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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. QFFIEl.t.L: Uii QD:I! X need for computational modeling of hyperson ic wakes to predict the characteristic signature of new, unknown aircraft. A hypersonic vehicle database of wake characteristics for existing aircraft should be developed based on optical and Doppler RADAR data. Doppler RADAR provides information on turbulent intensities and eddy formation within the wake. Computational fluid mechanics models of hypersonic wakes have been done since the early 1960s, such as the work done by Zieberg and Bleich. 30 Such modeling work should continue capitalizing on the increasing computer performance that will be available during the next 30 years. Recommendation #2 - Exploit the Detectability of Hypersonic Aircraft Based on the Features That Allow Them To Fly Efficiently at High Speeds Several new propulsion systems for hypersonic aircraft will be tested over the next 30 years. These include pulsed detonation engines (PDE) successfully tested in 2008 by the Air Force Research Laboratory and Innovative Scientific Solutions, Inc. over the Mojave Desert. While these engines are capable of Mach > 6, t hey have one characteristic that makes them very detectable. The pulsed detonation of combustible fuel creates a wake with periodic bulges referred to as "donuts on a rope." As mentioned earlier, measurements of the turbulent wake behind hypersonic aircraft can be used for detection, identification, and tracking. The AYAKS hypersonic transport plane under development in Russia uses an MHD engine, lasers, and RF generators to decrease aircraft drag. The lasers and RF ionize the air ahead of the aircraft, creating a plasma to disrupt the bow shock and significantly reduce aerodynamic drag. Drag reduction allows the aircraft to double its maximum speed. The RF and laser emissions from this aircraft can possibly be used to detect the aircraft in flight from ground based antenna or telescopes or from satellites. The MHD engine also generates electromagnetic radiation that can possibly be detected. Every new propulsion or drag reduction system under development will have some characteristic that may make it more detectable from the ground or from satellite. The Aerospike engine proposed for the SSTO and under development by Rocketdyne and Garvey Spacecraft involves the use of a novel virtual Laval nozzle that is external to the engine. The IR emissions from an Aerospike engine may increase its detectability. Recommendation #3 - Explore the Detection of Vehicles Designed To Be Undetectable Over the next 30 years, hypersonic cru ise missiles will have the ability to travel at speeds of up to Mach 8 decreasing the chances of being detected or defeated by antimissiles. The unmanned NASA X-51 tested in 2010 is capab le of greater than Mach 7 (over 4,000 mph), for example, and is designed to be launched from a B-52. The DARPA/USAF Falcon Project has resulted in the testing of the HTV-2 at Mach 6. 7 over the Pacific Ocean, designed as a hypersonic cruise vehicle. Efforts to disguise aircraft through the use of novel vehicle shapes and stealth materials can also increase their detectability in other ways. Golovitichev and Hansson presented a paper in 199931 that stated the following: "The concentrated energy drag reduction concept has proven to be effective for the cruise range vehicles, preventing the missile deceleration with the benefit that the spike "products" could envelope the missile in a film of ionized gas which would be impervious to RADAR pulses, thereby rendering it electronically "invisible". The infra- UNCLASSIFIED//EQA: QlililEl.t.L: W&&: O,.L'l 30
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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.