Gun Director/Predictor Base
This appears to be a plinth for the mounting of a "Predictor"; a heavy tripod based device to facilitate more efficient targeting of incoming aircraft. The British Army's new Bofors guns were intended as low-altitude anti-aircraft weapons. However, existing gunnery control systems were inadequate for the purpose; the range was too far to "guess" the lead, but at the same time close enough that the angle could change faster that the gunners could turn the traversal handles.
The Predictor solved the problem by doing all of the calculations mechanically through a complex system of gears. Inputs to its calculations included wind speed, gravity, ballistics of the gun and the rounds it fired, angle to the target in azimuth and altitude, and a user-input estimated speed. Some of these inputs were fed in via dials, which turned gearing inside the Predictor to calculate the range (from the change in angle and estimated speed) and direction of motion. The "output" of the device drove hydraulic servo-motors attached to the traversal and elevation gears of the otherwise unmodified Bofors gun, allowing it to follow the Predictor's indications automatically without manual intervention.
There are pictures of these machines and more information about their function on this site and wikipedia.
Click here for an aerial view of where this picture was taken.
Gun Director/Predictor Base
This appears to be a plinth for the mounting of a "Predictor"; a heavy tripod based device to facilitate more efficient targeting of incoming aircraft. The British Army's new Bofors guns were intended as low-altitude anti-aircraft weapons. However, existing gunnery control systems were inadequate for the purpose; the range was too far to "guess" the lead, but at the same time close enough that the angle could change faster that the gunners could turn the traversal handles.
The Predictor solved the problem by doing all of the calculations mechanically through a complex system of gears. Inputs to its calculations included wind speed, gravity, ballistics of the gun and the rounds it fired, angle to the target in azimuth and altitude, and a user-input estimated speed. Some of these inputs were fed in via dials, which turned gearing inside the Predictor to calculate the range (from the change in angle and estimated speed) and direction of motion. The "output" of the device drove hydraulic servo-motors attached to the traversal and elevation gears of the otherwise unmodified Bofors gun, allowing it to follow the Predictor's indications automatically without manual intervention.
There are pictures of these machines and more information about their function on this site and wikipedia.
Click here for an aerial view of where this picture was taken.