Additive Manufacturing of an Unmanned Aircraft named Sulsa

1. Customer reference
Staff and students at the University of Southampton
fly the world‘s first laser-sintered aircraft
It is not the first time that aviation history has been made in Southampton. It was in this city in the south
of England that the brilliant designer, Reginald Joseph Mitchell, developed the Spitfire, the most famous
British fighter aircraft in the Second World War. Happily, the more recent entry in the annals of aviation
history is of a far more peaceful nature: The engineers at Southampton University have taken an innova-
tive step in implementing their idea of an experimental, unmanned aircraft. They have developed a UAV,
or unmanned aerial vehicle, using unique design and production methods made possible by laser-sintering
technology. Last summer, the team successfully designed and flew the first 3D-printed unmanned plane,
made entirely of nylon and known as the Southampton University Laser Sintered Aircraft – or SULSA for short.
Industry Aerospace
Application Rapid prototyping
Short profiles
Southampton is one of the
leading entrepreneurial
universities in the UK. It has
eight faculties that cover a
huge range of subject areas.
3T RPD Ltd was established in
1999 and has become a leading
additive manufacturer through-
out the UK and Europe.
Challenge
To design an unmanned
experimental aircraft to
demonstrate the use of
leading-edge manufacturing
technology in the production
of UAVs.
Solution
Manufacturing of a flight-capable
prototype within one week,
using the EOSINT P 730.
Results
• Optimised: functional
integration simplifies assembly
and excludes the need for
fasteners
• Freedom of design: production
of complex structures to achieve
the best-possible flight
characteristics
• Speedy: from the sketch to the
maiden flight in less than one
month
• Economic: one-off production
can be conducted cheaply
Further information
University of Southampton
www.soton.ac.uk
3T RPD Ltd.
www.3trpd.co.uk
Image source: University of Southampton
impossible or prohibitively expen-
sive using other manufacturing
techniques.
“Essentially, what we wanted was
to create something completely new
and rather complex but using a
method that was as fast, simple and
cheap as possible. In itself, this is a
classic trade-off. Because if you
want to build something simple,
the usual way is to employ parts
that already exist. But since we had
the opportunity to manufacture in
Challenge
Laser sintering offers structural
freedom, meaning that designers
can think in new ways. The design
team from the University of South-
ampton wanted to build a UAV
that was light and sturdy, with no
structural restrictions in either
design or production. By building
with laser-sintering technology,
they were able to use forms and
structures in the construction of
the aircraft that would have been
3D printing, we found a solution to
the challenge quite quickly,” says
Professor James Scanlan, who
heads the project together with his
colleague, Andy Keane. The basic
framework data for the aircraft was
soon determined. It was designed
as a ‘pusher’, with an electrically
driven tail propeller and a V-shaped
vertical and horizontal tailplane.
The drive components and energy
supply had to be easy both to
incorporate and to replace.
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Solution
To implement the plan, the designers
from the University of Southampton
partnered with 3T RPD, who
undertook the manufacture and
detailing of the design as well as
supplying laser sintering knowledge
and expertise. The whole project
centred on the production of the
structural components, using an
EOSINT P 730 laser-sintering system
made by EOS. Laser sintering is a
procedure by which components
can be made directly from three-
dimensional digital data. Before
production, the data is sliced. The
system then builds up the object
layer by layer, using a concentrated
laser beam that acts on a special
powder and solidifies it. By the end
of the process, the Southampton
team had successfully produced
an aircraft according to plan,
cheaply and quickly. The unmanned
aircraft comprises four parts plus
a component tray, which simply clip
together. The airplane can be pre-
pared for flight in no more than
ten minutes. Clip fasteners for the
internal components – of which
there are only ten, including the
engine, batteries, and avionics
– are integrated in the fuselage.
PA 2200 plastic was chosen as the
material as it keeps the weight of
the aircraft low while offering a
high degree of structural rigidity.
The production procedure was
followed by the only manual activity
involved in the process: removing
the surplus powder. Upon completion
of the printing process, the parts
were immediately ready for use.
“This production method was the
only way of creating the UAV in a
development time of little more than
a month, from the initial drawings
to the successful maiden flight,”
adds Stuart Offer, Sales manager at
3T RPD. Spare parts can be made in
a few days, no tools are required,
and design alterations can be
incorporated very quickly.
Results
The unmanned aircraft displays
great aerodynamic efficiency thanks
to its form of construction. As a
result of the production process
and the materials used, the weight
of the aircraft could be kept below
three kilograms, despite it having
a wingspan of approximately
1.2 metres. This is necessary because
the electric motor of the pusher has
a power rating of only 400 W.
The performance specifications of
the small aircraft are exemplary,
largely thanks to its low take-off
mass, and the engineers were able
to achieve a maximum speed of
140 kilometres per hour. With a
cruising speed of 70 kilometres per
hour, SULSA has a range of about
45 kilometres or more than 30 min-
utes in the air. The control system
was developed by Dr. Matt Bennett,
who was also involved in the project.
“The flexibility of the laser-sintering
process allowed the design team to
revisit historical techniques and ideas
that would have been prohibitively
expensive using conventional
manufacturing”, says Scanlan.
One of these ideas involved the use
of a geodetic structure. This type of
structure was initially developed by
Barnes Wallis and famously used
on the Vickers Wellington bomber,
which first flew in 1936. This form
of structure is very stiff and light-
weight, but very complex. Scanlan
adds: “If it was manufactured
„The laser-sintering process allowed us to give the wings an elliptical form. Aerodynamics engineers
have known about the advantages of this wing form for decades. By using laser sintering, we no longer
had to consider the usual constraints that the production process places on this complex construction
form. With SULSA, we were able to build elliptical wings, without falling victim to excessive costs.“
James Scanlan, Professor at the University of Southampton
“We were able to conduct the project in less than a month from the initial draft design in May to the
maiden flight on June. The internal design features were just one of the advantages of using laser
sintering; a further benefit of the technique was the combination of rigidity and a low weight of only two
kilograms. This made it possible for us to produce complex components with a lightweight construction.”
Stuart Offer, Sales manager at 3T RPD
conventionally it would require a
large number of individually tailored
parts that would have to be bonded
or fastened at great expense.”
Professor Keane notes: “Another
design benefit that laser sintering
provides is the use of an elliptical
wing planform. Again, laser sinter-
ing removes the manufacturing
constraint associated with shape
complexity, and in the SULSA
aircraft there is no cost penalty in
using an elliptical shape.”
Thanks to the laser-sintering
technology, it was also possible to
integrate the moving parts, such as
the aerodynamic flaps and hinges,
directly into the wings or fuselage
in a single production step. “This
means that there were no additional
parts to attach after production,
with the effect that SULSA contains
absolutely no screws or rivets. The
entire structure of the aircraft is
printed,” confirms Offer.
Customer reference
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