Qualification of the basic Snecma M88-2 was completed in early 1996, with the first production engine delivered at the end of the same year.
The M88-2 has a thrust-to-weight ratio of 8.5, producing 11,250/16,850lb of dry/afterburner thrust (50/75kN). The engine has proved extremely reliable in flight tests to-date, by early May building up 6,200 flight hours on the Rafale, giving a total of 16,400h, including test bench running. "It is now ready for entry into operational service," says Jean Massot, M88 general manager.
Development took place under a fixed (unrevealed) price contract. The engine features state of the art technologies found also in its contemporaries, including single-crystal high-pressure turbine blades, powder metallurgy discs and full authority digital engine controls. Unrestricted operation throughout the flight envelope has been demonstrated, as has "extremely fast throttle response, low observability and multimission flexibility".
Construction is based around 21 modules, interchangeable without the need for recalibration or balancing, along with a number of line replaceable units.
Snecma is developing the M88-2 Stage 4, which has the same thrust as the standard M88-2, but incorporates improvements aimed at extending the service life of the engine and reducing fuel consumption, which Massot says "will also reduce operating costs significantly". Another benefit will be to improve the duration of the low-level penetration missions.
The changes include the introduction of three-dimensional high-pressure (HP) compressor and turbine blades, blisks (one-piece blades and discs) improved thermal coatings on the HP turbine, and advanced cooling channels for the combustion chamber. The Stage 4 development will be ready in early 2001 and the modifications will be retrofitted to the M88-2. It will power the 48 Rafales ordered in the Government's multi-year procurement plan.
A further development, the M88-3, rated at 9.5t thrust, still awaits funding, but has been benchtested on a privately funded demonstrator. "We are proposing the M88-3 to the French government for the future standard of the Rafale in the early 2000s and to prospective export customers", says Massot.
The M88-3 features a new LP compressor with higher mass flow (from 65kg/s in the -2 to 73.4kg/s). A new variable stator vane stage has been introduced, permitting the engine to operate at optimum conditions through a much wider range, reducing part-power-specific fuel consumption and providing more operational flexibility to suit the Rafale's multimission role. The development comes out of Snecma's CENTOR LP compressor research programme and from other exploratory developments carried out by Snecma in recent years. Orders for the M88-2 stand at 42 engines, plus modules and spares, with a further order for 96 units (for the 48 Rafales) expected at the Paris air show.
Source: Flight International
