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Aviation History
1949
1949 - 1418.PDF
182 FLIGHT AUGUST ISTH, 1949 Zero Reader Air Experience of Sperry's New Flight Instrument : Simplified Presentation for Flying, Navigation and Landing Approach " WORK on the instrument known as the Sperry ZeroReader has been proceeding for many months onboth sides of the Atlantic, and quite shortly the '' streamlined " production version of the equipment is ex- pecfed to emerge. It will be the result of the combined efforts of engineers and the many pilots who have had air experience of experimental and prototype equipment; the indications are that it will be very well received by all pilots: MacArthur Field, north of New York, has been the centre of much of Sperry's experimental flying. -:. -' \ Any device which will simplify instrument flying, in- crease safety in bad weather and help to make traffic con- trol at main terminals more efficient is worthy of most careful consideration. We in this country are, of course, particularly concerned with the traffic-control problems and congestion over principal airports because of the re- markable progress made with the prototypes of our jet and turboprop airliners. The introduction into service of these advanced machines is to a great extent dependent upon arrangements which can be made for accepting them with- out delay at their destinations in all weather conditions. The only satisfactory way for operators to assess the value of such devices as the Zero Reader, which was developed with the above aims in mind, is to try them themselves; but a description and written experiences are likely to be useful as a basis for preliminary consideration. A week or two ago I was fortunate enough to be able to try out the Zero Reader (installed in an M.C.A. Avro XIX) both for general flying and for approach in conjunction with the London Airport I.L.S. Before describing my im- pressions or discussing the instrument, it might be well to give quick answers to three questions: (i) what is the Zero Reader? (ii) what does it do? and (iii) what does the pilot do with it? In order, the answers are: (i) It is a flight instrument with simple cross-pointer meter for the panel; (ii) it automatically pieces together the information provided by conventional instruments and presents the result to the pilot in the form of instructions on a simple, two-element indicator; (iii) the pilot is required only to maintain the centre spot on the inter-section of the crossed pointers. He steers spot-on to inter-section. -' . • By THE EDITOR The Zero Reader is provided with its own selector switch to control the information fed to the pointers, and it must be made clear that the indication given to the pilot is not how far he may be off a pre-set course (for example) or how much above or below selected altitude or glide-path he may be, but of what change of attitude he should make in order to regain his correct course and height. Expressed differently* the instrument tells him which way to fly—not, how much he is high, low or to port or starboard. Spot-on intersection means your j are "doing the right thing" even if the air- craft is making a 20 deg bank turn. In an article in Sperry scope, Mr. F. Glen Nesbitt, Appli- cation Aeronautical Engineer for Sperry in America, points out that there are only two things that can be done with an aircraft in flight: you can steer right or left, and you can go. up or down. Based upon this fundamental concept, the two pointers of the Zero Reader, one horizontal, one verti- cal, tell the pilot exactly where he should point his aircraft in order to maintain the desired altitude find direction. Mr. Nesbitt adds that for some years it has been possible to control flight automatically with the aircraft completely stabilized in smooth or rough air with the aid of the gyro- pilot, but it has now been established that it is not humanly possible for a man to fly an aircraft manually for extended periods under all weather conditions so well as the gyro- pilot can do it. It is not suggested that the Zero Reader can ever take the place of the high-performance gyro- pilot which is "destined to become an integral part of future high-performance aircraft," but for the first time, with the use of this instrument, the human pilot is pro- vided with an indication which permits him to fly and navi- gate an aircraft manually with a degree of accuracy and precision that approaches the performance of the automatic control. I might digress at this point to mention that some time ago it had been noted that, as indicated by localizer -flight recordings, a pilot flying manually and using the conven- tional cross-pointer meter could not achieve anything like the accuracy recorded during an automatic approach with an A. 12 gyropilot, even though the same information was provided for the human as for the automatic pilot. Re- 100' 200' 300' 400' CEILING 35 70 105 140 175 210 245 280 315 350 385 420 455 490 FULL SCALE IFLY RIGHT \ APPROX ALTITUDE 60 65 TO SEOONDS APPROX DISTANCE FROM TOUCHDOWN 0 1600 3200 4800 6400 8000 9600 11200 .800 2400 4000 5600 7200 «800 10400 100' 2001 300- 400" CEILING 0 35 70 105 140 175 210 245 280 315 350 385 420 455 490 XMTR 10 15 20 25 FULL SCALEFLY LEFT 35 40 45 50 55 FULL SCALEi FLY RIGHT I APPROX ALTITUDE 170 SECONDSMfiiTI APPROX DISTANCEFROM TOUCHDOWN 6 ' 1600 ' 3200 4800 ' MOO ' 8000 ' 9600 11200 800 2400 4000 5600 7200 8800 10400 100' 200' 300' 400' CEILING 0 35 70 105 140 175 2)0 245 280 1315 350 3851 420 455 490 FULL SCALEFLY LEFT 30 35 40 45 50 55 CULL SCALE rLY RIGHT I APPROX ALTITUDE 60 65 7|0. SECONDS APPROX. DISTANCEFROM TOUCHDOWN 0 1600 3200 4800 6400 8000 9600 11200 800 2400 4000 5600 7200 8800 10400 100' 200' 300' 400' CEILING 70 405 140 175 2(0 245 280 315 350 385 420 4S5 490 • G.P.XMTR FULL SCALEFLY LEFT APPROX ALTITUDE . -60~65—SCSIECONDS APPROX. DISTANCE FROM TOUCHDOWN 0 1600 3200 4800 6400 8000 9600 11200 800 2400 4000 5600 7200 8800 10400 (Above) I.L.S. localizer recordings made during an automatic approach with A. 12 gyropilot left), and during a manual approach with Zero Reader (right). (Below) Two representative reproductions of I.L.S. localizer flight recordings taken during c manual approach using conven- tional instruments. Minimum ceiling authorized for use of U.S. by U.S. airlines at suitable airfields is 200ft.
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