Altitude and Airspeed Handset, B-29 Superfortress Gunnery System
This artifact resides in our Private Collection, yet we welcome inquiries from restorers, museums, or serious enthusiasts. Please email us with the name of the artifact at Curator@AeroAntique.com.
Here is an original WWII-era Altitude and Airspeed Handset as used in the Boeing B-29 Superfortress bomber. This was a module of the B-29's Central Fire Control System, the remote control gun turret system.
This critical component was installed at the Navigator's station. It was his responsibility to ensure that the dials on the handset for altitude, outside air temperature, and airspeed are set to match the actual readings on the altimeter and indicators for temperature and airspeed on the Navigator's instrument panel every ten minutes. These settings fed into the 5 onboard gunnery computers that determined proper lead and ballistics corrections for each of the 5 gunsights.
The left knob adjusts the indicated airspeed which is displayed in the left window. The center knob adjusts the outside air temperature which is displayed on the upper dial of the right window. The altitude is set by the left knob and is displayed in the right window. As the temperature is set, a "Y" on the bottom of the temperature scale moves left or right. The altitude is then set to align with the bottom leg of the "Y". There is one other version of this handset used in the B-29 gunnery system that has 3 separate windows- airspeed, temperature, and altitude.
For as sophisticated the B-29 gunnery system was, it is interesting to note that it relied upon a human to read these metrics from instruments and physically input them into the computer system.
Although termed a "handset", at 9 x 7 x 4 inches the unit is larger than one might regard a handset, and it was hard-mounted to the aircraft.