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Aviation History
1954
1954 - 0868.PDF
390 FLIGHT I.F.R. WITHOUT TEARS the stick progressively forward to regain level flight attitude as he reaches the correct height. Thus it can be seen that with only two pointers the Zero Reader will give complete and easily followed instructions for pitch, roll and yaw. A turn on to a new heading can be carried out by resetting the tramlines to the new heading and following the instructions of the instrument. The application and taking off of bank, and the amount of bank to be applied, will be dictated by the vertical needle and there is no need to anticipate it as one must with standard instruments. In like manner a climb or descent of anything up to 10 deg can be selected on the pitch control at the left of me Reader's control dial. The only limitation so far is that a turn of more than 165 deg must be completed in two stages, i.e., by setting the course selector first to an intermediate heading and then to the final heading. It is possible to take off with the aid of the Zero Reader, simply by setting the runway QDM on the course selector and on the panel, setting the top switch to "FLIGHT INSTRUMENT" and selecting a suitable angle of climb in degrees on the pitch control. The vertical pointer only is used until climbing speed is gained and the pilot zeros the pointers and climbs away. It is literally as simple as that. A great variety of standard manoeuvres can be selected and flown on a Zero Reader by the use of the controls described above. In the air near Cranfield we found it delightfully simple and accurate. We had the great relief (and it must be even greater for a tired pilot) of knowing that, whatever the attitude of the aircraft, so long as the two needles were central we were doing what we had intended. We had not previously flown an Anson, but the Zero Reader made it seem like a familiar aircraft. In fact, it would be shooting no line to say that it was quite as easy to fly on the Reader as by the normal external visual references. We come now, however, to a function which may seem to be the Zero Reader's party trick, but which is in fact one of its normal duties. It guides even an uninitiated pilot through an I.L.S. approach so that his aircraft is accurately positioned for a landing in bad weather even though his experience of I.L.S. is extremely limited. We describe an "outbound" as opposed to an "inbound" pro cedure in order to illustrate all the positions on the Zero Reader selector switch. The first step is to home on the airfield and to arrive overhead at the height required for the initial stages of the landing pattern. The aircraft is then turned on to a reciprocal bearing of the I.L.S. runway (QDR). The Zero Reader height lock is engaged and the course selector set to the QDR. On such a heading the normal I.L.S. azimuth needle would give reverse indications, since it senses the blue and yellow sides of the beam regardless of the aircraft heading. The Zero Reader, however, is set to "LEFT." This ensures that correct signals are fed to the Zero Reader and, so long as the needles are correcdy crossed, the aircraft is either closing the beam outbound or is on it. During this leg, drift due to cross-wind can be assessed in the normal manner and compensated by offsetting the course selector. The amount of drift is noted for future reference. At a predetermined point after passing the outer marker (flash ing green light next to the I.L.S. indicator) the course selector is turned 45 deg right and the aircraft flown for the required time on the first leg of the procedure turn. The Zero Reader is switched to "FLIGHT INSTRUMENT." A 180-deg turn to port or star board is then accomplished in two stages with the course selector, and flaps and undercarriage lowered for landing. As the beam is closed the Zero Reader is reset to "RIGHT" to give the correct azimuthal directions for the QDM. With the height lock still engaged die Reader "zeros" on the beam and the course selector is set to the QDM corrected for wind drift. During our trial there was a cross-wind of some 20 kt, but we The instruments fitted in the cabin of the Sperry Anson: Top row, second C.L.2 repeater, H.L5 horizon gyro unit, C.L.2 master indicator; second row, H.L.8 air-driven horizon, gyro direction indicator, altimeter and A.S.I. Another A.S.I, is fitted below. had very little difficulty in settling on to the beam. We had previously tried an I.L.S. approach without Zero Reader, and although we had successfully completed the Service exercises on the aural T.B.A., we found it difficult in the bumpy conditions and with the strong cross-wind. When the horizontal needle of the I.L.S. indicator showed that we were intersecting the glide slope we switched the Zero Reader to "GLIDE PATH." This automatically disengaged the height lock and, with the required power adjustment, the Anson settled happily on to the glide path. With a blinding afternoon sun shining directly through the windscreen we kept heads well down and made a genuine instrument approach; and when we finally glanced over the nose at about 150ft we saw the runway stretched out before us, dead ahead and truly lined up. There would have been no difficulty in making the landing, but we selected the instrument's last control position, marked "OVERSHOOT." This has been incorporated to allow a pilot to overshoot on the Zero Reader without having to readjust suddenly at low level to normal six-instrument blind flying. It works extremely well. He simply has to keep the needles truly crossed as before, apply power, and raise flaps and undercarriage at suitable altitude; and when next he looks over the side he will find himself climbing smoothly away. He can then reset the Reader for the next move. This instrument is the obvious answer to fatigue in long I.F.R. flights. It is simple and accurate. Traces made by Sperry show that the smoothness of a flight-path held with a Zero Reader is very nearly the same as that held by an extremely accurate elec tronic autopilot. The human pilot using the Zero Reader becomes, in fact, the servo in an autopilot circuit. The importance which the airline companies attach to the instrument is shown by the fact that on the new B.O.A.C. instru ment panel the Zero Reader holds the central position. In fact, with the Reader, artificial horizon and gyro magnetic compass, the turn-and-bank indicator becomes a standby instrument; in Sperry's Anson the electric turn-and-bank indicator was provided outside the panel and at no time did we require to refer to it. The simplicity and accuracy of instrument flying with the Zero Reader enables the pilot to keep a constant monitoring check on all his other instruments. Gyro Magnetic Compass. The G.4.F (fighters) and G.4.B (bombers) will already be familiar to most Service pilots. The instrument supplies on a vertical face a constant indication of actual magnetic heading. No longer need heading information be obtained from the constantly swinging liquid compass and fed into a constantly drifting gyro D.I. This compass is both magnetic and gyro-stabilized. In all reasonable aircraft attitudes it indicates actual heading. There is no noticeable swing or waver, and the face itself is large enough to permit accurate course-holding to within extremely small limits. It functions, moreover in the "natural" sense; that is in a left turn the lubber line moves to the left round the dial, and vice versa. Being partially a gyr>' instrument it has, of course, limits (at plus or minus 85 deg ir pitch or roll). It may subsequently take a long time t< The Sperry Anson XIX, resplendent in blue finish, prickly with aeria<:. and static-discharge wicks.
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