The Bristol Type 172 was a proposed British long range four-engined bomber project developed by the

Bristol Aeroplane Company The Bristol Aeroplane Company, originally the British and Colonial Aeroplane Company, was both one of the first and one of the most important British aviation companies, designing and manufacturing both airframes and aircraft engines. Notable ...

. It is closely related to the ''Type 174'' and ''Type 176'' proposals. In response to official interest in the development of increasingly capable

strategic bomber A strategic bomber is a medium- to long-range Penetrator (aircraft), penetration bomber aircraft designed to drop large amounts of air-to-ground weaponry onto a distant target for the purposes of debilitating the enemy's capacity to wage war. Unl ...

in the aftermath of the

Second World War World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

, Bristol commenced work during late 1946 on its own new bomber design, which made use of relatively new aviation trends, such as

turbojet The turbojet is an airbreathing jet engine which is typically used in aircraft. It consists of a gas turbine with a propelling nozzle. The gas turbine has an air inlet which includes inlet guide vanes, a compressor, a combustion chamber, and ...

propulsion and a sweptback wing. The Type 172 quickly garnered the Air Staff's interest and, on 23 July 1947, the

Air Ministry The Air Ministry was a department of the Government of the United Kingdom with the responsibility of managing the affairs of the Royal Air Force and civil aviation that existed from 1918 to 1964. It was under the political authority of the ...

issued Specification E.8/47 to Bristol. The firm began work on the comprehensive evaluation of the Type 172 aerodynamic properties and other key performance attributes. To support the project's experimental stage, a half-scale flight-capable model, the Type 174, was devised. This was geometrically similar to the full-scale Type 172, but powered by a single

Rolls-Royce Nene The Rolls-Royce RB.41 Nene is a 1940s British centrifugal compressor turbojet engine. The Nene was a complete redesign, rather than a scaled-up Rolls-Royce Derwent,"Rolls-Royce Aero Engines" Bill Gunston, Patrick Stephens Limited 1989, , p.111 ...

turbojet engine instead of four units. As the programme developed, it was recognised that the unsuitably high subsonic flow around the wing-body junction would necessitate the redesign of the wing, thus work on the Type 174 was stopped in November 1947 and a revision of the E.8/47 specification was issued on 8 June 1948, which stipulated numerous new design requirements and changes. In response, Bristol designed the Type 176. Work on the Type 176 proceeded further than the prior efforts, reaching the mockup stage in late 1948. However, company management felt that other undertakings by the company, such as the

Bristol Britannia The Bristol Type 175 Britannia is a retired United Kingdom, British flight length, medium-to-long-range airliner built by the Bristol Aeroplane Company in 1952 to meet British civilian aviation needs. During development two prototypes were lo ...

turboprop A turboprop is a Gas turbine, gas turbine engine that drives an aircraft Propeller (aeronautics), propeller. A turboprop consists of an intake, reduction drive, reduction gearbox, gas compressor, compressor, combustor, turbine, and a propellin ...

-powered airliner, ought to be prioritised and, due to limited design resources, activity on the Type 176 was abandoned. No aircraft, full-scale or otherwise, were ever completed. Knowledge from the project was harnessed in several of the company's other proposals, including the Type 182, which was also known the ''Short Range Expendable Bomber''.

Design and development

Shortly after the end of the

, the British government was highly interested in developing the capabilities of the

Royal Air Force The Royal Air Force (RAF) is the Air force, air and space force of the United Kingdom, British Overseas Territories and Crown Dependencies. It was formed towards the end of the World War I, First World War on 1 April 1918, on the merger of t ...

fleet. This interest was present within the

, which sought a high-speed long-range bomber powered by four

engines.Barnes 1988, p. 376. During October 1946, the

decided to tendered its own design, designated ''Type 172''. In terms of its basic configuration, it was a high wing

monoplane A monoplane is a fixed-wing aircraft configuration with a single mainplane, in contrast to a biplane or other types of multiplanes, which have multiple wings. A monoplane has inherently the highest efficiency and lowest drag of any wing con ...

furnished with a 45 degree sweepback. Bristol's submission was warmly received by the Air Staff, leading to the formulation of plans for an experimental programme to comprehensively evaluate the design's stability, control, and manoeuvrability. On 23 July 1947, the Air Ministry issued Specification E.8/47 ("Prototype Flying Models to

Operational Requirement An Operational Requirement, commonly abbreviated OR, was a United Kingdom (UK) Air Ministry document setting out the required characteristics for a future (i.e., as-yet unbuilt) military aircraft or weapon system. The numbered OR would describe ...

