V8 with AHRS heading source and wind calculation

[lonkelly]

Does anyone know if the V8 with AHRS option has a magnetometer, and how heading information is derived, calibrated and used in wind calculation?

The LXNAV web site's description of the V8 says only, "An AHRS module is built in and is used for a wind calculation" with regard to the question.

In the LX90XX manual there is a several-page discussion of calibrating an external compass but nothing I can find about an internal magnetometer.

In my power flying I've used both Stratus 3 and Stratux DIY ADS-B-In receivers that incorporate AHRS and include magnetometers. I've read the Stratux developers have difficulty calibrating and compensating the magnetometer and use GPS track information instead. I'm not sure about the Stratus 3.

When flying in wave the ground track will vary significantly from the aircraft heading over fairly long periods of time. In such a situation, it is helpful to know what the wind is doing with some accuracy. So, it would be helpful to know how the LX90XX is deriving the wind it shows and how/if AHRS has an impact on the various heading and wind displays available.

[the_gle...@msn.com]

I cannot answer definitively. However, I had an LX9000 without the compass option which used to be sold as an optional extra. When wave flying in strong winds, the instrument certainly did not use ground track as an indicator of heading - it was able to show the glider pointing into wind, with a negative ground speed shown, and routinely it would show the nose pointing into wind rather than along the track line. I met Erazem boss of LXNav at a conference and asked him whether I should buy a compass upgrade and he advised me not to bother on the grounds that it would not signficantly increase the accuracy of the wind calculation. This was a few years ago and things may have changed. I don't think a compass module is listed as an option today. This is what the LXNav website says:

"An inertial variometer provides a very accurate wind indication during straight flight.4 different methods are used to precisely calculate wind speed and direction.  "

[*Eric Greenwell1*]

The compass module is still offered on the Accessories page, and the Lx90xx tech specs say this: "

Wind   Precise wind calculation with the Compass module

Perhaps someone who has flown with and without the module can describe the differences this makes in wind and direction readings.

Eric

[cdeerinck]

When I ordered by 9070 (9 months ago), I tried to order the compass.  

I was told "It isn't quite ready for prime-time yet".

I don't like what happens to the readings in wave as is, and would still love to add a compass, but don't want to spend the money and have poor results.

If anyone has an update regarding the compass, I would be very eager to hear any news on that front.

[jpg...@gmail.com]

Similar experience here.  Every time I have enquired about it over the last several years I have been told that they are working on an updated version.   I think you would have to find somewhere really isolated from EMF fields for a glider magnetometer to be genuinely useful for wind calculations. 

[Marc Arnold]

I have an early electronic compass. It has never worked properly. I fly with it disabled. 

On Nov 21, 2020, at 12:08 PM, jpg...@gmail.com <jpg...@gmail.com> wrote:

Similar experience here.  Every time I have enquired about it over the last several years I have been told that they are working on an updated version.   I think you would have to find somewhere really isolated from EMF fields for a glider magnetometer to be genuinely useful for wind calculations. 

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[Bob Caldwell (BC)]

I have an LX 9000 with the compass module.  It worked for about one season and then got funky.  It would work normally for a while showing say 270@10 and then suddenly show 049@50.  Like Marc I disabled it.  The wind info I get without circling on the LX is terrible compared to my AirGlide Display S (Butterfly).  That unit is excellent at supplying instantaneous wind data.  LX has not been at all supportive at all.

Bob

[dongrillo]

I have a 9050 and the compass I bought in 2017. I could never get the compass to work properly. It would start out working then in midflight would point some other direction than what I was flying. Many emails to Lxnav never solved the problems. It's now sitting in a box in the basement.  

[John B]

I could never get the compass module to work either.   Additionally it made the little airplane on SeeYou go crazy during flight playback.

J4

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[F Hersen]

I use this  LXNav compass  with my LX9000 / 9000D since 2015, with any problem.

I set the wind calculation on “combination”.

 

RC

From: John B

Sent: Sunday, November 22, 2020 2:36 AM

To: dongrillo

Cc: LXNav Soaring Glider Equipment User Discussion Group

Subject: Re: [LXNAV-user-group] Re: V8 with AHRS heading source and wind calculation

 

To view this discussion on the web visit https://groups.google.com/d/msgid/lxnav-user-group/CAO%2B1cwK5L-KjJ2mLE2XwCadtoO_kpa37UoV5X24%2B7oDHBxjQwQ%40mail.gmail.com.