Vickers Type 271 Wellington

Первый опыт с геодезической конструкцией самолета, полученный компанией «Vickers» при работе с Wellesley, позволил ей успешно принять участие в тендере на средний дневной бомбардировщик, требования к которому были изложены в спецификации B.9/32. «Vickers» получила контракт на постройку прототипа - моноплана со среднерасположенным крылом и убирающимся трехопорным шасси с хвостовым колесом, оснащенного двумя звездообразными моторами Bristol Pegasus X мощностью по 915 л. с. (682 кВт). Прототип был облетан 15 июня 1936 года, а 15 августа 1936 года компания получила первый заказ на 180 серийных Wellington Mk I. В октябре 1938 года самолеты стали поступать в IX эскадрилью, а к началу Второй мировой войны в сентябре следующего года в строю находилось уже восемь полностью оснащенных эскадрилий, тогда как другие продолжали принимать новые машины.
   Всего до октября 1945 года был построен 11461 самолет всех модификаций. Данные бомбардировщики, прозванные «Wimpey» (J. Wellington Wimpey - герой американского мультсериала «Рореуе»), стали основой бомбардировочной авиации британских ВВС в Европе в первой половине войны и сыграли важную роль в битве за Атлантику. И после войны они оставались на службе - в начале 1950-х годов использовались в качестве учебных. Именно Wellington нанесли первые удары по Германии, но из-за тяжелых потерь в дневное время, начиная с 18 декабря 1939 года, их стали применять только ночью. Они также составили основу армады самолетов в известном рейде 1000 бомбардировщиков, а также использовались для уничтожения вражеских магнитных мин, постановки мин в водах противника и для испытания разнообразных силовых установок и вооружения.


Варианты: опытные и серийные

   Type 271: первый прототип, облетанный 15 июня 1936 года
   Type 285 Wellington МКI: предсерийный самолет с двигателями Pegasus X, облетанный 23 декабря 1937 года
   Type 290 Wellington Mk I: начальный серийный вариант (183 самолета) с двигателями Pegasus XVIII мощностью по 1000 л.с.,турельными установками Vickers и турелью внизу носовой части фюзеляжа
   Type 408 Wellington Mk IA: серийный вариант (187) с двигателями Pegasus XVIII, турельными установками Nash &Thompson и турелью внизу носовой части фюзеляжа
   Type 416 Wellington Mk 1C: серийный вариант (2685); Type 423 включал в себя все бомбардировщики, переделанные для навески 1814-кг бомб; бортовые пулеметы сохранились, а подфюзеляжную турель удалили
   Type 298 Wellington Mk II: опытный самолет с двигателями Merlin X мощностью по 1145 л.с., облетанный 3 марта 1939 года
   Type 406 Wellington B.Mk II: серийный вариант с двигателями Merlin X; 400 самолетов
   Type 299 Wellington Mk III: два опытных самолета с двигателями Hercules НЕ1 .SM и с двигателями Геркулес III
   Type 417 Wellington B.Mk III: серийный вариант (1517) с двигателями Hercules XI мощностью 1500 л.с.
   Type 410 Wellington Mk IV: опытный образец со звездообразными двигателями Pratt & Whitney Twin Wasp
   Type 424 Wellington B.Mk IV: серийный вариант (220) с двигателями Twin Wasp
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   Type 440 Wellington B.Mk X: серийный вариант (3803) с двигателями Hercules VI или XVI; Type 619 - самолеты, переоборудованные после войны в вариант Wellington T.Mk 10; часть продана Франции и еще шесть - греческим ВВС в 1946 году
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Варианты: экспериментальные

