the predecessor to the U.S. Air Force's iconic SR-71 Blackbird ... also incorporated then-state-of-the-art features to reduce its radar cross-section. These included a combination of a stealthy overall shape and radar-evading structures, as well as the use of composites in its construction, and the incorporation of radar absorbing materials on its skin. A far less known, but still a key component of the Skunk Works plan to make the A-12 harder to spot on radar involved a cesium-laced fuel additive to dramatically reduce the radar signature of the plane's massive engine exhausts and afterburner plumes by creating an ionizing cloud...