B29: Did Central Fire Control Prevent Shooting Tail, Wings, Observation Bubbles?

[GunnyNelson]

I am learning about the B29, a new interest. I am curious to know if the Central Fire Control (CFC) computer was able to disingage shooting when the machine guns pointed towards the wings, tail, engines, or the observation bubbles?

 

[bruno_]

Interesting point.
Since these safety mechanisms were already used in B24 and B17, I presume the B29 had them.
As far as I know each gun in each turrett had a special " cylindrical cam" profiled to reproduce for any azimuth, the "allowed elevation". This cam inhibited gun fire whenever the gun line of fire intercepted some part of its own plane. This cam was included into the turret assembly and even if the gunner pushed "the fire button" these cam interrupters prevented the gun from firing. Thus, in this respect the position of the gunner should not be a problem.
But, that said, it would be still interesting to check if a "central" rather than "local" inhibition solution was implemented in B29.

 

[tyrodtom]

Even some WW1 aircraft had limits and other devices that kept the gunners from hitting their own aircraft. Sometimes it was just a pipe that kept them from aiming the guns straight back toward the tail.
But yes, WW2 American turrets used limiters that would keep the gun/guns from firing when it was pointed at the aircraft structure, and the gunners tested it's functioning in his preflight tests before every mission.
The B-29 would have it's own version of those cutouts on the central fire control.

 

[GunnyNelson]

Thanks!

 

[syscom3]

The B29 turrets had cams to prevent the guns from shooting any part of the plane.

 

[EAIAnalog]

Every turret, except the tail, had a rotary mechanism that went from the stationary aircraft to the revolving turret. It carried power and signals to and from the turret. Part of the overall mechanism was an interrupter piece which opened the firing circuit when the guns were pointed at aircraft structure or props. It consisted of a metal outline of the props and the structure, on the turret side, and several micro switches, on the aircraft side. As the turret rotated, one or another of the micro switches would ride up on the metal outline and open the firing circuit, stopping the machine gun(s) from firing. The metal outline was specific to the location of each turret, all four were different. Note that in a cookoff situation, where the guns are firing in an uncontrolled manner, the firing interruption has no effect. So … to prevent the upper forward turret from shooting the upper gunner in his bubble, there is an arm and a roller on the front of the 4 gun turret (look for it in photos or videos), and there is a "collar" at the rear of the turret. As the turret rotates towards the tail, the arm and roller rides up on the collar and forces the elevation axis of the guns up and over the bubble and possibly the tail. The upper rear turret does not have any mechanism like this, so I assume a cookoff event is less likely there.