Aerodynamic design validated and new understanding of thermal material properties gained
Following an extensive seven-month analysis of data collected from the Aug. 11, 2011, second flight of DARPA’s Hypersonic Technology Vehicle (HTV-2), an independent engineering review board (ERB) investigating the cause of a flight anomaly completed its report. The findings of the ERB validated the vehicle’s aerodynamic design and uncovered new information regarding the thermal material properties of the vehicle.
Source: DARPA
DARPA’s Falcon Hypersonic Technology Vehicle 2 (HTV-2) program is a multiyear research and development effort to increase the technical knowledge base and advance critical technologies to make long-duration hypersonic flight a reality.
Data from the program informs policy, acquisition, and operations decisions for future Department of Defense Conventional Prompt Global Strike programs. Hypersonic data is collected through extensive modeling and simulation, wind-tunnel testing and two experimental flight tests. The ultimate goal is a capability that can reach anywhere in the world in less than an hour.
Falcon HTV-2 is an unmanned, rocket-launched, maneuverable aircraft that glides through the Earth’s atmosphere at incredibly fast speeds—Mach 20 (approximately 13,000 miles per hour). At HTV-2 speeds, flight time between New York City and Los Angeles would be less than 12 minutes. The HTV-2 vehicle is a “data truck” with numerous sensors that collect data in an uncertain operating envelope.
Falcon HTV-2 Three Key Technical Challenges
1) Aerodynamics: 22x faster than a commercial jetliner in a regime that is not fully understood
- Requires detailed understanding of extreme pressures
- Expanding technical knowledge requires high-speed wind tunnel tests, computer simulations, and flight tests
- Air doesn’t travel around you — You rip it apart.
2) Aerothermal Effects: HTV-2 surface temperatures reach 3500°F – hotter than a blast furnace capable of melting steel
- Carbon composite material keeps internal electronics 3,300 degrees cooler than the shell, only a few inches away
- Equivalent to a ‘glove’ for your hand dipped in molten hot steel that would keep your hand at 98°F
3) Guidance, Navigation & Control: Extremely high velocities make small disturbances big problems
- Travelling 13,000 mph requires precise sensing and near simultaneous response to flight path disturbances
- Imagine trying to steer around a pothole in the highway while traveling 3.6 miles per second
HTV-2 flew its maiden flight on 22 Apr 2010, collecting nine minutes of unique flight data, including 139 seconds of Mach 22 to Mach 17 aerodynamic data.
Flight one achieved many “firsts”:
- Deployed largest number of sea, land, air and space data collection assets in support of hypersonic flight test
- Maintained Global Positioning System (GPS) signals while traveling 3.6 miles per second
- Validated two-way communication with the vehicle
- Verified effective use of the Reaction Control System (RCS)
The second and final planned flight test is scheduled for 7am August 11th, 2011. First flight lessons learned, high-speed wind tunnel testing and computer simulations were used to improve aerodynamic models and to optimize the vehicle design and trajectory for flight two.
The goal of the second flight is to validate current assumptions and increase technical understanding of the hypersonic flight regime. More than 20 test assets will collect continuous flight data to achieve this goal.
Experience HTV-2’s planned second-flight mission profile by clicking on the phases of flight depicted below:
Recent News: Engineering Review Board Concludes Review of HTV-2 Second Test Flight – April 20,2012
DARPA confirms HTV-2 (Hypersonic Vehicle) splashed down in the Pacific Ocean during controlled descent. – August 14, 2011
