Julian Moxon/PARIS

The French defence ministry and Aerospatiale Matra are discussing the funding of a second phase of the Prométhée research effort to explore the feasibility of a hypersonic air-to-ground missile. The work could include flight testing an experimental vehicle by 2004.

The first phase of the three-year programme began in January and is due to end with initial testing in early 2001. A full-scale model is in definition, based around a 6m (20ft)-long generic missile which would cruise at Mach 8 and weigh around 1,700kg (3,750lb) - including solid propellant boosters.

A missile using a combined variable geometry ramjet/supersonic combustion ramjet (scramjet) operating between M1.8 and M8 has been selected. Two other concepts, a pure scramjet operating between M5 and M8, and a fixed geometry, ramjet/scramjet operating from M2.3 to M8, were rejected.

The concept chosen will take advantage of promising variable geometry scramjet work being undertaken in co-operation with the Moscow Aviation Institute (MAI).

In the first half of next year, the MAI will deliver to Aerospatiale Matra the world's first variable-geometry scramjet combustor for tests at the French company's Bourges facility, just outside Paris. Tests of the combustor are set to begin later in the year.

Aerospatiale Matra says variable geometry will provide "a high level of thrust at low Mach numbers to give the missile the ability to reach its cruising speed and altitude more quickly". Other programme aims include studies of thermal problems associated with long-duration engine operation, particularly with respect to the effect on the combustor walls. Aerospatiale Matra notes that "long duration" might apply "in the case of a reuseable engine for a strategic drone, for example".

The structure will be all-composite, involving three main elements - the forebody, for the warhead and guidance section, centre body for the fixed and "cold" portion of the engine structure, including the hydrogen fuel tank, and the rear part, comprising the ramjet/scramjet nozzle, plus rocket boosters to provide initial acceleration.

Funding for French hypersonics research is running at around Fr40 million ($6.3 million) a year, but is likely to increase significantly if the Prométhée programme shows signs of success.

Source: Flight International