250") to Bristol.Meekcoms and Morgan 1994, pp. 368-369. Amongst other aspects, this programme called for the construction of a half-scale flying model, which was designated ''Type 174''. Geometrically similar to the Type 172, the Type 174 was to be powered by a single

turbojet engine and capable of seating a single pilot within its pressurised cockpit. The engine was installed in a central position, air was fed to it through bifurcated inlets which, along with the profiling of the tail pipes, intentionally reproduced the anticipated external air flow of the full-scale aircraft. Additionally, provisions were made in the design for the incorporation of

boundary layer control In engineering, boundary layer control refers to methods of controlling the behaviour of fluid flow boundary layers. It may be desirable to reduce flow separation on fast vehicles to reduce the size of the wake (streamlining), which may reduce ...

via suction; this was to be tested during the later portion of the flight test programme. The Type 174 was intended to achieve the same speed and altitude as had been projected for the Type 172, amongst other performance requirements. Aerodynamic investigation determined that the design's original shape would not work, specifically due to the high subsonic flow around the wing-body junction was unsuitable, thus the

leading edge The leading edge is the part of the wing that first contacts the air;Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 305. Aviation Supplies & Academics, 1997. alternatively it is the foremost edge of an airfoil sectio ...

of the wing would need to be swept. Accordingly, during November 1947, work on the Type 174 was stopped and the E.8/47 specification was revised. The updated specification, formally issued on 8 June 1948, called for a smaller 3/10th scale monoplane that would be powered by the newer

Rolls-Royce Avon The Rolls-Royce Avon was the first axial flow jet engine designed and produced by Rolls-Royce. Introduced in 1950, the engine went on to become one of their most successful post-World War II engine designs. It was used in a wide variety of ai ...

engine instead; other changes included the use of a swept shoulder-mounted wing, a swept but otherwise conventional tail unit, a single air intake in the nose, and the use of tandem

landing gear Landing gear is the undercarriage of an aircraft or spacecraft that is used for taxiing, takeoff or landing. For aircraft, it is generally needed for all three of these. It was also formerly called ''alighting gear'' by some manufacturers, s ...

. In response to the changing requirements of the Air Ministry, Bristol had already begun to produce their latest design revision, designated ''Type 176'', as early as February 1948. According to the aviation historian C.H. Barnes, progress on the Type 176 proceeded further it had with either the Type 172 or Type 174; however, by the time the mock-up conference was held in October 1948, the company's management was increasingly aware that its design resources had been spread relatively thin across multiple undertakings. At that time, projects such as the

, an airliner incorporating ground-breaking

propulsion and capable of the then-uncommon feat of regular

transatlantic flight A transatlantic flight is the flight of an aircraft across the Atlantic Ocean from Europe, Africa, South Asia, or the Middle East to North America, South America, or ''vice versa''. Such flights have been made by fixed-wing aircraft, airships, bal ...

s, was judged to take precedence.Barnes 1988, pp. 376-377. Accordingly, work on the lower priority Type 176 was shelved in favour of Bristol's other endeavours.Barnes 1988, p. 377. Despite this decision, Bristol retained a handful of personnel working in this area, who continued to generate design brochures and tenders to various specifications. Their continued efforts in this area led to the Type 182, also referred to as the ''Short Range Expendable Bomber'', which was intended to be operationally alike to the

V-1 flying bomb The V-1 flying bomb ( "Vengeance Weapon 1") was an early cruise missile. Its official Reich Aviation Ministry () name was Fieseler Fi 103 and its suggestive name was (hellhound). It was also known to the Allies as the buzz bomb or doodlebug a ...

deployed by

Nazi Germany Nazi Germany, officially known as the German Reich and later the Greater German Reich, was the German Reich, German state between 1933 and 1945, when Adolf Hitler and the Nazi Party controlled the country, transforming it into a Totalit ...

during the Second World War.

Variants

;Bristol Type 172 :Proposal for a four-engined long-range bomber, not built.Barnes 1988, pp. 376 - 377. ;Bristol Type 174 :Half-scale variant of the Type 172 for design evaluation powered by a Nene engine, not built. ;Bristol Type 176 :Revised 3/10th Scale development aircraft for the Type 172 powered by a Avon engine, mock-up only, not built.

Specification (Type 172 as proposed)

References

Citations

Bibliography

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External links

Bristol Aero Engines Olympus
{{Bristol aircraft 172 Abandoned military projects of the United Kingdom High-wing aircraft Quadjets 1940s British bomber aircraft