Tachometer, Helicopter, USSR 0-4000 RPM C-7 such as the P-40

such as the P-40

The round turret silhouette in the center of the dial rotated as the turret rotated relative to the forward direction of the aircraft

The star chart for the intended course of the aircraft was selected from among the 7 canisters stored in the wooden case

Doing so rotates the circular inset card displaying the BHP

type AChS-1

Tachometer, Helicopter, USSR 0-4000 RPM C-7 such as the P-40Here is a Cold War era electronic dual Tachometer, 0 4000 RPM, as used in military helicopters of the USSR and Poland such as the MIL MI 1 (see cockpit photo, the tachometer is in the middle of the second column of instruments from the right) and MIL MI 4 (see cockpit photo, the tach is in the bottom row 3rd instrument from left). The pointer labeled "P" indicates RPMs of the Rotor, while the pointer labeled "M" indicates RPMs of the Engine. It is in