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Overhead compass


peter
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Firstly upside down compasses are not as common as a standard one PLUS on top of that, you have to get a Southern Hemisphere one which makes it even harder to source...be careful buying a compass from any Northern Hemisphere supplier

 

 

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Aircraft Spruce have northern and southern hemisphere selections on most if available.

 

If you can get your hands on a Winjeel standby compass, it has a top mount suitable for attachment to a windscreen bow.

 

 

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I'm not 100% sure, but those compasses such as sold in the Clear Prop shop, can be rotated in the mount to allow mounting from the top. Like the one in the front of my Drifter... http://www.recreationalflying.com/threads/wings-over-warwick-clifton-photo-gallery.123815/

How about that, YES they can...I just grabbed one out of stock and turned the housing which puts the mounting plate at the top...You learn something every day, thanks M61A1

 

 

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Id suggest they are the same type, nothing special about Jabiru supplied one

 

I do recall some issue where when I turned it over could see part of the innards and had to cover it with black tape.

 

Also I removed and relocated correction chart holder as it was pretty sharp steel thing located around forehead height

 

 

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How is the card supported? I hope I am wrong but I thought that the card sat atop a needle like bearing.

I think he means the deviation card. The little card that is filled out on a compass swing to give correction data.

 

 

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This may help:

 

1.jpg.affe03266537f2d7140d9c874752b1dc.jpg

 

You can see that there is a line between the Back Housing and Face Plate, that is because they are two separate components. The Mounting plate at the bottom is attached to the Back Housing. At the rear of the compass there is a screw that attaches the Back Housing to the inner frame of the compass of which the Face Plate is a part of.

 

You loosen off the screw and turn the Back Housing around 180deg and then tighten the screw. It is basically just a barrel with the mounting plate attached to it. This then places the mounting plate at the top of the compass.

 

The Deviation Card is attached to the Face Plate so it remains where it is. BUT it would be very very important to ensure that after turning the Back Housing 180deg that you do so exactly 180deg

 

 

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No I wasn't referring to the deviation card. I was referring to the actual part of the compass that revolves, which is sometimes referred to as the card. dates back to nautical compasses which had a card with all the points on it. If the back of the compass can be turnrd 180 deg it is basicly, just a mounting for the main compass works and will work well. I was just afraid that the idea was to invert the compass, which would have left the "card" floating off its pivot.

 

 

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No I wasn't referring to the deviation card. I was referring to the actual part of the compass that revolves, which is sometimes referred to as the card. dates back to nautical compasses which had a card with all the points on it. If the back of the compass can be turnrd 180 deg it is basicly, just a mounting for the main compass works and will work well. I was just afraid that the idea was to invert the compass, which would have left the "card" floating off its pivot.

Aplogies, I thought you were referring to jetjr's post about the deviation card holder having sharp corners.

 

 

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Don't forget that most aluminium planes have a chrome moly (steel) frame across the top of the cabin carrying the wing attachments, so you wouldn't want to mount your compass anywhere near that. Wouldn't be a problem in a plastic one unless it has a steel bearer buried in the plastic.

 

 

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