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Aviation History
1953
1953 - 0930.PDF
86 FLIGHT THE S.E.5 . a completely redesigned rear fuselage and tail unit. The fin and rudder were considerably enlarged, and the rear portion of the fuselage was fabric-covered in place of the monocoque struc ture used on the B.S.i and B.S.2/S.E.2. It was the S.E.2A which saw operational service in France with No. 3 Sqn., R.P.C., from October 1914, until March 1915, and of it was said : "Its speed enabled it to circle round the enemy's machines and gave it a decided ascendancy." A further development was projected as the S.E.3, but seems not to have been built. The S.E.4 was perhaps the most revolutionary of all the S.E. series. It bore a family resemblance to the S.E.2 and S.E.2A, but much of the design was the work of Mr. H. P. Folland, and the whole aeroplane was remarkably clean for its day. The engine fitted to the S.E.4 was the 160 h.p. 14-cylinder two-row Gn6me, closely cowled and driving a four-bladed airscrew. The large spinner had a fan built in to assist cooling, and full span ailerons- cum-flaps were fitted : all joints between control and fixed surfaces were faired. The original undercarriage consisted of an inverted tripod which had a car spring, with a wheel at each end, mounted on its apex; but the machine rolled too much when taxying and a plain vee-type structure was substituted. A transparent cockpit cover of moulded celluloid was provided, but no pilot could be persuaded to fly the S.E.4 with the cover on : it was considered to be too dangerous. The S.E.4 was the fastest aeroplane in the world at the time of its existence : the top speed was 135 m.p.h. and the initial rate of climb was in the neighbourhood of 1,600ft per minute. Unfortunately, the big Gnome engine was unreliable, and the 100 h.p. Monosoupape was later tried: with the latter engine the maximum speed was reduced to 92 m.p.h. The S.E.4 was never used operationally, but from it was developed the S.E.4A. This machine bore little resemblance to the S.E.4, although it had similar full-span control surfaces on the mainplanes which could act as either ailerons or flaps. It may have been designed with more regard to production, for it had a plain fabric-covered fuselage whereas that of the S.E.4 was a plywood monocoque. Four S.E.4AS were built in 1915, and the type is of considerable interest because its vertical tail surfaces were very similar to those used on the later S.E.5. The 80 h.p. Gn6me was fitted, the two-bladed airscrew having a large spinner with built-in cooling fan. The spinner was later discarded, and the 80 h.p. Le Rhone was also fitted as an alternative power plant. A weapon of some kind could be carried on special brackets above the upper wing, and fired forward over the airscrew. The S.E.4A was highly manoeuvrable, and its tractability was demonstrated frequently and to the full by Frank W. Goodden, that great prewar pilot who became chief test pilot at the factory. It is doubtful whether any S.E.4A saw service in France, but at least one was used on Home Defence duties: in late 1915 it shared Joyce Green Aerodrome with, a B.E.2C, as pan of the defences of London. It was not until late in 1916 that the next machine of the S.E. series appeared. Designated S.E.5, this aeroplane was the pro totype of the single-seat fighter which proved to be one of the most successful aeroplanes of the First World War, and on which the greatest British fighting pilots scored many of their victories. Those chiefly concerned in the design were H. P. Folland, J. Ken- worthy and F. W. Goodden, under the general control of F. M. Green, then chief engineer at the factory, and S. W. Hiscocks, then chief draughtsman. The S.E.5 was designed round the 150 h.p. Hispano-Suiza liquid-cooled vee-eight engine, for at that time no suitable British engine was available. The Hispano-Suiza first appeared in 1915, and the first British order for 50 engines was placed in August of that year on the recommendation of Lt. Col. H. R. M. Brooke-Popham, who had examined one in Paris. First deliveries against this order were not made until August, 1916, and most were diverted to the S.E.5s. The first prototype, numbered A.4561, made its first flights in December3 1916, and the machine proved to be satisfactory. However, an unsuspected weakness in wing design led to the destruction of the prototype at the end of January 1917, and in the crash Major Frank W. Goodden lost his life. Not only was he a fine pilot, but he had assisted considerably in the design of the S.E.5, and his loss was a severe one. Production was halted while the wing design was modified : stronger lift-bracing was fitted, and the production machines began to appear in March 1917. By the end of that month 16 had been delivered. The wings of some of the earliest production machines (e.g., A.4848, A.4850, A.4853), as issued to No. 56 Squadron, retained the same plan-form as those of the first and second prototypes, but others (A.8904, A.8910, etc.) had the wings with blunter tips and slightly reduced span which became standard on all S.E.5S and 5AS. Structurally there was nothing very unusual about the S.E.5, but it was characterized by excellent detail design. A good deal of the aerodynamic refinement which its predecessors had dis played was sacrificed to achieve serviceability and ease of main tenance, and in service the aeroplane acquired a reputation for great structural strength. The fuselage was a typical box girder of wooden construction, cross-braced for rigidity and fitted with a rounded top-decking : a streamlined headrest was fitted to some machines. The covering was of fabric over most of the structure, but plywood was used about the cockpit and as a reinforcing web on the fuselage sides below the engine-bearers. The wings had spruce spars, but no compression struts were fitted: instead cer tain ribs were made solid and acted as compression members. The incidence of the tailplane was variable in flight, and a sprung steerable tailskid was fitted. The early production S.E.5s had an external gravity fuel tank mounted above the centre section, but later machines had the gravity fuel supply carried in a tank shaped to fit the nose portion of the upper centre section. Exhausts varied considerably in design, for it was some time before the long horizontal pipes became more or less standard. The first and second prototypes had short manifolds with a single central outlet; other S.E.5s had L-shaped manifolds with the outlet either at the forward or the rear end of the manifold. Most of the early production machines supplied to No. 56 Squadron seem to have had the L-shaped mani folds with forward outlet. One of the more remarkable features of the S.E.5 was the arrange ment of its armament. At a time when twin fixed belt-fed machine- guns were just beginning to come into fashion, the S.E. struck a different note with its single synchronized Vickers in the fuselage and a Lewis on a Foster mounting, firing forwards over the upper wing. The Foster mounting underwent slight modifications from time to time in service, and on some S.E.s it was a little higher above the centre-section than on others. At first the Lewis gun fired parallel to the Vickers, but before long the rail of the Foster mount ing was raised a little at the rear to provide converging fire. The Lewis could, of course, be pulled down for firing upwards, a com-
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