High-flying engineers from the University of Sheffield have unveiled new developments that push the boundaries of design and rapid manufacturing technology at a top US aerospace conference.

The team, from the Advanced Manufacturing Research Centre's Design and Prototyping Group, gained worldwide publicity when they used their expertise to develop an Unmanned Aerial Vehicle (UAV).

Now, they have taken another step forward, developing their original glider to incorporate electric-powered, ducted fan engines.

Members of the team recently returned from Salt Lake City, after being invited to deliver a presentation on the UAV project to an aerospace manufacturing conference organised by SAE, the global association for aerospace, automotive and commercial vehicle industries engineers and technical experts.

The project is designed to showcase the Group's skills and technological capabilities - particularly for helping small and medium-sized manufacturers to develop new products and move into new markets.

Making the glider involved developing new techniques that rapidly reduced the time, the amount of materials and the cost of manufacturing components using 3D printing technology.

Creating the latest version of the UAV has involved further advances in making functional parts using Rapid Manufacturing (RM) technology.

These include developing new manufacturing techniques for producing carbon fibre components and making component jigs, fixtures and moulds, as well as parts of the UAV's airframe, by Fused Deposition Modelling (FDM).

The team succeeded in making the central body of the UAV, complete with the twin engine ducts and complex internal features, as a single, printed part, demonstrating how RM technologies can replace assemblies involving multiple components.

Designers also improved pitch control by creating a moveable "Duck Tail" that uses concepts similar to those recently used in Formula One racing to harness the air leaving the UAV's engines for aerodynamic effect

Last, but not least, the team designed a launch catapult, using a number of RM parts.

The catapult is capable of propelling the UAV into the air with an acceleration up to three times that of gravity, achieving a launch speed of 12 metres a second or just under 30 miles an hour.

Having turned their 2kg glider into a 3.5kg powered UAV, capable of cruising at around 20 metres a second, or almost 45 miles an hour, the team members' next challenge will be to replace the electric ducted fans with miniature gas turbine engines and seeking to double the UAV's wingspan to three metres.

The team is also looking at using novel methods of controlling flight to replace conventional elevons, employing vapour polishing for finishing some printed components, including composite moulds, and developing structural batteries - batteries made from carbon composites that could act as part of the UAV's structure.

Senior design engineer Dr Garth Nicholson said: "The project was a success on all levels, from team building, experience gained in structural and systems design and design for manufacture through to testing and validation of Computational Fluid Dynamics.

"The aircraft was developed using both an incremental design philosophy, as well as trialling experimental manufacturing techniques in carbon fibre production".

Lead additive manufacturing engineer Mark Cocking said the UAV project pushed the limits of design for Rapid Manufacturing, making the transition from theory to reality.

Understanding and playing to the strengths of RM processes allowed the AMRC's Design and Prototyping Group to continually develop exciting, tangible, products.

For further details of the glider prototype, visit www.amrc.co.uk/featuredstudy/printed-uav/