Drift Sight, Tail, RAF Mk IV Kit Ref No 1846/40, 21584 1940 Air Forces of USA This indicator appeared on the

This indicator appeared on the boom operator's control panel and indicated the length of the refueling boom as it is extended from the rear of the aircraft to mate with the aircraft being refueled

This is a Flap Position Indicator as used in the US Army Air Force Flying Fortress B-17

Here is a WWII-era Sensitive Altimeter

Measures ~7 inches diameter and ~4 inches in height

achieving the same results by monitoring EGT (exhaust gas temperature)

Drift Sight, Tail, RAF Mk IV Kit Ref No 1846/40, 21584 1940 Air Forces of USA This indicator appeared on theHere is a WWII era Tail Drift Sight, Mark IV Kit, as used in bomber and transport aircraft of the British Royal Air Force with navigator aircrew, such as the Avro Lancaster, and likely used in other bombers such as the Vickers Wellington and Short Stirling. This is a complete set that includes the optical periscope, base plate, two aluminum drift plates that screw onto the base plate, an electric cord for illuminating the sight, and wooden carry case