Category Archives: Medium Bomber

Medium Bomber

Armstrong-Whitworth A.W.52 (A+V Models, Resin)

TYPE: Flying Wing, Fast Transport, Bomber Project

ACCOMMODATION: Crew of two (Pilot and navigator/flight test observer

POWER PLANT: Two Rolls-Royce Nene centrifugal-flow turbojets, rated at 2.240 kp thrust each

PERFORMANCE: 500 mph at sea level

COMMENT: The Armstrong Whitworth A.W.52 was a British flying wing aircraft design of the late 1940s for research into a proposed flying wing bomber and/or jet liner. Three aircraft, the A.W.52G glider and two turbojet-powered research aircraft, were built for the programme. The airliner was cancelled but research flying continued until 1954.
Armstrong-Witworth Aircraft proposed a turbojet-powered six or four-engine flying wing bomber/airliner design, using a laminar flow wing, during the Second World War. This had to be a large aircraft in order to provide bomb bay resp. passenger head-room within the wing. The low-speed characteristics of the design were tested on a 16.41 m span wooden glider known as the A.W. 52G; the glider was designed to be roughly half the size of the powered A.W.52, which in turn would be about half the size of the airliner. Construction of the AW.52G began in March 1943, with the glider making its maiden flight, towed by an Armstrong Whitworth Whitley bomber, on 2 March 1945. Flight testing, with tug releases from 20,000 ft giving flights of around 30 min continued, mostly satisfactorily until 1947. In 1944, Armstrong Whitworth received a contract that would allow them to produce two A.W.52 prototypes for evaluation, nominally asmail carrying aircraft.
The A.W.52 was intended for high speeds and was an all-metal turbojet-powered aircraft, with a retractable undercarriage; aerodynamically it had much in common with the glider. Both aircraft were moderately-swept flying wings with a centre section having a straight trailing edge. The wing tips carried small (not full chord) end-plate fin and rudders, which operated differentially, with a greater angle on the outer one. Roll and pitch were controlled with evelons that extended inward from the wing tips over most (in the case of the A.W.52 about three-quarters) of the outer, swept part of the trailing edge. The elevons moved together as elevators and differentially as ailerons. They were quite complicated surfaces – which included trim tabs – and hinged not from the wing but from “correctors”, which were wing-mounted; the correctors provided pitch trim. To delay tip stall, air was sucked out of a slot just in front of the elevons, by pumps powered by undercarriage-mounted fans on the glider and directly from the engine in the A.W.52. The inner centre section wing carried Fowler flaps and the upper surface of the outer section carried spoilers.
Maintenance of laminar flow over the wings was vital to the design and so they were built with great attention to surface flatness. Rather than the usual approach, where skinning is added to a structure defined by ribs, the A.W.52’s wings were built in two halves (upper and lower) from the outside in, starting from pre-formed surfaces, adding stringers and ribs then joining the two halves together. The result was a surface smooth to better than 2/1000 of an inch.
The crew sat in tandem in a nacelle so that the pilot was just forward of the wing leading edge, providing a better view than in the glider. The pressurised cockpit was slightly off-set to port. The engines were mounted in the wing centre section, close to the centre line and so not disturbing the upper wing surface.
The first prototype flew on 13 November 1947 powered by two Rolls-Royce Nene turbojet engines of 2.240 kp thrust each. This was followed by the second prototype on 1 September 1948 with the lower-powered  Rolls-Royce Dervent engines, rated at 1.580 kp each. Trials were disappointing: laminar flow could not be maintained, so maximum speeds, though respectable, were less than expected. As in any tail-less aircraft, take-off and landing runs were longer than for a conventional aircraft (at similar wing loadings) because at high angles of attack, downward elevon forces were much greater than those of elevators with their large moment.
The first prototype crashed without loss of life on 30 May 1949, making it the first occasion of an emergency ejection by a British pilot. Despite the termination of development, the second prototype remained flying with the Royal Aircraft Establishment until 1954 (Ref.: 27).

