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Aviation History
1954
1954 - 1634.PDF
4 June 1954 725 TIGER MOTH MODIFICATIONS "CROM the outset, the engineering side of aerial topdressing has •*• had a constant struggle to keep up with the increased skill and improved methods of operation. The first Tiger Moth to be used for topdressing was modified by removing the seat and stick from the front cockpit and cutting a hole through the cockpit floor. Into the cockpit was fitted a leather bag with a metal frame-end which came through the hole in the floor. The shutters on this door were fitted with a control so that the pilot could operate them. The aircraft was loaded manually as it only carried one bag of 180 lb. Soon a new metal hopper was designed. This was folded up and fitted into the front cockpit and then extended to its full size. The sides of the hopper were then slid into place and secured with screws and stop nuts. This new hopper increased the load to about 300 lb per trip. The hand loading method proved to be far too slow for this improved topdresser and a better method of loading had to be devised. A hay boom was rigged on the job and a canvas hopper fitted into the boom. The superphosphate was loaded into the canvas hopper, which was elevated to a convenient height. When the aircraft landed, two of the loading staff would run out and lift up its tail and wheel it backwards under the boom. A cover made like a curved dustbin lid was put over the pilot's cockpit before the fertilizer was dropped from the canvas hopper into the aircraft hopper. But this improvement, which had more than doubled the tonnage, still did not prove to be good enough— the pilot soon mastered it and was eager for a greater load. As no further improvement could be made with the removable- type hopper, the aircraft was drastically altered to take a larger one. Everything was removed from the front cockpit and two tubular metal frames were fitted, one on each side of the cockpit. The wings, centre section and top fuselage fairing were removed and a large narrow galvanized iron tank was fitted between, and bolted to, the two metal frames. The aircraft was assembled again and, as the top of the tank was level with the top of the fuselage, a fairing was made to cover right over the front cockpit and a spring-loaded lid was fitted, which covered over the top opening of the hopper tank. The aircraft was now capable of carrying 450 lb of fertilizer and still able to operate from farm paddocks or airstrips bulldozed out of hill sides. The worry was now with the loading, for the aircraft was so improved that the old system was far too slow. It was realized that, rather than the aircraft being wheeled under the boom with its canvas hopper filled with manure, the boom must move to the aircraft. The only way of doing this was to build the boom on a truck. A large T-shaped boom was made and mounted on bearings fitted to a heavily reinforced section which took the place of the front bumper of the truck. A winch was then mounted under the tray of the truck and through a system of pulleys a cable was run up through the boom and out to one end of the "T." The canvas loading hopper could now be raised or lowered mechanically. However, it was soon found that loading operations could be further streamlined by keeping the boom in a fixed position and driving the truck from the manure loading stack to the aircraft for reloading its hopper. TWO well known firms, F. G. Miles, Ltd., and British Emulsifiers, Ltd., have lately co-operated in the formation of a new company under the title of Jet Tanks, Ltd. When it is remembered that the aircraft firm have a versatile plastics division at their Shoreham Airport works, and that their partners in the venture have been making drop tanks and other sheet- metal aircraft components for the past 20 years, the nature of the new enterprise begins to become apparent: its principal object, in fact, is the development and manufacture of tanks—particu larly drop-tanks—in non-metallic materials. Other products in the same general line may follow. Two basic "Milestos" plastics, phenolic-resin-bonded asbestos fibre and similarly treated glass fibre are the materials principally being employed in the tank development work, which is being done at Shoreham (production will begin shortly at a works in Islington, London). The drop tanks, in any size, are moulded not in longitudinal halves, as might be thought, but in three trans verse sections—nose, centre and tail—several varying methods of fuel-tight joining having been developed. These methods will permit simple assembly of transported sections "in the field." Design-advantages afforded by the use of moulded plastics include the consideration that thickness can conveniently be added where required for local strengthening. Attachment- fittings, valves, etc., are moulded in. The material