TBF-1 Avenger Torpedo Bomber Cruising Calculator Mark 1-A, Ser # 4785-43 He-111 A few pages have a

A few pages have a sometext with highlight marks

with the civilian version used in the Britannia and Comet airliners

as well as a close-up of an illustration from a B-25G technical manual

The C-13 Altimeter was used across all aircraft of the Air Corps US Army

dated Oct 1943 revised July 1948

TBF-1 Avenger Torpedo Bomber Cruising Calculator Mark 1-A, Ser # 4785-43 He-111 A few pages have aThis 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