Vertical Compass Card

kevin47881

kevin47881

Final Approach
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We are discussing installing a VCC in 89S when it goes in for annual next month.

I have flown one plane with a VCC and liked it better than the wet compass. The primary reason for my liking it was that it rotates the same direction as the DG. I found that easier with regards to situational awareness when doing my IR training.

So, what brands/models should I be looking at or running from? 89S is a 12volt system if that alters your opinions.

Any other opinions/comments?

Thanks!
 
Do you have a slaved HSI?

AFAIK, the only thing the 12V will do to your vertical compass is to illuminate the light bulb. They are simply a magnetic compass. The only criticism I've heard of them in general is that they are somewhat harder to calibrate. I like mine just fine. But it's just a compass and really not a big deal either way.
 
Other than a non-TSO'd Chinese made unit I'm pretty sure the only VCC available is one made by Precision Aviation.

http://www.gulf-coast-avionics.com/detail/4295/Instrument/PRECISION_AVIATION/PAI-700/


When I was looking at upgrading my panel I considered a VCC, but I found a couple of articles/blogs that indicated they are pretty sensitive to handling during installation so I decided not to go with one for now. The existing Airpath is doing fine and most shops know how to overhaul them.

I'm considering this one if I ever do replace the original:

http://www.aircraftspruce.com/catalog/inpages/sirs_compass.php

I learned to "fly around" the compass so it's not been a big deal to do the mental intepretation of the older style.

Another factor is I have two digital magnetometer driven heading indicators and HSI (TruTrak a/p display and Aspen PFD) so the old "whiskey compass" is more of a backup now.
 
The only vertical card compass that I've installed is the Hamilton brand and lots of them. Choosing the correct mount and calibration are the only snags.

Kevin
 
Both airplanes I have owned had VCC's and I had no problem what so ever. But like what was said above, its just a compass.
 
Ken Ibold said:
Do you have a slaved HSI?

AFAIK, the only thing the 12V will do to your vertical compass is to illuminate the light bulb. They are simply a magnetic compass. The only criticism I've heard of them in general is that they are somewhat harder to calibrate. I like mine just fine. But it's just a compass and really not a big deal either way.
Click to expand...

I do not Ken. Thanks for the personal experience comment!
 
Steve said:
Other than a non-TSO'd Chinese made unit I'm pretty sure the only VCC available is one made by Precision Aviation.

http://www.gulf-coast-avionics.com/detail/4295/Instrument/PRECISION_AVIATION/PAI-700/


When I was looking at upgrading my panel I considered a VCC, but I found a couple of articles/blogs that indicated they are pretty sensitive to handling during installation so I decided not to go with one for now. The existing Airpath is doing fine and most shops know how to overhaul them.

I'm considering this one if I ever do replace the original:

http://www.aircraftspruce.com/catalog/inpages/sirs_compass.php

I learned to "fly around" the compass so it's not been a big deal to do the mental intepretation of the older style.

Another factor is I have two digital magnetometer driven heading indicators and HSI (TruTrak a/p display and Aspen PFD) so the old "whiskey compass" is more of a backup now.
Click to expand...

Thanks, Steve!
 
We installed the PAI unit 8/07. We just love it!

After getting the compensation done, we found that it had little error all the way around (<3 degrees on any point). It is also much more stable than the wet units, deviating far less during accelleration, decelleration, climbs and turns than the wet units.

I have been told that they are not as durable as wet ones due to more moving parts, but........
 
helifino

They're made in England. Maybe they can charge more to Aussies.

I do know they use silicone instead of "kerosene" and have metal bellows instead of an elastomeric diaphragm for fluid expansion.

http://www.sirs.co.uk/aircraft avionic.htm


vontresc said:
I noticed that they have different models for the Northern, and Southern hemispheres. What do you do if you live on the equator???

On a serious note why would they be different?
Click to expand...
 
The Old Man said:
We installed the PAI unit 8/07. We just love it!

After getting the compensation done, we found that it had little error all the way around (<3 degrees on any point). It is also much more stable than the wet units, deviating far less during accelleration, decelleration, climbs and turns than the wet units.

I have been told that they are not as durable as wet ones due to more moving parts, but........
Click to expand...

