AVIATION NEWS

Otago Daily Times, Issue 21549, 22 January 1932, Page 13

AVIATION NEWS

REMARKABLE SEARCHLIGHT INVENTION \IR TRANSPORT BELOW SEALEVEL. (Fisoit Our Own Correspondent.) LONDON, December 10. Seven hundred feet below sea-level, the little town and harbour of Tiberias, on the Sea of Galilee, has now for the first time been brought into regular high speed communication with the outside world througn the regular visits of bin British flying boats, the Short “ Kent ” biplane giants which fly long stages of the Imperial Airways main line between England and India. This is the lowest level at which ah--craft are regularly operated anywhere in the world. Below sea-level the atmosphere gets denser. Theoretically, a flying machine should take off a little more quickly with a large load on board and, given a suitable engine and airscrew, slightly higher speeds should be possible several hundred feet below sea-level than at normal height. Each of the air transport boats is powered with four moderately supercharged “ Jupiter ” engines, designed to give full output at about 5000 Feel ! above sea-level, and the pilot flying below sea-level therefore throttles his engine more than is usually necessary, assuming that the air conditions are not abnormal at the time. Probably there is a consequent gain in economy, the slight closing of the throttle saving fuel. Unfortunately regions of any size sufficiently far below sea-level to confer these small- but useful advantages in aeroplane operations are rare. The addition in the reverse direction of several hundred feet to the height range of the “ Kent ” boats is all the more noteworthy. LIGHT IN AIR DEFENCE. Details recently revealed of an astonishing new British searchlight device for accurate calculation of the height, speed, and direction of aeroplane flying at any height up to 15,000 or 20,000 feet show in dramatic fashion unexpected possibilities of defence against air attack. Invented and developed at Hendon aerodrome by Major J. C. Savage, the skywriting expert and his staff, the new apparatus is fundamentally a searchlight of enormous power, the light available being no less than three thousand million candle power, which makes it the most powerful searchlight in the world. This light throw’s patterns on the sky—in tests recently made by the War Office the pattern selected was a square “ grid,” divided by transverse lines into 16 smaller squares—and enables positions in the sky to be plotted in a way similar to the marking of artillery targets' on map squares. A special method of projection, utilising 300 parallel beams each deflected by a mirror along its particular path in the pattern, secures intensity of illumination up to great heights. During the tests the speed, height, and direction of aeroplanes flying overhead were determined within one minute of their crossing two of the parallel lines in the illuminated “ grid ” thrown up by ' the searchlight. An uncanny attribute of the device is that the aeroplane pilot

sees no grid line till he enters its path, darkness prevailing between each, line, and he is therefore unable to guess whicl| way to turn to escape from the probing rays. Means of circumventing the device occur instantly to the mind, as in every, contest between weapons of attack and apparatus of defence. When dense clouds hang low over the searchlight station its' usefulness will clearly be limited, andthe laying of artificial smoke screens might baffle the exact spotting of raiders overhead. But the invention undoubtedly marks a great advance in searchlight construction, and sooner or later lights of this kind are certain to take their place in the air defence system gradually' taking shape round London. A CLUB FLYING BOAT. Members of the Singapore Flying Club are being instructed in the handling of a small twin-engined flying boat which was sent from England last April, Members who have qualified for the “A” pilot’s license, entitling them to fly an aeroplane outside the precincts of an aerodrome but not to ply for “ hire or reward," are permitted to make solo flights in the machine. This enterprise is something unusual in club flying, and points the way to an extension of private aviation which many experts believe to hold much promise. The small flying boat in suitable country’ is capable of much that the land plane, can do only with risk. The boat is; i freed from the “aerodrome” problem;, any decent stretch of water provides room for “ take-off " and every sheltered harbour or creek is its anchorage. The traveller may fly in perfect safety low above the waiter, gaining a pleasant sensation of movement and much closer and more vivid impressions of the scenery than he can hope to get from the heights imposed by safety when flying in a land' machine. Further, the flying boat is a vehicle calling for a mingling Of sea and; air knowledge that many airmen find intensely fascinating. The Singapore Club’s boat is a Saro “ Cutty Sark ” four-seater cabin mono-r plane, driven by two 110 h.p. air-cooled’ motors. It has dual control and side-' by-side seats in the front of the cabin, an arrangement which considerably simplifies the task of instruction. The design provides for , the attachment ,of a land under-carriage, and in amphibious' form the “Cutty Sark” is used, ib theRoyal Air Force, and for service and commercial flying in various parts of the Empire, while more than one Biitrsh private owner has adopted a similar craft for use as an air yacht in pleasure and business cruising.