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Aviation History
1964
1964 - 1953.PDF
1076 FLIGHT International, 25 June 1964 The arched windscreen and rather low-set side windows tend to restrict visibility sideways and upwards; but performance and handling are good power and 7,550ft a very respectable 234 m.p.h. Maximum range is 1,000 miles. So long as twin-engined torque—about which more later—can be kept reasonable, and providing the range works out no less than planned, the 360-6 should prove an extremely useful aircraft. Price is still unknown, but Sud are keenly aware that this is a dominant factor. But to return to the prototype, F-WLKE, which has now flown a total of around lOOhr, only 30hr of which have been calibrated, serious test-flying. This airframe has an empty weight of 2,5351b and gross weight of 4,1341b, allowing for five occupants, 1101b of baggage and equipment and 88 Imp gal fuel, giving a maximum range at 55 per cent power of 1,150 miles and a power : weight ratio of 11.5lb/h.p. The weights, power : weight ratio and fuel tankage are quite reasonable for this type of aircraft and the performance is certainly good. Wing structure is simplified by absence of engine nacelles: undercarriage track is wide and the spars cross the cabin well aft. The whole leading-edge is available for high-lift systems or de-icing should either be included in future develop- ment. At 29ft 6in, the fuselage is in fact quite short. The tailplane is close to the wing but well above it, of exceptionally large span and favoured by the end-plate fins. The elevators are located out- board of the rear propeller disc. Though the central fin has an aerodynamic function, it also serves to house the bell cranks carry- ing the elevator controls from the main fore-and-aft cable runs beneath the cabin floor. This fin is to be made thinner, and this and the removal of various drag-producing excrescences such as control surface position transmitters and brackets will further improve per- formance, so that the TAS at best cruising power should com- fortably reach the forecast 204 m.p.h. By virtue of having an engine at each end, the fuselage offers a constant width throughout the cabin area, producing in the Jupiter something of a "suitcase effect" which MATRA might well treat with respect when deciding on interior furnishing. In the proto- type, the width is adequate for two people side-by-side, but not the widest available. It probably compares with a Baron for width. The windows also provide much more restricted visibility than at first appears, and the Jupiter is frankly admitted to be virtually blind in a turn. This will definitely be altered in any production version. But the tandem engine layout has pushed the wing well back, allowing for a comfortable access door to be placed com- pletely ahead of the wing, where only a small step is required to make entry better than in any aircraft of this class. The two front occupants also sit completely clear of the wing leading-edge, so that they have virtually unrestricted visibility beside the nose and down to the ground. The Jupiter would cer- tainly be wonderful for map-reading. MATRA have achieved the best of both high-wing and low-wing worlds for the front occu- pants. The remaining passengers view will not be obscured by any engines and they should have quite a reasonable view past the leading-edge of the wing. Apart from overall geometry, the Jupiter's structure and aero- dynamics seem to be quite normal, with a noticeably washed-out wing and tips cut off square. The flaps are at the moment manually set to either 10° or 25°, but wilt be electrically actuated. The under- carriage is electrically driven, and has remarkably short extension and retraction times of respectively 2sec and 3sec. Brakes are hydraulic, at the moment actuated from a central pull-handle, but to be changed to toe-pedal operation. The rudder bar is to be replaced by pendant pedals. The nosewheel is steerable. Flaps are slotted and ailerons have inset hinges and their gaps are internally sealed by a rubber membrane. Engine cooling requires neither fan nor gills. Instrument panel layout is at present rather plain, but does provide space for a blind-flying panel of full-sized dials in "airline T" layout, on the left and a good deal of radio on the right. Space for a complete IFR radio package is to be provided in the centre, where the prototype's two columns of four engine instruments— r.p.m., intake pressure, fuel flow and triple secondary dials—at present make a hump in the coaming which badly interferes with forward'visibility. This too will be changed. I soon became involved in a discussion with Lucien Tieles, who engineered the Jupiter design with Andre Moynet, and test pilot Cormerais on the subject of control lever layout for tandem twins. It seemed to me that Cessna had missed the boat in this respect, by not carrying the tandem philosophy through to the control levers. Cessna admit that their original intentions went astray by the time all the "experts" had contributed their requirements, and that the original hope to make the Skymaster, for certification purposes, a "single-engined" machine had gone astray with them. MATRA are carefully considering the question and pondering three diff- erent layouts. Though the prototype has absolutely conventional paired levers, MATRA do hope to provide some instinctively "tandem" layout—even though this is very difficult within reas- onable limits of throttle-quadrant arc or console length. An effective compromise could be to place both throttles side-by-side with long levers, and to put a short pitch lever either side of the throttles with arrow-head knobs pointed appropriately aft and for- ward. In the prototype the rear-engine levers were wrapped in red sticky tape, because confusion had already caused an unintentional double-engine cut—though this is perfectly possible with a side-by- side twin as well. The Theory in Practice For the trial flight, Cormcrais proposed a climb to 9,000ft and a demonstration of stalls, which have so far been tested only in straight, unaccelerated flight. After that, he said, I could play with the Jupiter. We were only 801b below gross weight, with a large package of flight-test instrumentation in the rear cabin and full fuel. Engine starting produced some quite severe vibrations, because both engines seemed to start very rich on two cylinders. Noise level was difficult to judge because we wore earphones, but there was no soundproofing. I noticed that the elevator trim wheel was half "buried" in the cabin roof and so arranged that tail-down trim was applied by pulling the lower edge of the wheel rearwards. Though this is strictly speaking the natural sense, I tended to visualize the device as a complete wheel and therefore to move the lower edge forward for tail-down trim, in effect rotating the wheel rearwards. The Aero Commander trimmer is operated in this latter way; and so is the Baron's except that the wheel is at knee level. No two pilots are likely to agree on the correct sense of movement. The ride while taxying on Cannes' rough airfield was decently smooth and, though the front engine interfered slightly with forward view, this was no more than to be expected in a single-engined air- craft. Cormerais lined-up and took off southwards, climbing away over the sea at 112 m.p.h. and l,000ft/min in the 25°C ambient temper- ature. The a.s.i. was, incidentally, marked in km/hr and the v.s.i. in ft/min. At 3,000ft, slightly throttled back, individual cylinder-
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