Keane's team set out to see how quickly they could design a 1.5-metre-wingspan, super-low-drag UAV, print it and get it airborne. A UK-based 3D-printing firm, 3T RPD of Greenham Common, Berkshire, joined the venture, agreeing to print the UAV out of hard nylon. The budget for the Southampton University Laser Sintered Aircraft (Sulsa) was £5000 (US$8000), which imposed a number of design constraints.
The electric-powered aircraft, with a 2-metres wingspan, has a top speed of nearly 100 miles per hour, but when in cruise mode is almost silent. The aircraft is also equipped with a miniature autopilot developed by Dr Matt Bennett, one of the members of the team.
* laser-assisted machines to fabricate plastic or metal objects, building up the item layer by layer, each slice just 100 micrometres thick.
* the 3D printer first slices up an object's computerised design into hundreds of easily printable layers.
* Each layer is then "printed" by training a laser beam on a bed of polyamide plastic, stainless steel or titanium powder – depending on the object being created – tracing out the entire 2D shape required for that layer. The laser's heat fuses the particles together at their boundaries. Once each layer is complete, more powder is scattered over it and the process repeated until a complete artefact is produced.
* for areas that need to be stronger an electron beam can be used in place of a laser to melt the powder particles completely
The plane parts took just two days to design and a further five days to print, making Sulsa a one-week plane. But customising future variants of this ready made design would take minutes on automated design software, says Scanlan.
Strength where you need it
The strength of 3D-printed titanium can equal that of the traditionally machined metal, says Dan Johns, who is printing strong, lightweight metal parts for Bloodhound SSC, the rocket car aiming to break the land-speed record in 2013.
To give a part the required strength, engineers can choose a metal – or mixture of metals and plastics – to suit their needs. For instance, an electron-beam-fused titanium/aluminium alloy elongates 10 per cent before snapping, while laser sintered stainless steel elongates 25 per cent.
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