Mag Compass

supercub

MEMBER

Let me check my GPS, gee how'd we ever navigate w

• Oct 12, 2002

• #1

Curious, has anyone tried one of the SIRS naviagation Ltd compassses in their Super Cub? www.sirs.com.uk/ Also, do the vertical card compasses do any better. Like so many of you my compass is inacurate, it's off as much as 30 degrees on certain headings.
Brian

 

B

BIGFOOT

Registered User

Kalama,Wa

• Oct 12, 2002

• #2

Supercub: I have the same problem.....Was wondering if a vertical card compass could be panel mounted?Seems like a nice way to fix the problem and update the panel. Also when swinging a compass( for the compass correction card) should a cub be in the level flight attitude?.Or is three point as accurate? Currious to hear how you resolve this issue. BIGFOOT

 

C

Carl

Registered User

Petersburg, Alaska

• Oct 13, 2002

• #3

Tried a vertical card compas in a Citabria- same problem as the whiskey compas. All the iron airplanes I've been around are easy to hold a heading in, 230 west and 150 east. Olnly one I've seen worl righ was a remote compas with the sendining unit in the wing.
Carl

 

Steve Pierce

BENEFACTOR

Graham, TX

• Oct 13, 2002

• #4

I've tried the SIRS and the verticle card both in the panel and on top. They work the same as a whiskey. On some cubs they work on the left side of the glare shield. You have to make a bracket to let it sit level. As far as level flight when swinging a compass it would probably be better but a pain in the @$$. I run the engine when I am swinging the compass with the radios on. I have taken a compass and moved it around the cockpit with the nose pointed in different directions. Sometimes you find a spot but most often I don't.

Steve

 

supercub

MEMBER

Let me check my GPS, gee how'd we ever navigate w

• Oct 13, 2002

• #5

I know I've seen pics of Piper swinging the compasses in new J-3s and they had the tail up, level flight attitude and engines running.
Brian

 

Ursa Major

Registered User

Coeur d'Alene, Idaho

• Oct 13, 2002

• #6

You know it's interesting the number of times that magnetic compass problems have shown up on this site. I'm beginning to wonder if there are any SuperCubs with a funtional wet compass.

My vertical card has never been close, even though I've tried every conceivable way of mounting it. I've even taken the cub to a couple of radio shops who were unable to get the VC (or any other wet compass) to work properly in it. (The shops had no problem charging me for the work though) Outside the plane it works fine. Degasussing doesn't seem to work either.

The remote compass works fine though the FAA doesn't consider it to be legal (needs power). The GPS works even better. Anymore, I consider the vertcal card compass to be like a hood ornament -- nice to look at but not partcularly useful. I'm just a wee bit worried that come next annual my IA will decide to inspect the compass function and deviation card for accuracy. Maybe he will be able to solve the problem, but I'm sceptical.

 

SuperCub MD

Registered User

Collins, Wisconsin

• Oct 13, 2002

• #7

I've watch this raging debate about why a magnetic compass just doesn't work also. Does anyone remember when Piper made Super Cubs? They went to great pains to keep electrics out of the panel, ran wires along wooden stringers, kept current flowing wires in wing roots and other rear mounted places. Wonder why they did that?

Remember being a kid in science class and wrapping a wire around a nail and running current through the wire? What did the nail become? Now look behind your instrument panel at all the wires that have been add to your plane that run next to, around the fuselage tubing and other metal structures, and think about the nail, and ask again why your compass doesn't work.

 

Dave Calkins

Registered User

Anchorage, Alaska

• Oct 13, 2002

• #8

Hey guys, do a little maneuvering around this site and look at some of the other debate on this same subject. There are answers there.

Mark, sounds like you hit the nail on the head.

Dave Calkins.