   Type 416 Wellington (II): вариант прототипа Wellington Mk II с 40-мм пушкой Vickers в верхней части фюзеляжа и двухкилевым оперением
   Type 418 Wellington DWI.Mk I: один самолет с оборудованием для подрыва мин и вспомогательной силовой установкой Ford
   Type 419 Wellington DWI.Mk II: один самолет для подрыва мин; вспомогательная силовая установка Gipsy Six
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   Type 435 Wellington Mk 1C: один самолет для оценочных испытаний установки Turbinlite
   Type 439 Wellington Mk II: экспериментальная установка 40-мм пушки Vickers в носовой части фюзеляжа самолета Wellington Mk II
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   Type 445 Wellington (II): летная лаборатория для испытаний турбореактивного двигателя Whittle W2B/23 в хвостовой части;
   Type 470 и Type 486 - варианты Wellington Mk II с двигателями Whittle W2B и W2/700, соответственно
   Type 478 Wellington Mk X: один опытный самолет с двигателем Hercules 100
   Type 602 Wellington Mk X: летная лаборатория для испытаний турбовинтовых двигателей Rolls-Royce Dart
   Wellington Mk III: один самолет для буксировки планеров Hadrian, Hotspur и Horsa


ТАКТИКО-ТЕХНИЧЕСКИЕ ХАРАКТЕРИСТИКИ

   Vickers Wellington B.Mk III

   Тип: средний бомбардировщик с экипажем из шести человек
   Силовая установка: два звездообразных ПД Bristol Hercules XI мощностью по 1500 л. с. (1119 кВт)
   Летные характеристики: максимальная скорость на высоте 3810 м - 410 км/ч; практический потолок 5790 м; дальность полета с бомбовой нагрузкой 2041 кг - 2478 км
   Масса: пустого 8417 кг; максимальная взлетная 13381 кг
   Размеры: размах крыла 26,26 м; длина 18,54 м; высота 5,31 м; площадь крыла 78,04 м2
   Вооружение: восемь 7,7-мм пулеметов (два в носовой и четыре в хвостовой установке, а также по одному бортовому пулемету), плюс максимум до 2041 кг бомб или одна 1814-кг бомба

Flight, July 1939

GEODETICS on the GRAND SCALE
A Detailed Description op the Vickers-Armstrongs Wellington I : Exceptional Range and Large Bomb Capacity : Ingenious Structural Features

