0 f LIG HT JANUARY 29TH, 1942 H \fi£> 9k SHORT

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First Details of Great Britain's Biggest : 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 . 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 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 is carried, who has his separate its 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 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- structure, with spar flanges stringers are a cross between V- and that all external 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. This form of For many years it, was the practice of not be tolerated, but had to be joggled construction has been found excellent Short Brothers, in their flying boat at the joints. All of which added to in the boats, and there wasirthus no hulls, to cut the stringers at the manufacturing difficulties, but was,t reason for changing it in the landplane points of intersection with the frames, presumably, deemed necessary. One bomber. One minor change is thafc^ and to attach them by gussets. In does rather wonder whether the few the inter-spar bracing is now of the^K

The motor cyclist in the foreground gives " scale " to this pict_ the Stirling. The camouflage painting of this particular specimen shows it to be intended for daylight operations two side-by-side tail wheels may be noted.

7 ^5J§^ JANUARY 29TH, 1942 FLIGHT il V THE SHORT STIRLING

same tubular torm as that of the spars section also makes a useful storage themselves, whereas in the boats it space for small articles. In the centre took the form of tie-rod tension of it is cut a large circular hole, so members. that a member of the crew may stand up here and be within reacii of any Plug Connections of the stored articles. An interesting feature of the Short A feature which the Stirling also type of wing truss, and one which shares with the Short flying boats is facilitates assembly, is the type of plug the single fin and rudder. Their end used. Instead of the usual plug shape is different, and the area is with plain or forked lug, the Short smaller, owing to the fact that there plug is rather in the form of a piston, is not, as in the fore body of the flying with the lug coming down from the boat hull, a large vertical area for­ crown. The "skirt," to continue the ward, and therefore the rudder simile, makes very easy the operation volume needed is not so great. of riveting the plug to the tube end. The control surfaces are of the type Wing covering is of aluminium-alloy familiar from the Short boats. The sheet, riveted to spars and rib mem­ same type of Gouge is used. bers, and the leading-edge is a separate This resembles somewhat the Ameri­ structure, portion of which contains can Fowler flap, but there is no gap tanks. As in the Short boats, the reai between it and the main wing, and portion of the wing, from rear spar to the flap works solely by the increase *£rai]iiig-edge, is a light tubular girder in area and angle of incidence. That structure. this increase in area is substantial will The wings of the Stirling are, sur­ be gathered when we point out that prisingly enough, designed to be the chord of the flap is 48 per cent, assembled in one piece ; that is to say, of the main wing chord. on each side, port and starboard, the wing is in one piece from fuselage side Unusual Undercarriage to wing tip. The T-section spat Reference has been made to the flanges are, of course, in shorter sec­ lengthening of the undercarriage tions, as they taper from root to tip, caused by placing the wing midway and machining down from the root size up the fuselage sides. In addition to would waste a lot of material and the extra weight which this entailed, time. the design of the undercarriage struc­ Inside the fuselage the main wing ture itself was rendered more difficult, structure, so far as the spars are con­ as the long struts and bracing members cerned, runs through from side to as well as the wheel had to be accom­ side. More unusual is the fact that modated between the wing spars. the top wing covering is also con­ The design evolved makes use of a tinued across the fuselage. Presum­ sort of double-jointed arrangement Three stages in the lowering of the ably this was done for purposes of which looks somewhat complicated, undercarriage of the Stirling, showing strength, but the top of this centre but which is actually about the how struts as well as bracing members are "broken" in the folding process.

simplest that could function fault­ lessly. It must be remembered that the loads to be supported are very great. When retracted the undercarriage is housed in the inboard engine ; all, that is, except a small portion of the wheel, which projects but is quite well faired by the doors and- the fair­ ing, which is of plastic material. Landings can be made with the wheels retracted, and the very sturdy bomb bay in the floor of the fuselage has been found to prevent serious damage to the main fuselage structure. The wheels are Dunlops, with a tyre dia­ meter of about 6ft. and a'tyre width of 28m. Each wheel weighs 764 lb. com­ plete, a figure which will give some idea of the weight of the aircraft. Operation of the undercarriage is electric. In order to avoid encroaching on the space for the gunner's cockpit in the stern, a very unusual expedient has been adopted: two tail wheels are fitted to keep down the diameter. Twin tail wheels, linked together by chain and sprockets, are used on the Stirling in order to avoid too large a diameter, which would encroacb-on the space in the They retract into the fuselage. tail turret. The four Bristol Hercules engines w 95

