History Hour: first flight of Bristol Brabazon Mk.I prototype
On September 4, 1949, at 11:30 a.m. Sunday morning, the prototype Bristol Brabazon Mk.I, G-AGPW, made its first flight at Bristol Filton Aerodrome (UK). Chief Test Pilot Arthur J. “Bill” Pegg was in command with Walter Gibb as co-pilot. An 8-man flight test crew was also aboard. A crowd of spectators, estimated at 10,000 people, were present.
The prototype Bristol Type 167, G-AGPW, takes off from Filton Aerodrome, 11:30 a.m., 4 September 1949. Hundreds of Bristol employees are lining the runway. (Alfred Thompson)
Designed as a transatlantic commercial airliner, development of the Type 167 began in 1943. The Mk.I prototype, G-AGPW, had been rolled out in December 1948. On September 3, 1949, the flight test crew performed a series of taxi tests.
The first flight lasted 26 minutes. The Brabazon had reached 3,000 feet (914 meters) and 160 miles per hour (257 kilometers per hour).
The flight test crew of the Bristol Brabazon. Bill Pegg is at center. (Unattributed)
The Bristol Aeroplane Company Type 167 Brabazon Mk.I was a very large low-wing monoplane, designed to carry 100 passengers on transatlantic flights.
It had been named to honor John Theodore Cuthbert Moore-Brabazon, the first Baron Brabazon of Tara, the first man to fly an airplane in England, and a very important figure in the development of the British aeronautical industry.
The Type 167 was slightly larger than the United States Air Force Convair B-36A intercontinental strategic bomber.
Bristol Brabazon Mk.I G-AGPW.
It was 177 feet, 0 inches (53.950 meters) long with a wingspan of 230 feet, 0 inches (70.104 meters) and overall height of 50 feet, 0 inches (50.240 meters). The fuselage had a maximum diameter of 25 feet (7.62 meters).
The leading edge of the inboard section of the Brabazon’s wing was swept 4° 16′ and had no dihedral, while the outer section was swept 14° 56′ with 2° dihedral. The wings had an angle of incidence of +3° 30′.
The chord narrowed from 31 feet, 0 inches (9.449 meters) at the root, to 10 feet, 0 inches (3.048 meters) at the tip. The wings’ maximum thickness was 6 feet, 6 inches (1.981 meters). The Mk.I’s wing area was 5,317 square feet (494 square meters).
The horizontal stabilizer had a span of 75 feet, 0 inches (22.860 meters). The angle of incidence was +2° and there was no dihedral. The stabilizer’s area was 692 square feet (64.3 square meters).
The airplane’s empty weight was 169,500 pounds (76,884 kilograms), and its maximum takeoff weight of 290,000 pounds (131,542 kilograms). For the first flight, its gross weight was 200,000 pounds (90,718 kilograms).
The prototype was powered by eight air-cooled, supercharged, 3,271.87-cubic-inch-displacement (53.62 liter) Bristol Centaurus 20 eighteen-cylinder radial engines.
“Each Bristol Centaurus engine was coupled to a propeller gearbox at a 32-degree angle.” (Airbus, Filton)
They had a cruise power rating of 1,640 horsepower at 22,000 feet (6,706 meters); maximum continuous power and maximum climb power rating of 2,190 horsepower at 5,000 feet (1,524 meters); and 2,500 horsepower for takeoff.
Each pair of engines drove a set of coaxial counter-rotating three-bladed Rotol constant-speed wooden propellers with a diameter of 16 feet, 0 inches (4.877 meters).
Power was transmitted from each engine by an angled drive shaft to separate beveled gears in a dual reduction gear unit. The reduction gear ratio was 0.400:1.
For one-engine-out operation, the effected propeller would be feathered, while the other engine of the pair continued to power the other counter-rotating propeller. The propellers were reversible for braking on landing.
Turboprop engines were planned for the Brabazon Mk.II.
Bristol Brabazon Mk.I G-AGPW flying overhead reveals the double sweep of the wings. (BAE Systems)
Estimated performance of the Brabazon Mk.I (before flight testing was completed) was a cruise speed of 250 miles per hour (402 kilometers per hour), and maximum speed of 300 miles per hour (483 kilometers per hour), both at 25,000 feet (7,620 meters), the airplane’s service ceiling.
The maximum fuel capacity of the Mk.I was 13,650 gallons (51,671 liters), giving a maximum range at cruise speed of 5,460 miles (8,787 kilometers). This was sufficient for a flight from London to New York with the required fuel reserve.
Bristol Brabazon Mk. I G-AGPW landing at Farnborough, September 1950. (BAE Systems)
Only one Brabazon Mk.I was built. The prototype Mk.II was never completed. The project was cancelled in 1952. The total cost of the Brabazon program was approximately £6,500,000 (estimated at £170,981,807, or $221,489,833 in 2017. G-AGPW was eventually scrapped.
*In the top photograph: Bristol Brabazon Mk.I G-AGPW runs up its engines. (Unattributed)
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