Envelope
The envelope of the experimental prototype had a volume of 20,500 cu ft (580 m3), but production models used a 60,000 cu ft (1,700 m3) envelope of similar shape that provided a typical gross lift of 4,180 lb (1,900 kg), a net lift of 1,434 lb (650 kg) and a disposable lift of 659 lb (299 kg) with full fuel tanks and a crew of two on board. Each of the SS versions used similar envelopes that were composed of four layers: two of rubber-proofed fabric with a layer of rubber between them, and a further rubber layer on the inner, or gas surface. The external surface had five coats of dope applied to it to protect it from the elements and to render the envelope completely gastight. The first two coats were of "Delta dope" (a flexible dope used for the first time in 1913 on the British Army semi-rigid airship Delta), followed by two of aluminium dope and finally one of aluminium varnish. To stiffen the nose of the envelope and to prevent it blowing in, 24 canes were arranged radially from its centre and covered with an aluminium cap.
The envelope contained two ballonets of 6,375 cu ft (180.5 m3) each instead of just one as used on the prototype. These were supplied with air from the propeller draught via a scoop and a slanting aluminium tube to the underside of the envelope, and then via horizontal fabric hoses containing non-return fabric valves known as "crab-pots".
Read more about this topic: SS Class Blimp, Design and Development
Famous quotes containing the word envelope:
“Geroge Peatty: I’m gonna have it, Sherry. Hundreds of thousands, maybe a half million.
Sherry Peatty: Of course you are, darling. Did you put the right address on the envelope when you sent it to the North Pole?”
—Stanley Kubrick (b. 1928)
“Life is not a series of gig lamps symmetrically arranged; life is a luminous halo, a semi-transparent envelope surrounding us from the beginning of consciousness to the end.”
—Virginia Woolf (1882–1941)
“... all my letters are read. I like that. I usually put something in there that I would like the staff to see. If some of the staff are lazy and choose not to read the mail, I usually write on the envelope “Legal Mail.” This way it will surely be read. It’s important that we educate everybody as we go along.”
—Jean Gump, U.S. pacifist. As quoted in The Great Divide, book 2, section 10, by Studs Terkel (1988)