Bristol “Buckingham” B 1 (Valom)

TYPE: Medium bomber

ACCOMMODATION: Crew of two

POWER PLANT: Two Bristol “Centaurus” IX radial engines, rated at 2,520 hp each

PERFORMANCE: 336 mph at 12,000 ft

COMMENT : In early 1939 Bristol suggested a bomber variant of the “Beaufighter” with their Bristol “Hercules” engines. British policy at the time was an expectation for medium bombers to be provided from the US allowing British industry to concentrate on heavy bomber designs but a design was requested preferably based on an existing design which meant working with the Bristol “Beaufort” or “Beaufighter”.
Air Ministry specification B.7/40 called for a medium bomber to replace the Bristol “Blenheim”. The specification stipulated a speed of at least 300 mph at 5,000 ft, a normal load of 500 kg of bombs and a center turret armed with at least two 12.7 mm machine guns. Only Armstrong Whitworth Company tendered a full design but it did not meet with approval. So when Bristol brought their Type 162 (tentatively named “Beaumont”), which was fortunately well matched to B.7/40 specification, to the Air Staff, this led to a request to complete a mockup in 1940 and then a confirmed contract for three prototypes in February 1941. The “Beaumont” was based on the rear fuselage and tail of a “Beaufighter”, with a new center and front fuselage. The armament was a mid-upper turret with four machine guns, four more machine guns firing forward and two firing to the rear.
Construction began in late 1940, with a new Air Ministry Specification B.2/41 to be written around it. Changes in the requirements, removing dive bombing and ground attack support which incoming US bombers were expected to be capable of and increasing the performance to allow for the future, meant the “Beaumont” would no longer suffice. The changes in performance, requiring a bomb load of 4,000 lb, a speed of 360 mph and a range of 1,600 miles meant a redesign by Bristol to use the Bristol “Centaurus” engine.
The Bristol redesign with a larger wing and the more powerful engines was the Bristol ”Buckingham”. It had gun installations in the nose, dorsal and ventral turrets. Generally conventional in appearance, one unusual feature was that the bomb-aimer/navigator was housed in a mid-fuselage ventral gondola, resembling those on the earlier German Heinkel He 111H and American Boeing B-17C and -D in appearance. This was part of an attempt to give all the crew positions unobstructed views and access to each other’s positions. The bomb bay could hold up to 2,000 kg bombs. The rear of the gondola had a hydraulically powered turret with two Browning machine guns. The Bristol-designed dorsal turret carried four Brownings. A further four fixed, forward-firing Brownings were controlled by the pilot. Following more changes, specification B.2/41 was replaced by B.P/41. An order for 400, at an initial rate of 25 per month, was made with deliveries expected in March 1943. The first flight took place on 4 February 1943. During testing, the “Buckingham” exhibited poor stability which led to the enlargement of the twin fins, along with other modifications. The Bristol “Buckingham B1” was first flown 12 February 1944 with “Centarus” VI or XI engines, 400 ordered but reduced first to 300 then to 119, with only 54 built as bombers. Overtaken by events, it was mainly used primarily for transport and liaison duties (Ref.: 24).

Bristol “Beaufort” Mk.II (Special Hobby Models)

TYPE: Torpedo bomber, bomber, trainer

ACCOMMODATION: Crew of four

POWER PLANT: Two Prat & Whitney R1839 “Twin Wasp” radial engines, rated at 1,130 hp each