   IT is extremely unlikely that any foreign air force possesses bombers with as long a range as that attainable by the Vickers-Armstrongs Wellington I (Type 290), which forms the equipment of a number of squadrons of the Royal Air Force and of which it is now permissible to disclose structural details.
   The Wellington’s capacity for carrying heavy loads over great distances may be directly attributed to the Vickers geodetic system of construction, which proved its worth in the single-engined Wellesley used’ as standard equipment in a number of overseas squadrons of the R.A.F. But the qualities of the Wellington are not limited to load-carrying. It has a top speed of 265 m.p.h. (or considerably more when fitted with Rolls-Royce Merlin or Bristol Hercules engines in place of the Pegasus XVIIIs); it has provision for five turreted machine-guns; it is quite exceptionally roomy, and it is amazingly agile in the air.
   The Bristol Pegasus XVIII engines fitted as standard in the Mark I Wellington is a two-speed supercharged unit with the following ratings; Take-off power, 965 h.p. at 2,475 r.p.m.; international power (using medium supercharge), 780/815 h.p. at 2,250 r.p.m. at 4,750ft.; international power (using full supercharge), 720/ 750 h.p. at 2,250 r.p.m. at 14,750ft.; maximum power (medium supercharge), 1,000 h.p. at 2,600 r.p.m. at 3,000ft.; maximum power (full supercharge). 885 h.p. at 2,600 r.p.m. at 15,500ft.
   The Wellington’s engines drive De Havilland three-bladed constant-speed airscrews with a diameter of 12ft. 6in. They are carried on mountings bolted to the fireproof bulkhead frames, the installation being designed to allow quick replacement of a power unit. In addition to the usual Bristol long-chord gilled cowling with trailing-edge cooling gills, the engines are provided with louvred “dish pan” cowlings over the crankcases.
   The exhaust on the port engine heats a boiler, the steam from which passes through a heater in the wing root; air warmed in the heater flows into a fore-and-aft duct running practically the whole length of the fuselage.
   Each engine has its own fuel system, handling 500 gallons made up as follows: One main tank in engine nacelles (60 gal.); three wing tanks in front of spar in outer wing panel (138 gal.); three wing tanks behind outer spar (162 gal.), and one "overload" tank in the bomb compartment. The tanks are made of Alclad, the overload tanks being cylindrical in shape and secured in the bomb bays by straps. All fuel is available to either engine if required.
   When the Wellington is making short- or medium-range flights the engines draw oil from tanks in the nacelles, but for long-range work an additional tank with a pump is fitted on the starboard side of the cabin. Apart from a thermostatically controlled Serck oil cooler and a Tecalemit oil cleaner for the main oil system, there is an additional Tecalemit cleaner for the two-speed blower system.
   The “hydraulics” are of interest in that there are two separate systems. Of these the primary circuit supplies the undercarriage and tail wheel, the flaps, and the mechanism for operating the bomb doors, while the other system actuates the rotating, elevating, and depressing of the guns in their turrets.
   The undercarriage comprises the two main wheels and the tail wheel, all of which retract simultaneously under hydraulic power, their positions being signalled by visual and audible means. Each unit of the main gear embodies a double-acting hydraulic jack in conjunction with a twin-leg transversely braced assembly with a folding backstay. All three wheels are completely enclosed during flight.
   As at present in service the Wellington has Vickers power-driven gun turrets in the nose and stern, the forward turret housing one machine gun. and the rear turret two of these weapons. Provision is made in the bottom of the fuselage for the installation of a power-driven retractable turret housing another two.
   The Wellington I normally carries a crew of four, made up of a pilot, a front gunner (who is also the bomb aimer or navigator), a wireless operator (who acts alternatively as the midships gunner), and a rear gunner. Provision is made to carry a fifth man.
   The cabin - which, due to the geodetic construction, provides a large amount of unobstructed space - is exceptionally well lighted for a military machine, thanks to the deletion of fabric over a number of the geodetic panels. From the cabin proper a catwalk extends through the fuselage to the tail gun turret. In the nose, just behind the turret, is a prone position for the bomb aimer. This section of the fuselage is provided with a large trap door for emergency exit; it is spring-loaded and operated by a pedal. Additional emergency exits are provided farther aft in the fuselage, and the occupants of the nose and tail turrets are provided with firemen’s axes to enable them to hack through the Perspex enclosures.
   A number of the machines delivered have dual controls, but these are not normally fitted for active service.
   Equipment, in addition to an elaborate wireless and D/F installation, comfortable navigating facilities and an automatic pilot, includes an inflatable dinghy housed in the port engine nacelle; a lavatory; a rest bunk; stowage for ten Thermos flasks; sea markers and name floats; two retractable landing lights in the port wing; provision for landing flares in the wing roots; a launching chute amidships for parachute flares; and formation-keeping lights. Soundproofing is now being incorporated as standard.
   The Wellingtons for New Zealand are having flotation bags installed in their bomb compartments for the delivery flight, and arrangements are made in these machines to jettison the fuel from the wing tanks which, when empty, supply a very useful measure of flotation.
   In addition to the usual fire extinguishers, there is a Graviner installation in the engine nacelles for surrounding the rear of the engine with carbon-dioxide gas.
   Eleven inter-communication sockets (microphone or telephone) are provided, one each for the front gunner, prone bomber, first and second pilots, wireless operator, navigator, and “spare passenger.”

