Systems

Second World War created a massive technological demand. The immediate benefit for autopilots was the amplifier, which had advanced to support new radio equipment.

Early electrical sensors had to deliver the full current to operate the next component in the chain. Whether it was friction from a potentiometer wiper, or the torque to turn a rate sensor (effectively a miniature generator), mechanical resistance was too high, affecting sensitivity. With amplifiers, sensors could be scaled down until their mechanical resistance was negligible. Once signals were electrical, they could be distributed to any number of instruments in the aircraft. This enabled integration.

Accurate bombing required the entire aircraft to be in precisely the right position when the bombs were realeased. Until 1941, it involved a lot of shouting between the bomb aimer and the pilot; eventually, very simple commands (“left a bit”, “right a bit”) could be made via the autopilot. By integrating the autopilot with a bombsight, the pilot could hand control to the bomb aimer, who, for those few vital moments over target, would fly the aircraft himself.

The first truly successful, fully-electric autopilot was the Sperry A-5, designed by Sperry’s future

Sperry Bombsight

FLIGHT

Norden Bombsight

Public Domain

chairman, Carl Frische, in 1941. It was quickly followed by the Honeywell C-1, in 1942. Honeywell allied themselves with Norden, who were the sole supplier of bomb-sights to the US Navy. The Norden was the definitive bombsight of World War Two. Sperry developed a competitor, the "S-1" bombsight for the A-5, which was more advanced than the Norden, but failed to win the biggest contracts.

Of course, these were not the only bombsights. This very British perspective wouldn't be complete without mentioning the R.A.E. Mk XIV bombsight, designed by Patrick Blackett. It turned the problem on its head: instead of controlling the aircraft, it used an analogue computer to calculate when the bombs should be dropped, even while the pilot was climbing, diving, or turning. It was particularly successful where a long level run over the target was impossible, which became something of a speciality for the R.A.F.