羅爾斯-羅伊斯公司
“飛馬”(Pegasus)發動機
Rolls-Royce Pegasus
羅爾斯-羅伊斯公司
RB108發動機
Rolls-Royce RB 108
The RB108 was the first engine to be designed specifically as a direct VTOL engine. First running in July 1955 the engine was sub-sequently thrust rated at 2340 lb, giving a thrust to weight ratio of 8.7:1. In addition to powering a variety of VTOL test rigs, the RB108 flew in a Gloster Meteor, the Short SC1 and the Marcel Dassault Balzac.
INTRODUCTION
1. Vertical take-off and landing (VTOL) or short take-off and landing (STOL) are desirable character-istics for any type of aircraft, provided that the normal flight performance characteristics, including payload/range, are not unreasonably impaired. Until the introduction of the gas turbine engine, with its high power/weight ratio, the only powered lift system capable of VTOL was the low disc loading rotor, as on the helicopter.
2.
Early in 1941, the late Dr A. A. Griffiths, the then Chief Scientist at Rolls-Royce, envisaged the use of the jet engine as a powered lift system. However, it was not until 1947 that a light weight jet engine, designed by Rolls-Royce for missile propulsion, existed and had a high enough thrust/weight ratio for the first pure lift-jet engine to be developed from it.
3.
In 1956 the Bristol Aero-Engine Company was approached by Monsieur Michel Wibault with a proposal to use a turbo-shaft engine and a reduction gearbox to drive four centrifugal compressors which would be situated two on each side of the aircraft. The casing of these compressors could be rotated to change direction of the thrust (fig. 18-1). The concept incorporated two original ideas i.e. the ability to deflect the thrust over the complete range of angles from the position for normal flight to that for vertical lift and a system where the resultant thrust always acted near to the centre of gravity of the aircraft.
2.1941年初，羅爾斯-羅伊斯公司當時的首席科學家格里菲斯博士(Dr.A.A.Griffiths)就設想過利用噴氣發動機作為動力升力系統。但是直到1947年羅爾斯-羅伊斯公司設計的用作導彈推進裝置的輕重量噴氣發動機才終于問世，并具有足夠高的推重比，使首臺純升力噴氣發動機能從它發展出來。
Vertical/short take-off and landing
3.1956年布里斯托航空發動機公司收到米歇爾 維博特(Michel Wibault)先生的一個建議，用渦輪軸發動機和減速器來驅動裝在飛機兩側的4個離心式壓氣機(每側2個)。這些壓氣機的機匣可以旋轉以改變推力的方向(圖18-1)。這一概念包括兩個原先的設想，即具有從正常飛行位置到垂直升力的整個角度范圍內將推力變向的能力，和一個使總推力總是作用在飛機重心附近的系統。
4. The principle proposed by M. Wibault was each side of the aircraft. A further development was developed by using a pure jet engine with a free to use the fan to supercharge the engine, exhausting power turbine to drive an axial flow fan which the by-pass air through one pair of swivelling nozzles exhausted into a pair of swivelling nozzles, one on and adding a second pair of swivelling nozzles to the
圖18-1 1956年米歇尓 維博特的對地攻擊旋翼飛機(方案)
離心式鼓風機
渦軸發動機
齒輪箱
4.M.維博特提出的原理得到了發展，即利用一臺帶自由功力渦輪的純噴氣發動機來驅動軸流式風扇，而該風扇向位于飛機兩側的一對可轉向噴管噴氣。由此更進一步的發展是利用風扇為發動機加壓，通過一對可轉向噴管排放外涵空氣并為發動機渦輪排氣系統增加第二對可轉向噴管。正是用這種方法研制出了第一臺涵道風扇升力／推力發動機(圖18-2中的“飛馬”發動機)。
圖18-2 升力/推力發動機
Fig. 18-2 Lift/Propulsion engine.
5．“飛馬”發動機用于“鷂”(Harrier)式垂自／短距起
落戰斗機(圖18-2)的經驗，導致了對短距起飛垂直降落實用技術的開發。利用這種技術，即使在短距起飛滑跑后，飛機機翼產生的額外升力與純垂直起飛的飛機相比較可大大提高飛機的商載／航程能力。垂直降落與短距降落相比具有若干使用方面的優點，所以這種降落方式得以繼續使用。
Vertical/short take-off and landing
提供動力升力的方法
6．盡管 “飛馬”發動機是西方世界中唯一服役的垂直／短距起落發動機，但還有若干提供動力升力的方法，例如：
(1)將排氣也即發動機推力偏轉(改變矢量方向)。
(2)使用專門設計的只提供升力的發動機。
(3)由發動機或一個獨立的動力裝置驅動遠離發動機的升力系統。
(4)旋轉發動機。
(5)對短距起落飛機而言，利用發動機引氣來增加機翼四周的環流，從而增加升力。
在幾種垂直／短距起落飛機方案上。都曾把上述方法中的兩種或更多種組合起來使用。
exhaust system from the engine turbine. In this way the first ducted fan lift/propulsion engine (the Pegasus) evolved (fig. 18-2).
5. Subsequent experience with the Pegasus engine in the Harrier V/STOL fighter aircraft (fig. 18-3), lead to the development of the short take-off and vertical landing (STOVL) operational technique. In this way the additional lift generated by the aircraft wing, even after a short take-off run, provided a large increase in the payload/range capability of the aircraft compared to a pure vertical take-off. Vertical landing had several operational advantages compared to a short landing and so was maintained.
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