New Test Chambers for Aircraft Electric Apparatus With Particular Reference to Carbon Brushes

When electric machines were taken to high altitudes of 25,000 to 40,000 feet on modern military aircraft, the brushes wore rapidly, insulation sometimes failed, lubrication was uncertain, windings over-heated, and other vexing problems appeared. New materials and methods were needed for this new environment. To accelerate the development of aircraft apparatus, air-conditioned chambers are provided to duplicate the cold, clean, dry, rarefied air of the stratosphere. Facilities being used to test a range of equipment from totally enclosed one-watt computer motors to pressure-ventilated 40-kva alternators¹ are described. Reasons are given for the selection of specific equipment. From simulated-high-altitude tests under controlled conditions, designers are more quickly completing new apparatus, are better predicting its performance, and are reducing the amount of flight testing required to develop new aircraft.