WORLD NETWORK OF AIR LINES

Otago Daily Times, Issue 21668, 11 June 1932, Page 8

WORLD NETWORK OF AIR LINES

AERODYNAMICAL PROBLEMS ’ ' LARGEST WIND TUNNEL., (From Gor Own Correspondent.) T , LONDON,. April 28. ' Survey operations of the air route between Calcutta and Singapore, conducted by, the Royal A|r Force with the cooperation of the Siamese Government, pro- ' raise to simplify'flying over country which is in many places hazardous terrain for the airman, but is vastly important because of its location along the,main: air trunk line to the Far East and Australia. British, Dutch, and French air liners have flpwn many! times- over the route. Light aeroplane adventurers, set on breaking the Australia-England record, have passed swiftly along it. More than once Royal Air Force flying boats have flown ip formation along the coast between Calcutta and Singapore. In. these ways much information has been gathered about flying conditions along the routes. But ; much more remains to be done before the airway in this region is suitable for regular ‘flying, at alj times of the year, particularly in landplapee, and the survey operations now iii progress are directed to the improvement of the route front this, point of view. The risks are greatly intensified during the monsoon period, and when the • survey work was begun it. was recognised that a first essential was an exhaustive reconnaissance planned to correct and to modernise Existing maps. Sites suitable : for emergency landings • and areas which ape known to be exceptionally dangerrius in bad flying weather are being, carefully charted, and other information useful to the airman got together in easily accessible form. A portion of the route, between Victoria Point and Alor Star, Siamese territory, had never previously been developed, though it is one of ’the most difficult stages of the entire journey of 2000 miles from Calcutta to Singapore. The Siamese authorities had already surveyed the northern sections of the main Burma-Malaya air line, and their co-operation was sought by the Royal Air Force for the closing of the hiatus between Victoria Point'and Alor Star. An offer that the Siamese Government should utilise the services and experience of the Royal Air Force in the proposed survey and choice of sites for landing grounds was heartily accepted, and the work was begun. , : - Thus, in this and many other Regions, the task of establishing a world-wide network of air lines goes steadily forward. When the present survey is completed the flying machines will be able to move more surely over the hills and jungle. of tM Malay Peninsula. And once again; the British military air service blazes the trail for the air liner and the private flyer. > ENGLAND’S LARGEST “WIND , TUNNEL.” 1 Much of the research work directed to the elucidation of aerodynamical problems is done, in wind tunnels—chambers of tubular shape through which air is blown over model aeroplanes that are linked up with recording instruments. In this way the experimenter learns much about the behaviour of an aeroplane in a moving current of air, and this knowledge is applicable to actual flight of the full-size machine. But the wind tunnel which is only large enough to permit the use of scaled-down models of the actual aeroplane or aeroplane component has obvious drawbacks. Experience shows that there is always some discrepancy between the results obtained in the tunnel and those got in actual flight. This discrepanby is known as “scale effect,” and, though it may frequently be Calculated with a fair degree of accuracy, it may prove sufficiently serious and intractable to invalidate many of the figures recorded in the wind tunnel. An obvious way out of this difficulty is the building of a wind turinej so large that a full-sized aeroplane may be pladed in it. This costly equipment is now taking shape at the Royal Aircraft Estab-. lisbment, Farnborough, and when the work is completed the establishment will possess the largest wind tunnel in Great Britain. Designed and constructed by Messrs Boulton and Paul, the aircraft builders, the new tunnel is made of steel and reinforced concrete, and will be housed in a building 230 ft long, 140 ft wide, and 90ft high. In shape it will be a tube between 400 ft and 500 ft long, bent round on itself to make a closed circuit. A gigantic fan, driven by motors developing 2000 h.p., will force air continuously round the tunnel. One section of the tube is cut away for a distance of approximately 45ft, and the two free ends open into a hermetically sealed chamber. This arrangement produces about the centre of the chamber a jet of air no less than 25ft in diameter which moves at a velocity of more than 100 miles- an hour. Aeroplanes under test Urill be placed in the sphere of influence of this jet, and subjected to wind forces similar to those encountered in actual flight. Much information leading to improvements in the design of British aeroplanes is expected from the diligent use of the new tunnel.