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Aviation History
1953
1953 - 0513.PDF
The piston-engined Freccia (left) had fixed slots, slotted flaps, spring-tab ailerons, fences and spoilers when it first flew to prove the airframe, the Marbore jet had been fitted and it became the Sagittario (right) the wings were much cleaned-up. After Like some strange fish or reptile swallowing its prey, the Sagittario opens its mouth to give access to the Turbomeca Marbore of 840 lb thrust. In later prototypes the cockpit, fitted with a bubble canopy, will be moved forward behind the turbojet and over the wing leading-edge. up all the wing trailing-edge inboard of the ailerons, are power operated. At this comparatively early stage in the flight trials, the spoilers have been found to be effective and we are informed that manoevr- ability generally, and rate of roll in particular, are of a very high order. The test pilot also told us that the machine was particularly stable at high speeds, there being no tendency to "Dutch roll." The temporary tailwheel-arrangement was adopted simply to enable the aircraft to get into the air without delay. The wheel has a separate retracting system with its own individual lever. Being in the jet stream—though well back from the nozzle—the leg and tyre have been protected by heat-resisting metal fairings. The assembly is retracted rearwards by a hydraulic jack. For take-off the pilot opens up and the present heavy tail is airborne after about 1,000 yards. At this point the tailwheel is retracted and the loss of its drag and jet-spoiling effect then allows more rapid acceleration for another 500 yards, when the machine takes off and the main wheels are retracted. For landing all wheels are lowered—the tail wheel on the approach—and thus the run is rather long, due to the reduced hold-off angle of attack. The removal of the wing-mounted dive brakes, referred to earlier, followed the trial of the tailwheel as a brake. It was most effective for drag and thrust-spoiling, and proved to be excellently placed from the trim and structural points of view. Later, nose- wheel prototypes will probably carry their dive brakes in this position. The Marbore at present carries no airframe accessories, so a large ground-charged hydraulic reservoir is used. It is positioned ahead of the cockpit in the vacant bay existing, and can give power for two ups and downs each of the wheels and flaps. A hand pump in the cockpit (starboard-side lever) can be used for further operations or in emergency. A nautical-looking fuel cock of three-position twist type is fitted in the cockpit. The Marbore is started and closed-down on petrol, but operates on kerosine; the starting cycle is a two-phase auto matic one. The power-lever has a gated stop which looks after idling or, with stop out, gives a total cut-out. The fuel is all con tained in the fuselage behind the cockpit (in place of the S.7's second cockpit). It is believed that the present main air intake is not as efficient as it could be. The installation is, however, a quickly designed temporary one, and, as the photograph shows, it is unusually accessible. The underside of the fuselage behind the jet outlet is shrouded against heat, cold air being scooped in beside the engine and fed back between outer and inner under-skins. The Marbore has air-cooled bearings, the outlet pipe for which can be seen protruding in the centre of the jet outlet where it exhausts down the jet stream. The present Sagittario is heavy—some 4,500 lb —and the cockpit design is the same as that of the S.7. On subsequent lighter metal prototypes, of which there may be three, a bubble enclosure is to be fitted and the cockpit moved forward over the wing leading-edge. The fuel tanks can then be fitted mainly over the e.g. With the fitting of a nosewheel the mainwheel attachments will probably be moved back to the rear spar. One comes away from a first encounter with the Sagittario impressed firstly by its attractive appearance but more perhaps by the practical and economical short-cuts taken by its designers and constructors in their desire to get flying experience as quickly and cheaply as possible. M.A.S.
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