A VCC doesn't exhibit acceleration and deceleration errors because the magnet's axis is fixed to the airplane. Instead you get a similar error when the deck angle isn't level. WRT turning errors, vertical compasses behave the same as wet compasses as long as the turn is coordinated. If you skid the error will be less with a VCC. In a forward slip a VCC will show a "turning" error that's not present in a wet compass. Vertical compasses are generally more damped than wet compasses which mostly results in less "swinging" in turbulence.

The most serious issue I've heard about WRT VCC longevity is the tendency to jump the bearings when a ferrous object is near the compass. The magnets in a VCC must be much stronger since there's a lot more friction to overcome and as a result there's a strong force present if you put a steel bladed screwdriver up against the case. Tom Rogers posted an article about this several years ago but apparently it's been pulled. I don't know if the problem has been addressed in the current product but it seems likely.
 
I've run across quite a few VCC's in my training work. I haven't seen one that was even close to accurate all the way around, with errors of up to 30 degrees in some directions despite all the swinging anyone could do with it. Further, if you have any kind of GPS, you're not going to be looking at the wet compass during partial panel operations anyway. Thus, I would not recommend spending the money on one of these.
 
I tend to agree with Cap'n' Ron, I also have seen my fair share of both Vertical card compasses and standard compass. They tend to really get a work out when doing instrument training as they get checked vs the DG a lot more often than they normally do in VFR flying.

Also mentioned above, is that the VCC seems to be more difficult to calibrate than the old Wet compass, my experience would seem to confirm this in that the VCC tend have more errors than the wet compasses. Perhaps this is a factor of the experience of the installer.

I agree I like the VCC better than the wet compass for ease of reading but am not convinced that they are as accurate as the wet compass.
FWIW I have also seen plenty of Wet compass's with significant errors as well.
If you all you do is VFR flying you will probably never really notice the errors, unless they are severe.



Brian
CFIIG/ASEL
 
vontresc said:
If you want a Unique compass, check out the Bohli compass. This device can give you limited pitch information.
Click to expand...
In Figuare 2.8 of that document, there is a "Lines of Equal Dip." The one shown is for 1965.

Does anyone know of a source for a more recent chart or the rate of change through time? This would be an interesting teaching tool.
 
Ron Levy said:
I've run across quite a few VCC's in my training work. I haven't seen one that was even close to accurate all the way around, with errors of up to 30 degrees in some directions despite all the swinging anyone could do with it. Further, if you have any kind of GPS, you're not going to be looking at the wet compass during partial panel operations anyway. Thus, I would not recommend spending the money on one of these.
Click to expand...

You. Tried to make a Hamilton work in an Ercoupe and couldn't get the errors down within reason or legal limits (+/- 10°). They are hypersensitive to vibration and require a very soft shockmount.

Dan
 
Ron Levy said:
I've run across quite a few VCC's in my training work. I haven't seen one that was even close to accurate all the way around, with errors of up to 30 degrees in some directions despite all the swinging anyone could do with it. Further, if you have any kind of GPS, you're not going to be looking at the wet compass during partial panel operations anyway. Thus, I would not recommend spending the money on one of these.
Click to expand...



Mine was. And Bill Scott verified it this past Annual.
 
Ron Levy said:
I've run across quite a few VCC's in my training work. I haven't seen one that was even close to accurate all the way around, with errors of up to 30 degrees in some directions despite all the swinging anyone could do with it. Further, if you have any kind of GPS, you're not going to be looking at the wet compass during partial panel operations anyway. Thus, I would not recommend spending the money on one of these.
Click to expand...

Interesting perspective I had not considered. Thanks!
 
Ron Levy said:
This I gotta see. BTW, I've seen several which looked OK on the ground, but not in flight.
Click to expand...


We checked it in flight, because we wrung it out making sure everything was as it should be. He's, ahh, interesting to fly with too. :D
 
I put one in my AA1B, easy to calibrate and within 3-4 in all quads.
2.5years and still working great when I sold the 'plane.

Put one in the Hiperbipe and got within 5* in all quads (E-W is PERFECT!) and this is a steel cage-type fuselage...I bought the Balancing Balls but didn't need 'em. Go figure. And after 60+ hours of Flip-Flop-Flying it still gives me the NEWS!

So far, mine plus the other dozen or so I've installed I've only had trouble with 2. One was dud out of the box (cheerfully replaced @ ACS) an another got drift induced by a GEM moniter I didn't know had been installed post-calibration.

I love 'em. They can't be that fragile, I rattle the crap outta' mine.

JMPO

Chris
 
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