way to measure it before. This instrument is really in a class of its own.

On Wednesday, 21 October 2015 03:32:11 UTC+3, jfitch wrote:

Regarding the description of wind accuracy in the first link: This was my impression also: that the instantaneous wind indication could not be accurate, as it was so dynamic. However after two years of use I have come to believe it is accurate, and the wind field really is that dynamic, you just had no way to measure it before. This instrument is really in a class of its own.

I agree, I started noticing noise in wind measurement when going to under 2 sec time constant. Wind measurement is basically as fast as the variometer.. Now who would do a software where I could record 3D airmass movement with AIR Glide to a file and visualize it later with Seeyou or similar?

Of what use is instantaneous wind? Can you react to it without flapping
control surfaces all over the place? Do you use it for planning your
next turn in a thermal?

Not knocking it, I just don't get it why it would be important. Please
enlighten me.

On 10/21/2015 3:06 AM, krasw wrote:
On Wednesday, 21 October 2015 03:32:11 UTC+3, jfitch wrote:
Regarding the description of wind accuracy in the first link: This was my impression also: that the instantaneous wind indication could not be accurate, as it was so dynamic. However after two years of use I have come to believe it is accurate, and the wind field really is that dynamic, you just had no way to measure it before. This instrument is really in a class of its own.
I agree, I started noticing noise in wind measurement when going to under 2 sec time constant. Wind measurement is basically as fast as the variometer. Now who would do a software where I could record 3D airmass movement with AIR Glide to a file and visualize it later with Seeyou or similar?

--
Dan, 5J

Comparing instantaneous wind to average wind will show you any local wind deviations as they occur near thermals. Can't find the thermal under a cloud? Just follow the diverging local wind. Need to find the best line along a cloud street or convergance? Watch the local wind. Feel that blue thermal nearby, but not sure where to turn? The wind will tell you.



Am Mittwoch, 21. Oktober 2015 16:01:38 UTC+2 schrieb Dan Marotta:
Of what use is instantaneous wind?* Can you react to it without
flapping control surfaces all over the place?* Do you use it for
planning your next turn in a thermal?



Not knocking it, I just don't get it why it would be important.*
Please enlighten me.

That's great for telling me what does, but not how to use it. Are you
saying to always turn downwind in the local micro wind to get to the
center of the thermal?

Maybe my CNvXC vario has this capability, maybe not. I'll have to do
some research on that. In the mean time, I've had good luck with
finding thermals at the upwind edge of cumulus clouds. That's not
always the case but true more often than not.

On 10/21/2015 8:34 AM, Alex wrote:
Comparing instantaneous wind to average wind will show you any local wind deviations as they occur near thermals. Can't find the thermal under a cloud? Just follow the diverging local wind. Need to find the best line along a cloud street or convergance? Watch the local wind. Feel that blue thermal nearby, but not sure where to turn? The wind will tell you.



Am Mittwoch, 21. Oktober 2015 16:01:38 UTC+2 schrieb Dan Marotta:
Of what use is instantaneous wind? Can you react to it without
flapping control surfaces all over the place? Do you use it for
planning your next turn in a thermal?



Not knocking it, I just don't get it why it would be important.
Please enlighten me.

--
Dan, 5J

Dan et al,
Flying in convergence, the Air-Glide informs you of approaching shear line conditions. The wind changes from a ~10Kt tailwind through 9, 6, 4, 3, to "Still", at which point your vario is going up. If you fly through the shear, there will be a similar indicated headwind.
Running along the shear, if the wind is from your right, move left. If it is from your left, move right. Simple. Accurate. Just as you imagine this shear stuff works.
No other vario I have personally flown with that will do that.
Jim


On Wednesday, October 21, 2015 at 2:33:02 PM UTC-7, Dan Marotta wrote:
That's great for telling me what does, but not how to use it.* Are
you saying to always turn downwind in the local micro wind to get to
the center of the thermal?



Maybe my CNvXC vario has this capability, maybe not.* I'll have to
do some research on that.* In the mean time, I've had good luck with
finding thermals at the upwind edge of cumulus clouds.* That's not
always the case but true more often than not.




On 10/21/2015 8:34 AM, Alex wrote:



Comparing instantaneous wind to average wind will show you any local wind deviations as they occur near thermals. Can't find the thermal under a cloud? Just follow the diverging local wind. Need to find the best line along a cloud street or convergance? Watch the local wind. Feel that blue thermal nearby, but not sure where to turn? The wind will tell you.



Am Mittwoch, 21. Oktober 2015 16:01:38 UTC+2 schrieb Dan Marotta:


Of what use is instantaneous wind?* Can you react to it without
flapping control surfaces all over the place?* Do you use it for
planning your next turn in a thermal?

Not knocking it, I just don't get it why it would be important.*
Please enlighten me.

Dan, 5J

Does the LX 9070 or similar with the compass option provide the same information?

