WHAT looks like a flying saucer, takes off like a helicopter and flies like a
plane? The next remote-controlled surveillance aircraft on the hunt for
terrorist fugitives like Osama bin Laden, apparently.
Pilotless aircraft came into their own in the Afghan conflict, greatly
reducing casualties in US Air Force and ground troops on both reconnaissance and
attack missions. But today鈥檚 uninhabited aerial vehicles, or UAVs, have big
drawbacks: they need a runway, they are slow and they cannot hover. But a
bizarre machine that aims to fix all these problems passed its first wind tunnel
tests last week at Norway鈥檚 National University for Technology and Science in
Trondheim.
The disc-shaped SiMiCon Rotor Craft (SRC) appears to be inspired at least
partly by the design of Star Trek鈥檚 USS Enterprise, but instead of twin
engines raised above the main body it has a single rear jet engine below
it鈥攁nd a conventional tailplane above. It鈥檚 also tiny. A full-size machine
will have a diameter of just 4.5 metres, though development work and testing is
being done with three scale models, each with a diameter of 1.5 metres.
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The circular fuselage is shaped like an aerofoil and contains retractable
rotor blades that extend telescopically from the disc as they spin up to speed.
These are driven by a small jet engine and allow vertical take-off. When the
craft has taken off, the jet engine, which is fixed below, takes over to propel
it forward. The rotor blades then retract into the circular wing, but can be
extended again when the craft needs to hover or land. To prevent the craft from
spinning like a top, sideways thrust from the jet engine, or a small tail rotor,
counters the effect of rotor torque.
The SRC鈥檚 three-man design team hopes military and civilian organisations
will be interested. 鈥淭he UAV market is more accepting of unusual designs than
the manned aircraft industry,鈥� says Ragnvald Otterlei of Trondheim-based
SiMiCon. With no people on board, safety is a low priority.
More than 150 UAV designs have emerged in recent years, but few have combined
vertical take-off with high-speed forward flight and the ability to hover. Both
types of UAV that the Americans used in Afghanistan need conventional runways.
The Predator from General Atomics needs a 670-metre take-off strip, while the
high-altitude Global Hawk from Northrop Grumman needs more than a kilometre to
get airborne. The SRC, however, should be able to take off from the back of a
flatbed truck.
The wind tunnel tests proved the SRC would be stable at low and high rotor
speeds and during the transition from vertical flight to forward flight, says
SiMiCon designer Vegard Evjen Hovstein. 鈥淭he next challenge is to find a
low-profile jet engine design which doesn鈥檛 project too far below the aircraft鈥檚
bottom disc,鈥� he says.
The project is brimming with unknowns: how will the extension and retraction
of the rotor blades work? And can the rotor be angled to change the craft鈥檚
direction?
鈥淲hat we have done so far is build models with off-the-shelf components from
radio-controlled kits and shown that our ideas are robust enough to work even
with such poor materials,鈥� says Hovstein.
He鈥檚 bullish about potential civilian applications for his versatile UAV. The
vehicle could be used by police for surveillance, or to track pollution and map
terrain, he says. But he adds that it could be five years before the first SRC
takes to the air.