Hillson Bi-mono
The Hillson Bi - Mono was an experimental aircraft of the British manufacturer Hillson from the 1940s. The aim of the investigations was to determine the configuration that allowed to keep the wing loading at startup as low as possible. For this purpose, the starting should be carried out as a double -deck and the upper deck are discarded after launching. The "Bi- mono" is still the only aircraft became known, were performed with the proven such attempts.
History
Background
The efforts of the builders in the late 1930s was to increase the efficiency of aircraft, primarily for military use by a reduced power to weight ratio ( aircraft weight per kW engine power ), or by improving the aerodynamics.
Another limiting factor in increasing the flight performance, especially the control of high wing loads at the start turned out. Between the wing loading and the start line is a linear relationship, so an increase of 100 N / m leads to an extension of the take-off distance of about 21 m. The high wing loading in the 1930s resulted not least due to the inefficient engine piston engines, since a large amount of fuel had to be carried at startup.
As a remedy, so different measures such as piggyback aircraft or rocket -assisted start ( MODERATO ) have been implemented. Noel Pemberton Billing, a British pilot, inventor and politician who was also known as the founder of Supermarine, represented a very exotic alternative approach with a discarding second hydrofoil. The wing should even come back with their own drive to Earth and can be reused. A similar concept, but with a droppable " loss wing " suggested WR Chow before, as the factory director at the manufacturer of light aircraft " F. Hills and Son " was working in Manchester. After the outbreak of war he went to the Air Ministry approach to design a small, cheap, easy to build fighter plane, which should be able to operate from simple fields and roads and should be equipped with an ejectable for second wing.
Development
The Ministry rejected a promotion from though, but Hillson led the development continues on a privately funded basis. First, a scaled-down, but capable of flying manned version should be built. After 32 days, the construction work was completed for this purpose, and after only 72 days the Bi -mono -called model was completed and ready to fly. The first flight took place on 16 July 1941 PH Richmond at the wheel instead of Squires Gate aerodrome in Blackpool. The flight in the double-decker variant was accompanied by a Lockheed Hudson, who had two film cameras on board and so the dropping of the upper wing at a height of almost 1400 m ( 4500 ft) was able to document over the Irish Sea. The transition from slow - double for faster monoplane ran, according to the test pilots from a problem, only a gentle entering height loss of a few hundred feet was noted.
Further testing of
The machine was then the Royal Air Force handed over for official flight tests. In the first tests have an upper support surface is selected, which had a much larger range than the lower vane. This was then replaced by a surface that had with 6.1 m (20 ft) span the same as the lower wing. In the ground tests to verify the separation device and bungee cords were used that still held the upper wing when launched.
Since the result of the need for such a " Notjäger " was no longer viewed as urgent, and the full-scale model was not built. Only a Hawker Hurricane has been rebuilt as according to Hillson FH.40 and tested by the " Aeroplane and Armament Experimental Establishment" at RAF Sealand station from May 1943 flight. A drop of the second wing, however, was no longer performed. The experiments were subsequently updated in the sand, not least because of the in wartime is not responsible labor and the cost of producing a very short-lived disposable wing.
Construction
To the 200 hp de Havilland Gipsy engine payable Six constructed around the Bi -mono was designed as a low-wing monoplane. The structure consisted of welded steel tubes with wood moldings and a Sperrholzbeplankung. The lower clad with plywood wing had a single spar of wood, the flaps ailerons were hinged at one auxiliary spar. The fuel tanks were located in the wing leading edge between the fuselage and landing gear. The solid chassis had a rubber suspension.
Originally planned is to mount the upper support surface only in the cabin. After consideration of the forces due to the bending moments of the upper spar but then they decided to provide additional vertical V- struts, which connected the two main spars. The cabin itself is two vertical cylindrical pins that fit into corresponding pipe pieces on the wing, these recordings against rotation about the vertical axis fixed and also the horizontal forces from the air resistance were. This simple construction has made it impossible to use an electric or hydraulic release mechanism. Thus, a mechanical process has been developed, in which the V- struts remain during the release to the upper wing.