Famous aircraft types from a firm in active production since the early days of aviation
PRODUCED IN 1927, the Bristol Bulldog had a top speed of 178 miles an hour and a climb to 10,000 feet in five minutes. This performance was greatly increased with each successive medications of the type. The Bristol Bulldog was adopted as standard by several foreign countries as well as by the Royal Air Force.
THE Bristol Aeroplane Company, Limited, is the largest single aeronautical organization in the British Empire and was the first company to be formed exclusively for the production of aircraft in Great Britain. In 1910 the late Sir George White, Bart., one of the pioneers of electric tramway traction in Great Britain, founded the British and Colonial Aeroplane Company, as it was then called. One or two other companies began aeroplane construction at about the same time, but they were engaged in experimental work. The Bristol Company boldly began the design and manufacture of aeroplanes on a large commercial scale, a policy which required faith in the future of aviation.
A factory was erected at Filton, on the outskirts of Bristol, and the first aeroplane built to the company’s design was flown at the aviation meeting at Lanark, Scotland, in July 1910. This biplane came to be known as the Bristol Box-Kite. The span was 34 feet, the length 40 feet and the height 12 feet. The Bristol Box-Kite was built of the best selected ash and silver spruce, the wings being covered with varnished cotton fabric. A 50 horse-power Gnome rotary engine gave the machine a speed of about 40 miles an hour; the weight was just over 800 lb.
Bristol flying schools were established at Filton, at Brooklands and on Salisbury Plain at Larkhill. At these schools civil and military, British and foreign pilots received instruction and gained their certificates. A Bristol Box-Kite fitted with extensions to the top wings, which enabled the machine to carry one or two passengers in addition to the pilot, was the first and only machine to fly at the Army Manoeuvres on Salisbury Plain in the autumn of 1910. The type was known as the Bristol Military Biplane and it secured the first contract placed in Great Britain for military aircraft — one from the Russian Government.
Early in 1911 the first aeroplane contract placed by the British Government was for these machines. Two Bristol monoplanes gained prizes at the first British military aeroplane trials on Salisbury Plain in 1912; they were flown at the Bristol flying schools at Brooklands and at Larkhill, and were supplied to a number of foreign governments.
The first single-seater Scout to go into production at the beginning of the war of 1914-18 was the machine which came to be known as the Bristol Bullet. It performed useful service on various fronts early in the war and several hundred machines of this type were produced for the Royal Flying Corps. Four-fifths of the R.F.C. pilots were Bristol-trained at the outbreak of the war.
More famous was the Bristol Fighter, which, in 1917, gave superiority to the Allies in the war in the air. Popularly known as the “Brisfit”, it was produced in 1916 and was manufactured in enormous numbers by many firms. It was one of the most outstanding aeroplanes produced during the war. Fitted with a Rolls-Royce Falcon engine, it had a maximum speed of over 110 miles an hour, and the then astonishing climb of 5,000 feet in seven minutes and of 10,000 feet in seventeen minutes.
The Bristol Fighter was afterwards supplied in large numbers to foreign governments and remained in service with the R.A.F. for more than ten years. Thousands of machines were built and the type probably performed more general service in fighting, bombing and general reconnaissance work than any other.
Another outstanding machine was the Bristol single-seat fighter monoplane, which, fitted with a 110 horsepower Le Rhone engine, had a top speed of 111 miles an hour at 10,000 feet. Several hundred were supplied to the Royal Flying Corps in 1916 and 1917 and saw considerable service, especially on the Eastern Fronts.
Of different type was the Bristol Braemar Bomber, a large triplane with a span of 82 feet and a total wing area of nearly 2,000 square feet, completed just before the Armistice, and intended for the bombing of enemy territory. The triplane weighed 11,000 lb. empty and could carry 7,000 lb. The four 400 horse-power Liberty engines gave it a speed of 135 miles an hour. There were four Lewis guns, two of which were mounted on rotating turrets. The Bristol Pullman was the civil version of the bomber, with an enclosed cabin luxuriously fitted for fourteen passengers and in 1919 was the first large air liner to be produced.
