Saro A.27 London

После выпуска министерством авиации спецификации (технического задания) R.24/31 на патрульную летающую лодку компания «Saunders-Roe» разработала самолет A.27 London. Он имел такую же конфигурацию, как A.7 Severn (описан в отдельной статье), отличаясь несколько меньшими размерами. Новая летающая лодка первоначально была оснащена двумя радиальными ПД Bristol Pegasus III no 875 л.с. (652 кВт). После проведения испытаний был выдан заказ на 10 самолетов London Mk I, первый из которых был поставлен в 1936 году. За ними последовали 20 самолетов варианта London Mk II, отличавшихся в основном более мощными двигателями Pegasus X.
   Считавшиеся уже полностью устаревшими, лодки Saro London Mk II хорошо зарекомендовали себя на начальном этапе Второй мировой войны. Оснащенные парой 915-сильных (682 кВт) ПД Pegasus X, A.27 London развивали эксплуатационную скорость 159 км/ч и могли патрулировать на протяжении 5,2 часа с боевой нагрузкой 907 кг. Последним подразделением, использовавшим эти самолеты, была 202-я эскадрилья в Гибралтаре, сменившая их на Consolidated Catalina в 1941 году.


ТАКТИКО-ТЕХНИЧЕСКИЕ ХАРАКТЕРИСТИКИ

   Saro A.27 London Mk II

   Тип: патрульная летающая лодка
   Силовая установка: два радиальных ПД Bristol Pegasus X мощностью по 1055 л. с. (787 кВт)
   Летные характеристики: максимальная скорость на высоте 1905 м - 249 км/ч; потолок 6065 м; нормальная дальность полета 1770 км
   Масса: пустого 5035 кг; максимальная взлетная 8346 кг
   Размеры: размах крыла 24,38 м; длина 17,31 м; высота 5,72 м; площадь крыла 132,38 м2
   Вооружение: три 7,7-мм пулемета Lewis в носовой и средней стрелковых установках и до 907 кг обычных или глубинных бомб

Flight, February 1934

A NEW SARO FLYING BOAT
2 Bristol "Pegasus" Engines

   TO the ''family'' of flying boats designed and built by Saunders-Roe, Ltd., of East Cowes, Isle of Wight, has quite recently been added yet another, identified for the present as the 24/31. This boat is an all-metal production incorporating the Saro features which have proved so successful in previous machines. The hull plating shows the usual fore-and-aft corrugations with which one has become familiar in the "Clouds," "Windhovers" and "Cutty Sarks." The machine is, however, a biplane, resembling somewhat an earlier type of service flying boat, the A.7, but incorporating the experience which the firm has accumulated since the designing and building of that machine.
   As the Saro 24/31 has been built for the Air Ministry, and is a military type, no performance figures may be given, but it is thought that long non-stop flights from one base to another in the British Empire are among the objects for which the machine was designed.
   The very excellent photograph, taken by Mr. Beken of Cowes, which we publish on this page, shows that the Saro 24/31 has its two Bristol "Pegasus" engines mounted close under the top plane in a position where the airscrews are as far removed from spray as possible. The hull shows the usual flat, tumble-home sides of Saro boats, and the underwater portion has two steps of pronounced straight-vee formation. Lateral stability on the water is ensured by wing-tip floats. The flat-sided hull is very roomy and provides comfortable living accommodation for the crew. The machine has been designed to operate as a self-contained unit and carries its own dinghy and anchoring gear. Access to the interior of the hull is through a door in the side, so that the operation, of boarding the machine while it is at moorings is greatly facilitated.
   Ahead of the wings, and sheltered by a raised roof with windows of unbreakable glass, is the pilot's compartment, from which a good forward view is obtained, while the engines can always be seen from the compartment.
   The tail consists of a monoplane tailplane and elevator, and of two fins and rudders, placed at the extreme ends of the horizontal tailplane. The rudders have horn balances and are operated by servo rudders carried on outriggers.
   No performance figures may be published, but it is permissible to state that the gross weight of the machine is a little over 8 tons.

Flight, March 1936

FOR OPEN-SEA RECONNAISSANCE
The Saro London General-purpose Flying Boat: Robust Construction and Low Maintenance: Simplicity the Keynote of Design

