Defence

A scale model of a stealthy unmanned aircraft completely lacking conventional control surfaces is expected to make its maiden flight in the UK by the end of November.

Resembling Boeing’s X-45 unmanned combat air vehicle, the University of Manchester’s so-called Integrated Demonstrator weighs 4.5kg (9.9lb) and will fly at speeds of up to 9.7kt (17.9km/h).

“The Integrated Demonstrator will use two brushless-motor ducted fans for propulsion and it will be controlled remotely or by the autopilot software Micropilot,” says the project’s chief engineer, doctoral student Russell Sparks.

The demonstrator uses fluidic thrust vectoring in the pitch axis and aerodynamic circulation control in the roll axis to enable flight without conventional moving surfaces. In fluidic vectoring, a secondary jet parallel to the main flow over the curved exhaust surface entrains and redirects the main jet’s thrust. The control technique has been tested on a ducted-fan-powered Schübeler Vector II model aircraft.

Roll circulation control uses air blown over the wing’s rounded trailing edge to entrain the upper-surface flow and cause it to deflect in the same way that a flap would. It has been proven by the team on a conventional model aircraft.

Following the scale-model tests, fluidic thrust vectoring will be tested with a gas turbine next year. The work is part of the UK’s five-year, £6.2 million ($11.3 million) flapless air vehicle research programme.