The 2011 Aerospace winner - FLAVIIR
The Demon UAV has become the world’s first aircraft to gain ’mastery of the air’ without using flaps.
BAE Systems, Cranfield University, Imperial College London, University of Leicester, University of Liverpool, University of Manchester, University of Southampton, Warwick University, University of Wales in Swansea, Nottingham University, York University
People refer to flying as ’mastery of the air’. It might seem like a strange phrase – surely they mean mastery in the air? – but it’s literally true. Because what flying is really about is controlling the air, manipulating the pressure above and below to create lift, and changing the way that air flows around the body to manoeuvre.
Birds do it by flapping and changing the shape of their wings; insects do it by a complex interplay between different sets of wings that we don’t understand.
Aircraft, generally, do it with flaps, ailerons and rudders – control surfaces – attached to their wings, or in the case of helicopters, by changing the angle of the rotor blades. The mechanics are complicated, the moving parts numerous and the potential outcome of any of these systems failing catastrophic.
Doing away with control surfaces would reduce the complexity of aircraft considerably and also reduce the cost of maintaining all those complex mechanics. But without them, how would the aircraft fly? How would it gain its mastery of the air?
The FLAVIIR (Flapless Air Vehicle Integrated Industrial Research) Project, headed by BAE Systems and Cranfield University and bringing together nine other universities, represents a huge step towards solving that problem. The team has developed Demon, a diamond-shaped UAV (unmanned aerial vehicle) that, earlier this year, became the world’s first flying flapless aircraft, using a system known as fluidic control to change the direction of the engine’s thrust and to deflect the airflow over the wings.
FLAVIIR is a five-year project whose £6.5m funding comes from BAE Systems and the EPSRC (Engineering and Physical Sciences Research Council). Along with Cranfield, engineering departments from the universities of Leicester, Liverpool, Manchester, Nottingham, Southampton, Warwick, York, Imperial College London and the University of Wales in Swansea are involved in the effort to design an aircraft controlled without flaps that matches the performance of a conventional aircraft of the same power. It involves a dizzying array of technologies: aerodynamics, control systems, electromagnetics, manufacturing materials and structures, along with the numerical and computational techniques needed to model and understand the interplay of all the systems on board the compact aircraft.
“Research is aimed at producing an entire working system, rather than just individual technologies”
’What makes FLAVIIR unique is that research is aimed at producing an entire working system, rather than just looking at individual technologies,’ project manager Phil Woods, from BAE Systems’ Advanced Technology Centre, told The Engineer when we spoke to him about the project last year.
The fluidic-control system works using small air jets, developed at Manchester University. Positioned at the back of Demon’s wings, these jets force the layer of air immediately next to the skin of the aircraft to move towards or away from the surface of the wing. This layer of air is responsible for the pressure on the aircraft’s surface – and therefore dictates how it flies. If the layer moves away from the top of the wing, the pressure underneath is greater than the pressure above and the wing rises, forcing the aircraft to bank and turn.
Similarly, Demon’s jet exhaust is surrounded by a ring of secondary control jets that force the exhaust to ’bend’ in their direction when fired. For example, a control jet at the top of the exhaust nozzle bends the jet exhaust upwards, which forces the aircraft into a dive. The control jets on both wing and exhaust nozzle are operated by arrays of microsensors and actuators that measure the airflow over the surface of the aircraft and, using algorithms developed at Leicester and Imperial, ensure that the right combination of jets fire to move the aircraft in the desired direction.
Other parts of the project focused on manufacturing techniques for low-cost reinforcement fabrics and adaptable tooling for customising aircraft for specific duties. Southampton University took the lead on numerical simulation, while Nottingham, Swansea and York worked together on systems for reducing Demon’s susceptibility to interference from radio waves and lightning strikes.
“Representatives of the universities and BAE overcame bad weather and equipment failure”
CLYDE WARSOP, BAE SYSTEMS WARTON
The project came together with the manufacture of the UAV itself. Demon was designed at Cranfield and built by the university’s Composite Manufacturing Centre and by BAE Systems apprentices. Weighing 80kg and possessing a wingspan of 2.7m, Demon had its first flapless flight last September from Walney Island airfield near Barrow-in-Furness.
’This success could not have been achieved without the successful collaboration between the university partners, the flight-test department at BAE Systems Warton and the manufacturing input provided by the BAE Systems apprentice training college in Preston,’ said BAE executive scientist Clyde Warsop.
The spirit of collaboration continued all the way through the flight trials, he added. ’Representatives of the universities and BAE Systems overcame the adversities of bad weather and test-equipment failures. The team members often worked from 7am to 11pm preparing, modifying and checking out the aircraft with senior BAE engineers and managers working alongside students and academic staff, all pitching in and undertaking whatever tasks were necessary, however menial, to make things happen and take advantage of the limited weather opportunities.’
The fruits of the research aren’t just in the development of fluidic controls, which, as Warsop says, could potentially reduce the weight and through-life costs of aircraft. The demonstrator also provided a platform to test high-strength, high-temperature-resistant materials made by additive- manufacturing techniques, which are now used within BAE Systems in concepts it has proposed to the Ministry of Defence. Moreover, it has produced a method for predicting the failure of complex composite structures, which reduces the number of tests needed to certify the material and therefore cuts the cost and timescale of certification.
The other shortlisted candidates in this category were:
COPMA: Consolidated Off-Planet Manufacturing and Assembly System for Large Space Structures
Magna Parva, Excel Composites
It might seem like something from science fiction, but plans for how to manufacture structures in space are in fact well advanced. COPMA uses a system called pultrusion, which produces composites with a constant cross-section. It can make consistent high-strength lengths of material automatically and can even embed sensors directly into the structure as it is made. This project saw Magna Parva’s engineers develop a breadboard model of a deployment system that could build components for antennas, solar sails, or space-based solar arrays that could beam solar power back to Earth. As they would be made in the absence of gravity and would never have to withstand the stresses of a launch, they could be thinner and use less material than systems made on the
SeCSy: Sensor Coating System
Southside Thermal Sciences, Cranfield University, RWE nPower, Land Instruments
The efficiency of a gas turbine, whether in a jet engine or a power-generation system, is directly linked to the maximum temperature inside the hot-gas section of the turbine, but the available temperature-measurement systems are so unreliable at these temperatures that operators have to use safety margins as large as 150°C to ensure that vital components aren’t damaged. The SeCSy technique works by turning the material from which the turbine blades and vanes themselves are made into a temperature-measuring system. SeCSy works by embedding materials that fluoresce under ultraviolet light directly into functional ceramics. The character of the fluorescence changes as the material heats up and specially tailored instrumentation can use these changes to determine temperature, erosion, corrosion and ageing effects.