magnetic compass.. for car?

Peter Ha

Peter Ha

Pre-takeoff checklist
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Hey folks,
Looking for magnetic compass to mount on car so to mimic use on airplane. Any recommendation?
 
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I'm just going to say it. This is weird.
 
I have one sitting on the dash in my plane. You’re welcome to it since I don’t use it for anything. ;)
 
As a VFR pilot, the only time you will refer to the mag compass is when you are setting the heading indicator to agree with it (in the absence of a numbered runway). Wet compasses are notoriously difficult to read when there is the least little bit of turbulence. IOW, getting one for your car will not help you as a pilot. Your gyroscopic heading indicator, which is much more stable and easier to read than a mag compass, will be your primary heading reference.

A totally confusing thing about magnetic compasses is that if you begin a right turn (for example), the mag compass will initially show a left turn, but will catch up as the turn progresses. You will learn about magnetic compass errors when you study for the written exam.

I assume that you are a nascent aviator. Good for you! In the real world you will be navigating by looking out the window at ground references, not at a mag compass or heading indicator. Electronic navigation is another subject altogether.
 
A teacher told me years ago... there are no stupid questions. It's better to ask then to remain ignorant. :)
Guess I didn't phase the question correctly.
I'm looking for type of compass for car as to simulate looking directions (as done while im flying airplane).
If this sounds totally un-practicable... let me know why.
 
Got iPhone?

Native app does this.
Maybe Android too.

You can also get something low cost from AutoZone or the automotive aisle at WalMart.

but I really don’t see value to what you propose.

In airplane, lack of roads means you are able to “go any direction” you please, so the compass and DG are necessary tools

in automobile, travel is restricted to roadways, restricting travel direction in how they are lakes out. And not common are they headed in one compass direction for, as The Who once said, “for miles and miles and miles”.

I realize you’re headed toward your next step of an IFR rating. A magnetic compass is required equipment item, but one not often referenced these days. Most often you are keeping your DG or HSI in your scan. The magnetic compass is just referenced briefly to correct for gyro precession.

Im unsure how well the car will work as an analog to an airplane for the using a magnetic compass. Your time and dollars might be better spent focusing on the aircraft
 
I have one on my desk, taken from some airplane or other in the past. I thought about mounting it in the car, but since there's one in the nav system, it would just add another layer of dork to my life.
 
https://www.carbibles.com/best-car-compass/

OR

I guess this is a bit of overkill :)
It's a hall effect (I suppose) magnetic compass with integrated gyro compensation. $100 project.

https://kingtidesailing.blogspot.com/2015/09/how-to-setup-mpu-9150-9-axis.html

How to Setup the MPU-9150 9-Axis Accelerometer, Gyro, & Compass with an Arduino
mpulogo.jpg
 
Haven't seen one of those since I was a kid. My grandpa had a ball compass on either his dashboard or suction cupped to the windshield.

My car does have an electronic compass display "N, NE, E, SE, ..." that's sometimes, but rarely, useful.

5a9facf183042518fa648680-large.jpg
 
bobmrg said:
As a VFR pilot, the only time you will refer to the mag compass is when you are setting the heading indicator...
Click to expand...

...unless you don't have a heading indicator. None of the airplanes I've owned have had one. OTOH, they've all (with the exception of one ultralight) had magnetic compasses.

I've always had a compass in my car, too. Awful nice to have when you're trying to find your way in an unfamiliar area, you're not going to drive a course by it but it can be nice to know the general direction you're heading. Granted it's not as important nowadays when everybody has a GPS and Waze or google maps on their phone...

Peter, you can buy a cheap auto compass at Walmart. You can get better ones (boat compasses) at West Marine. Or get a real aircraft compass from Aircraft Spruce, or used on ebay.
 
For IFR, all you need is a cat and a duck.
 
Walmart. RV Section. Probably 8 bucks.

Get the cheapest one they sell, so that the automotive instrument can accurately mimic the uselessness of the aviation instrument. :D

Actually, since you're headed to IR training now, see if you can identify each of the 7 different reasons the whiskey compass sucks at its job ("compass errors"), while driving in your car. That will help with the written and the oral exams.
 
Dana said:
...unless you don't have a heading indicator. None of the airplanes I've owned have had one. OTOH, they've all (with the exception of one ultralight) had magnetic compasses.