 

PA12driver

Registered User

Battle Ground, WA

• Oct 13, 2002

• #9

to lazy to look it up? is there a maximum that the correction card can state to get the compass to be accurate? If not why not just put in what ever it takes and call it working? I can't find anyone using it anyway and if so they are most likely still out there trying to find there way home! If the compass is swung accurate in the plane than in many many places in Alaska the magnetic disturbance in the vicinity of the mountains was so bad it doesn't matter anyway? Common Sense still prevails with most IA's I know!

Thank God for GPS, McDonalds Billboards and highway signs.

Tim

 

Dave Calkins

Registered User

Anchorage, Alaska

• Oct 13, 2002

• #10

Tim, the FAR's require the thing to be within 10 degrees of each heading every 30 degrees around the rose:

0 30 60 90 120 , etc. gotta be within 10 degrees of each of these, all the way back around to 360/0 degrees.

Yep, it's a pain if you can't get yours to swing right. Those remote sensing compasses work great, though.

The whiskey compass in my -11 worked when the a/c was taken apart a few years back.

At the time I was running a starter, generator, nav lights, tail strobe, and a power wire for my handheld and a portable intercom box. Pretty simple panel also. Man that thing was fun to fly. I gotta get back out there and see some visible progress on that project.

Dave Calkins.

 

PA12driver

Registered User

Battle Ground, WA

• Oct 13, 2002

• #11

Mine is pretty close to that, I just don't use it for most of the flying I do? the only time I even check it is when sitting on the end of a strip

My second to the last PA18 had a remote compass and it was great! however we didn't have Loran or GPS then. I don't know how I got around with out the new stuff. I do miss listening to the Radio on the ADF!! the ol KR86 was a work horse down on the peninsula at 50 ft off the deck!

Tim

 

Ursa Major

Registered User

Coeur d'Alene, Idaho

• Oct 13, 2002

• #12

I'm a little confused. I have a remote mounted compass that works great, but the panel (or top of panel) magnetic compass doesn't get within 40 degrees of the proper heading. I agree that I have entirely too much electric crap in the panel probably causing the problem.

Is the remote compass an acceptable (legal) replacement for the whiskey or vertical card compasses? Can I get rid of the standard magnetic one or is it part of the required equipment?

I agree with you Mark, a simple cub with few electrics and a smaller panel would be advantageous but I fly in pretty busy airspace where a transponder/encoder and strobes as well as radio makes for (hopefully) a safer situation. I can use that extra set of controller's eyes looking for traffic.

The previous owner/builder also moved all of the electrical switches and breakers from the wing roots to the panel to (I assume) get the electricity mostly away from the fuel tanks. Its a nice installation but you pays the price -- in this case poor compass performance.

Anybody got any suggestions -- other than tearing out the panel and starting from scratch?

 

Crash

GONE WEST

Nikiski Alaska

• Oct 14, 2002

• #13

Compass

My A&P said to just write some figures on the card and stick it in the holder. Has the FAA ever ramped anyone for a compass card check? You guy's take this thing way too seriously. Let's get back to horepower and weight again. Crash

 

SuperCub MD

Registered User

Collins, Wisconsin

• Oct 14, 2002

• #14

Amen Crash, there are better things to discuse.

I'm not saying to relocate, remove electrics from your plane, I understand that some need this stuff in the environment they fly in. I am saying that if you have lots of electrical stuff in your panel, don't be so shocked when your compass card spins around in circles when the plane is not.

Again I ask, if I'm annualing a plane that has no compass card, can I not assume that the compass is dead on in all directions? Or if it has a card, that it is accurate? I have a lot more important things to look for on a inspection that the exact accuracy of a compass card.

 

SuperCub MD

Registered User

Collins, Wisconsin

• Oct 14, 2002

• #15

To PA12 driver, I used to fly all over the country with a compass, wristwatch, some ripped up sectionals and a road atlas. The best thing about having good eyes was not having to buzz so low to read the highway signs. And a big thanks to all the little burbs that paint their names on their watertowers. My navigational theory was, "If I still have gas, I ain't lost". How did we ever survive?

Sometimes I miss it, turn off the GPS, and wander around with a sectional and road atlas opened up on my knee, just for old times sake.

