|EXPERIMENTAL||Virtual Aircraft Museum / USA / Rockwell|
The X-31 Enhanced Fighter Maneuverability (EFM) programme grew from a joint initiative in 1987 between the US Department of Defense's Defense Advanced Research Projects Agency (DARPA, now renamed ARPA) and the Ministry of Defence for the then Federal Republic of Germany. Its aim was to develop a technology demonstrator to research aircraft manoeuvrability beyond normal flight parameters. It is so far the only 'X-plane' project to involve a foreign nation and was one of the first NATO collaborations to be instituted under the Nunn-Quayle Research and Development Initiative.
Studies in the early 1980s finally laid to rest any notions that the day of the dogfight was over. While it is still supremely important to kill the enemy when BVR (Beyond Visual Range), future fighter designs must be equipped with the capability to out-fly the opposition at close quarters. The X-31 was intended to research all aspects of this high-g, low-speed, post-stall flight envelope using new technology, such as vectored thrust engines. A keystone of the programme was the speed with which it progressed. Funding was approved in 1988 and 22 months later the first of two test aircraft was rolled out.
Rockwell and MBB were selected for their experience with the HIMAT and TKF-90 programmes, respectively. Both had been pursuing similar, but independent, research into highly manoeuvrable combat aircraft design and their efforts were finally merged. To keep on schedule and in budget, extensive use was made of existing systems and parts. The proven General Electric F404 turbofan was chosen as the powerplant.
The first X-31A, assembled by Rockwell, initially flew on 11 October 1990. The second followed on 19 January 1991. The thrust vectoring system had previously been static-tested on a modified F/A-18 Hornet and was first carried in flight by the X-31 A on 14 Februry 1991. Since then both aircraft have flown a consistent and detailed series of tests spurred by the proven capability of the Su-27 and MiG-29.