Ramjet

Lore & Background

The ramjet was conceived in fiction by Cyrano de Bergerac in 1657. French inventor René Lorin patented a ramjet design in 1913 but could not test it due to lack of sufficiently fast aircraft. René Leduc's Leduc 0.10 was one of the first ramjet-powered aircraft to fly, in 1949. The Nord 1500 Griffon reached Mach 2.19 in 1958.

In 1915, Hungarian inventor Albert Fonó devised a ramjet for artillery shells, but his proposal was rejected. He later patented an air-jet engine in Germany in 1932. In the Soviet Union, Boris Stechkin presented a theory in 1928, and I.A. Merkulov tested the GIRD-04 ramjet in 1933. A claim exists of a ramjet-powered airplane flight in December 1940 using two DM-2 engines on a modified Polikarpov I-15, but this is contested and not universally accepted; the more widely recognized first flight of a dedicated ramjet aircraft is the Leduc 0.10 in 1949.

During World War II, Japan developed ramjets at Kawasaki Aircraft Company, and Germany conducted tests under Eugen Sänger. The US developed ramjet missiles including the Gorgon IV, Lockheed X-7, and the CIM-10 Bomarc. The UK produced the Bloodhound and Sea Dart ramjet missiles. In 2020, the US and Norway partnered on the THOR-ER solid fuel ramjet program.

Reader's Guide

The ramjet is significant as a simple, high-speed propulsion system with no moving parts, relying entirely on forward motion to compress incoming air. Its development spanned multiple countries and decades, from early theoretical work by Lorin and Fonó to operational missiles like the US Talos and UK Sea Dart. The ramjet enabled sustained supersonic flight for missiles and aircraft, and its principles continue to inform hypersonic weapons research. The THOR-ER program, a US-Norwegian partnership announced in 2020, demonstrates ongoing interest in ramjet technology for extended-range high-speed weapons. Despite limitations—ramjets cannot operate at zero speed and require boost to reach operating speeds—they remain a key technology for compact, high-speed propulsion, particularly in military applications.

Did You Know?

• The widely accepted first flight of a dedicated ramjet aircraft is the Leduc 0.10 in 1949; a contested claim exists for a December 1940 Soviet flight.
• The US Navy's RIM-8 Talos was the first ship-launched missile to destroy an enemy aircraft in combat, in 1968.
• The THOR-ER program completed a solid fuel ramjet vehicle test in August 2022.