The Bristol Beaufort (manufacturer designation Type 152) is a British twin-engined torpedo bomber designed by the Bristol Aeroplane Company, and developed from experience gained designing and building the earlier Blenheim light bomber.
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.
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; Beaufort squadrons based in Egypt and on Malta helped interdict Axis shipping supplying Rommel’s Deutsches Afrika korps in North Africa.
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 Beaufighter, which proved to be very successful and many Beaufort units eventually converted to the Beaufighter.
The Beaufort came from Bristol’s submission to meet Air Ministry Specifications M.I5/35 and G.24/35 for a land-based, twin-engined torpedo-bomber and a general reconnaissance aircraft.
With a production order following under Specification 10/36, the Bristol Type 152 was given the name Beaufort after the Duke of Beaufort, whose ancestral home was nearby in Gloucestershire.
The competing torpedo bomber entry from Blackburn was also ordered as the Blackburn Botha; in an unprecedented step, both designs were ordered straight off the drawing board, an indication of how urgently the RAF needed a new torpedo bomber.
320 Beauforts were ordered.
Initially, because of their commitment to the Blenheim, Bristol were to build 78 at their Filton factory, with the other 242 being built by Blackburn.
These allocations would be changed later.
Although the design looked similar to the Blenheim, it was somewhat larger, with an 18 in (46 cm) increase in wingspan.
The fuselage was longer in the nose and taller to accommodate a fourth crew member and the aircraft was considerably heavier.
The larger bomb-bay was designed to house a semi-recessed torpedo or an increased bomb load.
Due to the increased weight the Bristol Mercury engines on the Blenheim were to be replaced by more powerful, sleeve valve, Bristol Perseus motors.
It was soon determined that even with the Perseus, the Beaufort would be slower than the Blenheim and so a switch was made to the larger Bristol Taurus engine, another sleeve valve design.
For these engines, chief designer Roy Fedden developed special low-drag NACA cowlings, which exhausted air through vertical slots flanking the nacelles under the wings.
Air flow was controlled by adjustable flaps.
The basic structure, although similar to the Blenheim, introduced refinements such as the use of high-strength light alloy forgings and extrusions in place of high-tensile steel plates and angles; as a result the structure was lighter than that of the Blenheim.
The wing centre section was inserted into the centre fuselage and the nacelle structure was an integral part of the ribs, to which the main undercarriage was attached.
Transport joints were used on the fuselage and wings: this allowed sub-contractors to manufacture the Beaufort in easily transportable sections and was to be important when Australian production got under way.
The Vickers main undercarriage units were similar to but larger than those of the Blenheim and used hydraulic retraction, with a cartridge operated emergency lowering system.
The first prototype rolled out of Filton in mid-1938.
Problems immediately arose with the Taurus engines continually overheating during ground testing.
New, more conventional engine cowlings, with circumferential cooling gills, had to be designed and installed, delaying the first flight, which took place on 15 October 1938.
As flight testing progressed, it was found that the large apron-type undercarriage doors, similar to those on the Blenheim, were causing the aircraft to yaw on landing.
These doors were taken off for subsequent flights.
On the second prototype and all production aircraft, more conventional split doors, which left a small part of the tyres exposed when retracted, were used.
The results of high-level bombing tests carried out at Boscombe Down at an altitude of 10,000 ft (3,000 m) and an airspeed of 238 mph (383 km/h) showed that the Beaufort was in an exceptionally poor bombing platform, it was subject to an excessive and continuous roll, which made determination of drift particularly difficult.
After 1941, British Beauforts were fitted with semi-circular plates on the trailing edges of the upper wing behind the engine nacelles to smooth airflow and improve directional stability.
As Blenheim production took priority and engine overheating problems continued, production was delayed; the bomber was first flown in October 1938 and should have been available almost immediately, it was not until November 1939 that production started in earnest.
Several of the first production Beauforts were engaged in working-up trials and final service entry began in January 1940 with 22 Squadron of RAF Coastal Command.
Torpedo bomber, reconnaissance version for the RAF,
Powered by two Bristol Taurus II, III, VI, XII
XVI sleeve valve radial engines.
First British production version.
Torpedo bomber / reconnaissance version for the RAF,
Powered by two Pratt & Whitney R-1830-S3C4-G Twin Wasp radial engines.
Beaufort T Mk. II
249 conversions from Mk II.
Trainer with rear turret position faired over; allocated to Torpedo training units and OTUs.
Intended to be powered by two Rolls-Royce Merlin XX inline piston engines.
One prototype only; powered by two Bristol Taurus XX radial piston engines.
Total Production = 1,180
1st Australian built version, powered by 2 Pratt & Whitney R-1830-S3C4-G Twin Wasp radial piston engines with Curtiss Electric propellers.
Pratt & Whitney S3C4-G with Hamilton Standard propellers.
Similar to the Beaufort Mk V, but fitted with a larger tail.
Pratt & Whitney-S1C3 Twin Wasp radial piston engines with Curtiss Electric propellers.
Pratt & Whitney S1C3-G with Hamilton Standard propellers.
Pratt & Whitney S3C4-G with Curtiss Electric propellers.
Improved version fitted with an ASV radar, it could carry American or British mines or torpedoes.
Total Production = 700
Beaufort Mk.IX Beaufreighter
46 Beauforts of various marks were converted into light transport aircraft for the RAAF and used Pratt & Whitney S3C4-G with Curtiss Electric propellers.
44 ft 2 in (13.46 m)
57 ft 10 in (17.63 m)
14 ft 3 in (4.34 m)
503 sq ft (46.7 m2)
13,107 lb (5,945 kg)
21,228 lb (9,629 kg)
2 × Bristol Taurus II, Taurus III, Taurus VI, Taurus XII
Taurus XVI 14-cylinder air-cooled sleeve-valve radial piston engine,
1,130 hp (840 kW) each
3-bladed de Havilland Hydromatic constant-speed propellers
271.5 mph (436.9 km/h, 235.9 kn) at 6,500 ft (2,000 m)
225 mph (196 kn; 362 km/h) at sea level
255 mph (410 km/h, 222 kn) at 6,500 ft (2,000 m)
1,600 mi (2,600 km, 1,400 nmi)
16,500 ft (5,000 m)
Rate of climb
1,150 ft/min (5.8 m/s)
42.2 lb/sq ft (206 kg/m2)
0.106 hp/lb (0.174 kW/kg)
3 x .303 in (7.7 mm) Vickers GO machine guns.
(Two in Bristol Mk IV dorsal turret, one in port wing)
6 x .303 in (7.7 mm) Vickers GO machine guns.
Two fixed in nose, two in turret, one in port wing
One firing laterally from entry hatch.
1 .303 in (7.7 mm) Browning machine gun in rear-firing chin blister