Bristol Type 92
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The Bristol Type 92, sometimes known as the Laboratory
biplane A biplane is a fixed-wing aircraft with two main wings stacked one above the other. The first powered, controlled aeroplane to fly, the Wright Flyer, used a biplane wing arrangement, as did many aircraft in the early years of aviation. While ...
, was an aircraft built 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 a ...
to address the differences between
wind tunnel Wind tunnels are large tubes with air blowing through them which are used to replicate the interaction between air and an object flying through the air or moving along the ground. Researchers use wind tunnels to learn more about how an aircraft ...
cowling A cowling is the removable covering of a vehicle's engine, most often found on automobiles, motorcycles, airplanes, and on outboard boat motors. On airplanes, cowlings are used to reduce drag and to cool the engine. On boats, cowlings are a cove ...
models and full scale cowling for
radial engine The radial engine is a reciprocating type internal combustion engine configuration in which the cylinders "radiate" outward from a central crankcase like the spokes of a wheel. It resembles a stylized star when viewed from the front, and is ca ...
s and was designed as a scaled-up version of a wind tunnel model aircraft. One was built and flew in the mid-1920s.


Development

In the development of the
Bristol Badger The Bristol Badger was designed to meet a British need for a two-seat fighter-reconnaissance aeroplane at the end of the First World War. Three Badgers were delivered to the Air Board to develop air-cooled radial engines, particularly that ...
in 1919, Bristol's chief designer
Frank Barnwell Captain Frank Sowter Barnwell OBE AFC FRAeS BSc (23 November 1880 – 2 August 1938) was a Scottish aeronautical engineer. With his elder brother Harold, he built the first successful powered aircraft made in Scotland and later went on to a c ...
had noted discrepancies between wind tunnel model tests and full-size aircraft, particularly in the failure to predict the Badger's lateral instability. He had responded by building the Badger X which had standard Badger wings combined with a very simple fuselage, intended to look like a scaled-up wind tunnel model for comparison. The Badger went on to become a testbed for Bristol's
Jupiter Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but ...
radial engine The radial engine is a reciprocating type internal combustion engine configuration in which the cylinders "radiate" outward from a central crankcase like the spokes of a wheel. It resembles a stylized star when viewed from the front, and is ca ...
in a variety of cowlings. Once again, it was difficult to extrapolate from wind tunnel measurements on cowling aerodynamics and engine cooling to the full scale, so that the cooling behaviour of cowlings that were aerodynamically efficient was hard to predict. Cooling difficulties were experienced with the Badger and later Jupiter-powered Bristol types like the Bullfinch and Ten-seater. Barnwell's response was again to design a full-scale aircraft which had the simplifications of a typical wind tunnel model, to which could be fitted any of several cowlings over the Jupiter engine; the Type 92 was the result. It was a two-bay biplane without stagger or
sweep Sweep or swept may refer to: Cleaning * Sweep, the action of using a brush to clean * Chimney sweep, a worker who clears ash and soot from chimneys * Street sweeper, a person's occupation, or a machine that cleans streets * Swept quartz, a cleani ...
on the equal span, square-tipped wings. These and the tail unit, which was also very rectangular and simple, were fabric-covered steel strip and tube structures. Part of the Type 92's odd appearance came from the wish to minimise wing-
fuselage The fuselage (; from the French ''fuselé'' "spindle-shaped") is an aircraft's main body section. It holds crew, passengers, or cargo. In single-engine aircraft, it will usually contain an engine as well, although in some amphibious aircraft t ...
aerodynamic interactions. To achieve this, the vertical gap between the wings was large: at it was 25% of the span. The
undercarriage Undercarriage is the part of a moving vehicle that is underneath the main body of the vehicle. The term originally applied to this part of a horse-drawn carriage, and usage has since broadened to include: *The landing gear of an aircraft. *The ch ...
had a wide track and was a single axle arrangement mounted below the ends of the inner
interplane strut In aeronautics, bracing comprises additional structural members which stiffen the functional airframe to give it rigidity and strength under load. Bracing may be applied both internally and externally, and may take the form of strut, which act in ...
s. The fuselage was also simple, the structural part being a
plywood Plywood is a material manufactured from thin layers or "plies" of wood veneer that are glued together with adjacent layers having their wood grain rotated up to 90 degrees to one another. It is an engineered wood from the family of manufactured ...
-covered box girder about square from the nose to aft of the second cockpit, where it tapered in plan only to an edge at the tail. Two streamlined pylons joined the wings to the box, above and below, carrying the fuselage at mid gap. For the aerodynamic investigations, the untapered part of the fuselage could be contained in circular fairings of different diameters; originally a range of five sizes was planned, but to reduce cost only the smallest () and largest () were flown. Since the diameter of the Jupiter was about , the cylinder heads were well exposed with the smaller fairing and enclosed by the larger.


Operational history

Powered by a Jupiter V engine, the Type 92 first flew from
Filton Filton is a town and civil parish in South Gloucestershire, England, north of Bristol. Along with nearby Patchway and Bradley Stoke, Filton forms part of the Bristol urban area and has become an overflow settlement for the city. Filton Church d ...
on 13 November 1925. It was ungainly in the air, was never registered nor flown far from Filton, but it was in use for more than two years, mostly with the fairing. The larger fairing was fitted in 1928, but not long after, the undercarriage was damaged in a heavy landing and the Type 92 did not fly again. By the end of the 1920s, the problem of cowling radial engines was beginning to be mastered, though it is not clear how much the Type 92 contributed to the solution. In 1929, the
Townend ring A Townend ring is a narrow- chord cowling ring fitted around the cylinders of an aircraft radial engine to reduce drag and improve cooling. Development The Townend ring was the invention of Dr.  Hubert Townend of the British National Physica ...
appeared, improving the airflow but open enough not to impede cooling; in 1928-9,
NACA The National Advisory Committee for Aeronautics (NACA) was a United States federal agency founded on March 3, 1915, to undertake, promote, and institutionalize aeronautical research. On October 1, 1958, the agency was dissolved and its assets ...
was releasing and applying the results of very successful tests on closely cowled engines in the diameter Propeller Research Tunnel (PRT). The PRT's ability to test full scale cowlings meant that they could be developed under ground-based laboratory conditions, rather than flying them on a laboratory aircraft, and the difficult problems of trying to scale low
Reynolds number In fluid mechanics, the Reynolds number () is a dimensionless quantity that helps predict fluid flow patterns in different situations by measuring the ratio between inertial and viscous forces. At low Reynolds numbers, flows tend to be domi ...
model data to realistic values were avoided.


Specifications


References


Notes


Bibliography

* * {{Bristol aircraft 1920s British experimental aircraft Type 092 Aircraft first flown in 1925 Biplanes