Wheel and Flap Position Indicator, AN5780-3, 8DJ26AAA Air Forces of USA The knob would rotate the

The knob would rotate the face of the dial while the pointer remains fixed to set the present field elevation

see page from its pilot manual dated 1944

See a photo the spec sheet in the photo gallery

observers could determine the location of friendly aircraft using triangulation

c)  if Single is selected

Wheel and Flap Position Indicator, AN5780-3, 8DJ26AAA Air Forces of USA The knob would rotate theThis is a late WWII era Wheel and Flap Position Indicator, Type AN5780 3, as used in aircraft of the US Army Air Force with either tricycle landing gear (i. e., nose wheel) or tail wheel configurations. According to the Maintenance Interchangeability Chart dated Feb 1945, late models of medium bomber B 26 Marauder, attack bomber A 20 Havoc, and night fighter P 61 Black Widow used this indicator. This particular indicator has a serial number prefix of