The Aviation World

New Zealand Herald, Volume LXX, Issue 21462, 8 April 1933, Page 5 (Supplement)

The Aviation World

AUCKLAND AERO CLUB NEWS BT AILEBON A problem of technical interest to members of tho Auckland Aero Club, 'which lias been confronting the ground staff since Mr. E. It. Boucher's forced landing in the vicinity of White Clifis in February, has now boon satisfactorily cleared up. Mr. Boucher had to land his plane in the only available field for a number of miles because of valve trouble temporarily putting 0110 cylinder out of action. It was discovered on investigation that the collets, which hold the spring in position on the valve stem, had come off tho end owing to the corrugations becoming worn and failing to retain a grip. Tho point that was then raised was to discover the cause of the wear. Almost touching tho collets, and on the end of the valve stem, is a thimble which takes the blow from the rocker arm, and in this particular instance the succession of blows had flattened the thimblo so that the sides of the thimble pushed down on tho collets. Consequently, each time tho valve was depressed, the initial thrust was taken by tho collets, and in this way tb.e corrugations on tho inside were soon worn, so that there was 110 longer any grip 011 the valve stem. There aro eight sets of collets on each engine, and if the metal had been of uniform quality in all of them the wear should also have been in the saino proportion. But on looking over the other sets it was found that there had been 110 appreciable wear, although collets and thimbles had been renewed when the last overhaul had heen made. Therefore, with the object of determining whether the thimbles were of unequal hardness, a test was carried out. The Rockwell system was used, the thimblo being placed 011 a small fiat-bed and a diamond attached to a vertical arm lowered on to it under hydraulic pressure. The hardness of the metal was discovered from the pressure required to make the diamond penetrate the skin of the metal, the effort needed to achieve this being registered on the machine. Tt was found that in a test of five thimbles, including two new ones, the readings of the units of pressure varied between S8 and 76, showing that there was quite an amount of difference in the hardness of the metals. Now that the fault is apparent, it will be a more simple matter to keep a constant watch for other worn thimbles. An Air Cog Fitted The fitting of an air log to ZK-ACC is a recent addition to tlie equipment of the metal Moth. This machine is used for a number of cross-country

flights as well as for instructional work, and the air log affords an accurate and useful check on the total time the machine has been in the air. The instrument is known as the ThorntonNorris automatic air log, and is in the form of a clock with the dial marked off in six divisions, each of which represents an hour's flying. The clock is operated from the pilot-head; as soon as the plane gains flying speed the pressure operates a trip inside the clock and sets it in motion. Beside the trip reading, there is a total flying time register, giving a permanent total of all trips. A pointer indicates the time of the trip. Previously there has been no attachment on the market which would tell the pilot how long he had been flying as well as giving the I total number of hours that the machine had been in the air. There is also an engine time log on the English market which starts recording the hours immediately the propellor is swung. The I instrument is useful when engine time ' has to be known accurately for main- ! tenance purposes. I The sports Avian owned by Mr. R. Kirkup has now been fitted with the ! popular " doughnut " wheels in place ! of the rather anaemic-looking tyres i which were generally standard a few | years ago. These wheels are a decided advantage to planes which have to be ready to land in mud. soft sand or bumpy ground, but against this is the fact that when long grass is en- | countered for a take-off they act as j a drag. All but one of the aero club machines are now fitted with " doughnuts." and while they might not be called on to land in such a variety of places as a private machine, the number of bounces they are sometimes required to withstand on the aerodrome is sufficient justification for the attachment of the larger wheels. As soon as the occasion offers, the remaining set of " doughnuts " is to be fitted. Takapuna Beach Pageant A pageant on Takapuna Beach is a tentative arrangement for May 13, depending upon permission being received from Squadron-Leader L. Issit, officer in charge of Hobsonville base. New associate members are as follows: Messrs. W. A. Grattan, G. A. Williamson, P. Forde and W. Sinton. Two aero club machines are available for the Wanganui Easter rally, and if more than the required number of pilots apply, the allocations are to be made by ballot in the usual way. It is intended to send all the club machines to the official South Island pageant at Christchurch on April 29, and already there are four applications. Flight-Lieutenant D. M. Allan is to represent the club in his orange Moth, as ho is to make the trip South to a refresher course at Wigram on April 18. Tho To Aroha pageant has been postponed until early in May, and a display will be held by the club at Tauranga about the samo time, when the tide is suitable. Members will be sorry to hear of the death of the chief-instructor's collie, Speed, who was always a well-known personality on the landing-ground whenever his master was about. In his more active days at Mangere, Speed used to round up sheep with a skill born of long practice, for ho and his master had spent some years farming before deciding to come North to aviation. A total of 5950 hours 35 minutes has been flown by tho club machines. The time is made up as follows: Dual, 1423 hours 25 minutes; solo, 438 hours 40 minutes; hire, 2474__ hours 15 minutes; test, 154 hours 55 minutes; miscellaneous, 507 hours 50 minutes; passenger, 981 hours 30 minutes. HIGH-SPEED TRAVEL One of tho fastest light planes in the world, rho Gull cabin monoplane, built according to tho ideas of Mr. Edgar Percival, who ranks high among British pilots, is now going through trials equipped with a new and more powerful engine. This is tho 155 horsepower, six-cylinder, air-cooled Napier J. motor, an inverted engine—constructed, ■*> that is, with tho cylinders below the 1 crankcase —which recently passed through official trials with flying colours. With this power unit in the place of the 130 horse-power motor fitted to tlie standard Gull, tho craft has a maximum speed of no less than 160 miles per hour, and cruises comfortably at 140 miles per hour, which is extraordinar'.v good going for a moderately powere 1 neroplano of this kind. The cabin has room for threo occupants and a considerable amount of luggage can also bo carried. Tliero is some talk of Mr. Percival attempting to fly from London to Cape Town and back in a week, using the Napier-powered machine. His cruising speed is high enough to make tho trip feasible; if successful, it would set new records for the outward, return and double journey*