With an eye towards developing a low-altitude penetrating fighter-bomber and long-range interceptor based on their successful Mirage 2000 airframe, Dassault of France drew up plans for the Mirage "4000" as a private venture endeavor to compete against the likes of the American McDonnell Douglas F-15 "Eagle". Overall the design mimicked the form and function of the its parent model but stood as a dimensionally larger offering. The aircraft continued the Dassault standard of using delta wing mainplanes, a single vertical tail fin, and semi-circle air intakes straddling the fuselage sides. After completion of the prototype form, the aircraft recorded its first flight on March 9th, 1979.
The Mirage 4000 set about to create a different aircraft type from the previous Mirage 2000. The original was a multirole fighter carrying a single turbofan engine, nine weapons hardpoints, and restrictive views to the rear due to the raised fuselage spine. Its speed reached over 1,500 miles per hour at high altitude (with reduced performance at lower flight envelopes) with an attainable service ceiling nearing 59,000 feet. The Mirage 4000, as a larger and heavier platform, carried a twin, side-by-side engine configuration aiding performance, maximum attainable altitude, climb-to-altitude, and over-battlefield survivability. The raised fuselage spine was done away with and a "bubble-style" canopy took the place of the original - offering much improved vision out-of-the-cockpit. Clean, sharp lines in the new product continued the Dassault approach to combat aircraft of the Cold War period (1947-1991).
The engine pairing became 2 x SNECMA M53-2 afterburning turbofans outputting 18,740lb of thrust each. This drove the aircraft to speeds of 1,520 miles per hour with an attainable altitude of 66,000 feet. Later, in its development life the aircraft was re-engined with the M53-5 turbofan of 19,378 lb thrust (x2).
Dimensionally, the Mirage 4000 exhibited a length of 18.7 meters, a wingspan of 12 meters and a height of 5.8 meters. Its empty weight stood at 29,000lb. Comparatively the Mirage 2000 held an overall length of 14.3 meters, a wingspan of 9 meters, and a height of 5.2 meters.
While armament was never fitted, it is assumed that the large airplane would have fielded short-, medium-, and long-range Air-to-Air Missiles (AAMs) as well as Air-to-Surface Missiles (ASMs), guided munitions, and conventional drop bombs across its eleven hardpoints. Provision for fuel drop tanks would also have been included. Internally, the aircraft was set to carry 2 x 30mm DEFA cannons for close-in work.
One of the key customers originally targeted in the Mirage 4000 program was Saudi Arabia. However, the nation eventually settled on the American F-15 as their primary multirole attack platform leaving the Mirage 4000 initiative with no prospective buyers - even locally with the French Air Force already committed to the Mirage 2000.
The single, flyable prototype Mirage 4000 was all that was realized as the program faced termination during the 1980s. However, this airframe was later to prove influential in the development of the Dassault Rafale 4th Generation Fighter as it was used to evaluate composites in aircraft construction, trial Fly-by-Wire digital control, assess computer aided design and the like. It was also re-engined, once again, to carry the M53-P2 turbofan engine that benefitted the Rafale's development.