Dassault Mirage IIIV

The Dassault Mirage IIIV, also spelled Mirage III V, is a French vertical take-off and landing (VTOL) prototype fighter aircraft of the mid-1960s developed and produced by Dassault Aviation.

The Mirage IIIV was a VTOL derivative of an existing conventional fighter, the Dassault Mirage III; the principal difference between the two types was the addition of eight small vertical lift jets which straddled the main engine. These lift jets would have been used during vertical takeoffs and landings, but would have been inactive during horizontal flight. The Mirage IIIV had come about as a response to the issuing of a NATO specification, NATO Basic Military Requirement 3 (NBMR-3), which sought a supersonic-capable VTOL strike fighter.

The Mirage IIIV was a competitor with Hawker Siddeley's P.1154 VTOL fighter, a cousin of the Hawker Siddeley Harrier. Both aircraft competed to be selected to meet the NBMR-3 requirement. While the Mirage IIIV is commonly viewed as being more politically palatable due to an emphasis having been placed upon multinational development and manufacturing plans, the design of P.1154 (which only used a single engine) was seen as more straightforward and reliable. Ultimately the P.1154 was selected to meet the NBMR-3 requirement to the detriment of the Mirage IIIV. One of the two prototypes constructed was destroyed in an accident; shortly following its loss, the whole project was abandoned; the surviving aircraft has since been placed on public display.

In August 1961, NATO released an updated revision of its VTOL strike fighter requirement, NATO Basic Military Requirement 3 (NBMR-3). Specifications called for a supersonic V/STOL strike fighter with a combat radius of 460 kilometres (250 nmi). Cruise speed was to be Mach 0.92, with a dash speed of Mach 1.5. The aircraft, with a 910-kilogram (2,000 lb) payload, had to be able to clear a 15-metre (50 ft) obstacle following a 150-metre (500 ft) takeoff roll. Victory in this competition was viewed being of a high importance at the time as it was seem as being potentially "the first real NATO combat aircraft".

During the 1950s and 1960, both French aircraft manufacturer Dassault Aviation and British aerospace company Hawker Siddeley Aviation (HSA) were deeply interested in vertical takeoff/landing (VTOL)-capable combat aircraft. HSA had already been keen to develop a new generation of combat aircraft that would be capable of supersonic speeds. HSA's chief aircraft designer Sir Sydney Camm decided that the company should investigate the prospects of developing and manufacturing a viable combat-capable vertical take-off and landing (VTOL) fighter aircraft. Along with the subsonic Hawker P.1127 fighter (which would become the Hawker Siddeley Harrier later on), a supersonic design, designated as the P.1150 was produced; however, the release of NBMR-3, and subsequent revisions to it, led to the P.1150 proposal being considered to be undersized and thus unsatisfactory, which led to a desire for a redesign. The new, larger aircraft design soon emerged, which was initially designated as P.1150/3 prior to being redesignated as the P.1154.

In January 1962, HSA submitted the proposed design of the P.1154 to NATO via the Ministry of Aviation. NBMR.3 attracted a total of eleven contenders, including Dassault's Mirage IIIV proposal, which would become viewed as the principal competitor to the P.1154. Substantial support for the Mirage IIIV came from Britain, work on the programme having involved the British Aircraft Corporation (BAC), while the Dassault-led design also held the favour of several members of the British Air Staff. While the P.1154 was judged to be technically superior, the Mirage IIIV had acquired a greater level of political palatability due to the co-operative development and production aspects proposed for the programme, under which work was to be distributed across a number of member nations.

In May 1962, the proposed P.1154 emerged as the winner of the NBMR.3 competition . According to aviation author Jeffort, the Mirage IIIV was rejected mainly because of its excessive complexity: using nine engines, compared to the P.1154's single-engine approach. However, the success of the P.1154 design did not lead to orders being placed for it. NATO lacked any central budget, instead relying on individual member nations to actually procure military equipment, contributing to the NBMR.3 selection going unheeded by all of the NATO member nations. Thus, in 1965, the NMBR.3 project was unceremoniously terminated.

While the French government formally withdrew its participation in NMBR.3, after the Mirage IIIV had been rejected, Dassault continued work towards the building of Mirage IIIV prototypes.