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Aviation History
1938
1938 - 0573.PDF
MARCH 3. T938. FLIGHT. 197 ONTINUED) Slotted Fighters GERMANY has stolen a march on us by taking thefirst Handley Page slotted single-seater fighters(Messerschmitt B.F.W. Me. 109) into service. Per- formance figures for this type of machine are still with- held, but it is said that the speed range sets a new record for fixed-wing aeroplanes. The top speed, of course, will be very much greater than that of the Westland Lysander army co-operation machine, though the landing speed will almost certainly be rather higher. It is a somewhat striking fact that many years ago British designers were experimenting with slotted single- seater fighters, but these were bid-style biplanes which would not benefit to the full from the installation. To-day, when practically every device—the v.p. airscrew, low- drag cowling, retractable undercarriage, and so forth—has been applied to the fighter to extract more speed, we have not one modern monoplane fighter with lift-slot equipment. 280—PlusT HINGS have changed indeed when, to get the truth, one has to add something like 15 per cent, to a figure quoted by the Air Ministry and a manufac- turer for the top speed of a Service aircraft. Time was when one automatically deducted a considerably greater percentage in order to arrive at the speed attainable in ser- vice, after Ministry "gadget wallahs" had festooned the long-suffering airframe with barbarous excrescences. But there seems to be very little doubt that the Bristol Blen- heim medium bomber is faster by far than we have been given to suppose; some specific figures are quoted on page 212 of this issue. That fact, in itself, is comforting enough, but there is even more cause for elation when it is realised that a standard British bomber, already in service in very con- siderable numbers, is as fast as, if not faster than, several of the new Continental twin-engined fighter prototypes. A Principle ProvedW ITH the public demonstration last week of the '' separation "of the two components of the Short- Mayo composite aircraft Maia and Mercury, Major R- H. Mayo may be said to have proved what he set out to prove, i.e., that it is possible, safely and surely, to launch one aircraft from the back of another in flight. Thr application of the principle is, strictly speaking, a matter for others to decide. It may be wide or it may be narrow; that will depend mainly upon the degree to which other forms of '' assisted take-off '' can do more or less and do it better or less well. Full-load trials still have to be made, but the ease and smoothness with which the separation took place gives one no cause for misgivings on that score. lh<? most pleasing feature of the breakaway, and one for which Major Mayo and the Short designers must be given their full share of credit, was the almost mathe- matical precision with which the two machines parted. One* of the risks, admitted by Major Mayo, but claimed by him to have been foreseen and guarded against, was that an instant after the separation the upper component might climb and slow down while the lower dived and accelerated. Should this happen, the tails of the two machines might have touched. Visual and cinemato- graphic evidence showed quite definitely that there was no relative movement in a horizontal plane until the machines were some 50ft. apart. This is brought out very strikingly m the strips of cine film published on page 209. Another possibility was that if, at the instant of separa- tion, the two machines yawed slightly in relation to one another, one of the floats of the upper component might 8et into the airscrew disc of the lower. Here again the pessimists were confounded. There is no trace visible in the cine film of any such movement until the two aircraft are well separated and clear of any danger. Thus, although the separation with Mercury loaded up to its "Atlantic" gross weight of 20,5001b. has not yet been attempted, it can be claimed that Major Mayo has proved his contention. Helicopter HopesW HEN a firm has spent some six years on calcula- tions and experiments a certain amount of reticence is understandable. Professor H. Focke, of the Focke-Wulf firm in Bremen, began to interest himself in helicopter problems in 1932. The first free flight of the Focke-Wulf F.W.61 helicopter was made on June 26, 1936, and one year later the machine broke by a wide margin all the then existing world's records for helicopters. Some months ago Fraulein Hanna Reitsch flew a second machine from Bremen to Berlin without landing, and the other day she made a free flight inside the Deutschland- halle in Berlin. That the control problem has been solved by Herr Focke and his collaborators can thus no longer be doubted. Sheer performance is now a matter for refinement in the aero- dynamic design of the machine itself, regarded purely as an aircraft. The unfaired rotor heads and the two open- girder structures which carry the two rotors must obviously offer a great deal of reducible drag, and there are prob- ably other directions in which it can be "cleaned up." Little has been allowed to become known concerning the details of the F.W.61, but in an article contributed to the German aviation journal Lujtwissen, Professor Focke does disclose a few interesting features of his machine. For instance, the drive to the two rotor heads is by bevel gears, friction clutch and inclined shafts. The blades are hinged to the rotor heads, and have their angle of incidence con- trolled in such a manner that the rotors provide all control with the exception of directional. One of the most interesting and significant aspects is the high rate of climb, which exceeds by far that of the Auto- giro and is even slightly better than that of the Focke-Wulf Stieglitz, being 3.6 metres per second. When flown as an Autogiro the F.W.61 had a climb of only 1.3 metres per second. The power loading is about 14 lb./h.p. In speed also the machine was superior when flown as a helicopter. Completing the CircuitD URING the past fortnight two important advances have been made in the construction of what may reasonably be called the Empire world air services. Just over a week ago the Imperial Airways boat Cen- turion left Southampton for Karachi, Calcutta, Burma and Malaya, with the first batch of unsurcharged first-class mail carried to these parts under the new scheme. A few days later a P. and O. liner left India carrying the last con- signment of sea-borne letters. The all-mail-by-air scheme has now been in action on the African route for nearly a year, and ordinary mail will be flown through to Australia in the early summer. It is significant and almost encouraging to find that, so far as the general Press was concerned, the matter was treated as one of natural sequence and not of news value. That is the state of mind which is wanted in considering air transport as such. It is hardly necessary to say again that the fact that the Post Office, a most conservative organisation—rightly so—is now treating air transport on level terms with other means is of the greatest importance. At the same time, the first stage in the trans-Canadian air service was flown on March 1, when a machine was due to leave Winnipeg for Vancouver. The Canadian Ministry of Transport expect that the Montreal-Winnipeg section will be in action during the summer, and that within a year the complete service should be in operation. When the Atlantic air services are flying on a regular semi-commercial basis, it will only be necessary .for the projected Pacific service to be started, and the girdle will be complete. DIARY OF FORTHCOMING EVENTS—PAGE 217
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