Recording Biggest Non-Nuclear Explosion
(reprinted from the October 1961 issue of The Roundel)
By C.A. Pope, DRB Public Relations Officer
The Defence Research Board’s shock and blast program at Suffield Experimental Station (SES), near Medicine Hat, Alta., was given a valuable assist by the RCAF on 3 August when a camera-equipped Lancaster photographed from the air the detonation of 100 tons of TNT. In addition, an RCAF helicopter obtained aerial photographs of the crater formed by the massive explosion.
Research agencies from Canada, the United Kingdom and the United States participated in the experiment. Their main objective was to obtain fundamental scientific information about phenomena in the air, in the ground and at the surface caused by the large non-atomic explosion. The effects of these phenomena on a variety of military and civilian configurations are still being examined in detail.
Navigating the wartime bomber so that it would be 10,000 feet over Ground Zero at detonation was forecast as “a virtual impossibility’? by a number of navigation experts outside Canada. Navigators F/L R.W. Buskard and F/O G.B. Foote, however, guided pilot F/L M.F. Chapin so accurately the Lanc reached its predetermined point in the air just one second before the explosion began.
Eight cine cameras, shooting at speeds ranging from three to 800 frames a second, provided the DRB scientists with a film of the detonation which complemented the cine footage taken on the ground by SES photographers. The Lancaster was also fitted with a pressure transducer which measured the pressure in excess of normal at 10,000 feet during the detonation to confirm predicted pressure from the explosion.
Aerial photographs of the crater and its specific characteristics, taken from the helicopter, were compared with ground measurements obtained after the explosion. The results should help to permit accurate interpretation of a variety of ground features from aerial photographs.
Both aircraft were provided by the Air Armament Evaluation Detachment of CEPE at RCAF Station Cold Lake. An RCAF team had worked closely with DRB preparing for the experiment since last January.
In the past, detonation investigations have been conducted principally with relatively small charges weighing up to a few hundred pounds. Reasonably accurate predictions about the behaviour of massive explosions have been extrapolated from this research. The experiments at SES, however, provide far more precise information about the magnitude of TNT air blast waves and should confirm or negate theoretical predictions made previously.
Approximately 70,000 feet of cable trench, dug to various depths, contained more than 1,500,000 feet of coaxial and other cables. One scientific group alone required the transportation of 50 tons of experimental material to the test site. On the day of the trial, approximately 300 scientific, engineering and technical individuals were directly involved. Many tens of thousands of specific measurements were carried out and the full interpretation of the trial results will probably require more than a year to complete.
