WWII era compass help

[Ant]

My Dad is great. We were chatting about all the stuff crammed into his loft and I asked him if he still had that old compass I remember seeing when I was a kid. He promptly asks me if I want to give it a home. "Yeah, why not." thinks I, not remembering anything much about it other than it looked kind of cool due to its size. I hadn't seen the thing since I was maybe 12, but as soon as he got it out, I recognized it from countless pictures of WWII era aircraft cockpits. He thinks it came out of a bomber, but knows nothing much else about it.

It's a P4 type aircraft compass, which I'm pretty sure is indeed WWII era. I've attempted some quick research on the web and have seen people mention it being an early war compass, possibly from a Lancaster. What I'm wondering is, does anyone here know anything about these?? Is there a source which might tell me for sure what types of aircraft they were used in? Is there any way of finding out exactly what type it came from?

Here are some pics ...

Any help / assistance appreciated.

[TonyT]

used in just about everything from spits etc through bombers

[Mattie Bee]

I'm afraid it could have been in pretty much any British Aircraft Pre or During the War.

But I can give you the meaning of the Numbers

No 5239 H.S.

This is the individual Serial Number of the item.

But before you start thinking you could track the serial number I'm afraid i may have some bad news.

If the system of tracking items fitted to aircraft is similar to what I use on Nimrods (For the RAF guys amongst us, No Lits for me) Only lifed components are tracked. So if you had for example, a Lancaster shock absorber. That would be lifed for so many FSL (Full Stop Landings) and would have a components record card that would stay with the item until fitted on the aircraft were the card would be placed into a components record folder. Each aircraft having its own and an entry made in the aircrafts 700. This would say how much life is remaining and when the item is next due bay maintenance meaning it would have to be removed from the aircraft. Not being an Avionics Tech, I don't think instruments are lifed but I may be wrong.

A M

Stands for Air Ministry

6A/0227

Is the stores reference for the item.

Like an Argos Reference number. I want a Book Shelf, I look in the Argos Catalogue for the one I want note the number, go to the shop give them the reference and hay presto I have a Book Shelf. Same for the Compass, It doesn't work, the "Erk" goes to the aircrafts illustrated parts catalogue. Finds the compass goes to the stacker (Storeman) gives him the reference and again hay presto a new or reconditioned compass and you don't have to pay.

Maybe of no help but I hope its given an insight to the numbers on the Compass

[Edgar]

First, take it into a darkened room, and see if the bars, cardinal points, and the internal bars glow. If they do, do not, under any circumstances, try to disassemble it, since it will have been painted with radium paint. There will be cries of "That small amount won't do much," but, after 60+ years, the paint turns to dust, and breathing it in can be lethal. From the photo, it doesn't appear to be radio-active paint, though. Post-war it was common for the radium paint to be replaced by fluorescent, and, if that example has been repaired, it could be perfectly safe. You might find, somewhere on the case, a series of letters and numbers, in my old company's case it was PIL/-----/--, with the last two digits being the year of repair.

The "innards" consist of a pivoted eight-point set of arms, balanced on a (valueless) sapphire, with the whole lot floating in a mix (most likely at that age) of 80/20 alcohol/water. Do not think alcohol, as in whisky, et., this is industrial alcohol, which tastes foul, and is poisonous. Post-war the liquid was 100% alcohol. If the bars, fitted to the internal "spider," glow in the dark, it means that they're still filled with powdered radium, with all the implications that it carries.

The "H.S." at the end of the serial no., is probably the initials of the manufacturing company (K.H., for example, were Kelvin & Hughes,) but I can't tell you who. The 6A/0227 is the military stores reference. The hooked "bar," bottom left, is a locking device, for the top ring, which can rotate. The P.4 was superceded (by the P.6, I think,) because it was found that, with just the two vertical bars in the ring, it was too easy to fly a reciprocal course. Later compasses had four bars, with those pointing N, E, & W painted, but the South pair left black.

Edgar

[TonyT]

I'm afraid it could have been in pretty much any British Aircraft Pre or During the War.

But I can give you the meaning of the Numbers

No 5239 H.S.

This is the individual Serial Number of the item.

But before you start thinking you could track the serial number I'm afraid i may have some bad news.

If the system of tracking items fitted to aircraft is similar to what I use on Nimrods (For the RAF guys amongst us, No Lits for me) Only lifed components are tracked. So if you had for example, a Lancaster shock absorber. That would be lifed for so many FSL (Full Stop Landings) and would have a components record card that would stay with the item until fitted on the aircraft were the card would be placed into a components record folder. Each aircraft having its own and an entry made in the aircrafts 700. This would say how much life is remaining and when the item is next due bay maintenance meaning it would have to be removed from the aircraft. Not being an Avionics Tech, I don't think instruments are lifed but I may be wrong.

Mattie it might be tracable as a high value item and the fact it would need to be perodically swung and adjusted, so would possibly be recorded in the lifed items listings, as Edgar says though, unless you want to end up like Mr Burns glowing in the dark, don't take it apart, BTW they often appear on ebay, so that will give you an idea of value....

Edited September 18, 2009 by TonyT

[StephenMG]

First, take it into a darkened room, and see if the bars, cardinal points, and the internal bars glow. If they do, do not, under any circumstances, try to disassemble it, since it will have been painted with radium paint.

Edgar, you're absolutely right to raise this point of course but the 'darkened room' test is very unreliable. Yes, it will prove that it is radioactive (if the compass glows), but it won't prove that it isn't. The problem is that the paint can deteriorate to the point where it doesn't glow anymore, but is still very 'lively'!

