TBF-1 Avenger Torpedo Bomber Cruising Calculator Mark 1-A, Ser # 4785-43 He-111 and ~4 inches tall

and ~4 inches tall

including the metal case and a set of green sunshade lenses

with the civilian version used in the Britannia and Comet airliners

indicative of a 1944 manufacturing date

A few pages have a sometext with highlight marks

TBF-1 Avenger Torpedo Bomber Cruising Calculator Mark 1-A, Ser # 4785-43 He-111 and ~4 inches tallThis is an authentic original WWII era Cruising Computer Mark 1 A designed specifically for the US Navy's Grumman Torpedo Bomber TBF 1. The purpose of the calculator was to determine the range, in nautical miles, of the aircraft under various conditions of aircraft weight, head tail winds, fuel quantity on board, true air speed, altitude, and throttle and supercharger blower settings. The calculator is essentially a custom 3 panel slide rule