After the war the company began a series of prototype designs which had a profound effect on the development of flying; the company decided also to build engines. During the war there had been a serious shortage of engines to fit into the aeroplanes, and the Bristol Company was determined not to be exposed to this shortage in the future. Near the flying school at Filton, the company built new works devoted solely to the production of radial air-cooled motors. Here the Bristol Jupiter engine, which came to be known all over the world, was produced in 1921.
The Bristol Jupiter was a nine-cylinder radial air-cooled engine, with an output of 400 horse-power. The engine was used to power many of the world’s most important civil and military aircraft. It was manufactured under licence in a large number of countries and for more than a decade it upheld the reputation of Bristol engines in all parts of the world.
Development of aircraft and engines proceeded regularly, although with difficulty in the early post-war period because of the lack of demand for machines. On the aircraft side attention was turned to light aeroplanes, and on the engine side a two-cylinder horizontally-opposed motor, the Bristol Cherub, was produced. This was fitted in the Bristol Brownie light aircraft, which was a light two-seater tractor cantilever monoplane, which gained five awards in competitions for the type in 1924 and 1925.
THE FIRST AEROPLANE to be built to a design of the British and Colonial Aeroplane Company, as the Bristol Aeroplane Company was first called. This aircraft was flown at the aviation meeting at Lanark, Scotland, in July 1910, and came to be known as the Bristol Box-Kite. The speed of the machine was about forty miles an hour.
The Bristol Bullfinch was one of several revolutionary designs in prototypes, and was a single-seat fighting tractor monoplane, with a high parasol wing of unusual section. It was powered by a Jupiter engine. A small lower plane could be attached if required, as well as an additional section to the fuselage to convert the machine into a two-seater. Steel structures were developed. Among the prototypes was a high-wing monoplane of unorthodox design for those days; this machine was fitted with two Jupiter engines. It was not until the first Bristol Bulldog was produced in 1927 that support was received from the Government. The Bulldog was the culmination of the company’s research into high-performance single-seat all-metal fighters. It was adopted as the standard day and night fighter of the R.A.F. for many years, and had a remarkable performance. The Jupiter engine gave it a top speed of 178 miles an hour, and it climbed to 10,000 feet in five minutes. It had a wing span of 33 ft. 8 in. on the top plane, and of 27 ft. 6 in. on the lower plane, the wing area being 293.6 square feet. Weight empty was 2,000 lb; weight loaded was about 4,000 lb. The Bulldog proved itself superior in general speed, manoeuvrability and performance to any aircraft of the single-seat fighter type then in existence, and it was adopted as standard by Great Britain and by several other countries.
During these developments of aircraft the engine section of the company produced, in addition to the Jupiter, radial engines of three, five and seven cylinders. In 1932 the company produced a new series of engines, known as the Bristol Pegasus. These engines still stand alone in their class for high performance, low weight, reliability and ease of maintenance. Designed to supersede the Jupiter, the Pegasus, also of nine cylinders, has the same bore and stroke, but the power is higher and the weight less, it was developed until it gave more than 1,000 horsepower for a weight of just over 1,000 lb. Pegasus engines, in universal use, are notable for their power-to-weight ratio.
Sleeve Valves Introduced
A similar engine, the Bristol Mercury, with the same number of cylinders but of shorter stroke, was developed for military purposes. The fully supercharged version is used for high performance military aircraft, and develops 840 horse-power at 14,000 feet.
New types of engines, with sleeve valves, have been produced by the company. They are called the Perseus, the Aquila and the Hercules. The Perseus is made in three versions: the civil rated engine, the XIIc, developing 900 horse-power for the take off, the medium supercharged versions, XI and XII, developing 905 horse-power at 6,500 feet, and the fully supercharged version, the X, developing 880 horse-power at 15,500 feet. The Perseus is the lightest and most powerful nine-cylinder aero engine yet produced, and its fuel economy and ease of maintenance are revolutionary.