SPECIFICATION TYPE : Mid-wing four-engined all-metal cantilever monoplane with retractable main and tail chassis. 1 ENGINES : Four Bristol Hercules 14-cylinder power 1,600 B.H.P. at 2,900 r.p.m. or alternatively Four Wright Cyclone engines, 14-cylinder power 1,600 B.H.P. at 2,400 r.p.m. AIRSCREWS : Three-bladed metal 13ft. 6in diameter—fully feathering, OVERALL DIMENSIONS : Wing Span, 99ft. in. ; Length, 87ft. 3in. ; Height, 22ft. 9in. ; Cross wing area, 1,460 sq. ft ; Tail Span, 40ft. 8in. ; Fuselage, 8ft. 8in. deep x 6ft. 8in. wide, 87ft. 3£in. length ; Length of bomb cell in fuselage, 42ft. 7in. Each main undercarriage wheel 70.8in. (nearly 6ft.) diameter. Twin wheels in tail chassis. WEIGHT : Fully loaded, over 30 tons.

BA^fcHJ-i-gR,. «JARY 29TH, 1942 SO BRITAIN'S BIGGEST BOMBER rHE FOUR-ENGINED SHORT STIRLING WHICH CARRIES UP TO EIGHT TONS OF BOMBS An Exclusive Drawing for "Flight " by M. A. Millar

PERFORMANCE iximum speed, approximately 300 m.p.h. Range over 2,000 miles. Capable of carrying 8 tons of bombs. ARMAMENT iree .303in. gun turrets, situated in the nose, dorsal, and rear positions of the fuselage. Altogether 8 Browning guns are mounted in these turrets. CREW .yen, consisting of two pilots, navigator/bomb aimer, front gunner/W/T operator, two air gunners and flight engineer/air gunner.

TAIL UNDERCARR]«?E WHEELS RETRACTED iOO FLIGHT JANUARY 29TH, 1942

THE SHORT STIRLING Rudder VUM

are mounted, as in the Empire and Sunderland boats, in complete nacelle monocoque units bolted to the front wing spar, the tail portions of the fairing into the wing surface. Fuel is carried in cylindrical tanks in the wing, outboard of the wing bomb cells. The absence of fuel in the fuselage, and the use of self-sealing tanks, reduces fire risk to a minimum. The engines drive three-bladed fully feathering airscrews of 13ft. bin. in diameter. They are fitted with de-icers. A Crew of Seven Before describing the internal lay­ out of the Stirling it may be mentioned that it carries normally a crew of seven: First and second pilot; the navigator, who is also the bomb- aimer ; the front gunner, who is also W/T operator ; two air gunners ; and the flight engineer, who mans a gun Mas* Balance. when required. Fuselage Break Main Prar Member*'' * 1 In the extreme nose of the fuselage Details of the construction of the tail surfaces and rear fuselage portion of the is the bomb-aimer's compartment, Stirling. The very long fuselage is built in sections, bolted together. situated under the floor of the pilot's cabin and nose-. In this good view when standing up, and pro­ coupe. The wireless operator and compartment is also a trap-door by tection is provided for him in the form flight engineer are located aft of the which the crew may enter and leave of hinged armour plates which swing flight compartment. the machine. The nose turret is, of out of the way when not in use. The Under the centre-section of the course, power-operated and contains first pilot has armour plates behind wing, and extending fore and aft, is two .303 Browning machine guns. his back and head, and further pro­ the bomb cell. No mention may be The pilots are seated side by side, tection is provided by a complete made of the actual composition of the with quite a wide space between armour-plate bulkhead with sliding bomb load, except that it may total them. The coupe top of the compart door at the after end of the cabin. as much as 8 tons. An idea of the inent afford an excellent view in all The navigator is housed within the load is obtained when it is pointed important directions, and under it is flight compartment, with chart table out that the length of the bomb cell also provided a station for the fight­ and other aids to efficient navigation. is 42ft. 7in., and that it extends right ing controller, who superintends the The retractable astral dome is incor­ across the floor of the fuselage, being air gunners when an action is going porated with an escape hatch in the divided by two longitudinal girders on. From his position he has a fairly roof, just aft of the rear end of the into three compartments, each of which houses a series of bombs. The three doors open simultaneously.

