FIRE EXTINGUISHING
20.
Before a fire extinguishing system is operated, the engine must be stopped to reduce the discharge of flammable fluids and air into the fire area. Any valves, such as the low pressure fuel cock, that control the flow of flammable fluid must be situated outside the 'hot' zone to prevent fire damage rendering them inoperative.
21.
After a fire has been extinguished, no attempt must be made to start the engine again as this would probably re-establish the fluid leak and the ignition source that were the original causes of the fire. Furthermore, the extinguishing system may be exhausted.
22.
The extinguishant that is used for engine fires is usually one of the Freon compounds. Pressurized containers are provided for the extinguishant and these are located outside the fire risk zone. When the relevant electrical circuit is manually operated, the
extinguishant is discharged from the containers through a series of perforated spray pipes or nozzles into the fire (fig. 14-4). The discharge must be sufficient to give a predetermined concentration of extinguishant for a period that may vary between 0.5 seconds and 2 seconds. The system is generally one that enables two separate discharges to be made.
ENGINE OVERHEAT DETECTION
23.
Turbine overheat does not constitute a serious fire risk. Detection of an overheat condition, however, is essential to enable the pilot to stop the engine before mechanical or material damage results.
24.
A warning system of a similar type to the fire detection system, or thermocouples suitably positioned in the cooling airflow, may be used to detect excessive temperatures. Thermal switches positioned in the engine overboard air vents, such as the cooling air outlets, may also be included to give an additional warning.
圖14-4 一種典型的滅火系統
羅爾斯-羅伊斯公司
“寶石”(Gem)2發動機
Rolls - Royce Gem 2
“巨蟒”（Pyghon）發動機是從ASX軸流渦輪噴氣發動機發展而來的，它于1943年4月進行了首次試車，1944年其
推力達2800磅，增設螺旋槳減速器后，該發動機產生了3600軸馬力和1100磅推力，被稱之為ASP。重新命名為“巨蟒”后，它投入使用，用作斯特蘭公司的“飛龍”（Wyvern）S4渦輪螺槳戰斗機的動力裝置。
The Python was developed from the ASX axial-flow turbo-jet which first ran in April 1943 and was producing 2800 lb thrust by 1944. With the addition of a propeller gearbox the engine produced 3600 shp plus 1100 lb thrust and was known as the ASP. Renamed the Python it entered service as the power plant for the Westland Wyvern S4 turbo-prop fighter.
阿姆斯特朗·西德利公司
“巨蟒”發動機
Armstrong Siddeley Python
15: Thrust reversal
第十五章 推力反向
Contents Page
Introduction 159 Principles of operation 160 Clamshell door system Bucket target system Cold stream reverser system Turbo-propeller reverse pitch system 緒言
1．現代飛機的剎車是十分有效的，但在潮濕、結冰或被雪覆蓋的跑道上，這種有效性則可能會因飛機輪胎和跑道間的附著力損失而降低。因此需要另一種方法在規定的距離內將飛機停住。
2．縮短飛機在干燥和濕滑跑道上著陸滑跑距離的一個簡單而有效的方法是將排氣流反向，這就是利用發動機動力作為減速力。推力反向曾經被用來在飛行中降低空速，但在現代飛機上用得并不普遍。不用反推力與利用反推力的飛機著陸距離之差異示于圖15-1。
3．在高涵道比(風扇)發動機上，反推力是通過將風扇(冷氣流)氣流反向而實現的。由于發動機大部分推力是由風扇產生的，所以沒有必要將排氣流(熱氣流)反向。
目錄
緒言
工作原理
哈殼形門系統
戽斗式盾牌系統
冷氣流反推器系統
渦輪螺槳反槳系統
結構和材料
Construction and materials 166
INTRODUCTION
1.
Modern aircraft brakes are very efficient but on wet, icy or snow covered runways this efficiency may be reduced by the loss of adhesion between the aircraft tyre and the runway thus creating a need for an additional method of bringing the aircraft to rest within the required distance.
2.
A simple and effective way to reduce the aircraft landing run on both dry and slippery runways is to reverse the direction of the exhaust gas stream, thus
using engine power as a deceleration force. Thrust reversal has been used to reduce airspeed in flight but it is not commonly used on modern aircraft. The difference in landing distances between an aircraft without reverse thrust and one using reverse thrust is illustrated in fig. 15-1.
3. On high by-pass ratio (fan) engines, reverse thrust action is achieved by reversing the fan (cold stream) airflow. It is not necessary to reverse the exhaust gas flow (hot stream) as the majority of the engine thrust is derived from the fan.
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