Airspeed Indicator 450+ Knots Mk 9L Ref 6A/4721 RAF KC-97 an amplifier and a master

an amplifier and a master indicator located at the navigator's position

B-25 Mitchell

This pocket-sized 97-page WWII manual was specifically prepared to acquaint those servicemen who were transferring from the European theater to the Pacific theater with the aircraft and naval craft that they would not have encountered in Europe

See photo of the instrument in the 1959 Collins Radio catalog page

This is a late WWII-era Wheel and Flap Position Indicator

Airspeed Indicator 450+ Knots Mk 9L Ref 6A/4721 RAF KC-97 an amplifier and a masterThis is an excellent example of a post WWII era Air Speed Indicator Mark 9L, Ref 6A 4721, as used in the British RAF fighters Supermarine Spitfire and Seafire. Air speed from 0 270 Knots is indicated by a clockwise rotating pointer, starting at the 6 o'clock position, along the outer perimeter scale. As the aircraft passes 270 Knots, air speed is indicated along the inner scale up to 450 Knots, with gradations up to 500 Knots. The indicator measures