“Above the Weather”

Manawatu Times, Volume 64, Issue 132, 7 June 1939, Page 4

“Above the Weather”

STRATOSPHERE ’PLANES The first of three stratosphere 'planes approaching completion at the Boeing works at Seattle was put through tests that demonstrate its ability to fly “above the weather" without the slightest discomfort to passengers, writes a Vancouver authority. Unfortunately it has since been wrecked, but the others will undergo tests shortly. Tho craft are designed to operate at 20,000 ft., and each- will carry 33 passengers. ‘ ‘ Sub-stratosphere flights'' were made without the 'plane leaving the hangar. This was done simply by introducing compressed air into the sealed cabin, to test its ability to withstand difference in pressure between the air inside and outside as would be required to give passengers tfie benefit of normal atmosphere at high levels. The situation would be reversed in actual flight, as then the pressure on the outside atmosphere would decrease, while the pressure on the air inside would remain substantially constant, whereas, in tests, the air pressure was increased inside, while it remained constant outside.

The performance of the 'plane under different flying strains was likewise tested in the “rehearsal," 28 tons of lead being used for this purpose. Ingots weighing one hundredweight were placed inside, in place or passengers, crew and cargo, and heavy weights we.re placed in the tail sectioa t 9 simulate and exceed the flight loads of the most severe air conditions or unusual manoeuvres. "It was interesting te note," said the assistant general manager, “that the cabin actually addod to the strength of the body, by virtue of the internal air pressure.' 1 The shell of the 'plane was coated with a film of soap during the prassura tests, so that bubbles would appear wherever there was the slightest leak. The leaks were filled at once with a sealing compound by workmen inside the cabin. Some leakage of the cabin during flight was not objectionable, the expert added, because as much air must be discharged as entered the cabin through the supercharger blowers and ventilation ducts. But, for efficient air distribution for ventitation purposes, it was desirable to reduce leakage to a minimum.

He explained that the 'plane was equipped with two superchargers-, either 1 of which could keep the air pressure at the desired level by itself. The superchargers accelerated the incoming fresh air in the vanes of a rapidly*rotating wheel, and the air was then glowed down to build up the pressure. In the laboratory the apparatus w r as tasted under refrigeration at temperatures far lower than would be encountered.