On Wednesday, October 21, 2015 at 8:09:54 PM UTC-7, JS wrote:
Dan et al,
Flying in convergence, the Air-Glide informs you of approaching shear line conditions. The wind changes from a ~10Kt tailwind through 9, 6, 4, 3, to "Still", at which point your vario is going up. If you fly through the shear, there will be a similar indicated headwind.
Running along the shear, if the wind is from your right, move left. If it is from your left, move right. Simple. Accurate. Just as you imagine this shear stuff works.
No other vario I have personally flown with that will do that.
Jim

Nice description, thanks!

Most of my experience with shear in New Mexico has involved a long line
of clouds with bases considerably higher on one side of the line. It's
a simple matter to find and use the lift. Next time I get the chance to
fly in shear I'll try to watch the wind indication on my ClearNav
vario. It's pretty quick to update, but I don't think it will be as
useful as you described.

On 10/21/2015 9:09 PM, JS wrote:
Dan et al,
Flying in convergence, the Air-Glide informs you of approaching shear line conditions. The wind changes from a ~10Kt tailwind through 9, 6, 4, 3, to "Still", at which point your vario is going up. If you fly through the shear, there will be a similar indicated headwind.
Running along the shear, if the wind is from your right, move left. If it is from your left, move right. Simple. Accurate. Just as you imagine this shear stuff works.
No other vario I have personally flown with that will do that.
Jim


On Wednesday, October 21, 2015 at 2:33:02 PM UTC-7, Dan Marotta wrote:
That's great for telling me what does, but not how to use it. Are
you saying to always turn downwind in the local micro wind to get to
the center of the thermal?



Maybe my CNvXC vario has this capability, maybe not. I'll have to
do some research on that. In the mean time, I've had good luck with
finding thermals at the upwind edge of cumulus clouds. That's not
always the case but true more often than not.




On 10/21/2015 8:34 AM, Alex wrote:



Comparing instantaneous wind to average wind will show you any local wind deviations as they occur near thermals. Can't find the thermal under a cloud? Just follow the diverging local wind. Need to find the best line along a cloud street or convergance? Watch the local wind. Feel that blue thermal nearby, but not sure where to turn? The wind will tell you.



Am Mittwoch, 21. Oktober 2015 16:01:38 UTC+2 schrieb Dan Marotta:


Of what use is instantaneous wind? Can you react to it without
flapping control surfaces all over the place? Do you use it for
planning your next turn in a thermal?

Not knocking it, I just don't get it why it would be important.
Please enlighten me.

Dan, 5J

--
Dan, 5J

Hi,

I've flown both, CNv XC and Air Glide S (aka Butterfly Vario). In terms of wind indication, Air Glide S has far superior capabilities. I don't know any instrument in gliding that has the same speed and resolution of wind vector and speed.

However, the sensor unit needs to be correctly placed and well compensated. This may require quite some effort, especially in motorgliders with a lot of cables and metal in the fuselage. But probably the same applies to other AHRS units.

Best,
Christoph

On Wednesday, October 21, 2015 at 7:01:38 AM UTC-7, Dan Marotta wrote:
Of what use is instantaneous wind?* Can you react to it without
flapping control surfaces all over the place?* Do you use it for
planning your next turn in a thermal?



Not knocking it, I just don't get it why it would be important.*
Please enlighten me.




On 10/21/2015 3:06 AM, krasw wrote:



On Wednesday, 21 October 2015 03:32:11 UTC+3, jfitch wrote:


Regarding the description of wind accuracy in the first link: This was my impression also: that the instantaneous wind indication could not be accurate, as it was so dynamic. However after two years of use I have come to believe it is accurate, and the wind field really is that dynamic, you just had no way to measure it before. This instrument is really in a class of its own.


I agree, I started noticing noise in wind measurement when going to under 2 sec time constant. Wind measurement is basically as fast as the variometer. Now who would do a software where I could record 3D airmass movement with AIR Glide to a file and visualize it later with Seeyou or similar?





--

Dan, 5J

The companion software iGlide uses it as a thermal centering tool. Each lift dot displayed each second while thermaling has in it an instantaneous wind vector. These point towards the center of the thermal with pretty good reliability. I have experimented with using the instantaneous wind deviation to judge which way to turn, however iGlide does not display the vectors until you have already turned about 270 or you zoom in to an otherwise unusable level. Something I would like them to work on.

There are other uses: flying out of Truckee and returning from the south we have long known that the glide over the Carson valley is usually better than fair at the end of the day. I thought this was due to delayed sink, buoyant air, or something. But now I know that there is very frequently a strong tailwind blowing up the middle of the valley above about 12,000 ft. Like 22 - 28 knots from the south on an otherwise 10 knots from the west day. So rather than crossing directly to Lake Tahoe, I now fly up the middle of the valley until I lose that tailwind, then turn. Never knew that before and most people still don't. This kind of tailwind will eventually show up on computers using traditional wind calculation methods, but the time constants are so long you will lose most of the benefit. The shift in velocity does not show up on CU or XCSoar until you are just about out of it.

I also now notice serious wind shears with increasing altitude. The headwind may increase from 12 knots to 22 knots in 500 ft of climb. Usually near the top of the thermal band, but worth exploiting in some instances.