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This Defense Intelligence Reference Document was prepared by the Defense Intelligence Agency's Defense Warning Office in fiscal year 2010 as part of the Advanced Aerospace Weapons System Applications program. It reviews how air flows around objects at subsonic, supersonic and hypersonic speeds, covering shock waves, wakes and ionization. It then compares ways to detect and track hypersonic vehicles, including radar, optical, infrared, LIDAR, infrasound and seismic methods. The report makes four recommendations, among them building a database of aircraft wake signatures and developing novel detectors.
From the source:Release of 2026-09-18 Incident: 11/20/10, Las Vegas, Nevada. Released with redactions. This document is a Defense Intelligence Reference Document (DIRD), a technical reference format used by the Defense Intelligence Agency (DIA) to capture baseline knowledge on a specific topic for later analytic use. DIRDs are best understood as reference and synthesis products rather than as original research. It is one of 38 DIRDs produced under the Advanced Aerospace Weapon System Applications Program (AAWSAP) between 2009 and 2011. Because AAWSAP’s scope permitted a broad range of supporting topics, not every DIRD in the series directly concerns aerospace systems or future threat assessment. The following summary reflects the DIRD’s scope and framing at the time of writing and should not be read as implying current validation of the concepts discussed. This DIRD surveys how hypersonic vehicles may be detected and tracked by exploiting the physical effects they create in flight, especially shock waves, ionized gas, hot surfaces, and turbulent atmospheric wakes. The report reviews a broad set of detection methods, including radar, infrared sensing, optical imaging, LIDAR, passive radio reflection, infrasound, and seismic techniques, and argues that the most effective systems will likely combine multiple sensor types, because each captures different features of a high-speed vehicle’s passage through the atmosphere. It presents radar and infrared sensing as the strongest existing tools for operational detection, while giving particular attention to wake-based methods such as LIDAR and passive radio techniques for improving tracking, identification, and discrimination of future hypersonic aircraft. The paper identifies hypersonic vehicles as an evolving surveillance problem in which future progress will depend on better multi-sensor integration, improved wake characterization, and novel signature-exploitation techniques.
UNCLASSIFIED/fFOR. QFFIEIA.L: Ulii Qt!! X o Manned military jet fighters - The fastest military jet is the MIG-25 Foxbat at 2,115 mph (M = 3). The fastest U.S. jet is the F-15 at 1,875 mph (Mach 2.6). Current U.S. efforts are concentrating on unmanned vehicles, such as the X-43A. o Surveillance aircraft - The SR- 71a "Blackbird" achieved 2,056 mph (Mach 3.3) in 1976 using an air-breathing engine. Its rumored replacement, the SR-91 Aurora, would have been capable of Mach 6. In 2008, the U.S. Air Force entered into an agreement to design a Mach 6 unmanned "blackswift" aircraft using a scramjet. o Passenger jets - The current record holder is the Tupolev Tu-144 "charger" at 1,553 mph (Mach 2.15). Reaction Engines Limited has proposed the A2 hypersonic passenger liner using liquid hydrogen to fuel the aircraft and to cool the wings and fuselage. This aircraft is expected to achieve Mach 5. In 2000, Russia and the People's Republic of China entered into a 25-year agreement to develop the Leninetz AYAKS hypersonic transport plane using kerosene fuel and a variety of techniques to attain Mach 8 to 10. An MHD (magnetohydrodynamic) engine is used to further accelerate combustion products produced by the engine. Lasers and RF generators are employed to disrupt the bow shock, reducing drag and doubling the velocity of the vehicle. o Stealth missiles - The USAF Falcon Project planned for building a Mach 6 HTV-3V "Blackswift" platform but was cancelled in 2008. The NASA X-51 scramjet vehicle is based on the Falcon scramjet and is scheduled for testing in 2010. This vehicle is capable of Mach 7+. DETECTABILITY OF NEW HYPERSONIC AIRCRAFT While conventional RADAR and optical systems may be able to track existing vehicles, future aircraft capable of Mach 8 and above are now being designed and tested. New propulsion technology and drag reduction techniques also offer new ways to detect such aircraft. Based on a review of hypersonic vehicle detection and tracking, four recommendations are made for research and technology development over the next 30 years to increase the detectability of hypersonic objects passin g through the Earth's atmosphere. Recommendation #1 - Build a Database of the Wake Characteristics for Existing Aircraft There is considerable information about the aircraft contained within the turbulent wake that trails it. The wake provides an indication of the vehicle's path and its current bearing. By analyzing the Strouhal eddy formation, it is possible to ascertain its velocity and hydraulic diameter. The wake can also provide information on the chem ical combustion products that can be obtained through LIDAR and can indicate the fuel used by the aircraft. Some aircraft, such as the X-43A and the proposed Reaction Engines Limited A2, use hydrogen as the fuel, so the absence of carbon molecules in their turbulent wakes could aid in their identification. Authors Mark Garnet and Aaron Altman from the University of Dayton 29 proposed the development of a database of turbulent wake data for conventional aircraft to allow their identification. They point out that, although the aircraft may be designed for stealth, their wakes cannot be hidden. They presented data on the unique characteristics that can be used to identify the wakes generated by the F-15, F-16, F-18, and B-52. They also point out the UNCLASSIFIED//FQR QfifilEIA.k W&lii O,.L\f 29
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Official release, from the pursue collection. The PDF is mirrored here; the original link is above. 46 pages are in the text index: search them above, or from the library's search.