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Aviation History
1980
1980 - 2439.PDF
800 Farnborough International FLIGHT International, 30 August 1980 Enter the Fieldmaster by CLIFF BARNETT ON the eve of Farnborough 1980 we reveal a new European challenge to ag aviation. One of the Western world's biggest single-engined ag designs, it has turboprop power, several major innovations, and comes from Desmond Norman, co-designer with the late John Britten of the Islander and Trislander. At Goodwood, base of Norman's company NDN Aircraft, neighbours call the partially complete full-scale green mockup the "jolly green giant." With a height of nearly 12ft it towers over the nearby Firecracker, NDN's brilliant contender for the military high - performance piston trainer market, and with a span of over 50ft has a bigger wing than the Islander. With a present capacity of 652 US gal (2,4681it) the Fieldmaster is likely to be beaten in certificated chemical-carrying ability only by Poland's huge M-18 Dromader and jet- powered M-15 Belphegor. But size is not the most interesting feature of the Fieldmaster. There are at least two other major innovations that have encouraged the UK's National Besearch and Development Corporation to finance research and development costs. First is an integral hopper that is a major part of the fuselage structure and in a sense the heart of the whole aeroplane. Hoppers in conventional aircraft are installed within the fuselage and weigh perhaps 1251b; this is "dead" weight and not part of the necessary aircraft struc ture, which has to be locally reinforced to bear this load. Since there is always the risk of chemicals being spilt and trapped between hopper and fuselage skin, detachable panels have to be incorporated to give access for cleaning, and there is unwanted addi tional frontal area in the fuselage because of all the supporting structure around the hopper. This is especially significant in the case of turboprop designs with their very slim engine installations. In the Fieldmaster, the hopper is part and parcel of the whole aero plane. The engine is mounted on the front, the sides form a skin continuity for the fuselage, wing spars are attached underneath and the mono- coque rear fuselage with cockpit area attaches behind. A baffle within the hopper contains a structural carry- through for the wing bracing. The hopper will be built of titanium, impervious to corrosion. This is very expensive, but the Fieldmaster is not going to be cheap and the extra cost is thought to be justified. Second big feature is full-span aero foil flaps, which apart from their aero- NDN Aircraft is at Goodwood Airport, Chichester. Sussex, tel 0243 84337. " "' « litj& dynamic benefits will also have integral spray nozzles. On conventional ag designs the drag of an external spray boom can account for over 40 h.p., but on the Fieldmaster the four segments of flap per wing should each contain five spray nozzles, existing at the leading edge. The flaps will give a small radius of turn, and when deflected by 13 for spraying should give a 6° nose-down pitch attitude for better visibility. Spraying speed should be lOOkt or less, but with flaps retracted the Fieldmaster is expected to fly from one job to the next at 150kt. Stalling speed for this 8,5001b aeroplane is estimated at 57kt. It has to be below 61kt in any case to meet international single-engine airworthi ness requirements. Four fuel tanks contain 244 US gal. Another unusual, although not new, feature of the Fieldmaster is its tricycle landing gear—New Zealand's Fu-24 and turboprop Cresco already use tricycle gear—and the Fieldmaster uses a big two-wheeled nosewheel assembly. Since the Fieldmaster is an Eighties aeroplane, Desmond Norman thinks tricycle gear has now replaced the tailwheel layout as "conventional gear," and that tomorrow's ag pilots are going to be much more attuned to tricycles than taildraggers. Doubts about tricycle performance on rough ground inevitably spring to mind, but the mainwheels are 29in in diameter and the Fieldmaster is not in any case destined for small, muddy English fields. Its market lies in the much bigger open spaces of such areas as South America, Africa, Australia and New Zealand. Powerplant is the faithful Pratt & Whitney PT6A-34-AG of 750 h.p. which already powers the Ayres Turbo Thrush and Turbo Ag Cat and is one of the most popular turbine engines. The Fieldmaster also has the distinction of being the first Western- world ag aeroplane to be designed specifically for turboprop power. A A tandem cockpit behind the hopper is expected to have dual controls as stan dard. Norman thinks that proper dual conversion training is warranted with an investment of this size, and the space available for a passenger is often useful. NDN will be exhibiting at Farn borough, and at the time of my visit work was progressing well. In answer to the inevitable question "when will it fly?", Desmond Norman says "before the end of 1981." He will go for full British type certification and intends to build production aircraft in the UK, unlike the Firecracker which is intended for overseas licensed pro duction. The top end of the ag market, for t which the Fieldmaster is clearly intended, is the fastest growing section, especially in the US where Nasa predictions estimate the big types will amount to about 7,000 out of a fleet of 18,000 ag aircraft by the year 2000. Norman hopes eventually for annual sales of 30 to 40 aircraft. While his name will always be asso ciated with the Islander and Trislander, sales of which have topped 850 and 50 respectively, Desmond Norman has a long background in ag aviation. Britten-Norman's Micronair atomiser has been produced to the tune of 25,000 aircraft sets, and his old firm Crop Culture (Aerial) once operated a fleet of 80. He was a director of Snow Aeronautical, whose Snow design later became the Rock well Thrush Commander and then the Ayres Thrush. If its ancestors are anything to go by, the Fieldmaster should make a big mark down on the farm.
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