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Descriptions of the Super VC1O's Hydraulic, Electrical, Flying Controls, Fuel, Air Conditioning and Pressurization, Flight Systems, Radio, Electronics and Anti‐icing Systems. THE June 1962 issue of AIRCRAFT ENGINEERING contained a comprehensive engineering description of the Standard VC10 and one of the articles contained in that issue dealt with systems, testing and equipment. However, the systems were dealt with comparatively briefly and it is therefore the object of this article to describe the principal systems in greater detail. The systems of the Standard and Super VC10 aircraft are essentially similar and the following description is based on British Aircraft Corporation's descriptive engineering notes.

FOR a number of years now it has been evident that a successor to the well‐tried Vickers Viscount and Convoir 240/340/440 series was required. However, the big problem was to design an aircraft such that its economics and passengerappealweresub‐stantially better than the machines it would ultimately replace. Other important factors which had to be con‐sidered were improved reliability, easier and cheaper maintenance, higher standards of safety and means of reducing ramp times. Furthermore, the difficult choice of passenger capacity and cruising speed had to be made. Probably the easiest decision was to employ the twin‐engine configuration with the power plants placed in the now familiar rear position, one on cither side of the fuselage.

The hardware and software development of a remotely controlled hydraulic valve assembly is described. The valve becomes a dedicated server in a distributed control environment. The communication system is an Ethernet network supporting the UDP/IP communications protocol. A client/server application model is developed that allows a client to specify a desired control position for a valve spool. The solution is being proposed as an alternative to a formal fieldbus solution, where precision real‐time operation is not required. The performance of the valve is measured under different configurations considering both open loop and closed loop models. The justification for selecting the UDP/IP protocol is stated. The resulting hydraulic valve control system is efficient, accurate and flexible.

Electrohydraulic servos have been widely applied to the task of precisely positioning heavy loads. Common examples from the military field are radar antenna and rocket engine swivelling drives. In the commercial area large machine tool position controls are a prime example. Even with relatively substantial driving linkages, the inertia of these loads frequently results in low natural frequency of the output load‐driver structure. Very commonly this is combined with extremely small natural damping forces. Natural frequencies from 5 to 20 c.p.s. with damping ratios in the oder of 0·05 critical are typical. This combination of resonance with low damping creates a severe stability and performance problem for the electrohydraulic servo drive. Efforts to deal with this problem have centred on introducing artificial damping. In the past this has been done either by use of a controlled piston by‐pass leakage path or by use of a load force feedback path. The former technique is simple but wasteful with respect to power and inherently involves serious performance compromises. The latter technique can be arranged to be unassailable on theoretical grounds. However, it leads to severe system complication and large incremental hardware requirements. Questions of a reliability penalty are raised. A new technique has been developed which possesses all the performance advantages of load feedback without serious increase in complexity. Called Dynamic Pressure Feedback, this technique involves only a modification of servo valve component. It utilizes for feedback purposes the inherently high load forces developed as piston differential pressures, insuring reliable operation. The pressures needed are already available at the valve. No new hydraulic or electrical connexions are added. The performance advantages adduced for the Dynamic Pressure Feedback Servo Valve have been confirmed in carefully controlled comparative tests on a typical load system. Correspondence of test data with analytical prediction is good. A sufficient number of Dynamic Pressure Feedback Servo Valves have been produced on a pilot production line and installed in several applications in the field to insure producibility and design reliability.

THE Trident IE fuel system, designed to operate on cither kerosene or JP.4, has a straightforward layout with few controls. Five integral tanks (FIG. 1), comprising four in the wings and one in the centre section, give a total of 5,880 Imp. gall, of which 2,000 Imp. gall, are contained in the centre tank. (Total fuel capacity of the Trident 1C is 4,960 Imp. gall, with 1,160 Imp. gall, in the centre tank.) Each wing inner tank has slightly more than twice the capacity of the outer.

BEFORE BEING SELECTED as the design authority and manufacturer of the Concorde units, Dowty Boulton Paul had obtained considerable experience of electrically signalled control systems on the Tay Viscount aircraft in 1957, this being possibly the first aircraft to be controlled by a fly‐by‐wire system. In addition, multiplex actuator packs controlled by electric signals and operating on a majority voting system were tested in investigating their possibilities for fly‐by‐wire systems. The work on advanced designs of multiplex electro‐hydraulic actuator packs progressed in parallel with the Concorde unit design and at the present moment 15 actuators in three packs are being simultaneously tested in an endurance rig which is scheduled to run for 12,000hr. In addition three quadruplex packs are installed in a Hunter Mk. 12 aircraft at RAE Farnborough for flight trials.

FROM the outset it was decided that the P.1127 cabin conditioning system should be based on the boot‐strap air cycle system. Hot air from a bleed off the engine h.p. compressor would be processed in a heat exchanger‐Cold Air Unit (C.A.U.) system and delivered, cooled and dewatered, to the cabin. For cabin heating a controlled amount of hot air would bypass the heat exchanger/cold air unit assembly and enter the main supply pipe, thus raising the air temperature the required amount. Cabin temperature control would be automatic following an initial selection by the pilot, but he would also have the facility to override the automatic control if required.

THE COMPLEXITY of modern pressurisation and air conditioning systems for jet aircraft have led increasingly to the practice of selecting a single contractor to design and integrate all of the components into a compatible system tailored to the mission requirements of the aircraft.

FUEL SYSTEM GENERALTHE standard version or the F.28 has a conventional two‐tank fuel system with an integral tank in each outer wing section contained by the wing torsion box with a total capacity of 2,170 Imp. gal. or 17,200 lb. of fuel. The centre wing torsion‐box pro‐vides space for additional bladder type tanks with a capacity varying from 312 to 700 Imp. gal. or 2,460 to 5,500 lb. as desired.

THE airframe systems division of Lucas Aerospace are involved in producing the high lift and wing sweep control unit for which the design rights are shared with Microtecnica SpA who hold the contract.