M88 | |
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M88-2 engine at Paris Air Show 2007 | |
Type | Turbofan |
National origin | France |
Manufacturer | Safran Aircraft Engines |
Major applications | Dassault Rafale |
The Snecma M88 is a French afterburning turbofan engine developed by Snecma (now known as Safran Aircraft Engines) for the Dassault Rafale fighter.
The program for the M88 arose from a need for a suitable propulsion system for air-superiority and ground-attack missions. In 1983, Dassault Aviation planned to produce a technology demonstrator for the Avion de Combat eXpérimental (ACX), which was expected to fly in 1986. Although the M88 was intended to be fitted to the definitive aircraft, [1] it was not expected to be ready in time, and the ACX was therefore initially powered by the General Electric F404.
Due to the broad application of the new engine (as the aircraft was to replace a considerable number of the French fleet), it was necessary for the engine to have a high thrust-to-weight ratio, low fuel consumption in all flight regimes, and a long engine life. [2] Additional considerations were afforded to good maintainability, and upgrade potential (73 kN to 105 kN using the same core). The program was officially launched in 1986. It was decided to flight test the engine, the M88-2, aboard the Dassault Breguet, and the Rafale A prototype. [3] [4] [5] : 35 Indeed, after having replaced the aircraft's left F404, the engine was first flight tested aboard the Rafale A on 27 February 1990. By then, the fourteen M88-2s had accumulated 1,600 hours of running time. The demonstrator thereafter reached supersonic speed without afterburners, reached a height of 50,000 ft, endured load factors of −2g and +9g and flown at an angle of attack of 30°. As of July 2022, M88 engine that powers Dassault Aviation’s multirole fighter has clocked up more than one million operating hours [6]
The SNECMA M88 engine main concepts and choices were settled at the end of the 1970's, both SNECMA and French Ministry of Defense concluded that a high overall pressure ratio and high Turbine Entry Temperature (TET) were needed. The layout was to be a twin spool, low bypass turbofan engine using new powder metal compressor blisks, a clean burning annular combustor and a key new technology, air cooled, ceramic coated, single crystal turbine blades made from a new AM1 alloy (N-18 alloy in the final production engines). The turbine performance was further enhanced with the use of active blade tip clearance control. [7] Full authority digital engine controls and monitoring were used throughout. Air cooling of the turbine blades was essential, as they were to operate in a gas stream 300k above the materials melting temperature. Component bench testing of the turbine sections began in 1978 seeking a TET of 1700K. After initially promising results, this goal was raised to 1850K. By 1987 this goal was reached and the first demonstrator engine, the M88-1 was presented for development.
In 1989 the engine M88-2 (Final production version) reached its designed maximum thrust of 75KN 5 months ahead of the contract deadline. By this time the first engine had been fitted to test airframe ACX-RAFALE. Engine life was certified up to 500 hours at this time.
The engine obtained flight qualification in 1995 after 5500hrs on the test bench at both sea level and simulated altitude conditions and included simulated Mach 1.6 airflows, as well as an additional 4000hrs over 600 flights on the prototype aircraft in real world conditions. [8]
The first serial production M88-2 engine was delivered in 1996. The engine design was focused on keeping weight and area to a minimum. Compared to the previous generation of 9K-50 Atar engines the M88 was 40% shorter and 45% lighter while improving thrust to weight ratio by 80%. [8] The engine is fitted with a digital condition monitoring and prognostic system in order to reduce engine downtime and increase the time between overhauls. Known as the Engine Condition Monitoring System it functions by collecting data from the engine monitoring sensors, vibrations, inversion and oil filter clogging sensors. The system is able to extend or shorten the engines TBO depending on the usage of that particular engine. [9]
The engine has to date clocked up over 1 million flight hours with over 600 units delivered. The M88-2 engine has seen regular development and improvement. Early Stage 1 engines were limited to a 300 hours time between overhauls "TBO". Stage 4 engines (Delivered from 2011 and onwards, designation M88-2E4) have TBO's exceeding 1000hrs and a reduced fuel consumption of 3%. [10]
M88-TREX
Data from Safran Aircraft Engines [18]
Comparable engines
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