Country of origin:

Australia

Description:

Single-seat agricultural monoplane

Power Plant:

(YA-1) One 186 kw (250 hp) Lycoming O-540-A1A-5 six-cylinder horizontally-opposed air-cooled engine

(250R) One 186 kw (250 hp) Rolls Royce/Continental IO-470-R six-cylinder horizontally-opposed air-cooled engine

Specifications:

History:

Yeoman Aviation Pty Ltd of Bankstown, NSW, was formed in 1958 as an associate company of Kingsford Smith Aviation Services Pty Ltd to specialise in the development and servicing of agricultural aircraft.  In the following year, on 20 June, the Company began the construction of an agricultural aircraft designated the Yeoman YA-1.  Even before the prototype was flown a number of agriculture operators expressed some interest in the new type.

The prototype VH-BJF (c/n 101 – later VH-CXS) was flown for the first time on 15 February 1960 with a Lycoming O-540 engine driving a Hartzell constant-speed propeller.  Aerial Spraying & Spreading Pty Ltd then commenced to operate this aircraft in April 1960.  Although it was intended that only the prototype and the first two production machines would have a tailwheel undercarriage, and the remainder would have a tricycle undercarriage, all aircraft completed were fitted with tailwheels.

The YA-1, like the KSAS KS-3, in fact adopted the fuselage of the retired RAAF trainer, the CAC Wackett, and was fitted with a new metal wing, a new fin, new engine, and completely new systems throughout.  An all-metal, low-wing monoplane conceived solely for the agricultural role, the YA-1’s fuselage was of welded steel-tube, chrome molybdenum structure with a composite skin of metal and fibreglass panels.  The hopper, constructed from heavy-gauge aluminium sheeting, had a capacity of 0.66 m³ (23 cub ft), and was located between the two centre-section spars.  High-lift slotted flaps made from 24-gauge alclad skin with five position settings (closed, 10, 20, 30 and 45 degrees) were fitted.  Frise ailerons of wooden construction were also fitted.  The hopper could hold either dry fertiliser or liquid spray, and for top-dressing a louvre box could be bolted on to the base of the hopper.  In May 1962 the Department of Civil Aviation (as it then was) issued a full Type Certificate, and orders were placed by Australian and New Zealand operators.

The first few Cropmasters produced had the original wooden Wackett tailplane fin and rudder. Subsequently an all-flying metal tailplane and a swept fin and rudder were designed and fitted to subsequent aircraft.  Developmental test flights of the new tail were carried out on a specially modified Wackett (VH-CYB –[ntu] c/n 258 – ex VH-AIV, A3-24).  Four further YA-1s were built to this configuration, and registered as VH-MSS (c/n 102), VH-CXH (c/n 103), VH-CXQ (c/n 104), and VH-TSD (c/n 105).  In January 1962 VH-CYW (c/n 106) became the first aircraft to be fitted with new control surfaces. By this time all that remained of the Wackett was the basic steel-tube fuselage frame.  The final Type Approval was completed and received in May 1962.

In 1965 Yeoman, Victa, Transavia and Aerostructures, which were all involved in the design and production of aircraft in Australia, sought protection for their industry from imported aircraft and made an application to the Australian Tariff Board to restrict the importation of light aircraft, or provide a bounty to subsidise local production.  The application was refused and all four manufacturers eventually ceased production of aircraft.

A further fifteen Cropmasters were built but, by this time, the cheaper Piper PA-25 Pawnee was starting to gain popularity, and production was terminated due to lack of Government support.  After production concluded, tools and jigs, and airframes 122 and 123, were exported to Cameron – Gray Alcorp at Plastidyne Manufacturing Corporation at Gardena in California, USA on 29 December 1966 where it was expected production would resume following a new partnership being formed for that purpose. But it seems production did not proceed.  Aircraft with construction numbers 118 to 121 became known as the YA-1 250R Series 2, the undercarriage on these aircraft being moved forward to correct a tendency towards nosing over.

Versions proposed, but which did not reach the production stage, included the Cropmaster 285 with a 219 kw (285 hp) Continental IO-520 engine, a 0.708 m³ (25 cub ft) hopper, additional wing and flap area, and an all-up-weight of 1,683 kg (3,710 lb), and the basically similar YA-5 Fieldmaster 285 with a tricycle undercarriage and a wider cockpit seating two, an 0.849 m³ (30 cub ft) hopper, and a loaded weight of 1,810 kg (3,990 lb).  In the long term it was proposed to fit a 224 kw (300 hp) variant of the IO-520 engine, design a monocoque fuselage, and re-design the wing with a span of 11.27 m (37 ft).

Cropmasters built comprised: c/n 101, the prototype, which became VH-BJF with Air Spraying & Spreading Pty Ltd of Albury, NSW on 8 November 1960.  It later went to Hazair (Albury) and became VH-CXS in June 1961.  It was later fitted with an all-metal tail conversion. After a couple of accidents it went to Murrayair (Albury) Ptd Ltd, and Eveready Airspray of Wee Waa, NSW in 1973 when it was used on night spraying of crops. It was withdrawn from use after being damaged in a storm at Rylestone, NSW on 11 January 1980.

C/n 102 became VH-MSS² with Marshall’s Spreading Services of Albury, in November 1960 and had a modified main spar.  It crashed on 28 July 1961 at Deniliquin, NSW.

C/n 103 became VH-CXH with Hazair Agricultural Services of Orange, NSW in February 1961 but on 21 December 1961, whilst being flown from Bankstown, NSW to Orange with a new engine, it hit power lines at Blackheath in the Blue Mountains in NSW and was destroyed.

