R.A.F. PLANE

Greymouth Evening Star, 17 December 1934, Page 4

R.A.F. PLANE

THREE SQUADRONS LAID UR. LONDON. October 17. At least three squadrons of the Royal Air Force have been confined for long periods to their aerodromes, during the past three months, by a disability causing excessive vibration. It was found at length that the recent “boosting” of engines throughout the R.A.F. to get an increase in power had pfoved too much for the

propellers. The airscrews developed vibration and transmitted it in some cases to tho whole aeroplane, threatening serious structural failure. in fact, it 'is not impossible that certain accidents are attributable to that cause. Two-bladed airscrews are almost invariably used in R.A.F.designs. They give high propeller . efficiency, having big diameters as , compared with three-bladed or four-bluded air screws. . On many large British civil machines and on most big foreign, aeroplanes, both civil and military, pro-

pellers of three or four blades are commonly used. Although in some respects slightly less efficient they run more smoothly and are less prone to flutter. The possibility that the “boosting” of engines would affect numbers of the big diameter propellers was not foreseen by the ’technical experts. When the trouble was diagnosed certain remedial measures were promptly ordered, which involved besides enforced temporary holiday for the aeroplanes, some slight structural modifications. Meanwhile, the propeller problem is being fully examined.