Research Note to Hypersonic Boost-Glide Weapons by James M. Acton: Analysis of the Boost Phase of the HTV-2 Hypersonic Glider Tests

“Hypersonic Boost-Glide Weapons,” by James M. Acton (this issue), analyzes the portion of the flight of the U.S. HTV-2 hypersonic glide vehicle after it has been boosted to high speed and begins to reenter the atmosphere.1 To understand more about the HTV-2 test flights that took place in 2010 and 2011, this research note discusses the powered portion of the booster’s flight based on simulations from launch through reentry into the atmosphere at about 100 km altitude—the so-called “pierce point.” This corresponds to Acton’s segments 1 and 2 of the trajectory: boost and exo-atmospheric phases. This analysis is based on descriptions of the launch vehicle used in the HTV-2 tests, the splashdown points of the booster stages and faring, and the reported speed and altitude of the HTV-2 at the pierce point. Two test routes were planned for the HTV-2, both starting at Vandenberg Air Force Base in California and ending near Kwajalein Atoll some 7,800 km away. The glide portion of trajectory A stretched essentially straight from the launch to impact point, while trajectory B headed west and then maneuvered during its glide to arc south toward the impact point (see Figure 3 of Acton). While tests were only conducted on trajectory A before the program ended, DARPA released the intended parameters for both trajectories, given in Table 1.