PERFORMANCE: 272 mph at 6,500 ft

COMMENT: The Bristol “Beaufort” was a British twin-engined torpedo bomber designed by the Bristol Aeroplane Company, and developed from experience gained designing and building the earlier Bristol “Blenheim” light bomber.“ Beauforts” first saw service with Royal Air Force Coastal Command and then the Royal Navy Fleet Air Arm from 1940. They were used as torpedo bombers, conventional bombers and mine-layers until 1942, when they were removed from active service and were then used as trainer aircraft until being declared obsolete in 1945. “Beauforts” also saw considerable action in the Mediterranean. Squadrons based in Egypt and on Malta helped interdict Axis shipping supplying Rommel’s “Deutsches Afrikakorps” in North Africa. Some were fitted with ASV radar aerial arrays under both wings and forward fuselage. Although it was designed as a torpedo-bomber, the “Beaufort” was more often used as a medium day bomber. The “Beaufort” also flew more hours in training than on operational missions and more were lost through accidents and mechanical failures than were lost to enemy fire. The “Beaufort” was adapted as a long-range heavy fighter variant called the Bristol “Beaufighter”, which proved to be very successful and many “Beaufort” units eventually converted to the “Beaufighter”. At least 1,180 “Beauforts” were built by Bristol and other British manufacturers.
The Australian government’s Department of Aircraft Production (DAP) also manufactured variants of the “Beaufort”. These are often known collectively as the DAP “Beaufort”. More than 700 Australian-built “Beauforts” saw service with the Royal Australian Air Force in the South West Pacific theatre where they were used until the end of the war (Ref.: 24).

Lockheed “Hudson Mk.V”, RAF, 500rd Squadron (Academy Models)

TYPE: Light bomber, reconnaissance aircraft

ACCOMMODATION: Crew of six

POWER PLANT: Two Pratt & Whitney “Twin Wasp” radial engines, rated at 1,200 hp each

PERFORMANCE: 246 mph

COMMENT: The Lockheed “Hudson” was an American-built light bomber and coastal reconnaissance aircraft built initially for the British Royal Air Force shortly before the outbreak of WW II and primarily operated by the RAF thereafter. The “Hudson” served throughout the war, mainly with Coastal Command but also in transport and training roles as well as delivering agents into occupied France. They were also used extensively with the Royal Canadian Air Force’s anti-submarine squadrons and by the Royal Australian Air Force.
In late 1937 Lockheed sent a cutaway drawing of the Model 14 to various publications, showing the new aircraft as a civilian aircraft and converted to a light bomber. This attracted the interest of various air forces and in 1938, the British Purchasing Commission sought an American maritime patrol aircraft for the United Kingdom to support the Avro “Anson”. On December 1938, Lockheed demonstrated a modified version of the Lockheed Model 14 “Super Electra” commercial airliner, which swiftly went into production as the “Hudson Mk I”.
A total of 350 Mk I and 20 Mk II “Hudsons” were supplied. These had two fixed Browning machine guns in the nose and two more in the Boulton Paul dorsal turret. The Hudson Mk III added one ventral and two beam machine guns and replaced the 1,100 hp Wright “Cyclone” cylinder radials with 1,200 hp versions (428 produced).
The “Hudson Mk V” (309 produced) and Mk VI (450 produced) were powered by the 1,200 hp Pratt & Whitney “Twin Wasp” 14-cylinder two-row radial. The RAF also obtained 380 Mk IIIA and 30 Mk IV “Hudsons” under the Lend-Lease programme.
By February 1939, RAF “Hudsons” began to be delivered, by the start of WW II in September, 78 “Hudsons” were in service. Due to the United States’ neutrality at that time, early series aircraft were flown to the Canada–US border, landed, and then towed on their wheels over the border into Canada by tractors or horse drawn teams, before then being flown to Royal Canadian Air Force (RCAF) airfields where they were then dismantled and “cocooned” for transport as deck cargo, by ship to Liverpool. The “Hudsons” were supplied without the Boulton Paul dorsal turret, which was installed on arrival in the United Kingdom.
Although later outclassed by larger bombers, the Lockheed “Hudson” achieved some significant feats during the first half of the war. Skilled and experienced pilots found that the Hudson had an exceptional maneuverability for a twin-engined aircraft, especially a tight turning circle if either engine was briefly feathered (Ref. 24).

