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Aviation History
1954
1954 - 0867.PDF
2 April 1954 389 Sampling the Zero Reader and other Instruments in the Sperry Company's Anson The pilots' panel of the Sperry Anson is straight forward and neat in appearance, despite the variety of instrument types it contains. The Hind panels are the new B.O.A.C. type and the Zero Reader controls are placed centrally above the engine instruments. I.F.R. WITHOUT TEARS A SPECIAL Anson XIX is kept at Cranfield by the Sperry Gyroscope Co., Ltd., for use in testing and demonstrating their range of flight instruments. This range has in the past year been considerably extended, prin cipally to meet the changing requirements of modern air craft, both civil and military, and to keep abreast of these developments, two representatives of Flight recently sought permission to fly Sperry's Anson with a view to observing the results at first hand. Although the instrument panel of the average airliner, bomber or fighter has altered comparatively little in appearance, con siderable changes have been wrought in the "works" behind the panel. For instance, increasing use is now made of electrically driven gyros for high-flying or highly manoeuvrable aircraft. The object of this is to provide higher rotational speeds, to overcome the difficulty of obtaining sufficient air to drive a gyro at high altitudes and to allow the horizon gyro increased freedom within its gimbals. For civil aircraft particular emphasis is now laid on instrumentation which will as far as possible facilitate blind approaches. B.O.A.C., for instance, have chosen a new basic six-instrument blind panel for their new aircraft (particularly the Comet) and this has been installed and tested in die Sperry Anson. Perhaps the best idea of the signi Seance of such developments can be given by a straightforward description of the new equip ment installed in the Anson. We spent altogether two hours in the air trying out all the "gadgetry" and, besides being consider ably impressed by its efficiency, we had ourselves (as the saying goes) a whale of a time. The Zero Reader. The most striking item was the Zero Reader flight director. This is a remarkable instrument, and although it was described in some detail in an article in Flight of August 18th, 1949, we have no hesitation in describing it again. First, a number of modifications have been incorporated and, secondly, the principle of the instrument is initially difficult to grasp by those accustomed to the standard type of instrument indication. Basically, the Zero Reader is a cross-pointer instru ment of quite small diameter which accepts and co-ordinates information from a number of sources. This information it resolves into instructions to the pilot, who has only to maintain the two needles of the cross-pointer in the central position in order to perform the manoeuvre he has at any point selected. Flight guidance is obtained by adjusting the three switches on the con trol panel and setting the course selector, illustrated at the foot of this column. Take first the simplest condition, the maintenance of a straight and level flight-path. The upper switch on the panel is set to "flight instrument" and the pitch control to zero. The tramline pointer on the course selector is then set with the knob at lower left of the dial to the required heading. If the tramlines are set to 270 deg and the aircraft is heading 300 deg, the vertical needle of the Zero Reader will move to the left. The pilot applies left bank until the needle moves back to central. By keeping it central he will maintain a correct and reasonable angle of bank. As soon as the aircraft begins to close the desired heading the Zero Reader vertical needle will move gently to the right, and the pilot will follow it by taking off bank. When the needle has again settled on the centre the pilot will find himself flying straight on 270 deg. At a chosen height he can then switch the height lock, marked "ALT." on the panel, to "ON." The horizontal needle of the Zero Reader will then give him height and pitch attitude directions to supplement the heading direc tions of the vertical needle. If he is low the needle will swing up, and by pulling back on the stick he will bring it back to zero. As he reaches the correct height the needle will tell him to push The new B.O.A.C. blind panel (left) with C.L.2 Gyrosyn repeater and Zero Reader at lower right and centre. (Be/ow) The Zero Reader control panel and course selector referred to in the text.
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