I've always had a compass in my car, too. Awful nice to have when you're trying to find your way in an unfamiliar area, you're not going to drive a course by it but it can be nice to know the general direction you're heading. Granted it's not as important nowadays when everybody has a GPS and Waze or google maps on their phone...

Peter, you can buy a cheap auto compass at Walmart. You can get better ones (boat compasses) at West Marine. Or get a real aircraft compass from Aircraft Spruce, or used on ebay.
Click to expand...

Right, Dana...I jumped to the conclusion that if the OP is a new student the trainer will have vacuum instruments. Full disclosure: I have a mag compass in my glove compartment. Doesn't look anything like an airplane compass.

Bob
 
I have a KI-13 MIG-21 compass mounted on the windshield of my truck. It doesn't have much practical use but I like it. (https://auction.catawiki.com/kavels...3-for-a-jet-fighter-mig-21-ussr-20-th-century) At one point, quite a few years ago, there was a lot of this kind of new military hardware coming out of Russia and sold online. I also have a MIG-27 clock (http://www.abbeyclock.com/photos/mig.html) that I used to have on my desk at work. PITA to keep it wound, though.

Finally, I have an English G150 marching compass in a nice leather case. Totally useless in my real world, but who could resist a compass with a mother-of-pearl compass card? (
)

I am surprised that a gang of people who fly light airplanes would be so spun up about the OP's idea of wanting a compass just for the fun of it.
 
Make sure you understand the variations for your locale and deviations for the installation. There’s no telling where you might end up if you’re 10 or 15 degrees off course.
 
Peter Ha said:
Hey folks,
Looking for magnetic compass to mount on car so to mimic use on airplane. Any recommendation?
Click to expand...

Heh...this is funny. I bought one recently on Amazon. I wanted one similar to the ones we use in the plane. I also clearly recall my grandfather had one in his car (my dad was a pilot but grandpa wasn’t, he just liked having a compass) that fascinated me as a child, and also seemed really lame to me when I was a teen.

I understand what bobmrg, among others, is saying here about only reading it when stable, to set the DG. But I wanted one for a couple of reasons.
Mostly, because I just want practice at reading it quickly and accurately. I may be slow, but I always feel a little uncertain for a few seconds, in front of my CFI...feel that small panic like someone asked me to multiply 672 by 40 right now. From the nearest visible number, I know it is “backwards” but I have to reacquaint (“okay it’s two marks away from 21, but 21 really means 210, so...okay, which way now?”) and I’d just like it to be more automatic.
Secondly, not reading it for total accuracy as when setting DG, but just in general direction, obviously also reading when stopped, or “straight and level driving”.

Thirdly, I like it better than fuzzy dice so..

But that said, there were not very many of the “old style” airplane compass ball style to choose from, and as far as I could see all looked like cheaper Chinese knockoffs. I chose the one that looked to be the best of them. When I got it some months ago, I still haven’t mounted it. It seems really cheaply made. Also the mount is weird.

I may just give up on that idea. Grandpa had a quality made one.
 
Matthew said:
Haven't seen one of those since I was a kid. My grandpa had a ball compass on either his dashboard or suction cupped to the windshield.

My car does have an electronic compass display "N, NE, E, SE, ..." that's sometimes, but rarely, useful.

5a9facf183042518fa648680-large.jpg
Click to expand...
I didn’t see your post yet when I posted.
What is it with grandfathers and these ball compasses?

My grandpa was up in Superior, Wisconsin. Where was yours from? (Was this a regional or national thing?) and why didn’t my dad, who actually was a pilot feel the need for one? Maybe because it was my mother’s father that had one, not his father, and...it looked really lame?

As I said, I was fascinated by it as a kid riding with grandpa, but when I got to be a teen scoffed at it and thought it lame. As a kid I think I asked him a bunch of times WHY he had it, and he never quite gave a good reason. He used to work for the highway department, maybe it had to do with that.
 
Last time I tried mounting a compass in my truck there was too much magnetic interference from the stuff in the panel for it to work.
 
you might consider looking at a marine compass. I suspect though that it'll be near impossible to get it swung properly.
regardless
Thinking it through.... most of the compass work has to do with turns to headings and timed turns. In a car, the turn radius is very small, in an airplane much larger.....so you turn from one heading to another in a car is almost instantaneous. It's also very fixed and defined, depending on the road....it's not like you're very likely to turn out 10° off course in a car...at least not very long.
So unless you have a hug parking lot or some wide open spaces to play in, it seems like the skill set just doesn't correlate all that well in my thinking....
 
