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Aviation History
1952
1952 - 2281.PDF
FLIGHT, 22 August 1952 213 7. 8. 9. 10. 11. 12. 13. 14. 15. Fresh-air intake Cabin blower (two-stage) Jet pump (ground only) Silencer Spifl valve (for mass-flow con trol) Dump valve (to off-load blower) Relief valve After-cooler Cooling air flap (for 8) Pressure test connection (3 in.) Filter Throttle valve (for heating control) Refrigerator valve (by-pass) Refrigerator (free running) Refrigerator cooler 16. 17. 18. 19. 20. 21. 22. 23. CI. C2. C3. C4. C5. C6. C7. C8. Cooling flap (for 15) (coupled to 13) Ground operating fan Direct ventilation valve Water separator Non-return valve (main air supply) ^Individual cold Non-return / «rsupply-port OUTER ^NACELLE INNER OvNACELLE Non-return l | only Recirculating fan (with n.r.v.) Supply to gearbox cooling Alternator (outer nacelle) Rectifier (outer nacelle) Jet pump (ground operation) for C3 Air intake Alternator (inner nacelle) Rectifier (inner nacelle) Spar ventilation supply Schematic diagram of port wing and fuselage installation of cabin air conditioning system. The starboard wing installation is, to all intents and purposes, a duplicate. THE BRITANNIA... main oleo leg carries a bogie beam pivoted so that, prior to retrac tion, the wheels can be swung up to a position in which the com mon plane through the axles is substantially parallel to the axis of the leg. Inthe landing condition the bogie is free to pivot through about 15 deg at low angular velocity, but is fitted with a damper to prevent the more rapid oscillations. Another ingenious feature of the design is that the disc-type brakes are articulated to a torque- reaction linkage whereby full compensation is provided and load transfer to the front wheels thus neutralized. The main tyre pressure, incidentally, is 125 lb/sq in. The attack made by Mr. Russell's design team on the problem of primary flight-controls was, perhaps, not uninfluenced by the Brabazon studies, if only in going full circle and coming to the conclusion that (for the Britannia, anyway) all the immense com plication of powered-control systems in the modern manner was just not wortr .while. So, on the basis that tabs have been used both for trimming and servo purposes for a long, long time, and their habits are now fairly well understood, it was reasoned that the most simple, effective and probably most efficient way of moving the control surfaces was to fit them with servo tabs and connect the pilot's controls to the tabs rather than to the parent surfaces. (In this context, credit must be given to Mr. D. J. Lyons and his colleagues at the R.A.E., for the initial develop ment of the servo-tab system as a primary control-actuation medium.) This delightfully simple solution is, however, not without its drawbacks; for example, so far as stick forces are con cerned, the hinge moments are much too small to serve adequately as sources of "feel" for the pilot. A method of introducing the requisite degree of feel had therefore to be evolved, but here again the system devised has the attraction of essential simplicity. In brief, proportional feel has been introduced by incorporating torsion springs in the control transmission linkages, the exertion of the springs being modified by a pitot system to compensate for flight speed. The artificial-feel system on the Britannia does, in fact, give the pilot an ideal stick force per degree of control-surface displacement, and this stick force increases proportionately with increase of speed. As already mentioned, the system was flight- proven as long ago as October, 1950, on a modified Type 170 Freighter. It would seem not unlikely that in its flight-control system, as in other aspects, the Britannia may well set a new standard of aircraft practice. The cabin atmosphere conditioning system is remarkably (Above) Access door to under- floor freight hold, showing hinge detail and pressurization seal. (Above, right) Layout of control transmission torque shafts and gearboxes in fuselage tail-cone. Before the main undercarriage is retracted, the bogies are swung upward parallel to the o/eo legs.
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