Martin B-10, B-12 и B-14

Компания "Martin" в начале 1930 года приступила к разработке проекта (фирменное обозначение Model 123) радикального нового бомбардировщика для Армии США. Проектировался среднеплан с крылом консольного типа, убираемым шасси, двумя моторами Wright SR-1820-E Cyclone мощностью по 600 л. с. и экипажем из трех человек. Испытания начались в июле 1932 года, перед ними самолет получил обозначение XB-907. В ходе испытаний прототип показал максимальную скорость 317 км/ч на высоте 1830 м, что было больше, чем у стоявших на вооружении Армии США истребителей. До начала серийного производства в конструкцию бомбардировщика внесли ряд изменений: увеличили размах крыла, смонтировали носовую турель для 7,62-мм пулемета, установили моторы Wright R-1820-19 мощностью по 675 л. с. Усовершенствованный вариант обозначался XB-907A. На официальных испытаниях XB-907A показал максимальную скорость на 16 км/ч большую, чем XB-907.17 января 1933 года одобрили запуск самолета в серийное производство. Прототип XB-907A купила Армия США, где он получил обозначение XB-10.
   Бомбардировщики начали поступать на вооружение строевых частей в июне 1934 года. В варианте с поплавковым шасси самолеты использовали для патрулирования прибрежных акваторий. На вооружении Армии США самолеты оставались до конца 1930-х годов. Бомбардировщики поставлялись в Аргентину (35), Китай (9), Голландию (118), Сиам (Таиланд, 23), СССР (1) и Турцию (20).


Варианты

   YB-10: первый серийный вариант с моторами R-1820-25 мощностью по 675 л. с. и отдельными закрытыми кабинами летчика и стрелка-радиста; построено 14
   B-10: два дополнительных серийных самолета, аналогичные YB-10
   YB-10A: 1 прототип с двумя моторами R-1820-31 мощностью по 675 л. с. с турбонагнетателями
   RB-10MA: обозначение авиакорпуса Армии для одного экспортного самолета, перелетевшего в 1942 году из голландской Восточной Индии и принятого на вооружение в США
   B-10B: основной серийный вариант, как YB-10, но с более мощными моторами R-1820-33, построено 103
   B-10M: обозначение B-10B, доработанных в буксировщики мишеней
   YB-12: серийный вариант, как YB-10, но с моторами Pratt & Whitney R-1690-11 мощностью 775 л. с., построено 7
   B-12A: серийный вариант как YB-12, но с возможностью подвески в бомбоотсеке дополнительного бака; построено 25
   B-12AM: несколько B-12A, доработанных в буксировщики мишеней
   YB-13: обозначение запланированного варианта YB-10 с моторами Pratt & Whitney R-1860-17 Hornet мощностью по 700 л. с., не строился
   XB-14: один самолет, схожий с YB-10, но с моторами Pratt & Whitney R-1830-9 Twin Wasp мощностью по 950 л. с.
   YO-45: временное обозначение одного YB-10 с моторами R-1820-17 мощностью по 675 л. с., использовался для оценки возможности использования как высотного скоростного разведчика
   Model 139: базовый экспортный вариант
   Model 139WH-1/2: первый экспортный вариант для голландской Восточной Индии
   Model 139WH-3/3A: последующий экспортный вариант для голландской Восточной Индии с единым прозрачным фонарем, известен также как Model 166


ТАКТИКО-ТЕХНИЧЕСКИЕ ХАРАКТЕРИСТИКИ

   Martin B-10B

   Тип: средний бомбардировщик с экипажем из трех человек
   Силовая установка: два звездообразных мотора Wright R-1820-33 Cyclone мощностью по 775 л. с. (578 кВт)
   Летные характеристики: макс. скорость на оптимальной высоте 343 км/ч; практический потолок 7375 м; максимальная дальность 1996 км
   Масса: пустого 4391 кг; максимальная взлетная 7439 кг
   Размеры: размах крыла 21,49 м; длина 13,64 м; высота 4,70 м; площадь крыла 62,99 м2
   Вооружение: три пулемета калибра 7,62 мм до 1025 кг бомб

