Helicopter Dual Tachometer Kollsman 981BX-8-023 H-21 Piasecki F-104 Type 99 Trainer

Type 99 Trainer

Type 95 Model 3 Trainer

and the markings are of both the classic Munsell green and white as used on US Navy aircraft instruments of the era

Bureau of Aeronautics US Navy)

but also on the US Army Air Corps' UC-43 Beech Staggerwing (see photo from flight manual dated 1944)

Helicopter Dual Tachometer Kollsman 981BX-8-023 H-21 Piasecki F-104 Type 99 TrainerHere is a dual Tachometer for use in military helicopters, indicating RPM for the rotor on the inner scale and rotor for the outer scale with a ratio of 9. 7: 1. The pointers will be aligned once the rotors are fully engaged. It has a serial # prefix of AF57, likely indicating manufacture date of 1957 for the US Air Force. It was used in the H 21 Shawnee Workhorse Piasecki Helicopter, as confirmed in its parts list dated 1957. See photo of cockpit