Drift Sight, Tail, RAF Mk IV Kit Ref No 6B/110, 1939 Viscount 75 inches diameter

75 inches diameter

These were often carried aboard aircraft as emergency back-ups in these latter decades in the event of failure of the more sophisticated navigation computers that emerged in the 1960's and 70's

intersecting them along the specified firing range

Here is an early WWII-era Airspeed Indicator

Drift Sight, Tail, RAF Mk IV Kit Ref No 6B/110, 1939 Viscount 75 inches diameterHere 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 kit includes the optical periscope, a base plate, and the aluminum drift plate that screws onto the base plate, and wooden carry case with leather strap. Stamped on the label on the case of