FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1960
1960 - 0785.PDF
FLIGHT, 10 June 1960 793 1 Research into jet-lift by Short's flat-riser By the Technical Editor SINCE December 17, 1903, men have been more or less con-tent to fly their aerodynes by the reaction of the atmosphereon fixed or rotating wings, so that the conventional aerofoil is today virtually the sole source of lift in all the aircraft in currentoperation. In recent years it has been increasingly evident that the gas turbine would gradually open the way to new forms offlying machine in which powerplant and airf rame are so integrated that propulsion and lift become merely vector directions of thesame thing. The extent to which this integration can be effected is considerable, and aircraft more efficient or versatile than any-thing hitherto seen can now be drawn on paper and tested in tunnels. Nevertheless, the extent to which jet lift has been appliedin practice is very limited. We British may take some pride in the fact that the only fully jet-supported flat-rising aeroplane inthe world to have demonstrated complete transition is the SC.l, built in Belfast by Short Brothers & Harland Ltd and poweredby five Rolls-Royce RB.108 turbojets. In truth the SC.l cannot be regarded as more than a relativelycrude and elementary expression of the jet-lift concept; yet it is a vehicle which has already performed unique feats, and as aresearch tool its value has been very great indeed. Short & Harland produced the SC.l under contract to the Ministry of Supply, whoannounced that the company were engaged in such a project (then known as the PD.ll) on November 12, 1955. From the outsetthe Belfast firm have held prime responsibility for the entire air- craft, although collaboration with Rolls-Royce and, on the vitalautostabihzation and control systems, with the RAE, has been intimate. Although the programme has never had the priority which itdeserves, so that the rate of funding has undoubtedly hampered progress, authorization was made for two SCls (XG900 and 905).The first aircraft started taxying trials at Belfast in December 1956, with only the propulsion engine installed. In this configura-tion the SCI could be flown only as a conventional aeroplane— and not a particularly sweet-handling or efficient one at that. Itsfirst flight was made from the main runway at Boscombe Down on April 2, 1957, and the preliminary assessment of the machineas a wing-supported aeroplane was completed here by XG900. Any piloted vehicle of such unusual character must be evaluatedvery thoroughly and in the greatest possible number of small discrete steps. Accordingly all the flight characteristics of the lift- ing and propulsion engines, their relationship with the airframeand the behaviour of the aircraft itself were determined in a pains- taking and methodical manner, making the maximum possibleuse of whatever tunnel models and other techniques could acceler- ate the programme and reduce its hazards. It was not until morethan a year after the first taxying tests that the two pairs of lift engines were installed in XG905. The aircraft was then tethered bycables in a specially designed gantry at Belfast, in which it became jet-supported for the first time on May 26, 1958. During the pasttwo years most of the further exploration of the flight envelope has been conducted by XG905. By November 1958 the aircraft wasflying freely as a jet-supported machine, and in that month was even landed (deliberately) on the soft turf of a football pitch. During 1959, XG905 was provided with a number of refine-ments preparatory to a new series of flight programmes at the RAE Bedford. At the SBAC flying display in September it provided un-expected evidence of its efficiency as a vacuum cleaner: while operating from the freshly mown surface of the RAE airfield itpicked up so many loose blades of grass that its entire lift-engine intake became masked and Tom Brooke-Smith—the company'schief test pilot, who has dominated all the test flying—had to make an abrupt return to earth. Last winter "Brookie" started in earneston attacking the greatest problem of all: that of transition. By this time the aircraft had been flown extensively in the jet-supported regime up to maximum forward speeds of the order of 40 m.p.h. In addition it had been flown as a wing-supported aero-plane over speeds from some 170kt down to the unaccelerated stall of 134kt. The gap was finally narrowed from both above and below.At the lower end speed was increased in increments of lOkt up to 80kt, checking at each stage that the plenum-chamber pressureabove the lift engines was always outside the surge boundary. From the wing-supported regime speed was reduced very gradu-ally from 140 down to 75kt, choosing an altitude band which, while maintaining sufficient height for complete safety, enabled maxi-mum lift-engine thrust to remain comfortably in excess of weight. Finally the gap was bridged on April 6 of this year, when com-plete transitions were made both to and from jet-supported flight. Taking off as a conventional aeroplane from Bedford, Brooke-Smith flew round the circuit and lit the four lift engines at loOkt. He then made a long approach to the main runway, gradually (Continued on page 796, after double-page drawing of SC.l)
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
