Burned from Above
In the early 1960s in British Columbia, following an increase in logging and cutblock, or clearcut, areas, it became apparent that a more efficient, cost-effective and safer method of controlling fire on the land was needed. Using fire to reduce hazard, remove fuel ahead of fire, prepare sites for reforestation and modify vegetation for wildlife enhancement was recognized as a valuable tool. However, to achieve these goals, the tools and techniques to pursue them needed to be safe, efficient and effective.
The challenges were many because Canada had limited staff with burn experience. Wildlife enhancement areas were large, and logging cutblocks were getting larger. The Interior of British Columbia was rapidly expanding logging operations, but the terrain and fuels were much different from the coasts where most logging had traditionally taken place. New techniques and equipment were needed for burning operations.
In 1966, three Australians who worked for the government's research group — Baxter, Pacham, and Peet — developed and used the first ever aerial ignition device, or AID. The process consisted of using a pharmaceutical vial that contained potassium permanganate powder, manually injecting glycol into that vial and tossing it out the window of a fixed-wing aircraft into the designated burn area. The two chemicals mixed, and a delayed exothermic reaction occurred, usually within 15 to 45 seconds, depending on climatic conditions.
Into the 1970s, Australia continued to pioneer airborne incendiary devices and techniques for fire suppression burning. Between the 1960s and early 1970s, the Canadian Forestry Service collected data and observed burning techniques used across Canada and around the world. The Federal Research Institute approached the Australians to learn more about their methods to see what could be used in Canada.
In 1972, the hand-release method was used to operationally test AID in the Yukon. The method used was the same as the Australians, except that a helicopter was employed as the aerial delivery platform. This was mostly successful, but the procedure was limited in that only 12 to 20 vials could be dropped per minute. Because this method of priming and dropping incendiary devices was slow, a mechanical device was needed. Recognizing the requirement to use aerial techniques to burn as well as the need for improved delivery methods, the Yukon Forest Service requested the Canadian Forestry Service, with which the Pacific and Northern Research Institutes were involved, to develop an efficient, effective and safe AID for burning out and back-firing large areas. The CFS immediately began to develop a mechanical device.
The need for safer, more efficient methods and mechanisms seemed to have been generally satisfied in Canada with the development of two types of fire ignition systems: the AID, developed in 1972 by the CFS, and the aerial drip torch developed in concert between the CFS and Northwood Pulp and Paper in 1973. Further testing and improvements of these devices continued over the years, but the operational need for automated aerial burning had been fully embraced.
John Muraro, a researcher who worked for the CFS, and his colleagues conducted a 1972 study that consisted of two phases: The first phase was the testing of incendiaries, and the second phase was the design and construction of a priming and release mechanism. Under Muraro's guidance, the first truly operational AID was built.
Mounted on a Bell 47 helicopter, this device had a rotary turntable that could prime and release vials as fast as they could be placed in it. Neither the hand-powered nor hand-loaded prototypes constructed at the CFS Northern Forest Research Centre, nor the Australian hand-loaded, motorized dispensers, satisfied the need for a device that could dispense a large number of incendiary devices safely and efficiently over a wide area.
The first mechanical model used a pressurized glycol reservoir that shot a measured amount of fluid into a styrene vial containing the potassium permanganate through a hollow needle. The vials were contained in a 100-capacity magazine, gravity-fed into the dispenser, charged and then allowed to drop through a tube and fall to the forest for ignition.
The second model incorporated a centrifugal pump to force glycol through the needle. This provided a slightly faster (1.5 times) rate of dispensing vials. Roy Kruiger of the Alberta Forest Service became interested, and in consultation with CFS staff they focused their attention on an automatic feed gate system. They also developed a spherical container to hold the potassium permanganate, which improved efficiency in a hopper feed system. A machine was built to incorporate these features and was operationally tested in Alberta.
These trials were so successful that the CFS contracted a local machinist in Fulford Harbour, British Columbia, to immediately build five production models — two for the Yukon Forest Service, one for the Ontario Government and two for Alberta. These production models would later develop into the Mark III AID and become the only plastic sphere dispenser in the aerial fire ignition industry for the next 30 years.
In 1973, the United States became interested in aerial incendiary devices for suppression reasons, and the U.S. Forest Service purchased incendiary equipment from CFS.
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