 

PA12driver

Registered User

Battle Ground, WA

• Oct 14, 2002

• #16

Mark, Now you are getting Nostalgic! The ol 5 piece sectional, with all the little marks on it! yeh, was just the other day when I did that too, always had my finger where I was, trying to keep the map folded to be small enouh to stay on my lap! Technology is kinda cool, last summer when I went to Idaho, I scanned in sections of the chart to 81/2 X 11 and put them in sheet protectors and a ring in the corner, and I had a map with no tears in it! ($8) bucks apiece! now they last for ever!! By the way I really got modern last week I bought a new one for Anchorage Alaska! my last one said 1988! (the mountains hadn't moved abit)

Don't think I even still have a brass screwdriver?-replaced it with a low pressure tire guage! (can you believe it it is supposed to be 75 degrees today!! summer isn't over yet baby!!

Have fun! low, slow, and go!

 

T.J.

Registered User

Alaska

• Oct 14, 2002

• #17

delete

 

Ursa Major

Registered User

Coeur d'Alene, Idaho

• Oct 14, 2002

• #18

Good tips guys! Thanks for the info.

 

T.J.

Registered User

Alaska

• Oct 23, 2002

• #19

delete

 

Ursa Major

Registered User

Coeur d'Alene, Idaho

• Oct 24, 2002

• #20

TJ,

I think I understand your post. So, if you've got a "stabilized" compass that works (gyro compass) then the whiskey compass doesn't have to be within 10 degrees per 30 degree heading. Only question I have is; Does that mean that a remote compass is a "stabilized" compass?

It seems kind of odd that the non stabilized inaccurate compass needs a correction card that identifies electrical loads that make the compass inaccurate. You would think that the whiskey compass could have an "Inop" sticker on it as long as you have something else that works.

I'm beginning to agree with one of the previous posts that we're getting too hung up on this whole issue. I'm about ready to put a big magnet on the back of my compass and put a deviation card in that shows each heading reading "N".

 

cubdrvr

SPONSOR

YKN(mother city of the dakotas)

• Oct 24, 2002

• #21

TJ has the answer in that no one but you will know what the deviation is on your compass. Know what the deviation is for your compass (in case you need to use it), file it somewhere handy, then forget it and use your GPS. :fadein:

 

T.J.

Registered User

Alaska

• Oct 24, 2002

• #22

delete

 

Dave Calkins

Registered User

Anchorage, Alaska

• Oct 24, 2002

• #23

TJ. It seems that FAR 23.1327 paragraph (b) may be read to mean:

....."if the deviation is caused by a system like a hot windshield, etc. and you have a stabilized mag. hdng. ind. with less than 10 deg. deviation or a gyro heading ind. aboard, you're OK, as long as the non-stabilized mag. hdng. ind. is placarded IAW PART 23.1547."

In other words, if the cause of non-stab. mag. hdng. ind. deviation is a hot windshield, you can get away with it.

The other way to read this is that your CUB, Champ, etc. whiskey compass don't work WITHOUT the HOT windshield turned on......so, you're screwed.

The problem is....the FAR's may be interpretted differently from person-to person.

By the way.....My GPS only provides ground track information, not heading info. My remote compass provides heading info. not ground track info. soooooooo...with a good crosswind, the GPS and remote compass offer "interpretations" as to my heading and ground track info., and will never indicate the same.

 

Crash

GONE WEST

Nikiski Alaska

• Oct 24, 2002

• #24

Compass

P.S.: Most new GPS's have an option in the set up menu of "true north" or "magnetic north". Most factory settings are true north. If you try to swing your compass with the GPS inflight be sure it is set for "magnetic north" other wise you will be WAY off. In my area that could be up to 27 degrees off true north. Crash

 

RMREBOB

GONE WEST

Arlington, Texas

• Nov 5, 2002

• #25

COMPASS LOCATION

Don't give up on solving this problem until you've read my comment in the "Compass Location" thread.