Project BANSHEE (Balloon and Nike Scaled High Explosives Experiment) was a Defense Atomic Support Agency (DASA) research program established in 1960 to investigate the behavior of blast waves generated by large conventional high-explosive detonations at high altitude. The project was intended to obtain experimental data on blast propagation in the stratosphere, validate theoretical models, and assess the effects of high-altitude explosions on missile reentry vehicles, aircraft, and space systems. Existing laboratory simulations were unable to reproduce the required atmospheric conditions or generate blast pulses of sufficient duration for accurate measurements.

The program was conducted jointly by the Ballistic Research Laboratories (BRL), Naval Ordnance Laboratory (NOL), Air Force Cambridge Research Laboratories (AFCRL), White Sands Missile Range (WSMR), Picatinny Arsenal, Yuma Test Station, Sandia Corporation, and other supporting organizations. NOL developed the electronic instrumentation and firing systems, BRL developed the explosive charge and mechanical instrumentation, AFCRL conducted balloon operations and flight control, WSMR provided range support and safety services, and DASA managed and funded the program.

The experimental program consisted of four phases. Phase I employed a balloon carrying both the explosive charge and instrumentation. Phase II used a balloon-borne instrumentation system intercepted by a Nike-Hercules missile carrying a live warhead. Phase III used a balloon-borne charge and missile-borne instrumentation. Phase IV involved the interception of an instrumentation missile by a missile carrying a warhead. The first two phases that involved balloon-borne tests took place during 1961-1962 with primary measurements including shock overpressure as a function of distance, shock arrival time, acceleration loading on missile-like bodies, and pressure effects at both airborne and ground stations. The objective was to characterize blast-wave propagation in the upper atmosphere and compare experimental results with theoretical predictions.

The explosive payload consisted of a 500-pound spherical charge of 50/50 pentolite approximately 25.5 inches in diameter. Pentolite was selected because of its well-documented and repeatable blast characteristics. The spherical geometry minimized directional effects and simplified comparison with theoretical models. The charge size was selected to generate pressure pulses of sufficient duration for available instrumentation.

The balloon system carried a 200-foot instrumentation train suspended below polyethylene balloons ranging from 66 to 240 feet in diameter. Operational altitudes ranged from approximately 38,000 to 115,000 feet. The instrumentation train contained pressure transducers, accelerometers, telemetry equipment, magnetic tape recorders, command receivers, timing systems, radar beacons, recovery systems, and multiple instrument canisters positioned at known distances from the explosive charge.

NOL developed an electronic pressure-time recording system capable of operating at high altitude. BRL developed self-recording mechanical pressure gauges that provided reliable pressure-time measurements throughout the program. A redundant firing system incorporated dual detonators, independent firing circuits, radio-command initiation, electromechanical backup timers, and emergency firing channels to ensure both safety and successful detonation.

Ground instrumentation at White Sands Missile Range included high-speed optical cameras, microbarographs, pressure-recording stations, acoustic sensor arrays, tracking systems, and electromagnetic monitoring equipment. These systems measured fireball development, blast-wave arrival times, pressure histories, and long-range atmospheric propagation effects.

Operations were conducted primarily from launch sites in New Mexico, including Hobbs, Artesia, Holloman Air Force Base, and White Sands Missile Range. Extensive coordination with the Federal Aviation Administration was required because live explosive charges were transported through unrestricted airspace. White Sands provided radar tracking, safety control, recovery operations, communications, meteorological support, and logistical assistance.

AFCRL developed a specialized launch system using a modified M48 tank. The balloon, instrumentation train, and explosive payload were assembled on the vehicle and deployed through a sequence of controlled releases. The launch crew remained inside the armored vehicle during critical operations. Multiple safety systems, release mechanisms, explosive bolts, telemetry checks, and backup procedures were incorporated into the launch sequence.

Developmental flights were first conducted to validate deployment procedures, launch techniques, instrumentation performance, and recovery methods. Operational flights during 1961 and 1962 reached altitudes between approximately 25,000 and 102,000 feet. Several missions experienced instrumentation failures, communication problems, tape recorder malfunctions, damaged cables, balloon failures, and trajectory deviations caused by upper-atmosphere winds. Despite these difficulties, multiple flights successfully obtained airborne pressure measurements, ground-based blast data, and photographic records of detonations.

The program produced the first electronically recorded airblast measurements obtained directly in the high-altitude environment. NOL instrumentation recorded pressure-time histories at altitudes near 80,000 and 100,000 feet. BRL mechanical gauges consistently recorded overpressure data. High-speed photography documented fireball growth and secondary shock phenomena, while ground stations measured blast-wave propagation and attenuation over long distances. Preliminary analysis indicated that blast-wave attenuation was greater than predicted by existing theoretical models. BANSHEE provided one of the first large-scale experimental datasets on conventional explosive effects in the near-space environment.