C/n 104 became VH-CXQ with Air Culture in Western Australia but crashed at Narrogin on 20 February 1965.

C/n 105 was built as VH-TSD and was the first aircraft fitted with the Continental IO-470-G engine.  It became VH-COE in April 1964 and operated with Trojan Aerial Spraying of Parafield, SA and Coveair Ltd of Adelaide, but crashed at Myonga, SA on 29 April 1964.  It was re-built by Aero Kair at Parafield. It was withdrawn from use after being damaged near Orange on 28 March 1966.

C/n 106 became VH-CYW with Air Culture in June 1964.  Subsequent operators included Falcon Super Spread and AgSpray Aviation of Northam, WA.  It crashed on 6 August 1978 near Ballidu, WA.

C/n 107 became VH-BAQ in August 1962 with Boorowa Air Services on the south-west slopes of New South Wales.  It was destroyed when performing aerobatics on 24 October 1964 near Boorowa.

C/n 108 was registered VH-DCB to the manufacturers for testing and then shipped to New Zealand on board Qantas Super Constellation VH-EAQ on 28 September 1962.  It became ZK-CCP with Farmers Aerial Top Dressing of Invercargill but crashed on take-off on 5 April 1966 at Browns, Southland.

C/n 109 was noted at Bankstown in January 1963 under construction but does not appear to have been completed.

C/n 110 became VH-DEQ and was shipped to New Zealand (see Yeoman Hanes 250).

C/n 111 became VH-DCC with Hazelton Air Services at Cudal, NSW in April 1963.  It was damaged on 15 December 1968 and was re-built as VH-ENM in January 1974 with P Meek of Wee Waa, NSW.  It was used for night spraying with lights at Wee Waa. It hit power lines and crashed on 21 February 1978.

C/n 112 became VH-FPB and was registered to Agriculture Aviation of Wagga Wagga, NSW in July 1963, and then Swiftair Aviation Services of Casino, NSW where it became VH-SWC, then Air Express of Archerfield, QLD, but became submerged in floods at Lismore, NSW in 1974 and was written off.

C/n 113 was the first Model 250R and flew in March 1964, going to Drury Foster & Co of Glenroy, SA, later Westair Aviation Services at Coonabarabran, NSW as VH-CYY, later with Avia Guard of Ballarat, VIC, and became VH-AGL with P W Meek of Wee Waa, Eveready Airspray, and Emerald Aerial Treatments. It made a forced landing at Emerald, QLD on 29 January 1976.

C/n 114 became VH-ABH with Benders Spreading Service of Hobart, TAS in August 1964 but lost a propeller at Flinders Island on 10 May 1966.  It was rebuilt by Hazair at Orange, went to Westair and Avia Guard but crashed into trees near Yea, VIC on 31 March 1970.

C/n 115 became VH-BAK with Hazelton Air Services of Cudal, later going to Ron Thompson Haulage of Grafton, NSW.  It crashed on take-off at Coombadjha, NSW on 15 March 1968.

C/n 116 became VH-RPB with Benders Aerial Service in October 1964 but crashed on take-off at Kempton, TAS on 29 October 1965.

C/n 117 became VH-TPH for testing with Yeoman in February 1965 and was then shipped to New Zealand where it became ZK-CLW with Southern Aviation of Gore.  It later went to Wanganui Air Work, Barr Bros of Waipukurao, eventually going to Hanes Engineering to be used for spares in the construction of the Yeoman Hanes 250 ZK-CDI.

C/n 118 was built for Western Aerial services of Cunderdin, WA but the order was cancelled and the aircraft became VH-TPK in June 1965 to the manufacturer before going to New Zealand as ZK-COE, entering service with Southern Aviation at Gore.  It crashed at Waikaria near Mataura on 4 September 1966.

C/n 119 became VH-TPM with Cropmaster Aircraft Pty Ltd on 19 July 1965 and was then shipped to New Zealand where it became ZK-CPW at Gore with Southern Aviation.  It was leased to other companies.  It suffered a couple of accidents and was retired in August 1974.  At one stage it was fitted with wing-tip extensions.  It was rebuilt in 1978 using the wings from ZK-CTX and continued on agricultural work with John Slocombe until 1985.

C/n 120 was not completed until August 1965, being shipped to New Zealand in February 1967 where it became ZK-CTX with Southern Aviation in May.  The engine was changed at some stage to a 194 kw (260 hp) unit and the aircraft was retired in September 1971.  The fuselage was placed in storage and the wing was used to rebuild ZK-CPW in 1978.  By 2015 work was proceeding on the reconstruction of ZK-CTX.

The first of the Series 2 Cropmasters was c/n 121 which became VH-TPN in January 1966 and was operated in central Queensland.  It had a couple of operators, including Swiftair, but crashed at Ewenmar, NSW on 2 June 1971.

Only a couple survive. ZK-CPW is on display at the Ashburton Aviation Museum, NZ; ZK-CLW is stored at Thames; VH-CXS is under restoration to static display standard in Sydney NSW for the Power House Museum; and the wings of two are being used in the restoration to airworthiness of two CAC Wacketts, VH-WKT at Loftus, NSW (ex VH-DGR, VH-AMA) and VH-SWC (c/n 112 – ex VH-FPB) at Werribee, VIC.  The Australian National Aviation Museum at Moorabbin, VIC has the fuselage of VH-AGL, the wing from VH-TPN and the tailplane from VH-ENM.