Wet Compass vs Vertical Card Compass

[Dave Kaiser]

My wet compass in my 7KCAB will need to be replaced. Anyone have any opinions on the vertical card compass as a replacement. I do aerobatics and will the vertical card compass hold up to the "g's" and unusual attitudes?
Thanks,
Dave

 

[smitchell]

Hi Dave - I have a verical card compass in my 7KCAB that has been installed for about a year. I also do aerobatics and I have not noticed any problems with the compass as a result. I will tell you that I have had (still not totally sorted out) big problems with magnetic interference. My is mounted on the glare shield near the windshield. I had to place mu metal underneath the compass to even get it close to the point that I cound swing it. It is still off a bit and the interference seems to be coming from the electric turn and bank. There is still another thing to try (I have not done this yet) and that is something called "balancing balls" - available from Precision. It has been a real pain in the neck and I haven't been able to find an A/P or AI that is interested in the problem.

Good luck. Sally

 

[Dave Kaiser]

Sally,
Thanks for the info. I hadn't heard anything for a while on my original post so I did some investigating. From my research I went with the SIRS wet compass and installed it. It swung with minor adjustments almost perfectly with it installed in the orginal position. Only 2 headings were off and it was only a degree.

In my research I found an interesting article about the vertical compass card which had to due with issues in swinging the compass. It was due mainly to the magnets moving out of position during the installation phase if you used a normal (ferrous) screwdriver. If you feel like this might be the issue with yours let me know and I will try to dig up the article.

By the way when the compass was swung it was done with all electrical operating except the nav lights. It appeared that the xponder made the largest difference. The nav lights also had an impact but since I normally don't operate them in day vfr we adjusted it without them on. When then turned them on when we calibrated each heading and it consistantly resulted in a -2 degrees which I took note if I ever did intend to fly at night.

Dave

 

[smitchell]

Dave - Thanks for the reply. I'm glad you got everything working to your satisfaction. Yes I had the information on the appropriate tool to use when swinging the compass - still didn't help. The only upside to this issue was the excellent help from the technical folks at Precision - they were great to the extent that they could assist long distance.

Sally