Bristol Blenheim Mk. V, RHAF, 13th Squadron (MPM Models)

TYPE: Light bomber

ACCOMMODATION: Crew of three

POWER PLANT: Two Bristol “Mercury” XXX radial engines, rated at 920 hp

PERFORMANCE: 266 mph at 11,800 ft

COMMENT: In 1940, a new specification, Spec B. 6/40, was issued by the U.K. Air Ministry to redesign the Bristol “Blenheim” Mk. IV. The major changes included the replacement of the “Mercury” XV engines with the uprated “Mercury” XXX engines, a re-designed nose area, extra armor and a new oxygen system. On February 1941, two prototypes were ready for flight at the Bristol factory. One prototype was a three-seat, high-altitude day bomber. This version had a semi-glazed, asymmetrical nose with a rear-facing blister housing two machine guns. The second prototype was a two-seater close-support aircraft, with solid nose containing four more Browning machine guns, initially known as Bristol “Bisley” (after shooting competitions held at Bisley). This latter variant was not required, probably due to the advent of the single-seater close-support fighters then under development such as the Hawker “Typhoon”. A major improvement of the “Blenheim” Mk. V over its earlier predecessors was the new Bristol B. X. upper gun turret, which was fitted with two machine guns. This turret was capable of high-speed traverse and continuous rotation in either direction. The day bomber type went into production and, by June 1943, a total of 940 aircraft had been produced for the RAF. Manufacture of the “Blenheim” Mk. V was undertaken by the firm of Rootes Security Ltd, at their “shadow” factory at Blythe Bridges, Staffordshire. Although the “Blenheim” Mk. V served in North Africa and the Far East until 1943, its lack of success resulted in many aircraft converted to dual-control and being used as trainers and target tugs  (Ref.: MPM).

 

Martin “Baltimore” Mk. III, RAF, 13th Squadron Free Greece (Special Hobby)

TYPE: Light bomber

ACCOMMODATION: Crew of four

POWER PLANT: Two Wright GR-2600 radial engines, rated at 1,700 hp each

PERFORMANCE: 305 mph at 11,600 ft

COMMENT: Derived from the Martin A-22 “Maryland” the “Baltimore” had a deeper fuselage and more powerful engines. It met the needs for a light to medium bomber, originally ordered by the Anglo-French Purchasing Commission as a joint project in May 1940. The French Air Force sought to replace the earlier “Maryland”; 400 aircraft being ordered. With the fall of France, the Royal Air Force (RAF) took over the order and gave it the service name “Baltimore” To enable the aircraft to be supplied to the British under the Lend-and-Lease Act the U. S. Army Air Forces designation A-30 was allocated. In total 1.175 aircraft provided to the RAF.
The first British aircraft were delivered in late 1941 to equip Operational Training Units. Later, the RAF only used the “Baltimore” operationally in the Mediterranean theater and North Africa.
Many users were impressed by the step up that the “Baltimore” represented from older aircraft like the Bristol “Blenheim”. The users of the “Baltimore” praised the aircraft for its heavy armament, structural strength, maneuverability, bombing accuracy, and relatively high performance, but crews complained of cramped conditions similar to those in the earlier “Maryland” bomber. Due to the narrow fuselage it was nearly impossible for crew members to change positions during flight if wounded – the structure of the interior meant that the pilot and observer were separated from the wireless operator and rear gunner. This was common for most light bombers of the era like the Handley Page “Hampden”, Douglas “Boston” and Bristol “Blenheim”. Pilots also complained about the difficulties in handling the aircraft on the ground. On take-off, the pilot had to co-ordinate the throttles perfectly to avoid a nose-over, or worse. Thrown into action to stop Rommel’s advance, the “Baltimore” suffered massive losses when it was utilized as a low-level attack aircraft, especially in the chaos of the desert war where most missions went unescorted. However, operating at medium altitude with fighter escorts, the “Baltimore” had a very low loss rate, with the majority of losses coming from operational accidents.
Undertaking a variety of missions in the Middle East, Mediterranean and European theaters, the “Baltimore’s” roles included reconnaissance, target-towing, maritime patrol, night intruder and even served as highly uncomfortable fast transport. The “Baltimore” saw limited Royal Navy Fleet Air Arm service with aircraft transferred from the RAF in the Mediterranean to equip a squadron in 1944. More than 1.500 aircraft with a variety of subtypes rolled out of the Martin Company. The “Baltimore” Mk.III depicted here was supplied under Lend-and-Lease Act to the RAF, two 0.50 in machine guns in a Martin-built electrically powered dorsal turret (Ref.: 24).