Air Blast Measurements from the Detonation of an Explosive Gas Contained in a Hemispherical Balloon (Operation Distant Plain, Event 2a)

Air blast was measured from the detonation of a mixture of oxygen and propane equivalent to 20 tons of TNT in a hemispherical balloon anchored to the ground surface. Measured values of shock arrival time, overpressure, duration of positive and negative phase, overpressure impulse, dynamic pressure, and dynamic pressure impulse are plotted as functions of ground range. Pressure-distance comparisons with TNT show the overpressure to be less than TNT at pressures greater than 30 psi. Comparisons made of overpressure waveshape and impulse as a function of shock overpressure show an equivalent yield of 20 tons or larger and a dynamic pressure impulse about 60 percent larger than for a corresponding 20 Ton TNT charge.