FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1949
1949 - 1923.PDF
FLIGHT, 24 November 1949 680 FREIGHTER- FERTILIZER Suggested Employment of the Bristol 170 for Pkospkate- distribution ; ^ - Proposed conveyor-belt method of loading a Freighter with phosphate. For maximum utilization, the opera- tion would take place simultaneously with refuelling. GRADUALLY and unobtrusively, perhaps because of theprosaic nature of their occupation, extremely largenumbers of aircraft have in recent years been adopted for "utility " duties. Agriculture has been the major beneficiary,as testified by the announcement that no fewer than 8,000 air- craft are now employed in the United States for seeding, crop-protection and similar functions. Over twelve months ago, the Royal New Zealand Air Force,employing Grumman Avengers, began a series of experiments to assess the efficacy of aerial '' top-dressing ''—the distributionof phosphate fertilizer—in hilly, inaccessible territories. Con- siderable success was achieved, and a mass of operating dataaccumulated as a springboard from which to tackle the work of full-scale fertilization and conservation of soil from erosion;this is a project which will cover enormous areas of land, and, it is hoped, increase New Zealand's agricultural production byseveral million pounds. Largely on the basis of the R.N.Z.A.F. findings, the BristolAeroplane Company has made a detailed preliminary study of this work in relation to the potentialities of the BristolFreighter. As a fully developed, well-proven design, the Freighter is an obvious candidate; light aircraft, it is thought,will be able to do little more than scratch the surface of the enormous task. For quick and economic operation, the phos-phate-distributing aircraft must be capable of being fully loaded with fertilizer while refuelling is taking place, and must bereadily convertible for other duties; additional requirements are low initial and operating costs, ease of maintenance, safeslow-flying characteristics at low altitude, and the ability to fly from restricted and unimproved airfields. The Bristol suggestions, therefore, envisage use of theMilitary Type 170 fitted with an internal, removable, canvas hopper of six tons capacity, embodying integral equipment foragitating and distributing its contents. Loading time would be in the region of ten minutes, and removal of the hopperwould be facilitated by the Freighter's nose doors. Utilization, it -is claimed, would consequently be consider-ably greater than that afforded by a majority of more expen- sive, four-engined aircraft, since the latter would probablyrequire structural alteration to enable an adequate load to be carried internally. A sufficiently large externally slung hopper INTERCOM. POINT CONTROL VALVE FOR SHUTTER JACKS DETACHABLE PANEL & CHUTE 3OOcu ft HOPPER . (04401b OF FERTILIZER) Interior layout of the Freighter's fuselage, fitted with a hopper of 13,440 Ib capacity. The disposition of the integral agitator and distributor is also shown. might prove difficult to handle on the ground and would alsoconstitute an aerodynamic problem. Both methods might pre- clude quick conversion for a military transport role. Thepossibility that the R.N.Z.A.F. might be the only organization large enough to handle the top-dressing project emphasizes theneed for a machine with transport capabilities. Apart from the phosphate-container, the only other im-portant modifications to the Freighter would be the provision of a strengthened floor, incorporating a distribution aperture(variable according to the size of the required swathe of fer- tilizer), a loading duct in the top of the fuselage, and anintercom system between pilot and hopper-operator. The problem of quick and simple loading has occupied con-siderable thought on the part of the Bristol Company, and one of their suggestions (illustrated above), calls for theerection, near sources of bulk supply, of ground hoppers from which phosphate could be fed to the aircraft by conveyer beltvia a cantilever or jib structure terminating in a flexible hose and funnel,the final transfer being made by gravity. Cost Estimates V On the basis of assumed agricultural and operational requirements, the Company has made detailed estimates of utilization and performance. It was assumed, for example, that a 50 milt-radius of action between airfield and operating-area would be required in treatment of the 750,000 acres estimated to be theimmediate annual target. Resulting calculations show that the aircraft engaged could make a complete sortie in 1 hr 30min, time being allowed for refuelling, reloading and pilot briefing. Assuming, therefore, the completion of seven sorties,a Freighter could treat 420 acres per flying day. If the weather in New Zealand hill country permitted operation on about120 days of the year, a fleet of 15 Freighters, each flying 840 In per year, would be required to accomplish the immediateobjective, assuming an actual flying time of 1 hr per sortie. Since these estimates were made, however, it has beenlearned that flying would be possible on about 200 days of the year, with a consequent increase in Freighter utilization. Theannual target might in fact be considerably greater than 750,000 acres, and other assumptions have also proved to beconservative. The figures quoted above, therefore, are intended only to provide a working basis and do not in them-selves constitute a plan. Direct operating costs, allowing for deprecation of aircraftand equipment, but exclusive of the cost of phosphate and ancillary ground equipment, would be approximately 14s peracre. Should the Defence Budget cover the expenses of both capital outlay and maintenance of the aircraft, or of initial costalone, the approximate cost per acre would be reduced to, respectively, 4s iod or 8s 6d. Bristol's interest, it should be stressed, lies solely in thesupply of suitably equipped aircraft, and methods of operating, loading, etc., are the responsibility of the New Zealandauthorities. Nevertheless, the company's comprehensive study of the subject has met with considerable interest in NewZealand, and its proposals, in substance, are thought to be sound. On-the-spot information compiled recently by Bristolrepresentatives is being incorporated in the final design of phosphate-distribution equipment now being developed for theFreighter, which is likely to be the subject of further negotia- tions with the New Zealand Government. Major decisions haveyet to be taken, but the prospects are broad and intriguing, in that they suggest one of the first occasions of systematicoperation of a fleet of large utility aircraft on a national scale. 1 2%
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
