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Bennet PL-11 Air Truck

 

bennetpl11

 

The Te Kuiti Airtruck project was a collaboration of ideas between Jack Worthington, owner of Northern Air Services, his engineer Snow Bennett and Australian aircraft designer Luigi Pellarini in early 1957.


Luigi Pellarini was familiar with the requirements of aerial topdressing operators and had worked on several designs, including the PL-7 Air Tanker. Plans started arriving in Te Kuiti in early 1957 and construction of components began.


The idea was to build a hopper with a stub wing and attachment points for wings and the engine. The design was unusual in having no rear fuselage or conventional tailplane, the T-tail being mounted on booms attached to the wing and well away from the trail of corrosive superphosphate. To help reduce the cost, two retired Harvard trainers were bought from the Government Stores Board for component recovery.


It soon became apparent that a large number of Harvards would soon be up for tender and engines, propellers and various other items could be used in building a fleet of aircraft to replace the Cessna 180s then in service. Pellarini then designed a larger aircraft powered by the 600hp Pratt & Whitney R 1340 radial as fitted to the Harvard. At this point the project became twin tailed.


Work began in earnest in late 1957 and by October 1959 all major work had been completed. The aircraft was then disassembled at the airport and re-assembled upside down at a workshop in the town. The wings and tail components were loaded with bags of cement as part of the static load requirements and, once this test was passed, everything was returned to the airfield at Te Kuiti for reassembly and completion.


The civil aviation authorities placed many requirements on the builders Because Pellarini had been radical in his ideas and introduced some well thought out and well-designed parts, the Civil Aviation Department came up with equally novel ideas of testing them. One of the requirements was to taxi the aircraft at speed over railway sleepers.

 

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Throughout the construction the builders had the support of the NSW Branch of Civil Aviation in Australia, so the men from Te Kuiti knew they were on the right track.
On 27 April 1960 the PL-11 Airtruck took to the air, but just short hops as a test to see if there was any deflection in the tail booms. Again the aircraft passed the test and it finally flew as ZK-BPV on Tuesday 2 August with "Johnny" Johnstone at the controls. After a 35minute flight he returned and, with a thumbs up signal, shut the new topdresser down.


What he had flown was the first commercial aircraft to be built in New Zealand.


In 1959 Geoff Young joined the company and in October some of the staff travelled to Christchurch to dismantle and recover Harvard components.


By 1961 Pellarini had left the project and Geoff Young took over the design work in 1962. A number of components had to be redesigned and he took on this work. In the meantime, after a series of test flights at Ardmore, the Airtruck completed its first topdressing job at Te Kuiti in February 1961. Another eight hours of flight testing at Ardmore was completed in July and at the end of the year the aeroplane was taken out of service for modifications.


ZK-BPV didn't fly again until April 1963, by which time Waitomo Aircraft had been formed. Considerable interest had been shown in the aircraft and the company started on component manufacture. What looked a bright future at last for the Airtruck came to a halt when Jack Worthington wrote off ZK-BPV at Ngapaenga on 8 October 1963. The aircraft was found not to be at fault and its unusual design probably saved Worthington's life.

 

Waitorno Aircraft then set to work on a second aircraft and ZK-CKE was test flown by Jack Worthington on 9 February 1965. Other than cosmetic changes to the canopy and hopper mouth, the aircraft was the same as ZK-BPV but had to go through another series of test flights. By this stage Northern Air Services had sold out to Rural Aviation and with Geoff Young leaving at the end of 1964 the testing programme was taken on by Rex Aviation (NZ) Ltd.


ZK-CKE finally gained the Certificate of Type Approval on 17 February 1966. Leased to Rural Aviation (1963) Ltd, it was based in Te Kuiti, flown by Don Erceg, and at Taumarunui with pilot Peter Meek.


On 26 September 1966 a new company was formed, Commercial Aircraft Company (NZ) Ltd, with the idea of putting the Airtruck into production at Ardmore. An attempt to raise capital later in the year failed, mainly because of a serious downturn in wool receipts and the aerial ag industry suffering a serious slump.


In 1967 ZK-CKE was leased to Barr Bros Ltd and within a few weeks was written off at Mangakaramea, taking the life of Dick Tatham on 1 March 1967. For the second time, the accident cause was no fault of the aircraft.


It had been down to local business people of Te Kuiti - Jack Gardener who believed in the project and Jack Worthington and his pilots - who worked to fund the new aircraft. Engineers Snow Bennett, Geoff Young and later Jack Frost pushed on with the details and the hangar staff built the aircraft.


In the end both aircraft had flown a combined total of over 1000hr.

Engine: P&W, 600 hp.
Wing span: 48ft (16.3m)
Wing area: 369 sq.ft
Lower mainplane spanned: 11 ft 3in
Maximum height: 10ft 10in (3.3m)
Fuselage length: 14ft 3in
Overall length: 25ft 8in (7.82m)
Empty weight: 37001b (1678kg)
Maximum all-up takeoff weight: 72001b (3266 kg)

 

 


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