Aacbtttue to LCTW Tardus Shaft Drive. The Dorsal Turret K(Ar 5nxr BoHH Aft of the centre section of the CnidtVlod wing, in the roof of the fuselage, is the dorsal turret, which is a Boulton Flap* Our Paul power-operated one of streant*-^ Thp S»itcb Can* line shape, containing two Browning I .303s. From about this position in the fuselage rails run to the four- gun turret in the tail; by these am­ munition is sent to the rear gunner. The tail turret is reached by a walk­ way. All three gun turrets have armour protection. At the end of the bomb bay are installed the chutes ior the parachute flares. Equipment of the Stirling is, of course, extremely complete, as it must be in an aircraft of this type which has to operate over long distances and in all sorts of weather, sometimes in formation and sometimes alone. Inter­ communication telephones connect the members of the crew, but should the system be put out of action by gun fire, there is ample room for a mem The special Gouge flaps of the Stirling are operated by a worm drive actuated by her of the crew to walk from one end-r an electric motor. Trip switches stop the motor when the flap is in the " fully out " of the fuselage" to the other with mes­ and " fully in " positions. \ sages. Among the equipment are two JANUARY 29TH, 1942 FLIGHT ior

THE SHORT STIRLING

Elevator abuwtroi inflatable dinghies, one carried'in the fuselage and the other in the wing. The wing dinghy is inflated auto­ Rudder'Bar AijoeHo^ Screw matically when the aircraft touches the sea. The Breeze system of wiring Differential Brake by sections is employed. Control Unit Behind the dorsal gun turret is an interesting piece of equipment de­ signed to prevent the gunner from hit­ ting his own tail in the excitement of an air engagement. The device bears the intriguing title "taboo track." Comfort of the crew has been well looked after in the Stirling, and heat is provided by a Gallay boiler heated by the engine exhaust. Most of the internal equipment, and Rudder Servo Unit a good deal of the primary structure, Controls is shown in the drawing by Mr. Max Millar on pp. 9899. One feature Servoctat. which has characterised Short flying Automat­ .boats from the Empire type onwards, Control Coumm Huge Point ed* rd» ^Ht5*\vhich is even more pronounced Aileron Servo Unit, Automatic i in the Stirling, is the placing of the Elrvaior Lu di»Jt outer engines very far towards the r wing tips, and the amount of equip­ ment, «tc, carried inside the wings. Waarfioh BuUud. It is almost literally true to say that Flap RoSer Channel* every cubic inch of space has been Train? U/t fa Ifoyof Flap utilised. If the wing loading were to be further increased, as many advocate in connection with, assisted take-off, it is difficult to see where the Flap Support R*f equipment could be housed.

Some Stirling Data A few figures will help to convey some idea of the impressive size ot the Stirling bomber. The wing span is 99ft. iin. and the gross wing area 1,460 sq-. ft. Using the span: area formula, this gives an aspect ratio of just over 6.5, which must be regarded as low for a machine of this class, but, as already explained, the span was limited in the specification to which the Stirling was built. The overall length is 87ft. 3m., and * the inside dimensions of the fuselage are 8ft. 8in. in height and 6ft. 8in. In the top right-hand corner is a view from below oi the pilots' dual controls and in width. portions of the automatic pilot equipment. When fully loaded the Stirling The other sketch shows details of the wing construction of the Stirling, and the weighs over 30 tons (68,000 lb.), so system of dividing it into units. that the wing loading is in the neigh­ bourhood of 47 lb./sq. ft. In spite a few can be mentioned of the, hun­ his other duties, much to do with the of this, the machine is extremely dreds who contributed to the design. actual design in collaboration with manoeuvrable. The maximum speed Mr. Oswald Short deserves credit for Mr. Lipscomb. is approximately 300 m.p-.h., the having picked the team, Mr. Gouge for In addition to the parent company, maximum bomb load is 8 tons (18,000 his inspiring work as general manager a word of praise should be addressed lb.), and the maximum range is 2,000 and deputy chairman of the company ; to the different dispersal factories and miles. Mr. Lipscomb as chief designer, and the extremely numerous subcon­ Having been in service since 1940, Mr. Lankester Parker as chief test tracting firms, all of which have the Stirling has proved its'worth on pilot. For the benefit of the newer contributed so much to the transla many occasions, and not only has it readers of Flight it might be explained tion ol the designs and drawings into carried its heavy bomb loads to that Mr. Gouge's contribution has a powerful striking force. enemy targets, but it has given good actually been far greater than might Women labour is extensively em­ accounts of itself in many aerial be thought merely from his official ployed in Stirling bomber factories, encounters. So, once more, the Air position in the company. He has where work on light aluminium alloys i Ministry's faith in Short Brothers has worked in every department of the is clean and appealing to that big been fully justified, and the nation Short works, and for many years he army of patriotic woroc.i performing may be proud of the men who pro­ was chief designer, so that one may national service. There is room for duced the machine, among whom but assume that he had, in addition to many more!