|Last updated 10 February 2020
|SASIN-AEROSTRUCTURES SA-29 SPRAYMASTER
A 1960s Australian venture to create a low cost agricultural Tiger Moth replacement
Compiled by Geoff Goodall
Spraymaster VH-GEB at Adelaide-Parafield in September 1966 in sprayer
configuration. Photo by John M. Smith
During 1961 the Department of Civil Aviation introduced a range of new
requirements for Australian agricultural aviation, affecting pilot
licencing and aircraft safety standards. This was a response to
increasing numbers of agricultural aircraft accidents. The requirements
included a ruling that DH.82
Tiger Moths must be withdawn from agricultural flying over the
following three years because the type's accident statistics had an
unacceptably high percentage of pilot fatalities or serious injuries compared with purpose-designed types like the PA-25 Pawnee.
It was considered the Tiger Moth gave insufficient protection to the pilot.
Tiger Moths had been the mainstay of Australian aerial agriculture since its inception in 1947. RAAF disposals Tiger Moths were plentiful and cheap with seemingly limitless supplies of spare parts and Australian wartime production Gipsy Major engines. Literally hundreds of DH.82s had been converted to crop sprayers, dusters, seeders and spreaders. Many smaller businesses would struggle to raise the financing required to replace their Tigers with modern aircraft specifically designed for agricultural operations, like the Piper PA-25 Pawnee, CallAir A-9 and Yeoman YA-1 Cropmaster.
| Among those smaller companies was Sasin Aircraft Service, Goulburn NSW,
with a single Tiger Moth VH-RIN flown by company founder Mieczyslaw
"Mike" Sasin, born in Poland who had migrated to Australia in 1951. He become an
Aircraft Mechanical Engineer and commercial pilot working for a variety of
aviation companies in Australia and New Guinea before establishing his
own maintenance business at Goulburn Aerodrome in 1960. The following
year he started an aerial spraying operation with the Tiger Moth,
flying for several hours in the early mornings before commencing his day's
aircraft maintenance work.
|Mike Sasin's Tiger Moth sprayer VH-RIN outside his igloo hangar at Goulburn NSW in September 1965.
It was a typical ag Tiger fitted with an overturn truss to protect the pilot. Photo by Peter Limon
Sasin gave a lot of thought to a low-cost replacement during the
forced-retirement of agricultural Tiger Moths and decided on the DHC-1 Chipmunk. He was familiar with the type's fully
aerobatic structure because he carried out the maintainance for the
Goulburn Aero Club's Chipmunk training aircraft.
In July 1963 he purchased an airworthy Chipmunk VH-AMB, dismantled it in his Goulburn hangar and commenced metal work to modify the fuselage to his agricultural design. After an inspection by a DCA airworthiness surveyor rejected his modifications thus far, Sasin approached a small Sydney aeronautical engineering consultancy Aerostructures Pty Ltd at Bankstown Airport.
Aerostructures had been established by Sydney aeronautical engineer C.W. (Bill) Smith who had previously designed agricultural aircraft including the Yeoman YA-1 Cropmaster 250. Smith had been a Director of Yeoman Aviation and in 1964 set up his own business Aerostructures with his chosen design team. Aerostructures specialised as consultant aeronautical designers, gaining DCA approval for a range of light aircraft modifications. Refer: http://www.goodall.com.au/australian-aviation/wackett-cropmaster/wackett-cropmaster.htm
Sasin formed a 50/50 partnership with Aerostructures' senior aeronautical enginer Mike Burns. The project was named Sasin-Aerostructures Spraymaster with design number SA-29, implying it was Aerostructures' 29th project. Aerostructures commenced work on a revised design and submitted professional engineering drawings and stress analysis calculations to DCA for approval. Meanwhile a replacement fusalage was acquired for the prototype. The project was slowed by the lengthy DCA approval process for various components of the design. The Department's airworthiness branch at that time had a well-earned reputation for an ultra-conservative attitude towards modifications and variations to aircraft Type Certificates. DCA determined that the radical changes proposed for the humble Chipmunk trainer required a new Type Certificate and and Aerostructures would be required to comply with all stringent requirements to gain that certification. Mike Sasin's plans for a quick and cheap ag Tiger replacement were dashed but he still saw potential as a cheaper alternative to imported Piper and Cessna ag planes.
The first SA-29 VH-SJD took nearly two years to complete while waiting
for DCA approvals for stages of the modifications.
