Question about a B17 compass

[Cav Trooper]

Thanks for adding me. I have a question, I have a B17 compass that I'd like to install in my military vehicle. I need to know the lamp voltage, wher to find a connecto,. Can I disassemble to clean the lettering. What is the fluid used?
Can All of this be done?
Thanks
CT

 

[SaparotRob]

Howdy, Cav Trooper. I'm sure someone knowledgeable will have some answers. In the meantime, cool artifact. Have any pictures?

 

[Snautzer01]

Perhaps MiTasol has something.

 

[cvairwerks]

Compass fluid is available from multiple sources. Depending on which one you have, Airpath gaskets should fit. Voltage is going to depend on the bulb selected. This manual covers the B-16, which is what most people have. https://www.timetravelair.com/techlibrary/EO 20-25BC-2.pdf

Be advised, the numbering and lettering are most likely radium based paint, and is very toxic while being somewhat radioactive. If you want to know how bad, read "The Radium Girls" by Kate Moore.

 

[Cav Trooper]

Compass fluid is available from multiple sources. Depending on which one you have, Airpath gaskets should fit. Voltage is going to depend on the bulb selected. This manual covers the B-16, which is what most people have. https://www.timetravelair.com/techlibrary/EO 20-25BC-2.pdf

Be advised, the numbering and lettering are most likely radium based paint, and is very toxic while being somewhat radioactive. If you want to know how bad, read "The Radium Girls" by Kate Moore.

Thank you, I have the B-17 model and the manual is great, I did not find any reference to the bulb type or voltage in the manual. It looks like the only numbers with radium paint are the NSEW and some primary numbers. I see that they are corroded and I will not try to clean them. I wonder is there is a service for this? The fluid is full when the unit is level. No leakage so, I don't need to worry about it. Maybe the best thing is to donate it to an organization with a B-17.
Thanks again,
CT

 

[MiTasol]

I MAY have a manual for this unit but I am half a world away from home so will not be able to check until very late January
I am due home on the 20th but have a lot of commitments in the first week and a few the following. I know I have an RAF manual that probably covers cleaning radium letters and I think I posted to the thread called something like RAF instruments

 

[cvairwerks]

Cav: A B-17 compass was a generic model that was used in numerous different aircraft. The bulb selection would be based on what it was installed in. Some aircraft were 12V and others were 24V. The light is the only item on it that requires power. There are services out there that overhaul them. I don't know what the current cost is these days. My instrument guy used to charge about 150$ to overhaul and yellow tag one for flight. Non flight rated ones were cheaper.

 

[bse7entn]

This is from a Pilot's Compass Type B-16 Handbook of Instructions with Parts Catalog, but it's very similar and both made by Pioneer:

Revised May 5, 1943
(pg 4)

9. Lighting

a. A three volt lamp located at the top center of the compass provides an individual lighting system to illuminate the lubber line and exposed portion of the card. Connection is made to the aircraft's electrical system by means of a socket at the rear of the compass.​

 

[EAIAnalog]

Here are 2 B-17 engineering drawings relating to the pilot's compass. The 1-21911 drawing calls out the B-17 compass spec and shows a used on drawing of 74-1174. The 74-1174 drawing shows a small panel that has a clock, the compass, and a thermometer indicator mounted to it. Flag note 9 calls out the compass type, which is B-16. But Flag note 12 says that compass type B-17 is interchangeable with the B-16 type.

You have to assume the voltage for the bulb in the compass would be something like 24-28 volts DC. I would guess that the bulb (if it's there), would be under the plate on the top of the compass. I would remove the 4 corner screws on the plate and see if you can lift it off. I suspect that the other 2 screws are for a mounting bracket for the lamp. So when you lift the plate, the whole lamp assembly would come up. That would make it easier to replace the bulb if it burned out. If the bulb is there, remove it and look for information stamped into its base. Hopefully lamp number and voltage. Good luck.

 

[EAIAnalog]

OK, the 74-1174 missed the transfer for some reason.