3D printing: The world's first printed plane
The promise of 3D printing has finally taken off with the development of a drone that takes just a week to create
Under darkening skies on a grass
airstrip in the UK's Wiltshire Downs, north of Stonehenge, I am watching
half a dozen aeronautical engineers rushing to assemble an uncrewed
aircraft before the weather takes a turn for the worse. They are hoping
to show how 3D printing will revolutionise the economics of aircraft
design – by flying the world's first fully "printed" plane.
Led by Andy Keane and Jim Scanlan of
the University of Southampton, the team believes that 3D printing will
soon allow uncrewed aircraft known as drones or UAVs to go from the
drawing board to flight in a matter of days. No longer, they say, will
one design of UAV be repeatedly manufactured on a production line.
Instead, designers will be able to fine-tune a UAV for each specific
application – whether it be crop spraying, surveillance or infrared
photography – and then print a bespoke plane on demand.
3D printing has come on in leaps and
bounds since its origins as an expensive prototyping tool over two
decades ago. It uses laser-assisted machines to fabricate plastic or
metal objects, building up the item layer by layer, each slice just 100
micrometres thick.
To do this, 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.
What the printer spits out is a
powdery "cake" from which the desired object can be retrieved simply by
pulling it out, like a child yanking a buried toy from a sandpit
To create a stronger object that can
withstand higher loads and stresses, an electron beam can be used in
place of a laser to melt the powder particles completely. And because 3D
printing involves no cutting or grinding of metal, it offers vast
design freedom.
This is a huge deal for aircraft
designers. Some of the best ideas in aviation history have involved
designs which proved too pricey and tough to make. The Supermarine
Spitfire, for example, was among the most manoeuvrable fighter aircraft
of the second world war because its wings were of an ultra-low-drag
elliptical design. But it was a nightmare to produce, requiring complex
machinery and production expertise.
"With 3D printing we can go back to
pure forms and explore the mathematics of airflow without being forced
to put in straight lines to keep costs down," says Keane.
So 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.
"We designed in printable hinges that
would let the ailerons move," says 3T RPD spokesman Stuart Offer. "And
we decided where to split the fuselage so the nose could be snap-jointed
to the fuselage easily."
The budget for the Southampton
University Laser Sintered Aircraft (Sulsa) was £5000, which imposed a
number of design constraints. The aircraft would have no undercarriage
to keep complexity and weight down, necessitating the use of a launch
catapult – and a belly landing. It would be electric-motor-powered to
eliminate the need for starting equipment and heavy fuel. And it would
have a V-shaped tail rather than the usual upside-down-T, so that only
two parts had to be printed instead of three.
Cost savings here meant that the plane
could have Spitfire-style elliptical wings, as well as a strong
geodesic airframe – another expensive second world war-era design, this
time from the stout Vickers Wellington bomber, which was extraordinarily
resistant to anti-aircraft fire.
Back at the airstrip, two wings, a
nose cone and a fuselage with a built-in V-shaped tail have been ripped
from nylon cakes, dusted down and delivered. Sulsa's airframe designers
Jeroen van Schaik and Mario Ferraro, both grad students at the
University of Southampton – which launches a UAV masters course in September – are assembling the aircraft after stuffing it with electronics, servos and batteries.
Nearby, Matthew Bennett of
autopilot-maker SkyCircuits is discussing with the aircraft's
ground-based pilot, Paul Heckles, how to hand manual control to the
ARM-microchip-based autopilot once the plane is airborne.
Soon it's flight time. Sulsa twitches
like a giant, grounded butterfly flexing its wings as ailerons and
rudders are tested. Then the powerful launch catapult is cranked back.
As soon as Sulsa clears the rail, Heckles punches the throttle – and the
plane takes to the sky.
It is indeed a low-drag beast. All
tests are passed with flying colours – including recovery from an
intentional stall. On its second flight, Heckles cedes control to the
autopilot and a drone is born.
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.
As if on cue, the wind picks up and
the heavens finally open. But even the downpour can't dampen Scanlan's
spirits. We have witnessed some technomagic today, he says, as Sulsa
belly-lands on the grass. "It's very hard to believe this aircraft was
just a pile of dust last Friday."
Comments
Post a Comment