As costs increased there were further delays while additional financing was sought. Orders were secured from crop spraying businesses in SA and WA. DCA required an extensive test flying program to measure performance. Hawker De Havilland at Bankstown offered their company test pilot but Sasin considered the fee too high. He gained the DCA test pilot qualification himself and did most of the flying, using the cruise flight hours to visit Goulburn to show the new aeroplane to his financial backers and spraying customers.
The SA-29 modifications to the DHC-1 airframe included:
- rear pilot seat retained but raised
- front seat and controls removed and replaced by a chemical hopper
- clipped wings with endplates in lieu of slots
- enlarged low drag "blown" canopy to increase pilot's field of view, offered as clear or tinted
- anti-spin strakes between rear fuselage and horizontal tailplane
- fin fillet
- spring-leaf tailwheel assembly
- overturn truss for pilot protection
- trailing edge wing spraybars and spray pump system, and alternative belly drop hatch for spreading of dry fertiliser or seed
|The short-lived first Spraymaster
DCA type certification for the SA-29 was finalised on 1 September 1965
and CofA issued the same day for the first aircraft VH-SJD owned by
Mike Sasin. It was no longer a low-cost Ag Tiger replacement as first
envisioned, but hopes for further sales were high. The following day
Sasin flew VH-SJD home to Goulburn on delivery to a happy welcome from
local pilots and friends. He flew demonstrations and invited Goulburn
Aero Club instructors to fly the Spraymaster to compare its performance
with the club's Chipmunks. In the enjoyable and unusual
circumstances, the aircraft's fuel state was overlooked. When another
instructor got airborne, the engine failed due fuel exhaustion and the
aircraft dived into the ground. The pilot has badly injured and the
aircraft wrecked as Sasin watched on.
| Mike Sasin later wrote in his book The EP-9 Story:
"Engineering and design now became my interest. The complete redesigning of a Chipmunk aircraft for aerial spraying resulted in a completely new type of plane registered as a SA-29 Spraymaster. This was exacting work because of the strict requirements and regulations covering aircraft design at that time. After about a year of development at Goulburn, the new plane was built over a period of two years at Bankstown Airport, Sydney. Mike Burns, an aeronautical engineer also associated with the development of the plane and I were in a 50-50 partnership and planned to convert more Chipmunk aircraft to the new design. We already had orders and further plans to start production of a more powerful version of the Spraymaster. Financially we were under considerable strain but the future looked good.
After the Certificate of Airworthiness was issued I flew it back to Goulburn. Later that day one of the local pilot instructors took the plane up for as familiarisation flight, ran out of fuel and crashed it. The pilot surtvived but the plane was a complete wreck. It was the end of all our hard work.
There were aerial spraying contracts to fulful so I bought a Piper Pawnee 150 VH-SFF to get on with the work. Two weeks later on December 3rd 1965 while carrying out a spraying job for a local farmer, I crashed the aircraft and was badly hurt and hospitalised. I realised I could no longer fly as a result of the head injuries I suffered. I did not feel I could carry on the business of developing the Spraymaster. While still in hospital I held a meeting with my solicitor and Mike Burns, the outcome being I signed everything over to Mike. My life had changed so drastically I now wanted to move on away from the scene of so much sadness. I was offered a position in Western Australia as chief engineer of a spraying company. Four months after the Pawnee acciden I took up the position and moved my wife and children to a new life in WA."
Aerostructures at Bankstown continued with the construction of the next
two Spraymasters VH-BCA and VH-GEB. Further orders did not materialise,
which ended the Spraymaster. However Sasin and Aerostructures had been
considering options to develop the concept with a more powerful
power plant. Design work on various engine installations began,
but a launch customer was needed to commercially back the development.
That customer was John D. Roulston, owner of Nor'West Air Taxis Pty
Ltd, Carnarvon WA.
To supplement charter work he had pioneered aerial mustering of sheep and cattle on properties in the Murchison district inland from Carnarvon. He was looking for a specialised mustering aircraft to replace the Cessnas he was using. Roulston knew Chipmunks well from nine years as an instructor with the Royal Aero Club of WA, which had a large fleet of Chipmunks. Among aircraft he used for mustering was Chipmunk VH-UEZ which he found suitable for the task, but it was quickly lost in an accident. By early 1966 Roulston had ordered the first Sundowner, which was proposed to be a SA-29 without agricultural hopper and equipment with a modern Lycoming engine. Prospects for aerial mustering were good and his purchase contract included options for additional Sundowners. Aircraft magazine reported in April 1966 "Nor'West Air Taxis are noted for their aerial mustering on stations around Carnarvon. They are believed to have ordered a fleet of Aerostructures Sundowners."
