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Brad-M

Compass ID Question

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Gents,

I have a friend who came accross an aircraft compass in very good shape and we are trying to find out what aircraft may have used it. It looks RAF, it has two stanps on it, the first stamp is "Type P4A" and then over top of it it has aa stamp "Type P10" any ideas. The word "aft" is also stamped on it on the rear portion of the compass and there are two sets of two grid lines which run north/south and east west.

TIA

Brad

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Gents,

I have a friend who came accross an aircraft compass in very good shape and we are trying to find out what aircraft may have used it. It looks RAF, it has two stanps on it, the first stamp is "Type P4A" and then over top of it it has aa stamp "Type P10" any ideas. The word "aft" is also stamped on it on the rear portion of the compass and there are two sets of two grid lines which run north/south and east west.

TIA

Brad

the P4 compass was a fairly standard fit in RAF aircraft for years. I think the P10 is basically the same, slightly modified.

Keith

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scan0011.jpg

This is it, and it would have been used in many different aircraft, including (possibly) the Seafire 47 and some earlier Spitfires. Originally the rotating grid ring only had two wires, (on the P4 compass)which led to pilots flying reciprocal courses, by mistake. your compass has been updated, to carry four wires, forming a "T" of painted surfaces.

Now, the warning; if your compass is 50+ years old, it could, quite conceivably, still be wearing radium (i.e radioactive) paint on the wires, some of the letters/numbers, and in tubes "glued" to the internal 8-legged balanced "spider." Without[/b] removing the rotating grid ring, check the paint, and, if it's a dirty brown, with black specks, do not, under any circumstances, remove the grid ring. With the glass in place, you have a very efficient barrier to any radioactive particles, but the paint, by now, will have started to turn to dust, and breathing it in will do you immense harm. If in doubt, get it checked with a geiger counter, and this is not a joke.

If the paint still appears to be a fairly pristine white, the next step is to subject it to an ultra-violet lamp, and if it glows, this indicates that your compass has received a post-war modification, which replaced radium with U/V paint, and you can relax somewhat.

The compass was, basically an 8-point set of wires, carrying tubes, which indicated N, E, & W, no matter in which direction the a/c was headed. Opposite the "aft" stamp, you'll see a single small tube, which aligned with the a/c nose. The idea was for the pilot to set his required course against that tube, using the grid ring, then turn the a/c until the internal tubes settled within the "T" of the wires, meaning he was heading in the right direction. The compass had a permissible error of +/- 1 degree, and the spider had enough free movement to allow the compass to work anywhere in the world.

Edgar

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Thanks Guys. I found a site that pinpoints this compass to Hawker Harts and Sunderlands, but I was wondering why it was first stamped as a P4A, which is a modified P4, then stamped P10? We'll do some checking of the paint and the ultra-violet lamp trick too.

Cheers

Brad

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Thanks Guys. I found a site that pinpoints this compass to Hawker Harts and Sunderlands, but I was wondering why it was first stamped as a P4A, which is a modified P4, then stamped P10? We'll do some checking of the paint and the ultra-violet lamp trick too.

Cheers

Brad

Also fitted to Stirlings, just bought one to fit in our cockpit repro :coolio:

As stated be careful if it's hot. Should be ok just don't sleep with it next to your pillow LOL

John

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Thanks John. We're taking it to our NBC school and will check to see just how hot it is. :)

Brad

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It isn't a matter of how hot it is, it's whether it's hot at all, and it isn't a matter for levity. If the paint is radio-active, it will be, at the very least, 60 years old, and starting to crumble into dust. Breathe that dust in, and you're heading for lung cancer. It's the same with other old instruments, which, frighteningly, I often see on open sale at air shows. Lift off the glass, and you're in deep trouble.

Edgar

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Hi Edgar,

I guess I should have said we'll check it period.

Brad

It isn't a matter of how hot it is, it's whether it's hot at all, and it isn't a matter for levity. If the paint is radio-active, it will be, at the very least, 60 years old, and starting to crumble into dust. Breathe that dust in, and you're heading for lung cancer. It's the same with other old instruments, which, frighteningly, I often see on open sale at air shows. Lift off the glass, and you're in deep trouble.

Edgar

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I guess I should have said we'll check it period.

/quote]

Sorry, Brad, if I seem to have been getting at you; I was trying to ram home, to everybody, the extent of the danger, unless fairly simple precautions are taken, and it isn't just compasses.

Edgar

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