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Aviation History
1951
1951 - 1506.PDF
3 August 1951 149 increase by three-quarters of an inch. Pressure is provided by two Godfrey Type-30 Roots blowers, each unit being mounted on the accessory gearbox at the rear of an inner pair of engines. As each gearbox can be driven by either of the engines in the pair, four-engine reliability is provided for the pressurization system. A Normalair automatic controller regulates pressure, and for initial tests the target is 4.1 lb/sq in, or an equivalent cabin altitude of 10,000ft at 23,000ft. Development of the gust-alleviation equipment is also proceeding well. Response measurements are being made in flight with the detector vane, while the rest of the mechan- ism is undergoing bench testing. The detector vane itself, of aerofoil section, may be seen protruding from the nose of the fuselage near the captain's station. It registers the effect of gusts a fraction of a second before they reach the mainplane, and the reaction is translated to the ailerons, the position of which will automatically be altered to counteract the effect of the gust, so lessening the strain on the mainplane when flying in rough weather. Anyone who studied Brabazon I closely on her previous visit to London Airport will now note that the large external mass-balances on the rudder and elevators are no longer fitted—an important visual indication of the progress which has been made with controls. The reduction in drag resulting from the removal of these balances is considerable, and the feel of the machine is said to be greatly improved. Indicative of the scale of components on tfie Brabazon is the fact that the weight saved by removal of the mass balances is equivalent to that of three passengers. » The gust detector vane, seen on the side of the cockpit. Investigation of response in flight has already commenced. Another experimental fitting seen earlier but now removed is the extended pitot head which projected forward of the nose to a point where the air was undisturbed by the passage of the aircraft. Its removal is understood to have facilitated the installation of a Decca Navigator. Air speed is now measured by the normal pitot heads. Even if one has inspected the Brabazon at close quarters before, its great size still comes as a surprise. This is par- ticularly true of the interior, the main saloon being reminiscent of one of the larger-type Nissen huts used as mess rooms on R.A.F. dispersal stations. As the eight paired-Centaurus start up, one by one, a dis- tant rumble, some vibration and a high-pitched drone can be detected. Taxying on runways is unusually smooth, and on take-off it was not possible to tell when the wheels left the ground. The engines have a throaty roar at take-off power, and the noise level is comparable with that heard in current airliners such as the Stratocruiser. When climbing and cruis- ing the sound is more subdued and rumbling. It is most impressive to walk forward along the length of the fuselage; to look out of the windows in each compartment and to see the wings get nearer, then to look down their vast gently-flexing span, to stand abreast the co-axial airscrews, and finally to see them recede until they appear to belong to another machine in formation behind. One notices the comparatively large aileron deflection used to control the aircraft and, during take-off and landing, the rather unusual movement of the three huge flap sections on each mainplane. These appear to be capable of moving independently and in the fully lowered position present a truly formidable braking surface. On its passenger demonstration-flight Brabazon I was taken on a circuit of London at about 175 kt I.A.S. and 2,075 r.p.m. for the Centaurus engines. The ride was smooth but, frankly, very little different from that experi- enced in any other large aircraft. Few passengers realised, probably, that the occasional slight shudder was the Braba- zon's way of reacting to rough air. The conditions were distinctly bumpy at times, although there was little to indicate this in the aircraft's stately progress. A wide circuit and very long approach was made on return to Heathrow, and once the wheels had slowly moved down, the speed was kept at around 130 kt. Touch-down speed at the medium weight was 100 kt with the tail far enough down (Left) An ' impressive composite photograph of the Brabazon, which monages to convey an idea of its immense proportions. (Above) The pilots at their controls: Mr. •'bill" Pegg and Mr. WalterGibb.
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