|Object Type:||Control/Data Entry|
|Object Name:||Autothrottle Control Unit|
|Year of Manufacture:||1966|
|Location:||Archive Object Store|
Throttle Dual Controllor
In addition to the usual modern autopilot facilities, the VC10 autopilot provides Mach-number and IAS locks, and adjustable datum for the height, Mach and IAS locks; automatic throttle control of airspeed on the approach; automatic flare-out control of the pitch channel; and yaw stabilization. The automatic throttle control is for use only at low speeds, and it can be used under manual control as well as under the autopilot. A friction coupling in the autothrottle drive to each powerplant control linkage enables the pilot to override the system manually without electrically disengaging.
The autothrottle system is a dual system, either half of which can be engaged independently of the autopilot and can be used with either autopilot. The pilot's instinctive disconnect button will, however, disengage the system in use.
The throttle system drives the four throttle levers and controls the engine thrust in accordance with the required speed dialled on a digital counter located on the throttle dual controller. The Autothrottle Dual Controller is a single panel unit mounted on the flight deck centre console. It carries the switches and controls necessary for selection and engagement of the dual throttle system (System no. 1 or No. 2)
The unit is also marked V.A.A.S. No 202(ET)
From the early days of the company it had been hoped to enter the civil aircraft flight control field, in order to reduce dependence on military projects, The opportunity to take this step came in the late 1950’s with the planning of the Vickers 'VC 10' for which Elliott Brothers secured an order to provide a complete automatic flight control system. From the outset, the 'VC 10' system was planned to make provision for fully automatic landing of the aircraft. For certification ever to be possible an extremely high standard of reliability was essential, and even in the case of failure of the equipment it was a requirement that the aircraft must not be subjected to violent manoeuvres. After a detailed study of possible alternatives, the solution chosen was to duplicate the whole of the major system, one half to be operative while the other was to be 'standing by', with a changeover mechanism of the utmost reliability to permit instant switching from one to another. By 1960 the basic development was substantially complete and the requirements for automatic landing were being explored in detail with full 'autoland' capability available from January 1963. Successful development of the 'VC 10' system resulted in the opportunity to supply broadly similar equipment for the British Aircraft Corporation 'BAC 111', which has been produced in substantial numbers. The automatic flight control system of the Standard and Super VC10 was designed to be capable of development to full blind landing. To meet this requirement the system had to be capable of failure survival and this includes associated services such as power supplies and flying controls. The method of autopilot failure survival chosen was to provide two monitored systems which are fail soft, i.e. there is negligible aircraft disturbance after a failure. Only one autopilot is used to fly the aircraft, and the two systems, including power supplies, are completely independent. Each autopilot has a comparison monitor which detects faults and, in flight, will disconnect the system if these faults are likely to lead to dangerous conditions. For autoflare the system provides for automatic changeover to the second monitored autopilot system, in the event of fault in the first. Under these conditions the second autopilot is primed and ready to take over. If for any reason the monitoring system fails to prevent an autopilot runaway, the control movement is limited to a safe amount by the yielding of a torque-limiting spring. Many of the needed components were already present in the autopilot fit on the Standard VC10s, to achieve the autoland capacity the system on the Super received some additional items. The system, supplied by Elliott Brothers (London) Ltd, was based largely on components of the well-proved Bendix PB-20 autopilot, made under licence by Elliott, and interchangeable with American built components as installed in Boeing 707s. However, the system as a whole i.e., the dual autopilot concept was novel, and designed entirely by Elliott.