The Perseus XIIc, the civil rated version, has an international rating of 680 710 horse-power at 4,000 feet at 2,250 revolutions a minute. The maximum level flight power at 6,000 feet at 2,600 revolutions is 815 horse-power. The engine is scheduled for installation in several of the Imperial Airways flying boats, as well as Bristol Pegasus engines, and has been chosen for other commercial aircraft. The latest sleeve-valve engine is the two-row 14-cylinder Hercules (see the chapter “Evolution of the Aero Engine”).
THE WORLD ALTITUDE RECORD was regained for Great Britain on June 30, 1937, when Flight Lieutenant M. J. Adam flew this Type 138A Bristol monoplane. It was powered by a Pegasus supercharged engine and attained a height of 53,937 feet. This machine had also gained the world height record for Great Britain on September 28, 1936, by reaching 49,944 feet.
The increase in the power-to-weight ratio necessitated a new technique in the design of engines and the materials, and required an increasing degree of accuracy and the use of elaborate and costly machine tool methods to produce mechanism to withstand the enormous increase in the powers obtained. The early Jupiter engine gave an output of about 400 horse-power for a weight of 750 lb. The latest series of Pegasus and Mercury engines deliver nearly one horse-power for each pound in weight.
To achieve these results, thousands of hours of research, testing and development running have been completed — an elaboration unheard of in the earlier days. In addition, the maintenance of laboratories for chemical and physical research, the adoption of new processes for heat treatment, and entirely new electrical methods necessary for the investigation of materials have been introduced as essential to modern production methods. The new Bristol Aero Engine Factory, erected in 1937, is one of the most modern in the world.
In 1933 the company turned its attention to the civil branch of aviation. A ten-seater low-wing all-metal monoplane fitted with two of the new Bristol Aquila sleeve valve engines was designed. A high-speed private aeroplane was then produced; it became known as Britain First. This six-seater all-metal stressed-skin cantilever monoplane was fitted with two Bristol Mercury engines, and was credited with a speed of more than 300 miles an hour.
When the aeroplane was tested at Martlesham (Suffolk) for its Certificate of Airworthiness the performance was so remarkable that the Air Ministry asked for permission to make further tests. The results were so outstanding and the official interest was so great that the owner presented Britain First to the nation.
In 1936 the Bristol Company produced the Blenheim Bomber, now in quantity production for the R.A.F. It is standard equipment in many squadrons, and has also been supplied to several foreign countries, including Finland, Yugoslavia and Turkey. It is scheduled for manufacture under licence in Canada for the R.C.A.F.
Blenheim Medium Bomber
The Blenheim medium bomber is an all-metal low-wing twin-engined cantilever monoplane with retractable undercarriages and tail wheel, and is fitted with mass-balanced ailerons, split trail-ing-edge flaps, controllable-pitch airscrews and controllable-gill engine cowlings. It is a stressed-skin aircraft, with monocoque fuselage and stressed-skin covering to body, wings and tail; only the control surfaces are fabric-covered. It is jig-built in six sections, each of which is independent of the others, and is easily transportable; three sections comprise the fuselage, and three the wings. The front fuselage carries the cockpit, which is a combined structure, partly monocoque and partly tubular, with both fixed and sliding window panels and a transparent sliding roof, providing means of easy entrance or exit, and giving the pilots excellent visibility. The rear fuselage contains a gun turret mounting midway along the top, and a hinged hatch giving access to the interior. The bomb well is within the body immediately behind the front fuselage.
The stern frame forms the end of the fuselage, and comprises the tail unit, tail plane and fin, and a housing for the retractable tail wheel, which is fully swivelling when on the ground. The stern post carries the rudder hinges; both rudder and elevators are constructed from metal frames with fabric covering, and are fitted with servo or trimming tabs.
