Autopilot Directional Gyro Kit, Type GR-2, Grumman F7F, F8F US Navy P-63 but the center knob is

but the center knob is provided with which to rotate the dial

This is an original soft-cover WWII-era Instrument Flying Manual

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Eurofighter Typhoon

Here is a WW2-vintage Rate of Climb (Vertical Airspeed) Indicator

Autopilot Directional Gyro Kit, Type GR-2, Grumman F7F, F8F US Navy P-63 but the center knob isHere is a Directional Gyro Control Kit for the Type GR 2 Autopilot System made by Electric Auto Lite for Grumman Aircraft under license from Sperry, according to its markings. The directional gyro is powered pneumatically, and the module mounted on the rear appears to provide electronic sensing of the gyro's position for transmission to the autopilot system, judging from the electrical and pneumatic connections in back. The center knob is to set the