Sperry Aircraft Gyropilot Operation and Installation Manual 1936 B-52 it is our judgement that

it is our judgement that these are not reproductions

a mixture of anti-freeze could be used instead of water

The APA-44 was under development in 1945 and ultimately became a prime component of three bombing-navigation systems

It is mostly filled with fluid and the compass card rotates

Sperry Aircraft Gyropilot Operation and Installation Manual 1936 B-52 it is our judgement thatThis is an authentic reference Instructions for Operation and Installation of the Sperry Aircraft Gyropilot, Instructions No. 15 726A dated November 1936. The Gyropilot was an early automatic pilot system developed by Sperry which quickly became the standard system for private, commercial, and military aircraft of the day and during early WWII. It is in exceptional (i. e., very good) condition for its age. The cover is a thick index card stock which