   LATEST of a long “family” of flying boats, the London now being built at the Cowes works of Saunders-Roe, Ltd., is a general purpose twin-engined type in which robustness, low maintenance cost, simplicity of construction and seaworthiness were aimed at rather than a maximum of performance. The Air Ministry specification to which this machine was built called for these features, and the prototype machine passed its tests without difficulty. The production machines are now coming along, the work having been somewhat delayed by the necessity to build a new large erecting shop at East Cowes, Isle of Wight, before production in quantities could be undertaken. The huge shed is now completed, and the necessary reorganisation of the works is well on the way to completion, so that the machines should be emerging at very short intervals during the immediate future.
   In its general design the Saro London follows the practice established by British flying boat designers for a number of years, and is a twin-engined flying boat with the two Bristol Pegasus III engines mounted on the leading edge of the top plane, a position which gives the airscrews a maximum water clearance, so that it is only in exceptional conditions that they are not clear of water spray. The hull is of usual two-step type with vee bottom, but an innovation, from the hydrodynamic point of view, is the arrangement of the rear step, which is of less beam than the main hull at that point, so that a fore-and-aft step is between the chine of the step and the chine of the hull proper. In the London the hull beam is considerable, even towards the stern, in order to give a maximum of accommodation for crew, gear, and equipment. On the other hand, the rear step itself should not, for purposes of water performance, be too wide, and the particular step arrangement chosen was an outcome of these considerations.
   For several years it has been the practice of Mr. H. Knowler, Saunders-Roe chief designer, to use straight-line hull frames. This form is the simplest possible to manufacture, and has the further advantage that panel beating of portions of the hull planking is avoided. A plain vee bottom is, however, apt to be "dirty," as the water is thrown high into the air unless deflected by suitable shaping of the hull. Some years ago most British flying boat hulls had curved vee bottoms, the vee at the keel being gradually flattened out as the chine was approached. The resulting curvature of the bottom planking called for a certain amount of shaping, and Mr. Knowler evolved a simpler way of achieving the same results. Instead of the straight lines of the bottom frames pointing towards the chines, he pointed them towards a line some six inches inboard of the chine; where this straight line cut the horizontal through the two chines he ran horizontal planking, which served to keep down the water, just as the curved bottoms of earlier hulls had done. The vee bottom was, of course, still sufficient to give the desired absorption of shock when alighting.
   Having evolved this straight-line type of framing for the hull, the Saunders-Roe designers did not wish to spoil the resulting simplicity of construction by introducing internal longitudinal stringers such as are commonly used in the construction of flying boat hulls. The stringers require a good deal of riveting to the hull planking, and it they are kept continuous from stem to stern the frames have to be cut out to accommodate them. If this is not done it becomes necessary to interrupt the stringers where they cross the frames, and gussets then have to be used for attaching stringers to frames. The scheme ultimately evolved was to form corrugations in the planking itself, spaced some six inches apart. By the stiffness which they introduced these corrugations took the place of riveted-on stringers, and a structure involving a minimum of riveting resulted. For relatively slow aircraft the extra drag caused by the corrugations running fore and aft in the planking is probably of little consequence. When we come to build flying boats with a speed of more than 200 m.p.h. the corrugations will most likely disappear, as will also the projecting rivet heads used at present, which will give place to flat-headed rivets lying flush with the planking.
   The method of finishing off the ends of the corrugations in the planking of Saro boats is interesting. Where these corrugations intersect the chines, for instance, the actual corrugations are cut off a little short of the edge of the sheet, and a cap formed by pressing is riveted over the corrugations, as shown in the sketches. In landplane work it might be permissible merely to “bash” the ends of the corrugations flat. Such was, indeed, the practice of Junkers designers for many years. In flying-boat work, however, a water-tight joint has to be made, and this is attained by the Saro designers in the manner explained.
   Alclad is the material used throughout the Saro London hulls, and light alloys are used throughout the construction except for some highly stressed wing fittings. The wings for the Londons are being manufactured by Boulton Paul, of Norwich, and the wing construction is similar to that used in some Boulton Paul aircraft, with spars formed from "locked joint" tube booms surrounded by "open" tubes having flanges for riveting to the flat sheet spar webs. The details of the wing construction are similar to those used in the tailplane, which are illustrated by a sketch.
   Accommodation inside the hull of the London is almost luxurious, according to military standards. Provision is made for living on board, and comfortable bunks are provided in the compartments, as well as a cooking stove on which meals can be prepared. When not in use the bunks and bedding are stowed in one of the aft compartments.
   The defensive armament of the London includes three gunners' stations: one in the extreme bows, one in the extreme stern, and one aft of the wings. The bow compartment of the hull, in addition to marine gear, also contains the bomber's station. A hinged door in the nose opens forward and upward, thus giving him a free view for using his sight.
   A bulkhead with a sliding door separates the bow compartment from the pilots' cabin. Side-by-side dual control is provided, the two pilots' seats being mounted on raised platforms, with a lower level gangway between them. The controls on the starboard side are arranged to be unshipped when not in use.
   Aft of the pilots' cabin is the officers' ward room, with two bunks on the starboard side. On the port side is the navigator's table and equipment, a large window giving light and view.
   Next comes a large compartment with bunks for the crew. On the forward bulkhead is, on the starboard side, the engineer's instrument panel, and on the port side the wireless equipment with table and chair for the operator, as seen in the view above.
   Behind the crew's cabin is the middle gunner's post, with a firing step which also serves as a work bench and is equipped with a vice. Here also is the cooking stove and cupboards for food, cutlery, dishes, etc.
   A stowage space for bunks, bedding, spare airscrews, etc., follows, and a narrow and inevitably somewhat low gangway leads to the gunner's position in the extreme stern. From the firing step the rear gunner obtains a very wide range of view and fire, the only obstruction being the two fins and rudders. From the middle gunner's position, however, these "blindspots" are readily covered.
   The placing of the petrol tanks in the top centre-section leaves the entire hull available for accommodation, and almost every cubic foot of the space is taken into use, either during flight or when the boat is at moorings.

Load and Performance

   When fitted with the Bristol Pegasus III engines the Saro London has a tare weight of 11,100 lb. The normal fuel and oil load is 4,472 lb., and the military load 2,728 lb., giving a normal gross weight of 18,300 lb. The machine is, however, stressed for and will take off at a gross weight of 22,000 lb., which, of course, represents an overload. The normal range at a cruising speed of 115 m.p.h. is 1,100 miles, but with an overload of petrol this can be extended to 1,740 miles. The maximum speed at 6,560 ft. is 135 m.p.h.. and the service ceiling is 14,760 ft. The take-off time is 18 seconds, and the initial rate of climb 1,000 ft. /min.