Hillson bi-mono
| Hillson bi-mono | |
|---|---|
 3-side view with and without upper wing |
|
| Type: | Test aircraft |
| Design country: | |
| Manufacturer: |
F. Hills and Son (Hillson) |
| First flight: |
July 16, 1941 |
| Number of pieces: |
1 |
The Hillson Bi-mono was an experimental aircraft made by the British manufacturer Hillson in the 1940s. The aim of the investigations was to determine a configuration that allowed the wing loading to be kept as low as possible during take-off. To do this, the take-off should take place as a double-decker and after take-off the upper wing should be thrown off. The "Bi-mono" is still the only known aircraft with which such tests have been demonstrably carried out.
history
background
The endeavor of the designers at the end of the 1930s was to increase the performance of aircraft, especially for military use, by reducing the power-to-weight ratio (aircraft weight per kW engine power) or by improving the aerodynamics.
The main limiting factor in increasing flight performance turned out to be the control of high wing loads during take-off. There is a linear relationship between the wing loading and the take-off distance, so an increase of 100 N / m² leads to an extension of the take-off distance by about 21 m. The high wing loading in the 1930s was due not least to the inefficient piston engine, as a large amount of fuel had to be carried when starting.
Various measures such as piggyback aircraft or rocket-assisted take-off (RATO) were implemented as a remedy . Noel Pemberton-Billing , a British pilot, inventor and politician who was also known as the founder of Supermarine , advocated a very exotic alternative concept with a throwable second wing. The wing should even return to earth on its own and be able to be used again. A similar concept, but with a thrown-off "loss wing", was proposed by WR Chow, who was the factory director of the light aircraft manufacturer "F. Hills and Son ”in Manchester. After the outbreak of war , he approached the Air Ministry with the design of a small, cheap and easy-to-build fighter, which should be able to operate from simple fields and roads and should be equipped with a dropable second wing.
development
The Department declined funding, but Hillson continued development on a privately funded basis. The first thing to do was to build a scaled-down, but airworthy, manned version. The construction work for this was completed after 32 days, and after a total of only 72 days the model called Bi-mono was completed and ready to fly. The first flight took place on July 16, 1941 with PH Richmond at the controls from the Squires Gate Aerodrome in Blackpool . The flight in the double-decker variant was accompanied by a Lockheed Hudson , which had two film cameras on board and was able to document the dropping of the upper wing at an altitude of almost 1,400 m (4,500 ft) above the Irish Sea . According to the test pilot, the transition from the slow double to the faster monoplane went smoothly, with only a gentle drop in altitude of a few hundred feet.
Further testing
The machine was then handed over to the Royal Air Force for official flight tests. In the first tests, an upper wing was chosen that had a much larger span than the lower wing. However, this was then replaced by an area that had the same span as the lower wing at 6.1 m (20 ft). In the ground tests to check the separation device, rubber ropes were also used, which still held the upper wing in place after the drop.
As the need for such an “emergency hunter” was no longer seen as urgent, the full-scale model was no longer built. Only one Hawker Hurricane was converted accordingly as Hillson FH.40 and tested in flight by the Airplane and Armament Experimental Establishment at RAF Station Sealand from May 1943. However, the second wing was no longer released. The attempts subsequently fizzled out, not least because of the unreasonable amount of work involved in times of war and the cost of producing a very short-lived disposable wing.
construction
Constructed around the 200 hp engine de Havilland Gipsy Six, the Bi-mono was designed as a low-wing aircraft. The structure consisted of welded steel tubes with molded wooden parts and plywood planking. The lower wing, lined with plywood, had a single wooden spar, and the flap ailerons were hinged to an auxiliary spar. The fuel tanks were located in the wing leading edges between the fuselage and landing gear. The fixed chassis had a rubber suspension.
The original plan was to simply attach the upper wing to the cabin. After considering the forces that occurred as a result of the bending moments of the upper spar, it was decided to provide additional vertical V-struts that connected the two main spars. On the cabin itself there were two vertical cylinder pins that fit into corresponding pieces of pipe on the wing, fixed it against rotation about the vertical axis and also absorbed the horizontal forces from the air resistance. This simple structure made it impossible to use an electrical or hydraulic release mechanism. A mechanical process was developed in which the V-struts remained on the upper wing when released.
Technical specifications
| Parameter | Data |
|---|---|
| crew | 1 |
| length | 5.95 m |
| span | 6.10 m |
| height | 2.14 m (double decker) 1.95 m (single decker) |
| Wing area | 12.26 m² (double decker) 6.13 m² (single decker) |
| Wing profiles | Below: RAF 34, Above: Clark Y |
| Max. Takeoff mass | 881 kg (double decker) 840 kg (single decker) |
| Engines | A de Havilland Gipsy Six with 147 kW (200 PS) power |
See also
literature
- Philip Jarrett: Hillson Bi-mono (Nothing Ventured, Part 1) , in Airplane Monthly April 1990.
Individual evidence
- ↑ Jan Lesemann: Design of a quiet STOL aircraft by optimizing the main design parameters , p. 25. Online at server02.fb12.tu-berlin.de ( page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. as a pdf file
- ↑ Philip Jarrett: Hillson FH.40 (Nothing Ventured, Part 10). In: Airplane Monthly. January 1991, pp. 18-23.