Flight, February 1934

The Martin 123 Bomber

   FEW military aircraft have caused more comment in the U.S.A. in recent years than the Martin 123 bomber. Only the experimental model of this aircraft has been tested, and complete detailed weights and performance figures are not yet available, but it is claimed to have shown a superiority in maximum speed and rate of climb over any bombing type so far developed in America. It has been repeatedly rumoured that the top speed of the machine is about 200 m.p.h. A quantity of aircraft of this type is now being manufactured for the U.S. Government for Service tests.
   The machine is a mid-wing cantilever monoplane with the wing in three sections. The centre section is built into the fuselage and carries the two engine nacelles in the leading edge. The outer sections are detachable.
   The wing structure is of riveted aluminium alloy with highly-stressed fittings of heat-treated steel, and aluminium alloy stressed skin covering. Riveted aluminium alloy fuel and oil tanks are carried in the wings. Balanced ailerons are fitted.
   The fuselage is a riveted aluminium alloy monocoque structure, the shear loads being taken on the smooth side skin, and the top and bottom compression loads by corrugated sections of sheet metal covering.
   The structure is in three separable units, the nose section, the centre section, built round the centre section wing, and the tail section. Bombs are internally stowed in a bomb bay closed by doors controlled by the bomber, or, in an emergency, by the pilot. The fin and tail plane are of full cantilever structures of riveted aluminium alloy with aluminium alloy sheet covering. The rudder and elevator are fabric covered and are fitted with trailing edge "tabs" for trimming, which are adjustable in flight from the pilots' cockpit.
   A mechanically retractable landing gear is fitted with the retracting controls in the pilots' cockpit. Oleo shock-absorber struts and brakes are used and the tail wheel is of the swivelling type.
   Part of the Martin bombers to be delivered to the U.S. Government will be equipped with two Wright "Cyclone" geared and supercharged radial engines, and the rest of the machines will use two Pratt & Whitney geared and supercharged "Hornets." Electric inertia starters are provided. The airscrews are of the three-bladed adjustable-pitch type.
   In the nose of the fuselage is a cockpit equipped with bomb sights, bomb-release controls and movable gun mounting. A transparent cupola,, one section of which is omitted to allow for a machine gun, revolves with the gun ring. The pilots' cockpit is just forward of the leading edge of the wing. A compartment for the wireless operator is inside' the fuselage aft of the pilots' cockpit. Behind the wings is a third cockpit equipped with auxiliary flight controls and mountings for a movable machine gun on top of the fuselage and for a downward firing gun in the floor.

Flight, August 1934

AMERICAN MILITARY MONOPLANES
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   When the Army Air Corps believed that they had reached the ultimate in fast bombers, the Glenn Martin Company came forward with the squat-looking Martin B-10 and B-12 that are identical in appearance but have a few minor changes in equipment. These machines have two-geared Wright “Cyclone" engines of 650 h.p. built into the wings. They carry a bomb load of 2,500lb. at a speed of 220 miles per hour. The wing and fuselage construction in the Martin is something entirely new, the latter being of the "restrained shell" construction that provides extreme strength and rigidity with approximately half the weight of the monocoque type. Another feature of these machines is that the front gunner is completely enclosed in a transparent turret which affords the forward guns an effectiveness never attained before in high-speed aeroplanes. (The latest Boulton and Paul "Overstrand" has an improved gun turret in the nose. - ED.) The retractable landing gear when drawn up gives the machine the impression of a huge fish flying through the air. The dimensions are: Span 70 ft. 6 in., length 44 ft., height 11 ft. 6 in., chord 11 ft. 3 m. These aeroplanes are assigned to the 9th and 11th Bombardment Squadrons, while two other squadrons will also be similarly equipped as soon as the machines can be delivered.
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Flight, September 1935

