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Aviation History
1950
1950 - 2083.PDF
FLIGHT, 7 December 1950 HELICOPTER PILOTING . . . instrument interpretation, engine handling, and night and blindflying. Furthermore, he had the almost automatic ability to move the stick and rudder pedals in the correct direction, whilst,on the theoretical side, he had a wide and practical knowledge of navigation, signals, theory of flight, meteorology and aviationlaw. These advantages far outweighed the slight disadvantages the fixed-wing pilot might have as regards some of the habitsingrained into him during his lime on fixed-wing aircraft. Some of the main differences which the fixed-wing pilot wouldencounter were (i) the throttle was not closed when the aircraft was descending, but was used to maintain constant r.p.m.; (ii)when maintaining a constant heading, the rudder-pedal position was not necessarily a neutral one; (iii) the helicopter angle ofapproach for landing was steeper than that of the fixed-wing air- craft, and, when overshooting, it was rarely necessary to go roundagain, but was enough merely to reduced air speed; (iv) it was possible to reduce air speed to zero without the loss of controland lift which occurred in the fixed-wing aircraft. As to edu- cational and physical requirements, the lecturer did not believethat there should be any difference in qualification between the intending fixed-wing pilot and the intending helicopter pilot. Instrument Flying Of instrument flying, Capt. Fay stated that much fatigue couldbe eliminated and instrument flying made easier by careful positioning of instruments in the panel. In determining thesepositions, two factors stood out above all others, viz., the relative importance of the instrument in enabling the pilot to maintaincontrol, and the distance the eye had to move when obtaining the information from the dial itself. In the first case, it wasobvious that the artificial horizon should command a central position; in the second case, an instrument such as the rate-of-climb indicator, where the pilot was interested only in the extreme left-hand side of the dial, should be somewhere on theright-hand side of the panel—in this way an unnecessary move- ment of the eye right across the face of the dial would beeliminated. It was worth while to review how helicopter flight, as it appliedto instrument flying, differed from that of fixed-wing aircraft: (i) The helicopter had a pendular swing, mainly longitudinal,under the rotor, thereby making control movements somewhat more complex than those required in fixed-wing aircraft; (ii) dueto the pendular swing, and for other reasons, the helicopter was markedly unstable; (iii) there was a time-lag in response tomovement of the main control, i.e., the cyclic-pitch stick; (iv) the attitude of the fuselage often bore little relation to theflight-path of the aircraft; (v) as compared with the fixed-wing machine, the helicopter had an extra flying control, the collectivepitch-lever; and (vi) a change of power meant a change of torque and, therefore, a tendency to swing in the yawing plane. After dealing with the various instruments in detail, Capt.Fay went on to examine the reasons why at present it was not practicably possible to carry out normal manoeuvres at speedsbelow 40 m.p.h. under instrument-flying conditions with the normal instruments. (1) More control movements were neces-sary for precise flying, and the tendency to over-control in- creased. (2) There was a marked increase in possible differencesbetween fuselage attitude and the flight path; the correlation of the artificial horizon, rate-of-climb indicator and the A.S.I, inorder to obtain a mental picture of the flight-path was not possible when these differences were too marked. (3) Thedirectional stability of the helicopter decreased as speed fell, and there was no instrument which could tell the pilot in whichhorizontal direction the helicopter was moving through the air. (4) Although the effect w?is momentary, a gust tended toproduce a relatively large change to the indicated air speed. (5) In slow-speed descents, when the angle between the fuselageand the flight-path was greatly increased, the present A.S.I, became inaccurate, because the pitot head was not facing directlyinto the airflow. (6) Translational lifit was lost at slow speeds, and an accurate and immediate indication of changes of motionin the forward plane was required by the pilot: this was not given by the present type of fate-of-climb indicator, where thestatic vent could be adversely influenced both by rotor down- draught and the motion of the( fuselage through the air. (7) Inforward, or near-forward, powered descents, considerable dis- turbance was made when the helicopter was flying through itsown down-draught. In view of these and other matters, some requirements whichhelicopters would need to enable them to be flown by reference to instruments at slow speeds could be laid down: (1) Thehelicopter should have a good measure of stability