Aerostructures went to work on the protoype Sundowner fitted with a
180hp Lycoming O-360. The company design number is not known, it was
always just referred to as the Sundowner. Allocated registration
VH-CXZ, it was rolled out at Bankstown in July 1967 and commenced test
flying the following month. Sundowner modifications to the DHC-1
The Sundowner project was dogged by misfortune just like the
Spraymaster. Prior to the last of the structural design drawings and
stress analysis calculations to complete the DCA approval process, the
Aerostructures project aeronautical engineer died in a boating
accident. The loss of the designer was to severely hinder the approval process. However the test flying program was allowed
to continue. John Roulston had specified additional fuel capacity to
keep the Sundowners "on task"for longer periods to avoid diversions to
the nearest refelling point, often a considerable distance. Large
wing tip fuel tanks were installed and test flown with varying fuel
loads. A DCA report stated that test flying revealed spin problems when
the tip tanks were full and more design work was required. John
Roulston's order had lapsed due non-delivery and Aerostructures could
not invest further funds on development. But perhaps it could be sold
as a specialised
aerobatic aircraft. Several years of correspondence with the Department
followed, as Aerostructures offered compromises to get the Sundowner
certified, but without success. VH-CXZ was was rolled outside at
Bankstown and left in the weather.
All however had not been in vain. During 1967 while the first Sundowner
was being constructed, Sydney private pilot Dr. Lal McDonnell
comissioned Aerostructures to modify his Chipmunk VH-RJK with the same
Lycoming O-360 powerplant. The modification of Dr. McDonald's Chipmunk
was limited to just the re-engining and mods. already approved by DCA:
metal wing skinning, fin fillet and spring-leaf tailwheel. The cockpit
area was left as original. The work was seemingly completed by March
1968 when VH-RJK was seen at Bankstown with Lycoming and a gleaming new
paint scheme with "Sundowner"on the nose. However behind the
scenes it must have become entangled in the certification problems of
the "full" Sundowner because it was not issued with a new CofA until
December that year, under a new DCA type designation DHC-1/A1. In the
meantime it had been flying regularly on a DCA temporary permit.
|Aerostructures Pty Ltd
Founded by C.W. (Bill) Smith as a consulting aeronautical engineering
business at Bankstown Airport, Sydney. Bill Smith was an experienced
aeronautical engineer who had previously worked for Kingsford Smith
Aviation Service at Bankstown on modifying CA-6 Wackett Trainers for
agricultural use and he later designed the Yeoman YA-1
Aerostructures offered a design and stress-analysis service to gain DCA approval for airframe modifications, changes of engine type etc. The company employed aeronautical engineers on a wide variety of projects, believed to include the first Australian modification of Piper PA-25 Pawnees to two-seaters in 1966 to carry a loader-driver and allow pilot training.
Mid-Murray Flying Club Chipmunk VH-AMB visits Moorabbin Vic March 1963, allover red with white stripe.
Three months later it was sold to Mike Sasin to become the first SA-29. Photo by Bob Neate
|The prototype SA-29 under construction in the Aerostructures hangar at Bankstown on 23 May 1965.
Photo by John Hopton
|Completed as SA-29 VH-SJD at Bankstown 2 August 1965.
Photo by Dave Eyre
side view at Bankstown 2 August
Photo by Michael Croker
|Taxying at Bankstown 28 August 1965 for another test flight, three days before DCA type certification.
Photo by Neville Parnell
|SA-29 Spraymaster No.2 VH-BCA|
at Cunderdin WA in December 1969 as a crop
Photo by Geoff Goodall
|VH-BCA at Beverley WA in November 1970 while operating as a glider tug. Photo by Geoff Goodall
|Back to a sprayer, seen at Kellerberrin WA in October 1975. Note the wing endplates have been removed.
Photo by David Tanner
|Retired at Mareeba Qld in April 1978 after a short career as a glider tug at that field. Photo by Geoff Goodall
Looking much happier at Murwillumbah NSW in August 1990, after a restoration as a single-seat sport aircraft.
Although most agricultural gear was removed, the hopper door can be seen ahead of the cockpit.
Photo by Ben Dannecker
|Mareeba Qld May 2005 rebuilt by North Queensland Warbirds as a standard two-seater Chipmunk,
although retaining the spring-leaf tailwheel and anti-spin strakes. Photo by Paul Howard
|VH-BCA is at the rear of this Chipmunk formation during the 2017 AAAA fly-in at Echuca Vic.