THE MARTIN B-10

   FOR many months past the Martin B-10 twin-engined bomber has been a standard type in the U.S. Army Air Corps, and detailed information has been withheld at the request of that force. Now that improved versions of the machine are being put into service, however, it is permissible to give particulars of the earlier one, which automatically becomes eligible for export,
   Aluminium alloy sheet (24 ST), protected by anodising and <...>ting, is the basic structural material. Fabric, however, is used as a covering for the trailing edge of the main plane and on ailerons, rudder and elevators.
   Of oval cross-section, the fuselage is in three portions: the portion forward of the front spar; the centre portion, built integrated with the centre section of the wing and housing the bomb load; and the tail section. These three are bolted together, and all are of true monocoque construction.
   Longitudinal stresses are taken entirely by the skin covering, its shape being maintained by bulkheads of light sheet-metal with intermediate former rings of duralumin tube. The side covering is of smooth sheeting, unlike the covering of the top and bottom sections, which is corrugated. This latter feature is prominent in the big Martin Pan-American flying boat.
   Like the fuselage, the cantilever wing is built in three portions: a centre section, parallel in chord and two tapering outer panels. There are two spars in the form of deep plate <...>rs with extruded angle flanges and solid sheet webs with <...>ble stiffening.
   The formers for the leading edge are cantilevered out from the front spar, and the trailing-edge frame from the rear spar. The upper covering between the two spars is of a composite structure, consisting of an inner corrugated element covered by rivetted-on flat skin.
   Steel tubing is used for the engine mountings, being bolted to the front spar of the centre section. The engines are two Wright Cyclones of the SGR-1820-F3S type, giving 750 h.p. at 950 r.p.m. at 5.400ft. Their compression ratio is 6.4:1, supercharger drive 8.31:1, and airscrew gear ratio 11:16. The airscrews are three-bladed Hamiltons, 11ft. 3in. in diameter.
   Each unit of the retractable undercarriage hinges at a point below the front centre section spar in line with the engine mounting. The front strut is of welded sheet-steel of the "half-fork" cantilever variety with a single oleo-pneumatic shock absorber unit. A single "half-fork" tubular steel strut hinged to the axle and running to the rear spar along the centre line of the nacelle braces it fore and aft. At its upper end this strut is pinned to a trolley-like fitting running fore and aft on a track as the gear is raised or lowered. When the gear is raised this trolley moves to the rear of an extension of the track slightly behind the trailing edge of the wing, and when the wheels are down the sliding end of the trolley is firmly locked in position at a point just under the rear spar. The actual raising and lowering is effected through cables wound round an electrically operated drum which may, in an emergency, be turned by hand. The main wheels are of "streamlined" type, 45in. in diameter, being mounted on tapered roller bearings. Individually operated hydraulic brakes and a swivelling tail wheel are fitted.
   Tanks for 113 gallons of fuel are installed in the centre section outboard of the fuselage; the oil tanks, each of 31.5 gallons capacity, are mounted in each nacelle. Should extreme range be required, an additional 250-gallon tank can be installed in the bomb bay.
   A crew of four or five men is carried. The bomb-aimer (who is provided with a machine gun) and the pilot are in the nose section. Space is provided amidships for the wireless operator, who acts also as navigator. Machine guns are provided above and below the fuselage in the rear cockpit. In this position there is a set of auxiliary controls. A fifth man, who may be the High! commander, can be stationed amidships with the wireless operator. Both front and rear cockpits are covered with sliding transparent enclosures, and the bomber is protected from the airstream by a "birdcage" turret.
   The bomb load is normally carried in the centre portion of the fuselage, a pair of "clam shell" doors in the bottom of the bomb bay being opened when the projectiles are to be released. When the bomb bay is filled with auxiliary tanks the bombs are carried in external racks.

MARTIN B-10
TWIN-ENGINED BOMBER
TWO WRIGHT CYCLONE SGR-1820-F3S. 750 H.P. at 5,400 FT.

Dimensions and Weights.
   SPAN 70ft. 6in.
   LENGTH 44ft. 8 11/16 in.
   WING AREA 678 sq. ft.
   WING LOADING (NORMAL) 20.93 lb./sq.ft.
   WING LOADING (MAXIMUM) 23.09 lb./sq.ft.
   POWER LOADING (NORMAL) 9.46 h.p./sq.ft.
   POWER LOADING (OVERLOAD) 10.43 h.p./sq.ft.
   WEIGHT EMPTY 8,996 lb.
   GROSS WEIGHT (NORMAL) 14,192 lb.
   GROSS WEIGHT (OVERLOAD) 15,652 lb.

Performance
   MAXIMUM SPEED AT SEA LEVEL 196 m.p.h.
   MAXIMUM SPEED AT 6,500 ft. 215 m.p.h.
   MAXIMUM SPEED AT 10,000 ft. 213 m.p.h.
   SERVICE CEILING (BOTH ENGINES) 25,000 ft.
   SERVICE CEILING (ONE ENGINE) 10,600 ft.
   CLIMB TO 10,000 ft. 7 min.
   MAXIMUM RANGE (15,000FT. AND 170 M.P.H.) 1.400 miles.
   MAXIMUM RANGE (10,000FT. AND 170 M.P.H.) 1.300 miles.
   MAXIMUM RANGE (10,000FT. AND 200 M.P.H.) 1,000 miles.
   NORMAL RANGE (10,000FT. AND 170 M.P.H.) 700 miles approx.