LongRoadBob said:
Heh...this is funny. I bought one recently on Amazon. I wanted one similar to the ones we use in the plane. I also clearly recall my grandfather had one in his car (my dad was a pilot but grandpa wasn’t, he just liked having a compass) that fascinated me as a child, and also seemed really lame to me when I was a teen.

I understand what bobmrg, among others, is saying here about only reading it when stable, to set the DG. But I wanted one for a couple of reasons.
Mostly, because I just want practice at reading it quickly and accurately. I may be slow, but I always feel a little uncertain for a few seconds, in front of my CFI...feel that small panic like someone asked me to multiply 672 by 40 right now. From the nearest visible number, I know it is “backwards” but I have to reacquaint (“okay it’s two marks away from 21, but 21 really means 210, so...okay, which way now?”) and I’d just like it to be more automatic.
Secondly, not reading it for total accuracy as when setting DG, but just in general direction, obviously also reading when stopped, or “straight and level driving”.

Thirdly, I like it better than fuzzy dice so..

But that said, there were not very many of the “old style” airplane compass ball style to choose from, and as far as I could see all looked like cheaper Chinese knockoffs. I chose the one that looked to be the best of them. When I got it some months ago, I still haven’t mounted it. It seems really cheaply made. Also the mount is weird.

I may just give up on that idea. Grandpa had a quality made one.
Click to expand...

Hey Bob you and I think the same!
Your reason given is exactly what I was thinking. Thanks.
 
LongRoadBob said:
I didn’t see your post yet when I posted.
What is it with grandfathers and these ball compasses?

My grandpa was up in Superior, Wisconsin. Where was yours from? (Was this a regional or national thing?) and why didn’t my dad, who actually was a pilot feel the need for one? Maybe because it was my mother’s father that had one, not his father, and...it looked really lame?

As I said, I was fascinated by it as a kid riding with grandpa, but when I got to be a teen scoffed at it and thought it lame. As a kid I think I asked him a bunch of times WHY he had it, and he never quite gave a good reason. He used to work for the highway department, maybe it had to do with that.
Click to expand...
Chicago. Must have been a Midwestern thing.

In much if the midwestern US roads are on a nice N/S/E/W grid. Where the compass built into my car does come in handy is on the odd road that twists through a subdivision or industrial park or along a creek. When it pops me out on another street I don’t recognize, it helps to know what direction I’m facing. If I can’t figure it out otherwise, a glance at the compass does the job.
 
Why do you need a compass? You have no choice in an automobile but to go in the direction the road is pointed.
 
Silvaire said:
Why do you need a compass? You have no choice in an automobile but to go in the direction the road is pointed.
Click to expand...

As a young man in northern Chicago we have an interstate (not sure, I seem to recall it was I-95, but whatever it was) that is designated East-West, but in northern Il actually runs North-south until it straightens out again.

There were a few times in an unfamiliar area, knew I wanted to go south but wasn’t sure if I should take East or west. I could have figured out East = north, but...

But the main thing, I don’t think the OP, or I were thinking of using it for navigation. Just to see which direction we are at any given time. For fun. Not everything has to be utility. Also I want to get used to reading off headings.
 
bobmrg said:
As a VFR pilot, the only time you will refer to the mag compass is when you are setting the heading indicator to agree with it
Click to expand...
Since mine is usually 30 degrees (or so) off, I use my GPS to set the DG while taxiing. Then I rarely look at that either.

During the ferry flight home after prepurchase ATC gave us a heading to fly and a few minutes later basically asked where the heck we were going... that’s when we realized the MagC was unreliable.
 
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On the other hand, if you catch us putting up a deviation card on the dashboard, then we are fair game.
 
Matthew said:
Haven't seen one of those since I was a kid. My grandpa had a ball compass on either his dashboard or suction cupped to the windshield.

My car does have an electronic compass display "N, NE, E, SE, ..." that's sometimes, but rarely, useful.