Flying in the Wellington
   It was refreshingly pleasant on a sweltering afternoon at Brooklands to stand alongside Flt. Lt. Maurice Hare who, with Flt. Lt. J. Summers (chief test pilot to Vickers-Armstrongs, Ltd.), puts the Wellingtons through their tests prior to delivery. One stood, bracing oneself in the doorway leading from the cabin, no second pilot’s seat being installed.
   The take-off of the Wellington is exceptionally good, as demonstrated at quite a number of displays. The Mark III version, with Bristol Hercules engines giving something like 1,300 h.p. each, has an even quicker getaway.
   At 4,000ft. we were climbing fast at rather less than 3 lb. boost and 115 m.p.h. on the A.S.I. We kept on to 9,000ft., sending the hand of the sensitive altimeter chasing itself round the dial. Normally, the supercharger speed is not changed under about 10,000ft., when the boost has dropped to +1/2 lb., but Flt. Lt. Hare, to save the trouble of going any higher, throttled back until the boost gauge registered +1/2, and switched the blowers into high gear, sending the needles round to +3. It takes about 4 seconds for the hydraulically operated gear change to do its work. It may be remembered that the impeller/crankshaft speed ratio is changed through the medium of three double-acting hydraulic clutches operated by oil under pressure from the main lubrication system. There is no possibility of the control valve remaining in any intermediate position.
   Banks almost to the vertical with the clock showing something like 180 m.p.h. produced surprisingly little “G,” and, like the homeward dive at something well over 200 m.p.h., gave a feeling of solidity.
   Flt. Lt. Hare was good enough to demonstrate the well-known "Summers side-slip" approach, which was just another proof of the tractability of this formidable instrument of national defence.