THE FASTEST BOMBER OF ITS KIND IN SERVICE is the Bristol Blenheim, now in quantity production for the Royal Air Force at home and abroad. It is scheduled for manufacture under licence in Canada for the Royal Canadian Air Force.
The undercarriages are in two separate units, one under each engine nacelle, into which they are hydraulically retractable, with means for auxiliary hand operation. Intermediate-pressure tyred wheels are fitted, with pneumatic brakes having differential control from the rudder pedals. The wheels are mounted between two oleo-pneumatic shock-absorbing struts. Full indication and warning devices, visual and audible, are in the cockpit to show the position of the undercarriage, flaps and other movable parts.
The wings and centre section are built up with stressed-skin metal covering on two spars and ribs. The wings are bolted and riveted to the centre section and the fuselage, the wing tips being fitted separately so that they can easily be replaced if damaged. A double landing lamp is fitted in the port wing leading edge. Two 140-gallons fuel tanks are built in the wing centre section between the fuselage and the port and the starboard engine nacelles, the fuel being supplied by engine-driven pumps. Split trailing-edge flaps extend from fuselage to ailerons on either side. The fabric-covered ailerons, of the mass balanced type, are fitted with trimming tabs.
The nacelles for the two Bristol Mercury VIII engines are on the centre line of the wings, the engines being enclosed in long-chord cowlings with Bristol controllable gills for adequate cooling in all conditions. The oil supply for either engine is in the appropriate nacelle, in 10-gallons tanks, with cooling systems. Each engine develops its maximum output of 840 horse-power at 14,000 feet.
The crew consists of three: pilot, bomb-aimer-navigator and wireless-operator-gunner. The pilot’s seat is on the port side of the front fuselage and the navigator’s on the starboard side with a bombing station forward of it; the stations for the gunner are aft, midway along the fuselage.
The flying controls and dashboard are in front of the pilot. Indicators, engine and landing-lamp controls are on the port wall. The automatic pilot controls, fuel cocks and instrument stowage are on the starboard wall. Engine starting buttons and fuel gauges are above and the servo motors are behind the pilot’s seat. The grouping of the instruments and the size and arrangement of the cockpit enable dual controls to be fitted, without duplicating the instruments.
There are two guns, a fixed forward gun for the pilot, and a rear gun with a wide field of fire in the retractable turret aft. The bomb load is carried internally on the centre of gravity, under the centre plane. A loading winch is operated from inside the body.
The Blenheim is 39 ft. 9 in. long; the wing span is 56 ft. 4 in; the height 9 ft. 10 in, and all-up weight is 12,456 lb. The nominal figures released for publication about the performance give the speed with full military load at 279 miles an hour at 15,000 feet. The Blenheim will climb to 15,000 feet in 11½ minutes, and to 20,000 feet in 17½ minutes, with full load. The ceiling is 27,300 feet and the range with full load 1,000 miles. The average take-off run is 330 yards, and the Blenheim, using flaps and brakes, comes to rest 400 yards after it has touched down, so that it can be operated from all ordinary aerodromes.
In 1934 and 1935 the company designed and produced the Bristol Bombay bomber-transport. It is a large twin-engined high-wing monoplane, the span being 96 feet, the length 67 ft. 9 in. and the total weight about 18,000 lb. It was hoped that it would form the prototype for a fast air liner, but the requirements of the R.A.F. expansion scheme prevented this; it is in quantity production for the R.A.F. Of all-metal stressed-skin construction, the Bombay has two Pegasus engines, split trailing-edge flaps and a monoplane tail with twin fins and rudders. As a bomber it carries a crew of four and has long range and great striking power. Defensive armament is installed in power-driven turrets in the nose and tail; there is auxiliary armament amidships.
