Flight without flaps

An innovative pilotless aircraft with flapless wings has completed a test flight in the UK.

The model aeroplane was developed by a cross-disciplinary team from UK Universities as part of a £6.2m programme, funded jointly by the Engineering and Physical Sciences Research Council and BAE Systems.

The five-year programme, called FLAVIIR (flapless air vehicle integrated industrial research) involves teams from Leicester, Liverpool, Nottingham, Southampton, Swansea, Warwick, York and London. Manchester University’s Goldstein Aeronautical Research Laboratory developed the model aircraft and the programme is managed by Cranfield University.

“The overall programme is aimed at developing new technologies for future generation uninhabited air vehicles, so called UAVs,” said Professor Ian Postlethwaite, Pro-Vice-Chancellor and Professor of Engineering at Leicester.

The team involves experts from around the UK in aerodynamics, control systems, electromagnetics, manufacturing, materials and structures, and numerical simulation. The results from the different groups will be brought together in a single flying demonstrator in about 2009. The concept of a flapless vehicle, using fluidic thrust vectoring – where direction is changed with a secondary airflow – and air jets, is one important area of investigation. Another is the replacement of the pilot by sophisticated software that can autonomously fly the vehicle without collisions in what might be dangerous or remote environments.

Postlethwaite and the Leicester researchers are involved in increasing the levels of autonomy and performance in UAVs through research into coordinated control, integrated control and condition monitoring. Over the past year, the Leicester team has developed a software package for the flight path planning task. The package incorporates several planning methods and is able to run in real-time and deal with uncertain situations.

Algorithms for coordinated mission task planning involving several UAVs are currently under development. Some initial robust control systems have been designed for the demonstrator model. Control schemes which explore FTV (fluidic thrust vectoring) and CC (circulation control) actuators will be a major development. CC replaces conventional flaps by blowing air from the trailing edge of the wing. A health management/condition monitoring system is also planned.

The Leicester team will also explore the potential of sensor arrays distributed across an airframe to provide virtual air data for use in the health monitoring and improved control of future UAVs. Another key project will be developing fault detection mechanisms for use in a fault tolerant flight control system, which can automatically adapt for failures sustained during a mission thereby maintaining adequate flight performance and stability.