Precipitation Static, USAAF Manual No. 10 Dec 1944 SBD Dauntless The Army type E-9 tachometer

The Army type E-9 tachometer indicator consists of a three phase alternating current  synchronous motor and an indicating element

The APA-44 was under development in 1945 and ultimately became a prime component of three bombing-navigation systems

The other volumes were Airplane General

likely to set the desired course heading

Here is WWII-era vacuum-driven Gyro Horizon Indicator Type AN-5736-1

Precipitation Static, USAAF Manual No. 10 Dec 1944 SBD Dauntless The Army type E-9 tachometerThis is an original training manual covering the topic of Precipitation Static published by the US Army Air Corps in 1944 for use in training pilots. The manual discusses the build up of static charge on the aircraft in flight during different atmospheric conditions and how this affects radio receiving equipment. This 36 page manual is in good condition given its age. It came to us from the estate of a B 17 flight instructor.