THE BRISTOL BOMBAY BOMBER-TRANSPORT can carry twenty-four soldiers, with arms and equipment. It was hoped that this aircraft would form a prototype for a fast air liner, but the urgent requirements of the R.A.F. expansion scheme prevented this. As a bomber, the aircraft carries a crew of four; it can also be fitted as an ambulance to carry stretcher casualties.
A crew of three — pilot, navigator and gunner — operate the Bombay as a troop carrier, when the machine transports twenty-four soldiers with arms and equipment. It can be fitted as an air ambulance to take stretcher casualties and can be used for the transport of supplies. Its performance with two Bristol Pegasus XX engines is remarkable, particularly when climbing, and it is unusually easy to handle for so large an aeroplane.
The world altitude record for engines of the Diesel or crude oil type was gained in 1934 by the Bristol Phoenix compression ignition engine which the company had produced after about nine years’ development. Preliminary research comprised thousands of hours’ running on various types and sizes of cylinders until the company evolved the Phoenix, a nine-cylinder air-cooled radial engine of the same capacity as the Pegasus, and designed on the same general lines.
To secure comparative data the Air Ministry arranged to install a Phoenix in a Wapiti machine for flight tests to be made by the Westland Company. The tests proved the Phoenix to have such excellent characteristics that, although the aircraft was a standard two-seat general purpose type, it was decided to obtain the maximum height in officially-observed conditions.
The machine, which weighed 4,564 lb. with pilot and full equipment, reached a recorded height of 28,000 feet, which was ratified at 27,453 feet and exceeded the former record by a substantial margin. The net weight of the engine was 1,090 lb, the take-off power being 470 horse-power, and the international rated power 415 horse-power at 1,900 revolutions.
In 1934 the company designed and produced the Bristol 143 twin-engined ten-seater civil aircraft. This was an all-metal monocoque monoplane of stressed-skin construction, and was powered by two Bristol Aquila sleeve-valve engines. The Bristol 143 was not developed because the resources of the company were entirely concentrated on military requirements.
Regaining the Record
Great additions have been made to the aircraft and to the engine workshops. A new flight production shed, experimental department, erecting hall, assembly shops and plating department, drawing office and wind tunnel have been added, as well as a new engine factory.
World altitude records were established by the R.A.F. with the Bristol High Altitude Monoplane, known as Type 138A, fitted with a specially supercharged Bristol Pegasus engine. On the first occasion, September 28, 1936, a height of 49,944 feet was attained, the pilot being Squadron Leader F.R.D. Swain, R.A.F. This was the first time in aviation that this record had been secured by an aircraft and an engine manufactured by the same firm. In May 1937 Italy secured the record, but not for long, as on June 30, 1937, the Bristol monoplane reached a height of 53,937 feet, regaining the record. The pilot on this occasion was Flight Lieut. M. J. Adam, R.A.F.
At the beginning of 1938 seventy-four Bristol Jupiter engines were in service in Imperial Airways machines. Each engine had flown an average distance of 561,328 miles, one having flown nearly 800,000 miles. A total of 401,590 hours had been completed by the engines.
Bristol Pegasus engines in the Empire flying boats are adding to the records of reliability. It was this type of engine which made possible the flights over Mount Everest. In addition it has on three other occasions secured the altitude record for Great Britain, the first being in 1932, when a Vickers Vespa climbed to 43,976 feet. A Bristol Pegasus powered the Caproni machine which, after the record had passed to France, secured it for Italy in 1934 with an altitude of 47,360 feet. As a Bristol Jupiter powered the Junkers W.34 machine which gained the record for Germany in 1929, Bristol engines have on five occasions secured the world altitude record.
AN OUTSTANDING PRODUCT of the war of 1914-18, This Bristol Fighter was a two-seater tractor biplane colloquially called the “Brisfit”, and was made in two versions, a fighter-reconnaissance and a corps-reconnaissance type. This photograph shows a Bristol Fighter which was exhibited at an R.A.F. Display at Hendon.