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Aviation History
1961
1961 - 0211.PDF
FLIGHT, 17 February 1961 211 JINDIVIK in Theory and Practice THIS journal's review of the world's target and drone aircraft,published on December 23, demonstrated the immense varietyof target vehicles and pilotless surveillance drones which are in intensive operation in the United States. There are now 22distinct families of such vehicles, many of them highly sophisticated craft equipped with all manner of photographic and instrumenta-tion systems, infra-red, radar and countermeasures equipment and a host of other devices. In contrast, if one excludes pilotless con-versions of obsolescent military aeroplanes, there is only one such vehicle in the entire British Commonwealth: the Jindivik. Shortly after the war the RAE issued a requirement for ajet-propelled target drone, and early in 1948 meetings were held between the Ministry of Supply and the Australian Departmentof Supply with a view to giving Australia the job of producing the vehicle required, to specification E.7/48. Eventually the specifica-tion was passed to the Government Aircraft Factory, at Fishermen's Bend, Melbourne, who have since been entirely responsible fordesign, development and manufacture. As described in Flight for April 25, 1952, the GAF first built apiloted version named Pika (aboriginal "flier"). This flew in October 1949, and was of great assistance in enabling a directcheck to be made on flight characteristics and the functioning of the control equipment. The first true target was the Jindivik("hunted one") Mk 1, powered by an Armstrong Siddeley Adder ASA.l rated at 1,0501b. The first was delivered to the embryonicrange at Woomera in November 1951, and flew in August the following year. The original order for six for use at Woomera waslater doubled, and the Jindivik Mk 1 became an effective opera- tional target at the Weapons Research Establishment in the winterof 1952-53. Its principal systems included a three-axis autopilot incorporating some Elliott Bros (London) Ltd and German equip-ment, remote-control equipment built by GEC and a telemetry system by McMichael. All these systems were evolved at theRAE Farnborough. In December 1953 GAF flew the Jindivik 2. The first trueproduction version, the Mk 2 is powered by a Bristol Siddeley Viper ASV.3, rated at 1,6401b and appreciably lighter and simplerthan the Adder. The whole aircraft was refined and simplified, and for the first time provision was made for special trials equip-ment to be carried. The airframe is fabricated from light-alloy sheet and standard sections. Although riveting is widely employed,stringers and secondary joints are almost entirely Redux-bonded, and extensive use is made of paper-honeycomb filling throughoutthe leading edges. The rear part of the fin (there is no rudder), together with the elevators, ailerons and simple flaps, have thinskins stabilized by axial fluting. Fuel is carried in a 63gal flexible cell in the centre fuselage above the wing and in integral wingtanks with a capacity of 16gal on either side. The flaps and landing skid are actuated pneumatically, but most services are electric, theengine driving a 6kW generator delivering at 27.5V. After undergoing extensive functional tests a Jindivik requiredfor a mission is wheeled out on its handling trolley, mounted on the cleverly designed trolley from which it takes off, towed roundto the down-wind end of the runway and lined up for take-off by optical means. By this time the aircraft is in the hands of theteam that will control and monitor it throughout its flight. At Woomera there is normally a "pilot," one or two "bats," and aminimum of about six tower operators, navigators and recording engineers. Jindivik is not flown from a joystick box like an anti-tankmissile, but via a radio-command system which biases the auto- pilot with a set of positive orders transmitted from buttons orswitches on a large panel. The command signal is transmitted in the form of two audio tones, which frequency-modulate a carrierwave. Eight different tones are available, and each command is represented by a unique pair of tones. There are thus a total of 28 tonal pairs available, but only 24 are used to transmit commandsignals. Of these, 18 are used for normal flying, and have such forms as CLIMB, SLOW LEVEL, FAST LEVEL, TURN LEFT, and so forth;the remaining six signals are used to control the operation of special trials equipment. The airborne receiver translates theseaudio tones into direct commands. Since it normally rejects any signal other than a pair of tones, the receiver cannot respond tomore than one command at any given time. For this reason, when the Jindivik is receiving command signals from, say, the pilot andone of the bats concurrently, it responds smoothly to the sampled demands from both.An air hose is brought up to start the engine by direct air impingement on the turbine. The engine is then checked at 8,600and 13,400 r.p.m. to assess response to its command circuit, the trolley being held back by a tie-strop anchored to the runway.For take-off, the strop connecting-pin is withdrawn and the Viper opened up to 13,400 r.p.m. As the Jindivik accelerates down the centre of the runway,lateral disturbances, such as might be caused by a cross-wind, are sensed by a displacement gyro (17 in the cutaway drawing)mounted on the trolley which governs a servo-mechanism steering the nosewheel. During the run the aircraft is locked in a nose-down attitude, so that the three wheels of the trolley are held firmly on the ground. This is essential to the achievement, by brakingthe wheels, of the high retardation which would be necessary if the Jindivik were to fail to unstick cleanly at the point of take-off.This point is reached at a speed of llOkt. Triggered by the airspeed circuit of the Jindivik, a "take-off" signal lowers theflaps, fires a brilliant flash bulb (1) on the front of the trolley, releases the lower bomb-slip catches (4) of the nose anchorageand puts the elevators in the fully up position. To assist the latter to rotate the aircraft, the tail is pulled down by the bungee cord(16), and the rising nose of the Jindivik extends the telescopic nose strut (6) to its fullest extent. When the strut reaches the limitof its travel it trips a microswitch which releases all three trolley struts, which are hinged and fold forwards under the pull of strongbungees (3). The same microswitch also triggers the circuit which puts on the Dunlop Maxaret brakes. The trolley quickly comes torest (or is caught in a net if the runway is short), while the Jindivik climbs away. Complex though it sounds, the sequence worksexcellently. Should anything go wrong, the pilot counts 3sec from seeing the 1 lOkt flash and, if the drone is not by then fully airborne,he applies the brakes. In most missions it is desirable to climb as rapidly as possibleand thereafter fly a "race track" closed circuit at a typical jet operating height. It is possible to select an optimum climb condi-tion by a single command signal, and at the desired height the Jindivik can be made to fly SLOW LEVEL or FAST LEVEL. It is thenavailable, in the right place and with the right performance, either to act as a "wide open" target against which early R & D missilesmay have a fair chance of success, or as an elusive and counter- measure-filled simulated enemy, better able to test the lethalityof an operational or near-operational weapon. In former days a target merely had to be a piece of hardware put in the sky forgunners to shoot at. A modern target has to carry a wide array of trials equipment, and this will be referred to in greater detaillater. It is, of course, possible for the Jindivik to be destroyed in flight,either by a warhead or by direct impact, but in the vast majority of flights the drone is at all times under positive control and isbrought back on to the runway. The final approach is quite a lengthy one, in the configuration LAND GLIDE at about 150kt. Thetwo bats controllers are aligned upwind on the runway centreline, and each controls the Jindivik in either azimuth or elevation (butnot both). Observing the approaching drone through graticule- equipped binoculars, they can maintain it exactly on the glide-
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