SPEED IN THE AIR

Evening Post, Volume CIX, Issue 39, 15 February 1930, Page 26

SPEED IN THE AIR

ENGINEERING VALUE

(From "The Post's" Representative.) LONDON, 2nd January.

Mr. E. J. Mitchell, the designer of the victorious Supormarino Rolls Boyce in the Schneider contest, and Mr. H. P. Folland, the designer of the GlostcrNapier, have both boon giving their opinions of tho race and the result of tho contest on seaplane designs. Mr. Mitchell, writing in "Tho Aeroplane," says:— "Owing to the high taking-off speed of racing seaplanes the ■water resistance of the floats is very high right up to the moment of clearing the water. The propeller has, therefore, to be adapted for this, and cannot, tie the one giving the best possible results at high speed in the air. The use of variable pitch propellers is, therefore, indicated, and until this is possible much greater speeds will be unattainable. "Owing to this contest very extensive progress has been made in engine

.design, and the weight per horse-power of our racing engines has been reduced by 50 per cent, and the frontal air resistance area halved. A large proportion of this progress has been passed on to standard engines used in Service and civil aircraft.

"It is safe to say that the engine used in this year 'a winning machine would have taken at least three times as long to produce under normal processes of development had it not been for the spur of a great international competition. There is little doubt that this intensive engine development will have pronounced effect on our aircraft during the next few years. "The flat-bottomed box-section type of float with a spring chassis was universally used a few years ago. It has now almost completely disappeared, and given way to the V-bottom and round-top-sided type developed for racing craft. This modern type of float requires no shock-absorbing devices in the chassis, is more seaworthy, and offers much less air resistance.

"Radiators developed for racing craft, both for water and oil-cooling, have shown more progress than any other characteristic, and jfirm a highly potential source of improvement in general aircraft design." Mr. Holland, whoso design should have a speed of 350 miles per hour, points out in the journal "Gloster" that this is a satisfactory result for a machine with an engine giving only 1200 h.p. The Gloster type has proved notably good in taking off. He claims that the data obtained from the contest in two years at least equal the results that would have come normally in five to ten years for the same expenditure of money. As a Tesult of the work of preparation for this contest, the top speed of scout types has in six years been increased from 150 miles per hour to 210 miles per hour. The contest has stimulated the use of light alloy solid duralumin airscrews, and their trials under the most exacting conditions. It has proved the definite advantage of the geared engine over the direct-drive. The research work has enabled body drag and wing drag to approach the irreducible minimum. Extremely useful full-scale experiments have been made possible by means of the Schneider racers to explore the problem of aerodynamic control at high speed.