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Aviation History
1973
1973 - 0848.PDF
Original aboriginal By Hugh Field: Number 267 of the series FOR MANY PEOPLE who regularly attend the biennial SBAC display at • Farnborough the first week of September 1972 was made more-than-usually interest ing by the appearance of the Government Aircraft Factories' Nomad, a wholly native product of Australia and one which is uniquely placed in the light-transport marketplace. For project manager Alan Wrigley and his team the Farnborough appearance was a demonstration of confidence. It marked the opening of the second phase in the life of the project—marketing—following the successful achievement of type certification by the Australian Department of Civil Aviation on August 11, 1972, little over one year from the first flight of proto type 01. The second prototype aircraft, VH-SUR, had contributed its fair share to the 350 flying hours flown before type certification and it was granted a full C of A and given representative furnishing before setting course for the United Kingdom. It was to undertake a technically unevent ful tour amounting in all to a further 180 flying hours before returning to Melbourne. The background to the Nomad programme was described in Flight for August 3, 1972, and it is my intention to bring the development story up to date and to highlight some of the many unusual features of this stimulating design, relating them, where possible, to their effect on the behaviour in the air. I flew the Nomad one peaceful evening during the show when the bustle of the Red Arrows' performance had ceased. It was calm and ideal for Stol take-offs and approaches and, having watched several of Stewart Pearce's performances, I looked forward immensely to trying the slow-speed manoeuvres for myself. The whole concept of the Nomad centres on its slow- speed capability, and in the military sales brochure due mention is made of studies of Vietnam experience. The requirement for rugged reliability is common to military and commercial bush operations, and this has determined the use of the simplest possible systems. It must have been tempting at times to search for mechanically advanced solutions to some of the aerodynamic problems, but the temptations were resisted. The most striking example of an original approach is that which has been made to lateral control. Previous Stol designs with high-aspect-ratio wings and conventional ailerons have not always been comfortable compromises. The high inertia in roll that is a characteristic of such high- wing designs does not lend itself to crispness of control at low speed in turbulence, yet it is at the low-speed end of the range that aileron response is most needed. In the case of the Nomad the controls had to be acceptable over a speed range extending from the VNE of 200kt down to as low as 40kt, which was the figure I achieved during one of my stalls. The solution adopted was the ingenious one of melding together two methods of control in such a way that the transition between them could be smooth; moreover, this was done within the total control concept rather than as a separate exercise in one plane of control. Unusually for an extreme Stol design, the Nomad does not make use of leading-edge slots, high-lift devices being limited to the full-span, double-slotted flaps, the outboard pair of which serve as variable-datum ailerons. The slot shroud immediately forward of the outboard flaps has been made to act as a spoiler which comes progressively into use with increasing amounts of flap. These slot-lip ailerons have a travel from 38° up to 5° down and they are mechanically interconnected by a simple linkage to the aileron cables. Selection of flap, which is electric, alters the datum of the linkage. From a pilot's point of view the result is commendable and I did not find that I was conscious of any
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