is proof against any fuel used, or foreseen, in jet aircraft, and against ester lubricants. As regards vulnerability to machine-gun or cannon fire, test specimens we have examined suggest that penetration It was also found that the aircraft was capable of carrying yet a further 100 lb of fertilizer, bringing the payload to 550 lb. This is the maximum payload approved for Tiger Moths. With a full load of a quarter of a ton, very little reserve power was available in emergencies, and a series of accidents occurred. It was necessary, therefore, for the outlets on hoppers to be modified for jettisoning, and this was the next improvement carried out. The jettison, when finally approved, was capable of releasing a full load in about five seconds. A further modification was introduced about two years ago by 'fitting a collapsible seat in the hopper for carrying the loader operator to and from the airstrip (the operator's staff usually return to base every day after work). The Tiger Moth has stood up to the strain of aerial top- dressing in a remarkable way and its maintenance cost has not been high as is sometimes thought. The availability of replace ment Tiger Moths and spare parts, however, is becoming exhausted and very soon they will have to be completely replaced by new aircraft. EFFECT OF TOPDRESSING AND SEEDING THE great majority of hill country soils in New Zealand are deficient in phosphate; some are deficient in lime, many in molybdenum, and in only a few areas is potash required. The main effect of these deficiencies is seen in the absence of clovers in the pasture or in the presence of only a sparse cover of unthrifty plants. The effect of topdressing pastures completely devoid of clover may be disappointing. The grass species do not respond to phos phates, lime, potash or molybdenum as readily as do the clovers. In fact, in a clover-deficient sward, pasture production is likely to be limited, not by the fertilizing elements just indicated, but by nitrogen. Fertilizer application of nitrogen materials is out of the question, due to the high cost of nitrogenous fertilizers and frequent heavy applications of these that would be required to secure a sustained response. The hill-country farmer must, therefore, look to the clovers as his main source of nitrogen supply to the grass elements of the sward by stimulating the clovers with phosphates and other fertilizers. From this it may be seen that a vigorous clover element in the sward must be the first aim of topdressing. Where clovers are not present, seeding is being widely practised, with rather variable results. However, if seeding is done at the right time, with the right species and with adequate fertilizer, it may be expected to give pastures with greatly improved clover content and vigour and, as a result, more productive grasses and much- improved stock carrying-capacity. Much hill country in New Zealand carries pastures with con siderable amounts of annual clovers. These species will respond to topdressing, sometimes in a remarkable manner, but neither their production nor their nitrogen-supplying power approaches that of white or subterranean clover. For this reason pastures with annual clovers only should be seeded as well as topdressed. The impact of aerial fertilizing and seeding on hill country farming in New Zealand has hardly been felt as yet, but it must soon become a major factor in pastoral production. (To be continued) is clean both on entry and exit, without crumpling or tearing. No detailed figures for weights are yet available, but it is expected that the tanks will be somewhat lighter than metal tanks of similar capacity. In general, however, the company's aim will be "same weight at lower cost." Jet Tanks, Ltd.—the directors of which are Mr. F. G. Miles, F.R.Ae.S. and Mr. G. A. Rickards, M.C.—have their offices at 3, Red Place, London, W.l (Mayfair 9358 and 0708). CF-100 UNOFFICIAL RECORD N EWS appeared in Flight of February 5th of an unofficial unrefuelled-distance record for jet fighters set up by a CF-100 of No. 445 All-Weather Sqn., R.C.A.F. The aircraft flew 2,100 miles from Vancouver to North Bay non-stop in 3 hr 55 min. Belatedly, some further details of the flight have become available, and are worth quoting. The flight was planned by the crew one night and the take-off made at 0700 hr next morning. They climbed to 34,000ft in cloud and, using the "climb cruise" technique, thereafter gained height at the rate of 33 ft/min. Their only sight of the ground was at the lake-head cities on Lake Superior about an hour before landing. It was not until the evening of the day of the flight that the news leaked out to the local Press. The navigator, F/L. Turner, is now on an exchange posting to an R.A.F. night fighter squadron in the U.K. The pilot was F/L. M. Kobierski. MOULDED-PLASTIC DROP TANKS
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