Sperry Artificial Horizon – US vs UK version.

Hmm interesting.

Don’t know if two picture might illustrate the point better. I found these via Google image search.

Physically they look identical but the main differences I see are that on the RAF version you have “Artificial Horizon” painted around the bottom, the “U” shapes on the 9 and 3 o’clock position on the dial and the double line for the horizon indicator.

This is why I wondered if in fact the RAF version was the same as the US version.

(RAF left, US right)

When the war broke out, Sperry UK were already producing their own version of the Sperry DI and Horizon, both of which had also been in use in civil as well as military machines for some years. I haven’t got an image of the Kittyhawk’s panel, but since it was built in the US, it’s highly probable that the AI was produced there by Sperry too. Around the end of 1940, the AI’s started to be produced in the UK with an inverted display for clarity, with simplified graphics, and some of the pre-war detail (Which was being routinely painted-over anyway.). They moved from a ‘Skyview’ to a ‘Groundview’. As the war went on, a large number of other US manufacturers also began to produce these items to keep-up with the burgeoning demand. There are detail differences, but a close look at the face, or the data on the rear of the instrument will tell you straight-away where, and when it was produced. The same basic designs soldiered-on in types in both the UK & USA for some years after the war. The US aircraft went-on to use a cage-able version of the AI and of course on some aircraft, the DI & AI were versions integrated into the autopilot as they had been, in fact, since the 1930’s. The DI’s, or remanufactured version, went on to equip many post-war Cessnas etc. Sperry UK reverted to the pre-war style of DI’s graphic for civil a/c after the war, but retained the wartime simplified graticule.