Tachometer, Mk V, US Navy 88-I-2500 Pre-WW2 The keying switch is stiff

The keying switch is stiff

was used across all aircraft of the US Army Air Force during WWII

This is a WWII Flight Checklist "Flugklarmeldetafel" recovered from the crash site of a Luftwaffe Junkers Ju-88 A-4 twin-engine Medium Bomber in Poland

It received signals from two antennae (see photo) typically mounted on each side of the aircraft forward of the wing

Tachometer, Mk V, US Navy 88-I-2500 Pre-WW2 The keying switch is stiffThis is an original WWII era electrical aircraft Tachometer, Mark V FSSC 88 I 2500, as used across aircraft of the US Navy, such as the SBD Dauntless Dive Bomber, TBM Avenger Torpedo Bomber, and F6F Hellcat Fighter. Pioneer Bendix part number 2222 IF2 A. Range 0 3500 RPM, with the pointer indicating RPM hundreds and the inset window at 9 o'clock indicating RPM thousands. This tachometer is in exceptional condition given its age. Measures 3. 25 inches