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Aviation History
1976
1976 - 0025.PDF
FLIGHT International, w/e 3 January 1976 when it was produced in huge numbers for the AT-6 (Harvard) and other aircraft. It has not been manufactured for many years and its days are now clearly numbered. Reliability has begun to suffer from the natural fatigue of f e, abetted by the increasing use of parts made by other an the original manufacturer. Many of these are of sterling quality but not, apparently, all. Need for engines Although difficult to forecast precisely, the time is coming when this major segment of the industry will find itself with no supply of motors. The introduction of other overhauled engines—such as the Leonides—will delay this time but, sooner or later, factory-new engines will have to appear. When they do, from whatever source, they will inevitably hoist the economics of agricultural aviation to a new cost level. Indeed, it is estimated that the cost of a new 500 h.p. radial engine, whoever makes it, is likely to be around that of a complete Snow or Weatherley aircraft as current today. The world's third-level air-transport industry once had to clamber towards reality out of an artificial cost struc ture based on war-surplus Dakotas of only nominal book value; agricultural aviation will have to complete its maturity by adjustment to a basis of real costs, as far as engines are concerned. I believe that it will, without too many growing pains. After all, the extra cost of such en gines, amortised over the working life of an aircraft, is mere peanuts in terms of cost per acre—probably about six cents, based on a life of 6,000 operating hours aver aging 120 acres per hour for two-thirds of the life. Conjecture here can be most interesting. Greatly in creased activity and sales pressure was noticed in the turboprop camps of Garrett, Lycoming and P & W. Very neat installations of the Garrett and PT6, done by specialist companies such as Ayres, were seen in Thrush Com- 29 manders, while the new Lycoming LTP600 impressed on lookers by its neatness and its excellent specifics, especially a consumption of -551b/hr/e.s.h.p. These engines average around 600 h.p. and all seem likely to cost about a third more than equivalent new radials. This cost, too, may be capable of absorption if these engines gain general accept ance technically and in terms of real maintenance and other costs. Opinion is strongly divided on this score. The opponents of turbines (in the specific context of ag flying) point out that high-intensity crop-spraying involves frequent, rapid and large changes in power setting, often at near-zero height in hot, dusty conditions. This, they point out, is just not the environment for the turbine and they fear short life and high costs. Those in favour, however, make light of all this and are confident that experience in the field, as it accumulates, will prove such fears to be groundless. To date, hard ex perience of this kind of operation has been limited mainly to some 15,000hr accumulated by 15 PT6-engined Pilatus Turbo Porters operated by the parent Swiss Ciba company. There is a suspicion that much of this may have been in controlled conditions such as ferrying, demonstration and other non-ag work; but some Ayers conversions are des tined soon for Sweden and Iran and their careers will be watched with interest. Not necessarily in the context of ag aircraft, special mention must be made of the incredibly neat Geschwender engine; it is based on a 400 cu in Detroit Ford V-8 with neatly tailored reduction gears, which makes it look like a bijou Merlin. Currently rated at 290 h.p., its installed dry weight is 6151b, or 2-12 lb/h.p., but this will shortly be improved when a light-alloy sump is available, replacing the present steel one. This figure is by no means out of order for a light piston aero engine. I once flew some 200hr happily behind a Ford conversion weighing 6 • 21b/h.p. This was the Carden version of the little side-valve Ford '10' in the Chilton DW1. So far the Geschwender engine has flown some 60hr in an aged Funk ag monoplane. Ed Garner, the test pilot who had just flown it down from Oregon, re ported "uncanny smoothness and a consumption of 14 US gal/hr at 75 per cent power." Cylinder temperature, accord ing to Garner, "varies widely between 181° and 182°," and it was noticed that part of the oil cooler was neatly blocked off by adhesive foil. The target TBO is 2,000hr and, if it achieves this, the Geschwender engine must surely be regarded as a serious contender in the huge and expanding American general- aviation market, including the ag segment. A future en gine, based on a larger Chrysler unit, is expected to offer middle-range power. The scope of the spraying and dispersal equipment and of all the vast paraphernalia associated with it was very wide and some beautiful work in glass-fibre and stain less steel was evident. Paramount among such manufac turers is Transland Inc, whose president, Conrad Barlow, is one of the acknowledged leaders of the American ag industry today. His factory in the suburbs of Los Angeles exports world-wide and is a model of cleanliness.
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