Construction
   Turning to the structural and assembly aspect, there is no doubt that, from the point of view of greater ease of production, the Wellington is a considerable improvement on the Wellesley, described and illustrated in Flight of December 8, 1938. Fundamentally, the two types of structure are similar in that they are based on the geodetic principle, but nearly all the details differ in the two machines. This applies to both the fuselage and the wing. The magnitude of the order has been such that it has become possible to make much greater use of forgings and stampings, particularly for securing the ends of the geodesics and for the joints at the points where two bars cross one another.
   In the Wellesley, it may be remembered, the main scheme was to split the fuselage transversely into a number of fairly short units, each unit being completely stabilised (structurally speaking) in itself and joined to the next by a form of pipe-union joint. In the Wellington, on the contrary, the tubular longerons run almost through from nose to stern (excepting the extremes, which are separate units, “buttoned on”), joints in them being made by plain sleeves instead of the somewhat elaborate pipe unions of the Wellesley.
   The geodetic panels of the fuselage are of very large size. It is almost literally true to say that the complete top decking, for example, is a single panel except that where great changes in contour occur (such as at cockpit openings) the large panel is interrupted. The method is seen again in the sides, which consist of three panels: a medium-size one in front, a small one where the central wing spar passes through the fuselage, and a very long panel from there to the rear gun position.
   In production this scheme has considerable advantages. The two main spar frames, of which more anon, are set up in the jigs, the tubular longerons are located accurately in the jigs, and the panels of sides, top and bottom are dropped on to the longerons, and the whole bolted up. The fuselage primary structure is then complete, and is taken from the jigs and supported on jacks and/or trestles while the equipment is installed and the covering put on.
   This particular form of production would have been rendered somewhat difficult if the nodal points of the geodesics had met on the longerons, as rather complicated joints would have been necessary. To overcome the difficulty the panels of top and bottom deckings are staggered in relation to those of the sides, so that the ends of the respective geodesics can be (and, indeed, are) very simple forked joints. Theoretically, there may be some slight objection to this staggering, as offsets are introduced, but the loads are probably very small indeed, owing to the very geodetic principle by which the bars in tension relieve the loads in those which are in compression, so that the stresses in the longerons, resulting from these offsets, are probably quite negligible. Certainly from a manufacturing point of view the arrangement is much simpler than that used in the Wellesley.
   It is not, however, in the general scheme only that the Wellington fuselage differs from that of the Wellesley. The details themselves have been simplified considerably. Reference has already been made to the simple attachment of the geodesics to the tubular longerons. At the cross-over points, also, a different type of joint has been adopted. Where the two bars cross one another they are “halved together,” as we should have said in the old days of wood construction, and the joint is made by “butterflies” - rather like wing nuts - at right angles to one another, and having a bolt through their centres: there are gusset plates on the outside. The sketch on page d shows the arrangement. The geodesics themselves are of different form, with "hollow-backed" channel sections in place ot the plain straight-backed channels of the Wellesley.
   It may be recollected that in the Wellesley one of the problems was to provide sufficient strength in the spar frames to resist the very high concentrated stresses transmitted from the spar flanges. In fact, these frames had to be so substantial that they weighed as much as the whole of the rest of the fuselage. In the Wellington a most ingenious arrangement has been adopted whereby the loads in the spar frames are greatly reduced, so that the frames can be made much lighter than they would otherwise be.
   To understand the idea it is necessary to explain that the wing is of the three-spar type, with a single spar at the maximum depth of the wing section, and front and rear spars ot much smaller depth at the leading edge and towards the trailing edge. The central spar passes right through the fuselage (actually it is joined on the centre-line) and “floats” in it without touching it. The front and rear spars are attached to the sides of the fuselage or, more specifically, to the flanges of the spar frames by a form of cardan hinge which gives free movement about a vertical and a horizontal axis. From this it will be obvious that the central spar, which carries the wing bending loads, transmits no stresses to the fuselage structure direct.
   The front and rear spars, because oi the cardan hinges, cannot transmit compressive loads arising from lift, but only those which are caused by wing drag, and which are relatively small. The wing lift is transmitted from the central spar to the front and rear spar root fittings and through them to the fuselage. The joint between main central spar and wing root rib occurs in the centre of the section, and not at the flanges, the tube of which, in fact, crosses those of the spar without touching them.
   Although the spar frames have been relieved of loads in the matter just described, they still have to be of fairly substantial construction, as they do transmit the entire wing lift to the fuselage, and also serve as the basis for locating the whole fuselage structure. How the wing root fittings are attached to the flanges of these frames, and how the geodesics of the fuselage panels are secured to them, is shown in our sketches. Sheet-metal plates are first riveted to the flanges of those geodesics which cross the spar frames, and the plates are then bolted to the frames. In other words, the longerons are not attached to the spar frames direct, but via the geodesics. This arrangement results in very neat and simple joints. Except for the spar frames, and one or two others where local loads are heavy, all frames have disappeared from the Wellington fuselage.
   The straightforward geodetic arrangement is interrupted by the bomb bay in the bottom of the fuselage. For a distance of twelve feet or more the continuity is interrupted to give way to a flat raised floor above the bay. The amount of reinforcement that has been needed to carry the stresses past this break is really surprisingly small. The floor members themselves, by the way, are of the same geodetic construction as the curved panels.
   From the foregoing it may be gathered that the primary structure of the Wellington fuselage is very simple in its general theme, although the fact that the geodesics are of different lengths and different curvatures, according to their location in the structure, complicates matters somewhat metal structure at all. When the fabric tightens up after doping there is, of course, no tendency for the fabric to come away, other than that caused by airflow. Presumably this is not sufficiently great to cause any trouble, as one does not notice the fabric "flapping" in the way it can with some forms ot attachment. That it is indeed perfectly secure is shown by the fact that Wellingtons in service have been dived at about 300 m.p.h. without the fabric coming adrift.

