The Falcon Hypersonic Technology Vehicle 2 (HTV-2) is an unmanned experimental rocket launched aircraft which has the capability to fly up to Mach 20 (21,000 km/h). Launched on top of a Minotaur IV Lite rocket, the HTV-2 vehicle carries various sensors to collect data about aerodynamics, aerothermal effects and critical guidance, navigation and control. From an aerodynamic point of view, the HTV-2 flies 22 times faster than a commercial jet, in an extreme pressure condition which is not yet fully understood. From a aerothermal point of view, the craft surface temperature reaches 2,000°C, enough to melt steal, while the internal electronics is kept around 32°C by a thin carbon composite shell. Finally, the aircraft extreme velocity requires an incredible precision in guidance, navigation and control in order to detect disturbances and perform the required corrections.
HTV-2 flew two missions, one on Apr 22, 2010, and the second on August 11, 2011. Both missions ended prematurely 9 minutes into the flight. According to DARPA, the missions achieved the following remarkable objectives:
- Providing the largest sea, land, air and space data collection assets in support of hypersonic flight test;
- Maintaining Global Positioning System (GPS) signals while traveling 3.6 miles per second;
- Validation of two-way communication with the vehicle;
- Verification of effective use of the Reaction Control System (RCS).
The HTV-2 is part of the DARPA Falcon Project (Force Application and Launch fromContinental United States), a research and development project conducted jointly by the Defense Advanced Research Projects Agency (DARPA) and the United States Air Force (USAF) to develop “prompt global strike” capability. By combining a reusable, rapid strike Hipersonic Cruise Vehicle (HCV) and a launch system which could launch an HCV to cruise speed or to send small satellite into Earth orbit, the Falcon technology would provide the US with the capability of delivering a military strike anywhere in the world in less than an hour.