Dowty Ducted Propulsor
| Dowty Ducted Propulsor | |
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| Type: | Experimental airplane |
| Design country: | |
| Manufacturer: |
Dowty Rotol Ltd. / Britten-Norman |
| First flight: |
June 10, 1977 |
| Number of pieces: |
1 |
The Dowty Ducted Propulsor is an experimental aircraft from the British aviation accessories manufacturer Dowty Rotol Ltd., which is based on a Britten-Norman Islander .
history
Dowty Rotol, best known as a manufacturer of aircraft propellers, carried out studies to reduce noise emissions from propellers on a converted Britten-Norman Islander in the 1970s . The first approach with increasing the propeller diameter and a gearbox to significantly reduce the speed was soon discarded because the ground clearance of the propeller was insufficient and the chassis height was too high. Instead, it was decided to investigate the use of a ducted propeller with a large number of blades as a drive. In addition to reducing noise, this configuration was also expected to lead to a significant improvement in performance.
In the spring of 1976 a test frame was set up in which the seven-blade ducted propeller with a diameter of 1.22 m was driven by a 300 hp (224 kW) Continental IO-520 piston engine. The intended goal was to achieve a thrust of 5.38 kN (1200 lb st), which was even exceeded with 5.56 kN on the first runs. The sound level should not exceed 65 dB at a distance of 305 m (1000 ft) , it reached 62 dB. The engine cooling as well as the vibration behavior could be improved. The flow of cooling air and the engine exhaust gases were captured in the outlet of the engine nacelle and generated additional thrust.
In autumn 1976, a Britten-Norman Islander (license number 5Y-AMU) previously approved in Kenya was selected as a suitable test vehicle, whereupon the necessary modifications were made at Miles-Dufon in Shoreham . The aircraft was then re-registered with the appropriate registration G-FANS. The modifications included relocating the IO-540 engines to booms and coupling them directly to the adjustable seven-blade propellers. These received large hub caps, a casing and six solid blades located in the downstream flow to smooth the flow. The external impression of the engine nacelles was strongly reminiscent of the appearance of turbofan engines . The maiden flight in this configuration took place on June 10, 1977 in Shoreham with Neville Duke at the controls.
At full power, the 1.22 m propeller only had a blade tip speed of 172 m / s compared to 287 m / s on the original drive with a diameter of 2.03 m. The goal of a significant reduction in noise emissions was also achieved. It is not known why the investigations were ultimately not continued.
Whereabouts
On November 17, 1983, the machine was again registered with the standard drive as G-HGPC, on April 3, 1989 it was canceled and sold to Guyana (code 8R-GGU).
literature
- John WR Taylor (Ed.): Jane's All The World's Aircraft - 1978-1979 , McDonald and Jane's Publishers, London, 1978, pp. 711 f.