Over the last century of flight, virtually every aeroplane has used some variation of trailing edge flaps along the back of the wing and often on the tail surfaces as a requirement to control the aircraft's flight. These flaps are a very simple, reliable, and robust technology but have several important drawbacks, including significant drag and noise penalties. One major source of drag comes from the fact that these flaps, for various reasons, do not exist across the entire span of the wing. This creates discontinuities in the surface at the ends of the flaps where the wing suddenly changes from being a normal rigid aerofoil to a flapped section. The gap between the two surfaces increases in size and severity when the flaps are used, leading to pressure leakage from the lower to upper surfaces and the formation of drag intensive vortices. This increases fuel consumption and greenhouse gas emissions. For decades aerospace industry and academic researchers have been trying to find a way to fill this gap, but due to a very challenging set of structural and aerodynamic requirements a solution has been hard to find.
The Compliant Morphing Flap Transition (CMFT) developed by aerospace engineers at Swansea University is a novel solution to this problem that takes advantage of material and structural compliance to fill the flap gap. By combining new compliant structural architectures in a very specific way, the CMFT is able to be soft and flexible in various desired directions but quite stiff in the others. Furthermore, in order to be able to morph into the highly three-dimensional curved shape which requires both smooth changes in bending and continuous changes in twist angle of the trailing edge, the CMFT takes advantage of structural couplings which create the bending and twisting motions at the same time, with a single specially tailored component. A number of these bend-twist coupled internal components are then bonded together and covered in an elastomeric skin to create a continuous transition which acts as single section. The resulting CMFT structure has a promising combination of low force required to bend into the desired shape, direction and good surface smoothness. It can easily be designed to be fitted onto existing aircrafts as well as being designed into new types. Additionally the use of structural compliance means that the large shape changes certain parts of are achieved without the need for moving parts or mechanisms and their associated weight penalties and maintenance requirements.
Direct collaborations are sought with the industries that stand to benefit from this technology, including commercial airliners, helicopters, and wind turbine manufacturers. The CMFT provides a significant reduction in aerodynamic drag, both when the flap is deflected during aeroplane flight and when it is stored, leading to reduced fuel consumption. This novel product also offers a solution to reducing the significant noise pollution resulting from flap discontinuities, which is particularly important during take off and landing when the aircraft is likely to be in close proximity to residential areas.
A UK patent was filed by Swansea University under GB1412159.4