Series of non-nuclear explosive and detonable gas tests
Operation Distant Plain
125 foot 20-short-ton (18 t) propane-oxygen hemisphere is prepared for detonation as Event 2A. The striped poles carry instrumentation equipment and a human figure can be seen in the lower right.
Operation Distant Plain was a series of non-nuclear explosive and detonable gas tests performed on test sites in Alberta, Canada, during the course of 1966 and 1967. Their purpose was to provide airblast, cratering, and ground shock data in summer and winter conditions for testing new prototype equipment, military targets and coniferous forest blowdown, and defoliation.
Participants included Canada, the United Kingdom, Australia, and the United States under the Tripartite Technical Cooperation Program.[1] Detonable gas balloons were used in this operation in an attempt to find an economical substitute for TNT as well as for the fact that they could be placed at desired heights without a heavy support structure or towers. In addition, they were more adaptable to airblast phenomena and produced a well defined blast wave without perturbation or ejecta; they also produced no crater. However, it was found that they lacked the high pressure associated with high explosives, and difficulties were encountered as the 20-ton gas balloon ruptured and another detonated unexpectedly during inflation. Ultimately ANFO was elected as a lower cost alternative to TNT for non-nuclear explosives tests.[2][3]
Tests
The following table summarizes the events that took place during the operation in chronological order.
Event
Date
Charge
Yield (short tons)
Height of Burst (feet)
Location
Notes
1
7 July 1966
TNT sphere, tower
20
85
Drowning Ford Test Range, SES
Airblast and induced ground motions
2
July 1966
125 foot methane-oxygen balloon
20
85
Drowning Ford Test Range, SES
Cancelled, balloon ruptured during inflation
2A
22 July 1966
125 foot propane-oxygen hemisphere
20
0
Drowning Ford Test Range, SES
Test feasibility of detonable gas, compare with 20 ton TNT events
3
27 July 1966
TNT sphere, half buried
20
0
Drowning Ford Test Range, SES
Normal environment control for Event 5
4
16 August 1966
TNT Hemisphere
50
0
Edson Forest, 10 miles northwest of Hinton
Coniferous forest blowdown test
2B
October 1966
125 foot methane-oxygen balloon
18.6
63
Drowning Ford Test Range, SES
Rescheduled Event 2, detonated unexpectedly during inflation on ground
5
9 February, 1967
TNT sphere, half buried
20
0
Drowning Ford Test Range, SES
Frozen ground test
6
26 July 1967
TNT sphere, supported
100
0
Watchdog Hill Blast Range, SES
Nuclear weapon surface burst simulation
1A
18 August 1967
TNT sphere, tower
20
30
Watchdog Hill Blast Range, SES
Airblast and induced ground motions, repeat of event 1
Detonation of 20 tons of propane-oxygen hemisphere in Event 2A. The blast wave can be seen affecting the smoke trails.