Several nations are working on hypersonic aircraft, including the U.S. and China. However, most of the research and development work has been in aerodynamics, propulsion, and materials, while sensors have gone neglected.
The U.S. Air Force now wants to develop a radar designed for hypersonic planes. In particular, they are focusing on a Synthetic Aperture Radar/Ground Moving Target Indicator (SAR/GMTI) for an aircraft traveling at Mach 5 to Mach 7, at an altitude of 30 kilometers, according to an Air Force Small Business Innovation Research (SBIR) solicitation.
Resource: Read the SBIR Solicitation
SAR/GMTI sensors are tough for fast aircraft. Their velocity creates Doppler clutter, the high grazing angles add ground clutter, slender airframes limit antenna size and shape, high speeds limit data processing, radar signals contend with factors such as atmosphere and aperture, and high airframe heating creates antenna noise. SAR and GMTI also have different pulse repetition frequencies.
Phase I of the project will devise a SAR/GMTI sensor that can cover a 70-kilometer swath at a resolution of 1 meter. Phase II will include a simulation tool to estimate sensor performance for various hypersonic vehicles and trajectories. Phase III will see an actual sensor for the military, NASA and commercial users.
