9K SHORT STIRLING

0 f LIG HT JANUARY 29TH, 1942 H \fi£> 9k SHORT STIRLING •t First Details of Great Britain's Biggest Bomber : A Four-engined Type with Fighter Manceuvreability been developed and now forms the Until production of the Short A LMOST since the earliest days of Stirling was undertaken, the Scylla /A flying the name ' of Short basis of all modern Short aircraft. In more recent times there was the Scylla was the largest landplane built by •*• •*• Brothers has been associated Short Brothers. The long and suc with marine aircraft. Short seaplanes landplane, which really was the bi plane wings of the Kent class flying cessful experience with flying boats, made history even before the war however, was in itself a guaran 1914-18, and during that war the boat mounted on a metal fuselage instead of the hull. tee of the firm's qualifications to "Two-two-five" particularly became undertake the work of design famous in the Royal Naval Air ing and building a large Service. From then onwards bomber, but to make assurance Shorts specialised on sea doubly sure it was decided to planes, first twin-float types construct first a flying scale and afterwards flying boats. model of the bomber which Of the latter the Empire was to become famous as the boats, with variations, and Stirling. One of our pictures the Sunderland are particu shows this machine, which was larly noteworthy and are doing a fairly faithful model. Tb,e excellent work in the present Pobjoy Niagara IV engine*-^ war. were practically half-size (in ^ scale, not in power, of course) Landplanes of the Hercules engines of the Although they specialised large machine. The same on seaplanes. Short Brothers might be said of the airscrews, did not neglect the landplane so that slipstream effects were entirely. Every now and then quite well represented in the a landplane would make its model. The only thing, as appearance at Rochester, as if Mr. Lankester Parker, Short's to prove that the firm was chief test pilot, used to say, quite capable of producing air which was not to scale was the craft of that class if they were pilot, who had to look out in demand. Actually, it may Length 87ft. 3m. Engines : through a windscreen several be said that, although all- Wing span oc/t. lin. Four 1,600 h.p. Bristol Hercule sizes too small for him. How clones. metal marine aircraft were to Height 22ft. 9in. or Wright Double Cy ever, the flying scale model become the firm's very special provided the information re trade, it was with a landplane quired, and \,hen the Air that the foundation was laid. Ministry's specification for a In 1919 Mr. Oswald Short high-speed long-range bomber produced the first all-metal, was issued in 1936 the firm stressed-skin aircraft, the was ready to undertake the Silver Streak biplane. This work. y did not go into production as a tvpe but the principle of The prototype aircraft, fusdage construction used in and the first of the production it was that which has since machines, were built by the JANUARY 29TH, 1942 FLIGHT 95 'parent company, but it was obvious that the heavy demand could not Lfi met in time by the existing facilities, and the Stirling is now produced, in the form of main components, in more than twenty different factories,! in addition to a large sub-contracting scheme for the supply of smaller components. Recently the Ministry of Aircraft Production arranged for a party to visit a selected group of works so that activity on this. Great Britain's big gest bomber, could be appreciated. The huge workshops and lines of pro duction on such a massive type form a most impressive sight. Some delay was caused by a mis hap to the first machine, the under carriage of which collapsed on the Everything to scale except the pilot. This fqur-engined half-scale flying model, with first landing. The trouble was, how four 90 h.p. Pobjoy Niagara engines, was built in 1936 and thoroughly flight-tested ever, tracked down (it was, we be before the Stirling was built. This exclusive Flight photograph shows the similarity lieve, caused by the binding of a between the model and the full-scale machine. wheel brake), and in all subsequent aircraft the un- dynamic and partly by _j^tarriage has functioned operational considerations. as Intended. The placing of the wings on In its general design the the sides rather than at the Short Stirling is a mid-wing bottom corners of the cantilever monoplane with fuselage causes less inter four engines mounted on j ference with the air flow, the leading-edge of the calls for small fillets or no wings. The standard power fillets at all, and has much plant is the Bristol Hercules to recommend it aero- sleeve-valve 14-cyl. radial dynamically. The fact that air-cooled, of 1,600 b.h.p. to get the high performance maximum power at 2,900 aimed at it was necessary to rp.m. Arrangements house the bombs in the have, however, been made fuselage made it necessary for the fitting, as an to raise the wing so as to alternative, of four leave a clear space in the American Wright Cyclone floor, so that here again the engines of the same power. mid-wing arrangement was As not only the size and logical. Aircraft design is weight, but also the power, always a compromise; in of the two engine types are this case the' " price to be almost identical, it may be paid " for the advantages o( assumed that the per the mid-wing arrangement formance will be very much was a rather tall under the same whichever is carriage, which must weigh fitted . On the score of rather more than the shorter decibels, however, the undercarriage of a low-wing Cyclone wins easily. Its monoplane. However, it was noise is deafening. One of the four. The Bristol Hercules 14-cyl. sleeve-valve decided that the mid-wing engine fitted in the Stirling develops a maximum of 1,600 arrangement was preferable, The choice of the mid- b.h.p. at 2,900 r.p.m. The Wright Cyclone, which forms an wing position was probably alternative power plant, is of the same power (at 2,400 r,p.m.), and so the basic outline dictated partly by aero- but has poppet valves. of the Stirling was settled. This front view of the Stirling shows the large ground angle and the placing far out towards the wing tips of the outer engines. The airscrews are de Havillands of Jtfi^ fully feathering type. t>6 JANUARY 29TH, 1942 THE SHORT STIRLING Two more factors influenced the design: The wing span was limited by the Air Ministry to 100ft.—from considerations of hangar space, one presumes—and the fuselage dimen sions were largely determined by the size of packing case needed. Within those restrictions the Stirling took shape. There seems to be little doubt that if the designers had had a fret- hand they would have chosen a wing of greater span and higher aspect ratio for efficiency. On the other hand, it may well be that had such a wing been fitted the amazing manoeuvrability of the Stirling would not have been achieved. As it is, pilots say that the machine can be "thrown about" almost like a fighter, and in a scrap that is a feature well worth having, and has doubtless played its part in making the Stirling such a formidable antagonist. Well-tried Methods In the primary structure of the For a four-engined aircraft the instrument panel and controls of the Stirling are Stirling one fii|ds obvious evidence of very simple. The reason is that a flight engineer is carried, who has his separate its flying boat ancestry. The wings are instruments elsewhere. almost identical, so far as the type of design is concerned, with those of the the Stirling • iuselage, however, the miles per hour thus gained are worth Empire and Sunderland boats. The stringers are continuous and the the extra trouble. If the surface were fuselage, apart from the fact that it frames notched for them. From a left smooth the saving in drag might has, of course, no step, shows a form strength point of view there is prob be considerable, but by the time it is of construction very similar to that of ably nothing to choose between the camouflage painted there is probably • the boat hulls. two methods, but it appears likely that not much gained. The outward shape of the fuselage is in assembling, the type of construction a very straight top, a flat bottom, chosen is slightly quicker. Wing Structure and nearly flat sides. The corners at As high speed in addition to great The wing structure, as already men top and bottom longerons are, of load-carrying capacity was demanded, tioned, follows closely that of the course, rounded off. Frames are of everything possible had to be done to Short flying boats. Basically it is a Z-section, and the longitudinal obtain a smooth finish. This meant two-spar structure, with spar flanges stringers are a cross between V- and that all external rivet heads had to of extruded T-section, and top and I' sections, that is to say, a U with be flush with the surface ; it also meant bottom flanges connected by a tubular corners instead of a smooth curve. that free edges of skin panels could N-girder arrangement.

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