5a9facf183042518fa648680-large.jpg
Click to expand...
A dash icon from a Ford Lincoln Mercury Sable... A personal conveyance named after its inventor, an assassinated ruler, a character from Greco-Roman myth, and a small furry mammal.
 
Peter Ha said:
Hey folks,
Looking for magnetic compass to mount on car so to mimic use on airplane. Any recommendation?
Click to expand...
Try checking out a kayak shop. They have some great marine compasses that will attach to the kayak foredeck, or likely your dash. They work just like an aviation compass, but are much easier to read.
 
HAPPYDAN said:
Try checking out a kayak shop. They have some great marine compasses that will attach to the kayak foredeck, or likely your dash. They work just like an aviation compass, but are much easier to read.
Click to expand...

Heh...I was just coming here to post very similar. Had to do repairs on my little sailboat, and at West Marine and happened to grab a catalog. Was paving through it just to see, and saw almost the exact same type we are talking about here, but seem MUCH more sturdy and well made.
Hadn’t thought that boats still use these. Only difference from the aviation (at least this we have here) is they show three digits, so instead of 12 show 120.
 
I had a student do this to try to help himself. He was having a hard time wrapping his head around the degrees on the compass.
 
LongRoadBob said:
Heh...I was just coming here to post very similar. Had to do repairs on my little sailboat, and at West Marine and happened to grab a catalog. Was paving through it just to see, and saw almost the exact same type we are talking about here, but seem MUCH more sturdy and well made.
Hadn’t thought that boats still use these. Only difference from the aviation (at least this we have here) is they show three digits, so instead of 12 show 120.
Click to expand...
Right, Bob. West Marine has some really nice ones. Here in Puget Sound, especially where I live near Henderson Bay, morning ground fog is common. It really helps to get across open water, rather than follow an erratic coastline. Not much different that "paddling in an ocean of air", just slower (and cheaper).
 
Matthew said:
My grandpa had a ball compass on either his dashboard or suction cupped to the windshield.
Click to expand...
My Grandpa had the exact same one!! That brings back memories...
 
In my IFR training I had to use the magnetic compass, and not just for setting the heading indicator. That indicator can fail, or the vacuum pump can fail, and now you're left with the mag compass if you don't have GPS, and that too can fail if the electrical system pooches out. One had to be able to use the compass and use timed turns to headings. This is in Canada, too, where the compass has to be calibrated yearly and a new correction card installed.

A mag compass in a car is nearly useless. So much iron and electrical stuff all around it. And the same goes for the cellphone compass apps; I have two and neither are much use in the vehicle.

We did low-level navigation with the students in the basic-panel Citabria. Low level means landmarks are harder to find, and one had to use the compass. It was good training.
 
Dan Thomas said:
In my IFR training I had to use the magnetic compass, and not just for setting the heading indicator. That indicator can fail, or the vacuum pump can fail, and now you're left with the mag compass if you don't have GPS, and that too can fail if the electrical system pooches out. One had to be able to use the compass and use timed turns to headings. This is in Canada, too, where the compass has to be calibrated yearly and a new correction card installed.

A mag compass in a car is nearly useless. So much iron and electrical stuff all around it. And the same goes for the cellphone compass apps; I have two and neither are much use in the vehicle.

We did low-level navigation with the students in the basic-panel Citabria. Low level means landmarks are harder to find, and one had to use the compass. It was good training.
Click to expand...
Yeah, Dan, you're probably right. We were just trying to help out the OP and answer his question. He could try it out for himself and come to [his own] conclusion.
 
Dan Thomas said:
A mag compass in a car is nearly useless. So much iron and electrical stuff all around it.
Click to expand...
YMMV.

Lots of cars have magnetic compasses built-in to the rear-view mirror. I installed one aftermarket and it works fine. Now, it only give 8 directions, so it could have big errors I don't know, but I wouldn't call it "nearly useless"--I find it consistently useful.

My sister had a cheap whiskey compass glued to her windshield right below the rear view mirror for years. Worked fine. Again, might have had ~15 deg errors that we were oblivious to, but since she wasn't navigating via dead reckoning it worked fine for her.
 
I don’t know about you guys, but after I got my private certificate, the part of my brain that memorized compass action got a bad sector.

I started IFR this winter and we are doing partial panel. Rather than trying to memorize the same thing again, perhaps a compass in the car will get me watching the behavior daily and it’ll just sink in. I like the idea.
 
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