22.圖18-14表明了利用“襟翼吹氣” 形式來實(shí)現(xiàn)短距起落的一種方法。渦輪風(fēng)扇發(fā)動機(jī)具有一個齒輪傳動的變距風(fēng)扇和一個加大尺寸的低壓壓氣機(jī)，空氣從該壓氣機(jī)出口引出，再導(dǎo)入機(jī)翼后緣上的襟翼系統(tǒng)。變距風(fēng)扇使低壓壓氣機(jī)可作高轉(zhuǎn)速運(yùn)轉(zhuǎn)并因此能在寬廣的推力范圍內(nèi)保持高引氣壓力。這就在不同的飛行條件下獲得極佳的控制效果。
23.在許多情況下，有必要增大垂直/短距起落飛機(jī)的升力推力，因?yàn)樵谡ｏw行情況下，這種發(fā)動機(jī)的尺寸過大，其后果是與常規(guī)飛機(jī)相比，發(fā)動機(jī)重量和燃油消耗量都較大，升力推力的增加即升力加力可避免這種后果。升力加力可以通過許多不同的方法來實(shí)現(xiàn)：
（1）使用特殊發(fā)動機(jī)推力額定值。（2）在升力噴管燃?xì)饬髦腥紵＃?）使用引射器系統(tǒng)。
升力推力的增大
(升力加力)
194
發(fā)動機(jī)的特殊推力額定值
24.經(jīng)驗(yàn)證明額定推力的發(fā)動機(jī)結(jié)構(gòu)可在短時間內(nèi)提供高推力值而不降低發(fā)動機(jī)壽命。在地面效應(yīng)下運(yùn)轉(zhuǎn)和起飛降落動作需要不到15秒的最大推力，所以在這段時間內(nèi)使用短時間升力額定值是可行的。圖18-5表示了15秒短時間升力額定值允許的推力與2.5分鐘正常升力額定值允許值之間的比較的實(shí)例。
Vertical/short take-off and landing
增升的襟翼系統(tǒng)
Lift burning systems
26.
The thrust of the four nozzle lift/propulsion engine may be boosted by burning fuel in the bypass flow in the duct or plenum chamber supplying the front nozzles. This is called plenum chamber burning (P.C.B.) (fig. 18-16) and thrust of the by-pass air may be doubled by this process. This thrust capability is available for normal flight as well as take-off and landing and so can be used to increase manoeuvra-bility and give supersonic flight.
27.
The thrust of a remote lift jet can also be augmented by burning fuel in a combustion chamber just upstream of the lift nozzle (fig. 18-17). This system is commonly known as a remote augmented lift system (R.A.L.3.). The thrust boost available from the burner reduces the amount of airflow to be supplied to it and therefore reduces the size of the ducting needed to direct the air from the engine to the remote lift nozzle.
Ejectors
28. The principle of the ejector is that a small, high energy jet entrains large quantities of ambient air by viscous mixing and an increase in thrust over that of the high energy jet results. A number of projected V/STOL aircraft have incorporated this concept using either all the engine exhaust air or just the bypass flow.
引射器
28.引射器的原理是少量高能噴流通過與空氣的粘性混合而夾帶入大量的外界空氣，其結(jié)果是使推力增加，超過只用高能量噴流所能產(chǎn)生的推力。一些規(guī)劃中的垂直／短距起落飛機(jī)已采用這原理，它們或是使用發(fā)動機(jī)的全部排氣或只用外涵氣流。
高壓壓氣機(jī)
Vertical/short take-off and landing
圖18-17 遠(yuǎn)距增升系統(tǒng)
Fig. 18-17 Remote augmented lift system.
飛機(jī)的控制
29．垂直／短距起落飛機(jī)在起飛和過渡時的低前進(jìn)
速度不允許從飛機(jī)的正常飛行控制面產(chǎn)生足夠的空
氣動力，因此有必要利用下面所列的一個或多個控
制俯仰、橫滾和偏航的額外方法。
Vertical/short take-off and landing
圖18-18 反作用控制系統(tǒng)
Fig. 18-18 Reaction control system.
AIRCRAFT CONTROL
29. The low forward speeds of V/STOL aircraft during take-off and transition do not permit the generation of adequate aerodynamic forces from the normal flight control surfaces, it is therefore necessary to provide one or more of the following additonal methods of controlling pitch, roll and yaw.
Reaction controls
30. This system bleeds air from the engine and ducts it through nozzles at the four extremities of the aircraft (fig. 18-18), The air supply to the nozzles is automatically cut off when the main engine swivelling propulsion nozzles are turned for normal flight or when the lift engines are shut down. The thrust of the control nozzles is varied by changing their area which varies the amount of airflow passed. 發(fā)動機(jī)差動節(jié)流
31．這一控制方法用于布局合理的多發(fā)動機(jī)飛機(jī)上。快速響應(yīng)率對于將這些發(fā)動機(jī)用于飛機(jī)穩(wěn)定性和控制是十分關(guān)鍵的。通常有必要將差動節(jié)流和差動推力轉(zhuǎn)向起使用，以使飛機(jī)能進(jìn)行各個方面的控制。
自動控制系統(tǒng)
32．盡管駕駛員可以手動控制垂直／短距起落飛機(jī)但采用一些自動控制是有益的，特別是可以減輕駕駛員的工作負(fù)擔(dān)。駕駛員的駕駛桿以電子方式與計(jì)算機(jī)或安定面相連接，計(jì)算機(jī)從駕駛桿接收信號，將它們與從測量飛機(jī)姿態(tài)的傳感器來的信號相比較，自動調(diào)節(jié)噴氣反作用控制、差動節(jié)流或推力轉(zhuǎn)向以保持穩(wěn)定性。
反作用控制
30.該系統(tǒng)將空氣從發(fā)動機(jī)中引出并通過飛機(jī)的四個端點(diǎn)上的噴管排出(圖18-18)。當(dāng)主發(fā)動機(jī)可轉(zhuǎn)向推進(jìn)噴管轉(zhuǎn)入正常飛行或當(dāng)升力發(fā)動機(jī)關(guān)閉時，向這些噴管輸送的空氣自動被切斷。改變這些
控制噴管的面積就改變通過它們的氣流量，從而也改變了這些控制噴管的推力。
Differential engine throttling
31. This method of control is used on multi-engined aircraft with the engines positioned in a suitable con-figuration. A rapid response rate is essential to enable the engines to be used for aircraft stability and control. It is usually necessary to combine differ-ential throttling with differential thrust vectoring to give aircraft control in all areas.
Automatic control systems
32. Although it is possible for the pilot to control a V/STOL aircraft manually, some form of automation can be of benefit and in particular will reduce the pilot workload. The pilot's control column is electronically connected to a computer or stabilizer that receives signals from the control column, compares them with signals from the sensors that measure the attitude of the aircraft, and automatically adjusts the reaction controls, differential throttling or thrust vectoring controls to maintain stability.
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