Commercial Aviation in the Jet Era and the Systems that Make it Possible by Thomas Filburn

Author:Thomas Filburn
Language: eng
Format: epub, pdf
ISBN: 9783030201111
Publisher: Springer International Publishing

BF Goodrich, led by William Geer, were instrumental in the early deicing boot designs and continued to refine the inflatable boot concept. This idea, which seemed to have strong merit, after wind tunnel research indicated that clearing the stagnation point at the leading edge of the wing would allow the wind stream to strip the remaining wing surfaces of any accreted ice. This idea was installed on an Airmail plane in 1930 and then a Lockheed Vega (Miss Silvertown) with the boots put on the wings, struts, and tail surfaces. An air compressor automatically provided air to the boots. The New York Times announced (prematurely) “victory” over “one of aviation’s most dangerous enemies.” Airlines quickly lined up to adopt these devices. United Airlines ordered them for their Boeing 247s in the summer of 1933, while TWA installed them on their DC-2s and DC-3s [1] beginning in 1934. For TWA the cost of the deicing system (compressor, valves and boots) was about $65,000, and added nearly 180 pounds to the aircraft. But both financial and weight penalties seemed small compared to the hoped for improvement in safety provided by the system.

The key to the success from these inflatable boots is their ability to change the shape of the leading edge and initiate cracks within the ice layer. Due to the low ductility (inability to move without cracking) of the ice layer, the boot inflation moves the rigid ice layer, cracks it, and the high air velocity sweeps it away. Figure 8.3 below shows the concept for this inflated and deflated boot arrangement on both a wing and strut.

On March 26, 1937, all the optimism that surrounded the new pneumatic deicing system evaporated when a TWA DC-2 crashed while attempting to land at Pittsburgh’s airport. The impact caused the death of all 13 passengers and 3 crew members but did not result in any fire. First responders to the accident scene reported seeing ice on the wings and control surfaces.

The loss of the Pittsburgh bound TWA flight restarted NACA’s investigation into icing conditions and methods to prevent ice accumulation. The Langley laboratory built a larger scale wind tunnel to study icing, while in-parallel other researchers procured aircraft as flying test beds to investigate icing conditions and methods to mitigate its impact. The larger icing tunnel at Langley found itself being used for other purposes, while researchers used several different test aircraft to investigate the potential of using engine exhaust as a means to eliminate ice formation on the leading edges of wings. By 1940 NACA was convinced that the engine exhaust gas could be used to prevent ice formation at the wing leading edge (the most critical area). This testing and analysis indicated that sufficient energy was present in the exhaust gas to cover the wing leading edge in sufficient length to eliminate ice as a significant impediment to lift generated by the wing [6]. Engineers and material scientists worried that directly impinging the exhaust gas into the wing box area might overheat or increase corrosion of the now predominantly aluminum structure.

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.