about all three axes at slow speeds and when hovering. Fewer controlmovements would then be necessary, gusts would have less effect on the helicopter as a whole, and the consequences of the 519 turbulence encountered in vertical powered descents would notbe so great. (2) There should be an indication of the helicopter velocity relative to the air in the horizontal plane; indicationshould also be given of any tendency of the helicopter to change direction and speed. In the U.S.A., a system whereby theangle of tilt of the plane of the rotor disc relative to the horizon was measured continuously and indicated to the pilot hadbeen used with some success. (3) The accuracy and sensitivity of the rate-of-climb indicator as fitted to helicopters neededto be increased. These were the primary requirements, but one or two otherscould be added, especially when helicopters would be required to carry out blind approaches: (i) The helicopter should haveone less control—if the throttle and collective-pitch lever could be combined the pilot would have a less exacting task; (ii) aradio altimeter should be fitted; and (iii) there should be an accurate indication of translational motion relative to the ground—the lecturer visualized this last 7named as a form of DeccaFlight Log. The ways in which night flying of helicopters differed fromnight flying in fixed-wing aircraft were mainly concerned with the approaches and landings to small sites as opposed to largeairfields. As a bare minimum, the pilot required to see the ground sufficiently to take off and hover prior to the climb-away. The starboard navigation light gave enough illumination for this purpose. However, it was not always desirable to dothings the hard way, and basic ground equipment should include the provision of lights strong enough to enable the texture ofthe ground to be seen reasonably well when hovering at a height of 50ft. Ths sequence of taking off and attaining a normalclimb should be as follows: after leaving the ground, a verticil climb should be carried out to a height of 50ft., the cyclic stickthen being pushed forward and a translational climb at normal climbing speed begun. In order to land easily and safely at night, the pilot mustknow the wind direction; he must be able to see the ground, preferably with the aid of lights on the ground and by usingthe aircraft lighting; and he must be able to obtain from the ground lighting an indication of the horizon so as to enablehim to retain the aircraft level laterally when not looking at his instruments. In the case of engine failure in a single-engined helicopterat night, it was necessary for the pilot to see and choose a landing area and then to be able to touchdown visually. Both of theserequirements pointed to the need of parachute flares. Should the need arise for a landing to be made in an unlit field atnight, the parachute flares could be used for selecting a field and, if possible, for augmenting the aircraft landing lightsduring the approach. The main landing light should be a spot- light and should be adjustable in the fore-and-aft plane. Forthe touchdown, a lamp with a wider and diffused arc was of assistance. AWARDS TO H.P. APPRENTICES A IR MARSHAL SIR EDGAR LUDLOW-HEWITT (chair-^* man of the board of governors, College of Aeronautics, Cranfield) and Dr. Richardson, Principal of the NorthamptonPolytechnic, were guests at the recent annual prizegiving to Handley Page technical apprentices. Sir Edgar said that while young men should learn to in-vestigate and analyse special problems and so learn to con- centrate their efforts towards a specific objective, they shouldguard against becoming too narrow in their outlook. He was sure that the man with the broadest knowledge was the bestspecialist. Dr. Richardson spoke of the close co-operation which existedbetween the Polytechnic and Handley Page, Ltd., and said that over a hundred apprentices attended either part-time dayor evening classes. Sir Frederick Handley Page stressed the value of workshopexperience to the aeronautical engineer. An appreciation of the shops' point of view and the practical problems met therewas invaluable to the would-be designer and indispensable to the production engineer. In a good apprenticeship scheme,theoretical studies and planned practical work must be. complementary. Recipients of prizes and certificates were as follows: —Final Year.—E. L. Hassell (B.Sc, 2nd class hons.). Fourth Year.—J. Cownie (degree course), A. Creak (Higher NationalCertificate"). Third Year.—B Campion (B.Sc., 2nd class hons.), A. Gibbs (degreecourse). Second Year.—G. Jones (degree course), P. Jaffray (Ordinary NationalCertificate, distinction in all subjects). First Year.—K. Noble and A. Lynne (degree course).Special Prize (for good work by a trade apprentice, now up-graded to technical apprentice).—E. Martin. Certificates (on completion of five years' apprenticeship).—E. Hassell,D. Brown, P, Burton. G. Harrison. J Rowles, E. Berg, C. Yeowart.
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