McDONNELL DOUGLAS (MDC) and NASA are to unveil a newly de-classified future fighter research aircraft at the company's St Louis, Missouri headquarters on 19 March.

The exact configuration of the X-36, as the sub-scale vehicle is called, is being kept secret until the roll-out, but it is already clear that the aircraft is tail-less and equipped with a "unique" thrust-vectoring system, split ailerons and sophisticated flight-control laws.

Because the aircraft was designed to be tail-less from the beginning, "...our design philosophy does not actually require thrust-vectoring to control the vehicle", says NASA X-36 programme manager Dr Larry Birckelbaw. The X-36 is designed to maintain "level-one handling capabilities" and be controllable, even with engine power lost or the thrust-vectoring nozzle locked inadvertently in one position.

Two unmanned X-36 vehicles will be used for the flight-test programme, which is due to begin at NASA's Dryden site at Edwards AFB, California, in the middle of the year and run through to the end of the year. Each of the 28%-scale aircraft will be powered by a 3kN (675lb)-thrust Williams F112 turbojet originally destined for the now-cancelled advanced cruise-missile programme. The availability of the spare power plants was partially responsible for the scaling.

The 590kg vehicles are 5m long, with a 3.05m wingspan. The X-36's thrust-to-weight ratio gives it a potential top speed of 350-400kt (650-740km/h), but testing will be limited to "around 160kt" to prevent the structure failing in the event of a "worse-case" flight-control system failure. The MDC/NASA team predicts that all the required flight-test data for phase 1 of the programme will be collected over around 25 sorties.

The X-36 is not expected to become a full-scale aircraft, but will act as a flying test-bed for future technologies, "...providing design options and tools for designers of future fighters," says Birckelbaw. The X-36 will also exhibit basic low-observable design features such as aligned control surfaces.

MDC X-36 programme manager Dave Manley says that the company entered the project with NASA for two main reasons. Firstly, because there " a lot more interest now in tail-less vehicles". Secondly, "...and the reason we put up $10 million of the $17 million X-36 programme cost because we wanted to demonstrate the Phantom Works' capability, for rapid prototyping".

Birckelbaw says that the X-36 benefits include "...the significant breakthroughs in technology such as the vehicle's advanced aerodynamics, unique thrust-vectoring system and control laws that couple the whole thing together".

MDC's bid for the Joint Advanced Striker Technology programme is based on a tail-less configuration.

Source: Flight International