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Aviation History
1955
1955 - 0167.PDF
FLIGHT, 11 February 1955 ir- ,1*7 INTEGRATED FLIGHT SYSTEM Collins Two-Instrument System for Radio Navigation and I.L.S. Approach THE use of I.L.S. cross-pointers and visual radio-bearingindicators for instrument approaches and navigation hastended to complicate the task of instrument flying by increasing the numbers of dials to be watched. The indicators on these additional dials, furthermore, require interpretation by the pilot and call for added concentration which, often, he is ill able to afford. One remedy has been to develop instru- ments, operated by computed signals from several sources, that give the pilot visual instructions as to how to fly his aircraft to take up and maintain a selected flight path, whether this be along a radio beam or simply a certain path through the air. But many pilots prefer a combination of instructional and informative instruments, that is, they want to be told how to fly, while also being kept informed of their attitude and position. An excellent example of the plain instructional instrument isthe Sperry Zero Reader (described in Flight on April 2nd last year), while a method which provides both instruction andinformation for radio beacon navigation and I.L.S. beam-approach flying is the Collins Integrated Flight System, the subject of thepresent article. The Collins installation is produced by the Collins Radio Com-pany of Cedar Rapids, Iowa, and is used by Panagra among others. The American Sperry Gyroscope Company has alsoproduced its own integrated instrument system, which has been taken up by Pan American World Airways. Based on two instruments, called the course indicator and theapproach horizon, the Collins Integrated Flight System is intended to provide a means of semi-pictorial en route radio navigation,and also a complete presentation of all the information necessary to make an accurate and smooth I.L.S. approach. It wasdeveloped in an effort to reduce the number of instruments which a pilot now has to watch, both while flying a given course andwhile making an instrument approach. In I.F.R. conditions, for example, apart from flying the aircraft on the usual six instruments,he may be trying to listen to an aural range signal, use his R/T. and watch one or more radio direction indicators. And on aninstrument approach he will have to co-ordinate his flight instru- ments, the I.L.S. indicator—in all its jerky and wayward indica-tions—and his engine and utilities indicators. The Collins system gives him all his steering and attitudeinformation on two dials in such a way that, to quote the com- pany's brochures, he can feel that he is following a white linemarked on the ground. Instrument indications, particularly those of the steering needle, are given to him as control-movementinstructions rather than, as in conventional flight instruments, position-error indications. Apart from the two panel instruments the system consists of aremote vertical gyro, a gyro monitor (with small instrument-panel indicator), the steering computor, and its shock-resistant mount-ing. Besides this, the system requires a gyro-stabilized magnetic compass, a navigational receiver for V.O.R. and I.L.S. localizer, BY reason of their clarity in such a context, certain American naviga-tional terms are used throughout this description of a new pilot-aid. Thus "heading" (in England, "course") refers to the direction in whichthe aircraft is pointed in relation to magnetic north; and "course" (in England, "track") is the path followed, whether in relation to aradio reference or visually over the ground. a glide-slope receiver and a marker-beacon receiver, all part ofnormal aircraft equipment and produced by Collins (among others) except for the gyro-magnetic compass.The Integrated Flight System has appeared in four versions, FD-101 to 104, which differ from one another mainly in con-structional details. An exception is the FD-104, which is designed to be coupled with the Collins AP-101 autopilot for automaticI.L.S. approaches. The lightest of the systems is the FD-103, the total weight of whose four basic elements is 27.9 lb. The powersupply required is 27.5 v D.C., 115 v 400 c.p.s. and 26 v 400 c.p.s. Power consumption under operating conditions is 63 VA. There are two main instruments on the panel and one smallindicator, the gyro monitor. This shows by the movement of a needle whether the remote vertical gyro is fully erected andfunctioning properly. (The necessity for it is not universally accepted.) The course indicator (a 5-in dial in the FD-101 and102 and a 3-in dial in the FD-103) is a directional reference functioning as a compass repeater. In addition it supplies properlyorientated heading information and shows displacement in rela- tion to a V.O.R. radial or an I.L.S. beam. All markings arefluorescent yellow on a black background. The azimuth ring of the course indicator repeats the indicationof the aircraft gyro-magnetic compass, and the miniature aircraft in the centre of the dial and the lubber line in the "12 o'clock"position (both engraved on the instrument glass) show the aircraft heading at all times.The Course Indicator. The following description refers to the accompanying diagram. The course arrow (j) is set to thedesired omni-range or localizer course by turning the course selector knob. The course bar (2) and the instrument-glassminiature aircraft (3) serve with the course arrow to show the aircraft position and heading relative to the selected course. Asthe selected course is approached on a convergent heading, the course bar will gradually move into line with the course arrow.The short arrow (4) is the beacon "to-from" indicator. Thus, if a pilot wishes to take a bearing on an omni station,he tunes the receiver to it and rotates the course arrow until the course bar lines up with it. Noting the position of the to-fromarrow, he can read a magnetic bearing to the station. The heading marker (5) can be set to a desired magnetic heading by turningthe heading selector knob. It thereafter rotates with the azimuth ring. With the correct setting on the approach horizon (describedbelow) it is then possible to hold the selected heading by following the indications of the steering needle. The Approach Horizon. Basically, this instrument instructsthe pilot how to fly in order to turn smoothly onto a radio or magnetic heading or to hold such a heading, while keeping himinformed of his attitude. As shown in the accompanying diagram, (Left) The course indicator, showing (1) course arrow; (2) course bar; (3) miniature aircraft; (4) "to-from" pointer; (5) heading marker; and (6) lubber line. (Right) The approach horizon, with (1) steering needle; (2) "I.L.S./Heading" selector knob; (3) horizon bar, connected to (4) bank needle; (5) pitch bar; (6) pitch- trim adjustment knob; and (7) glide-slope pointer. Arranged for clarity, the indica- tions shown do not correspond to an actual flight condition. The "LOC" and "G.S." flags appear from under the bank scale at the top of the dial to denote failure of these two functions and also during en route navigation when "HDG" is selected.
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