B-29 Central Fire Control Computer

The famous B-29 bomber was a critical factor in ending World War II. It incorporated many technical innovations including a Central Station Fire Control System (CSFC) for its five gun turrets. Prior to the B-29, gun turrets in bomber such as the B-17 and B-24 contained a gunner responsible for aiming and firing the guns in the particular turret. The B-29, however, had four unmanned turrets (the tail gun was still manned) that could be (as shown in the left diagram) controlled from several remote locations: a central sighting station near the tail, a nose gunner station and the tail gunner. The advantages of the CSFC were several: smaller gun turrets (less drag), improved sighting accuracy, easier maintenance, redundancy if a sighting station is incapacitated, improved comfort for the gunners, and so forth.

The CSFC comprised many components (e.g., servo amplifiers, motor generators, sighting heads, the gun turrets themselves), but the critical component was the computer itself, which we have. There was one computer for each of the five sighting stations. Based on information from the sighting station along with the plane's altitude, air-speed, and temperature, the computer calculated the proper aiming of the turret considering ballistic factors (wind and gravity), parallax (offset between gun and sighting head) and the appropriate lead to the target based on range and relative velocity of the target.

Shown here are:

An overall view of the computer with its lid removed. Note the 3/8" thick steel case; this device wighs over 50 lbs.
A diagram from the Bombardier's Information Manual showing the turrets and the sighting stations.
Two closeups of the computing elements. (Note that one shows several types of computing components: gears, relays, and tubes. Also note the preservation grease; our computer seems to be brand new.)
A sample schematic from The CSFC Handbook of Operations and Service Instructions. This is a six hundred page manual we have that covers great detail about all of the CSFC components.
Figure 6 shows the computer was actually manufactured by IBM

We also have the tester for this computer. Figures 9, 10, and 11 show the tester.