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[Non-DoD Source] Re: Gyro compass adjustment

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mark.bitterlich(at)navy.m
Guest

Posted: Sun Apr 09, 2017 7:02 pm Post subject: [Non-DoD Source] Re: Gyro compass adjustment

Interesting Walt.



Are you trying to remove single or two cycle error?



Mark Bitterlich.



p.s.  Swinging a compass is an art form.  "First thing is to find the compass".  I think you might be talking about a flux valve.  I have not worked on this system in a YAK-52 and if it is what I think you are talking about, I have no desire to, but I would like to know the facts regarding this particular system.  Can you educate me please?  For what it is worth, my input is that first you have to find a calibrated north south line.   Good luck with that.



________________________________

From: owner-yak-list-server(at)matronics.com [owner-yak-list-server(at)matronics.com] on behalf of Walter Lannon [wlannon(at)shaw.ca]

Sent: Sunday, April 09, 2017 1:36 AM

To: yak-list(at)matronics.com

Subject: [Non-DoD Source] Re: Gyro compass adjustment






The gyrosyn compass is a gyro stabilized magnetic compass and is not tied to

the ADF.  First thing is find the compass.  Most likely in the aft

fuselage - remote from

electrical interference as much as possible.

It has a corrector unit like the standby compass and is swung in the same

manner but has an additional feature.  Once the standard swing is complete

calculate the average algebraic sum of the corrections  (+ or -), unlock and

rotate the entire compass in the correct direction to remove that error.



Walt



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wlannon(at)shaw.ca
Guest

Posted: Sun Apr 09, 2017 9:02 pm Post subject: [Non-DoD Source] Re: Gyro compass adjustment

Hi Mark;



Damned if I know;  That is way beyond my pay grade but I'm sure you could 

help.



Yes;  looking for the flux gate; transmitter; or whatever it may be called. 

But in my 1965 CJ it is still a magnetic compass (though a very large one), 

with a card and a viewing window to facilitate calibration.  Entirely 

possible I have made a grave error by assuming the Yak 52 uses the same 

unit, a mistake I make too often.



The calibrated North/South line is usually included in the compass rose 

which is found somewhere on most airport tarmacs.   Can't say I have ever 

seen one without that line, but then--------.



Don't know about "art form" but often the compass swing can be one hell of a 

lot of work and, in Canada, is a requirement for every Annual Inspection and 

Certification that I do.



Cheers;

Walt



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Looigi

Joined: 20 Apr 2015
Posts: 81
Location: Christchurch, New Zealand

Posted: Sun Apr 09, 2017 9:25 pm Post subject: Re: [Non-DoD Source] Re: Gyro compass adjustment

Hi Guys,



Getting rid of the deviation is easy if the whole card needs to be adjusted, like Walt says, just turn the flux valve to suit.



Does anyone know how to adjust the KM-8 Correction Mechanism that hides behind the back seat on the yak-52?   It looks like this..... https://forums.eagle.ru/attachment.php?attachmentid=135933&d=1457048380



I am guessing that by looking at it the adjusting know makes the same correction as turning the flux valve does, but has anyone else played with it?



Cheers

Chris

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wlannon(at)shaw.ca
Guest

Posted: Mon Apr 10, 2017 10:34 am Post subject: [Non-DoD Source] Re: Gyro compass adjustment

Hi Looigi;



Thanks for the photos.   Proves, again, that one should never make 

assumptions in this business.  The Yak 52 system is quite different than the 

CJ and likely much more modern.



Walt



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Ttail

Joined: 24 Jun 2013
Posts: 120

Posted: Mon Apr 10, 2017 2:09 pm Post subject: Re: [Non-DoD Source] Re: Gyro compass adjustment

This from a YAK40 manual might be of use:

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mark.bitterlich(at)navy.m
Guest

Posted: Mon Apr 10, 2017 2:30 pm Post subject: [Non-DoD Source] Re: Gyro compass adjustment

Yes, I have had experience swinging old compass systems that used a Flux "Valve", or Flux Gate Transmitter, or whatever you want to call them.  We did it by first checking the actual valve externally, then doing a visual site transfer (surveying scopes) into the airplane and then compensating for single and two cycle errors.  Each system is unique to some degree and sometimes some pretty elaborate equipment was used.



That said, the OLD way still works, and that is putting the airplane on a rose and simply adjusting the compensating magnets while moving the aircraft around the rose to align it with the cardinal points.  Moving a flux valve in an airplane ... as in simply moving it directionally to "adjust for deviation" changes the compensation of the valve.  Meaning you will get it to read properly in one direction only.



I do not know the system in the 52 at all.  But if it uses a REMOTE flux valve, then I would never move that valve in the mount to do a darn thing.  Instead I would find the compensation adjustment points and adjust those instead, pretty much like you would any other compass.  If you move the valve AT ALL, then you must re-compensate it, because it the airplanes single and dual cycle errors, induced by electrical fields and also fields around steel parts, etc.,etc., will change.



An interesting tid bit.  I have seen compass roses at small airports all over the place.  They are probably inaccurate.  We re-do the rose every 2 years.   A compass rose that was painted back in the day is no longer accurate.  In 40 years, the one here has shifted over two degrees, but that being said, it all depends on how accurate you need to get.  We had to be better than +/- one degree for the flux valve systems.  More than that for just a simple ole panel mount job like you normally see in general aviation aircraft.



So, again ... not knowing the 52, I am worried that it mightt be the "hard kind" and I would not turn anything until I found a manual, or an expert.  It could be dead easy.  It also could be one that you turn the flux valve and it never works correctly again.  



Mark



________________________________

From: owner-yak-list-server(at)matronics.com [owner-yak-list-server(at)matronics.com] on behalf of Walter Lannon [wlannon(at)shaw.ca]

Sent: Monday, April 10, 2017 12:59 AM

To: yak-list(at)matronics.com

Subject: Re: [Non-DoD Source] Re: Gyro compass adjustment






Hi Mark;



Damned if I know;  That is way beyond my pay grade but I'm sure you could

help.



Yes;  looking for the flux gate; transmitter; or whatever it may be called.

But in my 1965 CJ it is still a magnetic compass (though a very large one),

with a card and a viewing window to facilitate calibration.  Entirely

possible I have made a grave error by assuming the Yak 52 uses the same

unit, a mistake I make too often.



The calibrated North/South line is usually included in the compass rose

which is found somewhere on most airport tarmacs.   Can't say I have ever

seen one without that line, but then--------.



Don't know about "art form" but often the compass swing can be one hell of a

lot of work and, in Canada, is a requirement for every Annual Inspection and

Certification that I do.



Cheers;

Walt



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Looigi

Joined: 20 Apr 2015
Posts: 81
Location: Christchurch, New Zealand

Posted: Fri Apr 14, 2017 1:06 pm Post subject: Re: [Non-DoD Source] Re: Gyro compass adjustment

I fly from a grass airfield so no compass rose painted on the ground here!



We use the old school method with a calibrated compass.  The gyro compass system in the Yak is awesome!  The Correction Mechanism behind the rear seat has an adjustment for the deviation, and a slave indicator for the ones on the panels.  Mine was accurate to within a degree on all the compass points straight out of the box.



The little magnetic compass however wasn't quite so accurate, but a few tweaks and it is now close enough for government work.



Job done, and it didn't turn out to be rocket surgery at all!  Thanks to all for their input.



Chris

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