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compass

C

Cottonwood1

wing
SPONSOR
getttysburg pa.
Have 1989 supercub and whiskey compass works fine , unless alternator kicks in. battery is in original location and one wire is shielded. we also took demagnitizer around door framesw since they seemed to affect compass.. Compass was adjusted in alll directions with other compass. Compass works normal until alternator kicks on. if you pull fuse it corrects itself. Wondering what wire needs shielded.
Thanks,
Brett
 
Lots of discussions here over the years on the futility of getting a compass to work right in a Super Cub. Never had one that was even close myself.

sj
 
Shielding has minimal effect on high current wires. The best you can do is find out the routing of your alternator wires and move them away from the compass. Distance is the only sure way of lessening the effects of the magnetic field generated by wires.

And, as stated above, a whiskey compass in a ferrous tube aircraft is usually only good enough to point out the last weld.

Web
 
Actually, the SIRS compasses work fairly well when located fairly high in the windshield. I’ve used them in Cubs, Husky and Cessna, and they worked. Part of their design is that they are fairly well damped.

And, yes, I have flown on a whiskey compass and a map…..my philosophy is if it’s installed it should work.

I recently flew in a Carbon Cub, which had a SIRS compass. Seemed to work. Is that standard with CC?

MTV
 
When I redid my panel several years back I was reading posts and saw MTV's advice about the SIRS. I was going to mount it on the wind screen to save some panel space. I even picked up a degausser from Northern Lights Avionics and waved it all over the place. It took a while but I found a spot in the lower right side of the windscreen that worked great. Over the years it has continued to give and hold a general direction without any problem. I have had my GPS go down a few times in the mountains and in crap weather so having something that helps hold a heading while I figure out the problem is nice. DENNY
 
I bought a 39 J-3 in Jacksonville Fla. in 1976 and flew it home to Maine. No GPS of course, or a radio. compass swirled like crazy all the way home and still did when I sold it years later. LOL
 
Remote compasses used to be popular up here. Are they still used much? I had one in a couple of planes including a PA-18. The whiskey unit always pointed to sunrise

Gary
 
My experience was exactly as Denny’s! With a SIRS it was no good up high, but lower right of windscreen thumbs up. No where else in cabin worked at all.
 
BC12D-4-85 said:
Remote compasses used to be popular up here. Are they still used much? I had one in a couple of planes including a PA-18. The whiskey unit always pointed to sunrise

Gary
Click to expand...

Only type that I've seen that seems to work well. It gets the flux valve out in the wing and away from the steel in the fuselage.

Web
 
supercrow said:
I bought a 39 J-3 in Jacksonville Fla. in 1976 and flew it home to Maine. No GPS of course, or a radio. compass swirled like crazy all the way home and still did when I sold it years later. LOL
Click to expand...

Hard trip? Just keep the blue on your right. ;-)

Glenn
 
cubdriver2 said:
Hard trip? Just keep the blue on your right. ;-)

Glenn
Click to expand...

Try that in interior Alaska.....or North Dakota, for that matter.....in 2 mile visibility....just sayin.

Compasses point to magnetized metal. So, yes, you have to move it around to try to find a spot that's more or less neutral.

MTV
 
Mine is installed because it has to be. Compass on my I-phone works great........with a map on my lap......should my 3 GPS's fail.
 
Most Cub compasses work very well in one direction. Only compass I have seen work on a Cub was at the top of the windshield.
 
That’d be about right, failing tech because because I didn’t have a deviation card for my compass sticker;-)
 
Stuck it in many diff places and for some reason it works fine here. On top of dash with avionics on it was stuck on 210.
 

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You can collect Magnetic Flux data on your airframe using your iPhone. Get the "Smart Tools Pro" app. Go to the "Utility" features, and select "Mag Flux". I see a normal reading right now as I sit in a chair of around 50. If I move it over my laptop it shoots up to a bit over 1000 near the W key. You can pinpoint a spot on an airframe tube that is highly magnetized and locate areas where magnetism is minimal.

Minimal Magnatism and the Sirs Compass combo might give you hope.
 
Magnetometers work great. GPSs work almost as well. Compass apps in a smart phone are pretty good. Whiskey compasses? If they really contained whiskey they’d be handy. Otherwise? FAA required ballast. Like 121.5 ELTs.
 
Hamilton the vertical card compass folks at one time sold a magnetic field reducing tape (Iconel or nickel - something like that). The idea was to wrap any nearby offending spots that were creating magnetic fields. I bought some and tried it for my panel mounted compass. Don't recall how well it worked. Then I got their monkey ball accessory which attached to the back of the compass case and rotated them until the compass read close to reality. Similar to compasses on ships.

Gary
 

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Gary,

Called magnetic compensators, Gary. Funny how a compass can work, and has for a couple hundred years on board ships, but apparently some pilots can't figure out how to make them work.

If you want the ultimate, the submarine I served on had a magnetic compass....steel, lots of steel, in every direction....and, amazingly, we actually navigated with that thing.....

I used those compensators on my Cub's Hamilton VC compass, and it worked. On my 170, I went to a SIRS compass when they came out, and they worked really well.

MTV
 
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