Three-spar Wing
   Reference has already been made to the fact that the wing of the Wellington is of the three-spar type. The main spar is placed in the deepest part of the wing section, approximately on the centre of pressure, and is in the form of a girder, with tubular booms and channel-section bracing members. In the inner portion of the wing the spar boom tubes are in duplicate, but towards the tip this arrangement changes to a single-tube boom. The inner spar portions on each side extend from the centre-line of the fuselage (there is a joint here) to the outer face of the engine nacelle. From this latter point to the tip the spar is in one unit, although a joint occurs where the change from double to single booms takes place. The tubular booms are machined on their outer faces, leaving thick walls where the geodesics and certain other attachments are made, and a thinner wall in between. This type of spar boom, somewhat costly to make, is an example of the care taken in avoiding all unnecessary weight in the Wellington. It might be mentioned that when the materials manufacturers have perfected a system now being evolved, a tapered spar boom of extruded section will be used. The spar booms in each section are not necessarily continuous. Where joints occur they take the form of bolted plate joints, the plates and tube being serrated so as to relieve the bolts of the shear loads. A similar system was employed in the Wellesley, but there the plates were horizontal whereas in the Wellington they are vertical.
   Front and rear spars are of a totally different construction. They have webs of flat sheet and flanges or booms in the form of "open" tubes, as shown in one of the sketches. The use of this open tube greatly facilitates attachment of geodesics and other members.
   As in the case of the fuselage, the wing panels are made up in jigs and are of large size. They are attached to the centre spar booms by means of forgings, and to the open tube booms of front and rear spars by simple fork ends. The fabric is attached to the flanges of the geodesics by wires on top ot the fabric surface, these wires being threaded through holes in small bolts, as shown in a sketch.
   The mounting of the petrol tanks inside the wing provided something of a problem, owing to the considerable length of tanks involved. In the end a system was evolved which has proved satisfactory. The tank in each wing is divided into three independent units, mounted in the wing with single spigots at each extreme end, and with four rubber trunnion mountings between adjacent tanks. Each tank is connected to the next by external flexible pipes
   What made the problem difficult was that it was not desired to cut into the geodetic wing construction, as this would have involved considerable weight, with openings for the tanks. Instead, the tanks are slid on wooden rails into the wing and fastened there. From this it follows that to remove a tank it is necessary to unship the wing.
   At first sight it would appear that this was a bad feature in a military aircraft, the tanks of which might frequently get damaged. Actually, the outer wing portions are attached to the engine nacelles by 26 screws, which can be quickly dealt with by a brace similar to that used for removing the wheels of a car. By way of an experiment a wing was unshipped, the tanks changed, an A.I.D. inspection carried out, and the wing put back again ready for flight in three hours.
   It is much to be regretted that details of certain tests made cannot be published. They relate to the extent to which the geodesics can be damaged without endangering the strength of the wing, and show some very good results. In this connection one may recall the "basket" masts used on certain ships of the United States Navy some years ago. Tests of these showed that a large number of the geodesics could be shot away without bringing the mast down. Similar results were obtained in tests on a Wellington geodetic wing. It seems almost impossible so to damage such a wing that the machine could not be flown home safely.

VICKERS WELLINGTON I
Two Bristol Pegasus XVIII Engines

Span 86ft. 2in.
Length (guns extended) 64ft. 7in.
Track 20ft. 4in.
Wing area 750 sq. ft.
Wing loading 29-6 Ib./sq. ft.
Normal gross weight 24,850 lb.
Top speed 265 m.p.h. at 17,000 ft.
Maximum range 3,200 miles at 180 m.p.h.
Service ceiling 26,300 ft.
Climb to 15,000 ft. 18 min.

Flight, November 1939

Britain's Military Aircraft
A Survey of Our Service Machines

VICKERS ARMSTRONGS

   The Vickers Wellington twin-engined, long-range bomber is being produced in large numbers at the Vickers works. This machine is of geodetic construction and has fabric covering. With two Bristol Pegasus XVIII engines a top speed of 265 m.p.h. is attainable at 17,000ft. Other products of the Vickers Armstrongs group in service with the R.A.F. are the Supermarine Stranraer twin-engined biplane flying boat and the Walrus three-seater amphibian.

Vickers Armstrongs, Ltd.., Vickers House, Broadway, Westminster.