VH-WMA, the CSIRO and Rainmaking

by Bill Withers

I was introduced to Whisky Mike Alpha at ARDU (Aircraft Research and Development Unit), Detachment B, RAAF Base Richmond, NSW. It was early in 1956 and the Avro Anson was owned by CSIRO (Commonwealth Scientific and Industrial Research Organisation). At that time I was a Pilot Officer/Navigator with ARDU Det. B. The CSIRO’s flying officer in charge of the aircraft’s operation was Arthur Tapp and the contract pilot was John Aitken.

WMA had just been fitted with the prototype DME (Distance Measuring Equipment) that had been invented by the Radiophysics Division of CSIRO. The Chief of the Division, Dr. Taffy Bowen, accepted the World Navigation Award for the development of DME. The prototype was pre-transistor equipment constructed with radio valves in three black boxes that were, in total, larger than the 100 litre acetone and silver iodide tank fitted in the cabin. DME was given to AWA Ltd. for commercial production. DME was eventually used by all airlines in the world except the USSR airline, Aeroflot.

After working for twelve months with CSIRO as a RAAF officer in ARDU Det. B., I was asked to transfer into CSIRO as a civilian whilst still using RAAF aircraft and the Avro Anson, VH-WMA. Because of my technical and flying background I was employed as a specialist by the Radiophysics Division with the position of Senior Cloud Seeding Officer.

The CSIRO Avro Anson, VH-WMA, was maintained and piloted through a system of contracts with Butler Air Transport which was taken over by Airlines of New South Wales and then Ansett Airlines.

I used VH-WMA in South Australia with John Aitken as the contract pilot. Arthur Tapp and I used it in the Snowy Mountains cloud seeding experiment with John as skipper but when I used it in the Darling Downs and on the Warren/Haddon Rig and CRA, Mary Kathleen contracts it was with another contract pilot, Jim Robinson. The old Avro Anson had a very stressful life including some damage that had been patched up.

The Mary Kathleen CRA contract was the last straw for me. I ordered the return of the aircraft from Mount Isa to Sydney, contrary to the wish of the Radiophysics Division of CSIRO. It had a delaminating main spar, a faulty port tail-plane, electrical problems, pneumatic brake problems and it required a major overhaul on both engines. Jim Robinson and I flew the machine from Mount Isa to Kingsford Smith Airport, Sydney, on its final flight. I later returned to complete the CRA contract with Cessna 310B VH-REK. Adastra purchased VH-WMA for spares. It never flew again despite Adastra’s attempts to have it re-registered.

CSIRO had purchased two Cessna 310Bs (VH-REK and VH-REL) in November 1957 and both departed San Francisco as a formation on 21 November 1957. They were the first light aircraft to make a delivery flight across the Pacific. I navigated VH-REL with New Zealand pilot Phil Lightband. VH-REK was navigated by Arthur Tapp with N.Z. pilot Miles King (founder of Rex Aviation NZ). Arthur and I used bubble sextants. Both aircraft spent five days at New Plymouth, NZ where they were modified to withstand an operational stress of +5G. The aircraft arrived in Sydney on 5 December 1957 to be greeted by a civic reception hosted by the Rt. Honourable Richard Casey MHR (later Lord Casey). The silver iodide burners, which were manufactured in the Radiophysics workshops at Sydney University, were fitted later by Rex Aviation at Bankstown under the direction of the Radiophysics Division of CSIRO. The aircraft were operated on behalf of the CSIRO by Air Research, a company set up for the purpose by Rex Aviation.

Cloud Seeding

The Silver Iodide was made into a stable solution with acetone. That solution was then diluted to a usable mix with more acetone which then became the burning agent. The diluted liquid was atomised in the burners and ignited with a spark plug. When a silver iodide particle is burned and released as "smoke", that particle is much smaller than a particle of cigarette smoke. If the cigarette smoke particle were magnified to the size of a golf ball, then the silver iodide particle, under the same magnification, would only be the size of a pin's head. The silver iodide particle has an atomic lattice structure similar to an ice crystal so the super-cooled water vapour is "fooled" into thinking it is an ice crystal. The water vapour then condenses onto the nucleus and becomes an ice crystal. It grows with further condensation until it becomes too heavy for the convection in the air mass to hold it. The ice crystal then falls and begins to melt in the warmer air, whilst growing further by coalescence. It then falls as rain. However, if the cloud is very deep, with a low cloud base and very strong convection, then the particle can continue to grow as it is pushed into a higher and colder environment. Under those conditions it could later fall as hail. We endeavoured to avoid those conditions.

The Author

Bill Withers resigned from the CSIRO in March of 1964 to enter private enterprise as a new settler in the Ord River Scheme. On two occasions in later years he was asked by the CSIRO to do flying contracts for them. Bill later became the Member for North Province in the Legislative Council of the West Australian Parliament. He retired, with his wife Judy, to Perth in September 2002. One of his hobbies is singing with the Perth Male Voice Choir. Bill shares his name with singer/song writer, Bill Withers, an African American who is best remembered for his hit song "Ain't No Sunshine" (ironic, given Bill's rain-making activities!). Some years ago Bill and his wife Judy were dining in a Perth restaurant where a guitar toting troubadour invited him to sing. After the impromptu performance, Bill was complimented by the restaurant owner who confided in Bill; "You know I always thought you were black."