powered ramjet cruise missile capable of extended long range flight. It has been designated 9M730 "Burevestnik" (Petrel) by Russia and has the NATO reporting name SSC-X-9 "Skyfall". On 9 August 2019, an explosion and release of radioactive material was recorded at the State Central Navy Testing Range. Recovery efforts were underway to raise a test article which had landed in the White Sea during testing in 2018 when the nuclear power source of the missile detonated and killed 5 researchers. Germany In 1936, Hellmuth Walter constructed a test engine powered by natural gas. Theoretical work was carried out at BMW and Junkers, as well as DFL. In 1941, Eugen Sänger of DFL proposed a ramjet engine with a very high combustion chamber temperature. He constructed very large ramjet pipes with and diameter and carried out combustion tests on lorries and on a special test rig on a Dornier Do 17Z at flight speeds of up to . Later, with petrol becoming scarce in Germany due to wartime conditions, tests were carried out with blocks of pressed coal dust as a fuel (see e.g. Lippisch P.13a), which were not successful due to slow combustion. United States Stovepipe (flying/flaming/supersonic) was a popular name for the ramjet during the 1950s in trade magazines such as Aviation Week & Space Technology and other publications such as The Cornell Engineer and the Journal Of The American Rocket Society. The simplicity implied by the name came from a comparison with the turbojet engine which also has, together with the inlet, combustor and nozzle of a ramjet, complex and expensive spinning turbomachinery (compressor and turbine). The US Navy developed a series of air-to-air missiles under the name of "Gorgon" using different propulsion mechanisms, including ramjet propulsion on the Gorgon IV. The ramjet Gorgon IVs, made by Glenn Martin, were tested in 1948 and 1949 at Naval Air Station Point Mugu. The ramjet engine itself was designed at the University of Southern California and manufactured by the Marquardt Aircraft Company. The engine was long and in diameter and was positioned below the missile. In the early 1950s the US developed a Mach 4+ ramjet under the Lockheed X-7 program. This was developed into the Lockheed AQM-60 Kingfisher. Further development resulted in the Lockheed D-21 spy drone. In the late 1950s the US Navy introduced a system called the RIM-8 Talos, which was a long range surface-to-air missile fired