Researchers test groundbreaking boron ramjet for missiles that fly through the air and water

Chinese researchers have tested the world's first boron ramjet engine that operates in air and water. Originally designed for hypersonic weapons, it achieved nearly 90% combustion efficiency in submarine mode during tests. Using boron as fuel and switching between air and water as oxidizers, it can transition from hypersonic flight to high-speed underwater travel. This breakthrough could lead to "cross-medium" hybrid weapons capable of flying at hypersonic speeds and then attacking underwater targets at over 200 knots.