It is generally believed that the USA's interest in ramjet propulsion was rekindled, at least at a research level, during the 1973 Arab-Israeli war when it gained access to Soviet technology in the shape of captured SA-6 Gainful surface-to-air missiles. The SA-6, like the SA-4 Ganef, uses a ramjet sustainer, although in the case of the Gainful, the propellant is of solid-fuel rather than kerosene, which is used in the SA-4.

Ramjet sustainers have gone out of fashion within the surface-to-air missile (SAM) design fraternity as solid-rocket-propellant technology has improved. South Africa's Kentron, however, is working on a ramjet sustainer derivative of its SAHV SAM systems, while Taiwan has also carried out development work on a ramjet derivative of its Sky Bow SAM.

Ramjet propulsion has fared better in surface-to-surface applications, with Russia fielding at least one (and possibly more) ship-launched anti-ship missiles with this type of propulsion. Additional development projects were under way when the former Soviet Union collapsed, and some programmes are likely to have survived.

The Raduga 3M-80, SS-N-22 Sunburn, is a large ramjet-powered anti-ship missile which is reported to have entered service in the early 1980s. The missile has a launch weight of just over 4t and a range of 120km (70nm). With the ability to carry out pre-programmed evasive manoeuvres in the terminal engagement at Mach 2-plus, at an attack height of some 7m, it presents a considerable threat. Another Russian design bureau, NPO Mashinostroenia, is working on the Yakhont, a ramjet-powered anti-ship missile. A shore-launched derivative is known as the Bastion. The status of both projects remains uncertain.

NPO Mashinostroenia may also be responsible for the SS-N-19 Shipwreck anti-ship missile. Details of this in-service weapon remain scant, although recent images suggest that the missile may have an annular ramjet intake.

France's Aerospatiale has looked to its ramjet propulsion expertise in developing anti-ship missiles. A long-running collaborative project with Germany has so far failed to produce a fielded missile, but Aerospatiale, with French Government backing, is pushing ahead with a project to develop a successor to the Exocet, called the ANNG.

Aerospatiale will, under a $200 million development project, produce the "Vesta" testbed for the ANNG, with test launches set to begin in 2001. The ANNG will be offered to equip the European Horizon frigate.

Previously, the US Navy has preferred subsonic systems, such as the McDonnell Douglas Harpoon, to meet its anti-ship missile requirements. It has begun to examine a follow-on weapon to the Harpoon, and is considering a variety of options. It remains to be seen whether the USN will remain wedded to a subsonic approach.

Source: Flight International