Strange behaviour Directional Gyro

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Location: Netherlands

Strange behaviour Directional Gyro

Post by SuredT » 03 Oct 2006, 01:19

Hello Alex,

Today I did some more flying with your wonderful product.
Well why not some night flying, I thought. So I flew from EHLE Rwy 23 to EHAM Rwy 27.
My default startup in FS2004 is on Rwy 23 EHLE in the RLA in daylight.
Then I hit ALT->World->Time and so on till I have Night mode.
Full Throttle and off I went. Heh, what the heck, why is my gyro indicating 050 and not 230?
During flight I switched to the HB-DBL and I had gyro 230 again, finished the flight and thought, well a hickup of FS.

Then I started experimenting a bit and bear with me for the remainder of this message.

First I thought it could be the add-on scenery of the Netherlands and I switched to the default scenery of FS2004. No difference!

I started on St. Maarten, Dutch Caribean on Rwy 09 in the RLA at Dawn.
I switched to SF3. Gyro automatically goes to 180
I hit the letter D on the keyboard and Gyro goes to 090

I switched to DAYLIGHT. Gyro goes auto to 180
I hit D and Gyro stays at 180
I switched to RLA. Gyro goes auto to 200
I hit D and gyro goes to 090
I switched to SF3. Gyro goes to auto 200
I hit D and gyro goes to 090

I switched to DUSK. (still in SF3) Gyro goes auto to 190
I hit D and Gyro stays at 190
I switched to RLA. Gyro goes auto to 170
I hit D and Gyro goes to 090

I went further with switching from DUSK to NIGHT and switching also between the HB-DBL and the other 2 91D models and I kept having erratic behaviour of the Gyro.

To be sure I switched also between 2 Cessna models and between DAY and NIGHT. No such behaviour.

Hope you can sleep after this message :wink:

Regards, Sjoerd

P.S. The 3D instrument panel is outstanding in the NIGHT flying mode.
And the reflection of the lighted instruments in the sidewindows is SUPERB!!

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Post by Jure » 03 Oct 2006, 08:52

Hi Sjoerd,

Happened to me as well... somehow, the swsafir.gau in the \Gauges folder didn't get updated when I installed Update1.exe.

Can you please check the date of the swsafir.gau? If my memory serves me, the date should be Sept. 8th.


P.S.: Thanks for the pics, I'll get back to you ASAP. Work has been interfering in the last couple of days. :)

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Post by SuredT » 03 Oct 2006, 15:42

Hello Jure,

The date of my file shows sept 8 after update.

No hurry with the files, take your time.

Regards, Sjoerd

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Post by Voyager30 » 03 Oct 2006, 17:22

Hi SuredT

What i know about the directional gyro is that it has an inbuilt feature that will deflect the gyro alignment upon power up.
In the first version did the gyro self align to magnetic compass, but after a request from me did Sibwings change the function by adding a deviation of about +-15 degrees at power up, so you really do need to check/align the gyro to magnetic heading (actually you need to do it twice before take off IRL) to have it correctly aligned.
There is also an inbuilt drift of the gyro that is approx 1 degree per 4-5 minutes.
The tests i did was on the B-model and i think that the changes whent into the other models as well with the patch/update.

Unfortunattely don't i know what kind of parameters that are used in the calculation, but the missreading when changing from different timezones might come from the inbuilt drift (90 degrees deviation aquals approx 6 hours time difference eg day to dusk, dusk to night etc).

Although this is not a solution to your problem but maybe a hint in the right direction if you want to test more.
I will do a couple of tests in the B-model to se if there is the same problem in that aircraft.

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Post by SuredT » 03 Oct 2006, 18:15

Hello Gerth,

The drift of 1 degree per 4-5 min explains the 90 degrees automatic change of de Gyro when you change from Dawn to Day etc.
But there is no explanation why the gyro sometimes goes back to the correct heading and sometimes stays at a wrong value if you hit the letter D.
I did not mention it but I did align the Gyro sometimes with the align knob in the 3D panel, but then MSFS asked to align the Gyro with the D and off it went to a wrong algnment.

Normally I will not change from one aircraft to another so often of course, but my testing started because of the 180 degrees difference when changing from Day to Night as I mentioned in the beginning of my posting. I had experienced other strange things and found out that the HB-DBL has an other (better?) flightmodel than the SF3, that is why I changed to this aircraft when I had the Gyro drift.

Also I did not mention that my testing ended with staying in one aircraft and I changed only from Day to Dusk etc and kept getting erratic Gyro values.

Anyway thanks for the info.

Regards, Sjoerd

P.S. I will start an other subject about flightmodel difference between HB-DBL and SF3. Maybe you can give some explanation?

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Post by Alex » 03 Oct 2006, 21:19

Directional Gyro works from "PLANE HEADING DEGREES GYRO" variable.

Now I'm checking all version for this bug.
Please, waiting for results.
Alex Petrochenko
SibWings developer

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