High Boost Experiment (HIBEX)
| Type: | Research test vehicle |
| Guidance: | Inertial/radio command |
| Propellant: | Solid double-base |
| Altitude: | 19 miles (30km) |
| Range: | 25 miles (40km) |
| Speed: | Mach 8 (2,540m/s) |
| Length: | 17 feet (5.2m) |
| Diameter: | 42 inches (107cm) |
| Weight: | 2,760 pounds (1,250kg) |
| First firing: | 25 February 1965 |
HIBEX, sometimes referred to as the High-G Boost Experiment or the High Impulse Booster Experiment, was an experimental vehicle to develop high acceleration booster technology and explore the problems of extremely high accelerations. HIBEX was not linked to a specific weapon system, but the long-term objective was the development of an anti-ballistic missile, such as the Sprint.
The HIBEX program was conceived as early as 1962, shortly after the initiation of the Nike X program, which itself was started in response to serious limitations in the capabilities of the Nike Zeus, intended to be the highest tier air defense system in the US arsenal at the time. Missile technology was advancing rapidly, leading to more and more variables that needed to be addressed in the event of an attack on the US by the Soviet Union. Futuristic and complex-sounding phrases, such as nuclear blackout, neutron flux, and reentry vehicle ablation, began to effect the way that the military thought about ballistic missile defense.
With a conical body and hardly any noticeable external features, it would be easy to assume that this was just the warhead portion of the missile. However, this missile was designed to accelerate at 400 G’s and achieve Mach 8 velocities within two seconds of launch. The stress forces on the missile during launch could be enough to strip away any fins. If the missile was too long, the missile could rip itself apart due to the different times at which its components would begin to accelerate. The total time from launch to intercept was to be less than ten seconds.
Issues soon arose in the HIBEX program. At surface level, where atmospheric pressure is highest, the friction generated as HIBEX left its launching silo was so great that plasma being created around it could interfere with external guidance and communications. The missile’s skin would experience surface temperatures around 2,000 degrees Fahrenheit. New laser gyros had to be installed in the guidance and control section due to the fact that conventional mechanical gyros were too slow for the required reaction time. The fuel tank bladder for the thrust vector control unit ruptured in the first tests due to differential pressures experienced in the high-G environment.
The first test firings occurred in February 1965, with the first launch occurring in November later that year. The last of seven launches occurred in January 1966. The HIBEX missiles were launched from underground cells or surface-level launch platforms at Launch Complex 38. The last launch was made above ground. The Sprint missile, developed from the HIBEX program, was also tested at LC-38.