As you rightly point out flakey radium is an absolute no-no as the greatest risk is in inhaling the particles. Best bet is to get it checked out by someone with a Geiger counter to be sure.

[penfold]

The "H.S." at the end of the serial no., is probably the initials of the manufacturing company (K.H., for example, were Kelvin & Hughes,) but I can't tell you who.

Edgar

"H.S" wouldn't be Hawker Siddeley, would it, or is that too obvious ?? Did they make their own instruments ??

[Edgar]

Edgar, you're absolutely right to raise this point of course but the 'darkened room' test is very unreliable. Yes, it will prove that it is radioactive (if the compass glows), but it won't prove that it isn't. The problem is that the paint can deteriorate to the point where it doesn't glow anymore, but is still very 'lively'!

As you rightly point out flakey radium is an absolute no-no as the greatest risk is in inhaling the particles. Best bet is to get it checked out by someone with a Geiger counter to be sure.

Unfortunately, even Geiger counters can be foxed by glass; I had a compass, manufactured in Spain as late as 1980 (long after radium paint was banned in Europe,) which was declared safe, until I opened it, then all Hell let loose. To check a suspect compass, I had to take off the rotating bezel, turn it over, and then test it (wearing gloves and a dust-proof mask while doing it, of course, followed by having a Geiger counter run over my lab coat.) The inner tubes are the (potentially) worst problem; being glass, they might be intact, and give no indication on the counter, but crack one.......... On the other hand, if one is already broken, or inadequately sealed, the liquid could be contaminated, and that won't show up, until the compass is opened.

Edgar

Edited September 18, 2009 by Edgar

[Stonar]

Mattie it might be tracable as a high value item and the fact it would need to be perodically swung and adjusted

Slightly at a tangent but how do you "swing" a compass? My dad's log books (helicopters) from the mid '50s contain several short (15min.) flights for which the duty is noted as "compass swing." My mother remembers him regarding this as a chore.

As an ex - chemist I'd say the advice above is apt. BTW it is not the Radium that glows . It emits the radiation that causes the Zinc Sulphide in the paint to glow.

Thanks

Steve

Edited September 18, 2009 by Stonar

[Mattie Bee]

Slightly at a tangent but how do you "swing" a compass?

Basically the aircraft gets towed in a circle as slow as possible checking north is north south is south west is west etc etc etc over and over and over again.

Its a ground crew thing to do on fixed wing aircraft, but on Helicopters I would imagine the pilot would have to get involved and fly the aircraft on a pivot? Helo guys?

[TonyT]

As above, I do all the cardinal points N S E W then those in between 30 60 120 etc you use a hand compass bringing the aircraft onto the heading such as north, standing outside using a hand master compass with a sight on it you look through the centreline of the aircraft and read the error of yours, normally a couple of degrees, you then adjust the aircraft one by adjusting 2 brass screws that move a small magnet inside the compass which effects the reading, remember the compass you are adjusting is in a metal aircraft that will effect it, hence the requirements to adjust it.....

You normally do this with it running and all the normal avionics on, on a helicopter you require a pilot as it would be "turning and Burning" this is because the damn thing can get what's called ground resonance where it starts to shake itself to death and results in it falling over, the only way to get rid of this is to lift it off the ground, hence why it is in your dads logbooks.

Incidentally you tend to do this on a special compass base that it free from any magnetic presence, though you can do one in flight as well.

I can understand your Dad thinking it a chore, I did 6 about 3 weeks ago taking most of the morning, I was running the Aircraft and it involves lining it up accurately at each compass point, then holding it on the foot brakes at highish power with the nose gear hard over and rudder pedals the same, your calves soon start to know about it. Current civil requirements is every 3 years (used to be 2) or if major repairs/ eng change or major mods etc.

Edited September 18, 2009 by TonyT

[Mattie Bee]

You normally do this with it running and all the normal avionics on

Nimrod and I know the VC-10 also are not run, just the avionics powered up. We have a special tow rig so we can tow the aircraft and a powerset with the same tug.

Edited September 18, 2009 by Mattie Bee

[TonyT]

Was on VC10's for 5 years We did them turning and burning on Helis in the RAF, can't remember on Jags, but the most of the 200 plus Aircraft types on my Civi licences are done with it running, it's simpler, problem in the RAF is you cannot taxi them, I can hence I just hop in, fire it up and off I trundle.

I spent 4 hours following the old RAF Boscombe comet round the compass base at Brize with a tractor and powerset plugged in!!

Edited September 18, 2009 by TonyT

[Hurricane363]

I've done a few compass swings myself. Unfortunately they were on a type not unlike the one pictured at the top of this thread (p10 &p11). And yes they are the most BORING thing you could possibly imagine doing.... EVER!!

[Stonar]

Thanks very much for your replies. It is surprising the things you never thought to ask when you could. My father died, far too young, many years ago. No wonder he saw it as a chore. It is probably coincidental ,as I imagine the navy had a schedule for such things ,but it seems to have been done at times when he really didn't want to get lost, before a series of royal flights and before Musketeer (Suez) for example.

Thanks again

Steve

[Ant]

I've just realised I've completely forgotten to say THANKS! for all the replies to my original request for info; very helpful chaps, especially the health warning Edgar. It's doesn't glow in the dark as far as I can tell, but I'm not going to take it apart anyway!! Thanks again Chaps, you're a really knowledgeable and helpful lot.

[chris m]

hi just joined britmodeller and also just aquired a p4 compass after reading all the info on this item i would be grateful for some advice myself if anyone could help me , my compass does not glow in the dark nor does it have any liquid left in it however after reading all the info i do not want to open it to clean it out if it might be dangerous any ideas please many thanks chris