NEWS
University of maryland team
hovers near sikorsky prize
I
n 1980, the American Helicopter Society (Alexandria, Va.) announced the
Igor I. Sikorsky Human Powered Helicopter Competition to encourage just
that, development of the world's first
human-powered rotorcraft. In the years
since, no one has yet fulfilled the competition's requirements: controlled flight
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of at least 60 seconds, reaching an altitude of 3m/9.8 ft and remaining within a
10m/32.8 ft square. But in 2012 a team
from the University of Maryland showed
signs that the day is near.
On June 21, 2012, in the Reckord Armory on the campus of the University of
Maryland in College Park, the university's
high-performance composites
source: University of maryland
Gamera team flew its Gamera II rotorcraft.
Piloted by mechanical engineering doctoral candidate Kyle Gluesenkamp, the
craft set a new official U.S. record for
human-powered rotorcraft flight duration at 49.9 seconds. A refined version
of its earlier Gamera I vehicle, designed
and built by students in the Clark School
of Engineering, Gamera II is 30 percent
lighter than the original and is designed
for flights of more than 60 seconds —
much longer than the 11.4-second world
record set by Gamera I and enough to
meet the Sikorsky Prize requirement.
Gamera II features enhanced rotor design, an improved transmission and a redesigned cockpit. The June 21 flight was
verified by the National Aeronautic Assn.
(Washington, D.C.) on Aug. 9, 2012, and
has been submitted to the Fédération
Aéronautique Internationale (Lausanne,
Switzerland) for world-record review.
Gamera II features four substantial rotors at the ends of an X-shaped frame
made of carbon fiber trusses. The configuration increases vehicle stability yet
puts the rotors as close to the ground as
possible, increasing ground effect, a "free"
increase in lift experienced by wings and
rotor blades operating near the ground.
The team spent more than a year designing and building a ground-effect test rig
and developing empirical models to optimize Gamera II's rotor design to exploit
ground effect. The trusses are a novel
concept, with a truss-of-trusses design
wherein the most critically loaded members in the airframe truss have been replaced with "micro trusses" that provide
unmatched buckling resistance with significant weight savings, says the team.
In August and September the team
flew a further refined version of Gamera II.
One flight surpassed the Sikorsky competition's duration requirement, at 65
seconds, and stayed within a 10m/32.8
ft square area, but it did not reach the
required altitude. That flight is under
review for world-record consideration.
Subsequent flights of shorter duration
came close to the height requirement;
one flight reached 8 ft/2.44m and the
other was just short, at 9.4 ft/2.87m.
Although modifications increased
its weight by about 6 lb/2.72 kg, the re-