Photo courtesy Rod Blievers who was flying his VH-MMS nearest to the camera aircraft.
|SA-29 Spraymaster No.3 VH-GEB|
Aero Club Chipmunk VH-BSQ at Launceston circa
Photo by Norm Weeding
|Rebuilt as SA-29 Spraymaster VH-GEB for Tonair Pty Ltd, Tintinara SA where seen in September 1966.
Photo by Geoff Goodall
|Tintinara SA in December 1967. The town's name on the fuselage sides was misspelt by the Aerostructures
painter when the Spraymaster was completed 18 months earlier. Photo by Geoff Goodall
|Gawler SA in December 1969 in a smart new paint scheme, now a glider tug with the Adelaide Soaring Club.
Photo by Nigel Daw
|Wreck stored at Parafield August 1970 after a landing accident at Templars SA in March that year.
Photo by Nigel Daw
|A radical transformation in USA as N7DW, a two-seat, open cockpit Lycoming powered aerobatic aircraft.
Photo via Graham Orphan
|In a later "Super Chipmunk"paint scheme and more modifications
Chipmunk" N7DW in a more recent single-seat
Photo by Rod Blievers
|Aerostructures Sundowner No.1 VH-CXZ|
nearing completion in July 1967 at Bankstown.
Photo by Dave Eyre
Sundowner with wingtip fuel tanks, Bankstown March 1968.
Photo by Mike
abandoned and left out in the open at Bankstown April
Photo by David Carter
|Unmoved at Bankstown June 1972, just before it was packed and shipped to USA. Photo by Geoff Goodall
|Aerostructures Sundowner No.2 VH-RJK|
on the Royal Victorian Aero Club line at Moorabbin in
1962. Geoff Goodall
|Now Sundowner VH-RJK, Bankstown September 1968 with "Sundowner" painted on forward fuselage sides.
Photo by Geoff Goodall
|VH-RJK at an airshow at Warrnambool Vic January 1970, flying in a 3 Chipmunk aerobatic display team.
Photo by Nigel Daw
WA January 1976 as a glider
Photo by Nigel Daw
|VH-RJK at Kellerberrin WA May 1976 showing an underbelly auxiliary fuel tank. Photo by Geoff Goodall
|VH-RJK at Cunderdin July 2010, stripped for a rebuild that apparently has yet to be completed.
The Neptune VH-NEP behind was retired here after Perth company Aerocorp converted it to an air tanker
but failed to gain any Government fire bombing contracts or support. Photo by Brenden Scott
|Aerostructures after the Chipmunks
No other Chipmunk rebuilds were carried out by Aerostructures Pty Ltd, although
in all probability the company was involved with the installation
designs for several other Chipmunks re-engined with Lycoming or
Continental engines. Certainly their anti-spin strakes were fitted to other Chipmunks. During 1972
Aerostructures moved from Hangar 120 at Bankstown to a newly built
hangar at Canberra Airport, where the business was renamed Aerosmith Pty Ltd, still under C.W. (Bill) Smith.
Included in the move to Canberra by road was one of Aerostructures' better known projects, the Turbine Mustang. CAC Mustang A68-187 was being re-engined with a Rolls Royce Dart turbine engine for owner Hockey Treloar. The job was completed at Canberra and ground run with the turboprop, however it was not flown.
|The sleek lines of CAC Mustang A68-187 rebuilt by Aerostructures and Aerosmith with RR Dart turboprop.
Seen outside the company's hangar at Canberra Airport in April 1974. Photo by John Hopton
- Australian Civil Aircraft Register, Department of Civil Aviation and its successors
- British Civil Aircraft Register: g-info website
- US Civil Aircraft Register
- US Civil Aircraft News No.02, DHC-1 listing, Midland Counties Publications 1977
- Made in Australia, Australian Air Log, July 1966
- Bad Luck Comes in Threes, Australian Air Log, September 1966
- More on The Spraymaster, Australian Air Log, January 1967
- Antipodean Chipmunks, Geoff Goodall, Aviation Historical Society of Australia Journal, April-June 1978
- Chipmunk The First 50 Years, M.D.N.Fisher, R.W.Brown, T.Rothermel, Air Britain Publications 1996
- DHC-1 Chipmunk, Hugh Shields, Rod Brown, Jose Goncalves, Rod Blievers, SBGB Publishing 2009
- The E.P.9 Story, Mike Sasin, Hesperian Press, 2014