Here's the manual for the pneumatic mail system used on the Tupolev TB-3, dated 1934, that I've foundon airforce.ru . I never knew there was such a system ever used on an airplane.
Enjoy!
This year saw the long-anticipated Scaled Composites Stratolaunch satellite launch carrier airplane take to the skies for the first time, knocking the Hughes H-4 Hercules/Spruce Goose off its perch for the biggest plane by wingspan to ever fly. However, long before the H-4 Spruce Goose took to...