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Winged aircraft get their lift
force from rigid wings, while helicopters use one or more rotors with blades
revolving around the vertical axis. Helicopters are able to fly at low
velocities, while rigid-winged aircraft have to maintain a minimum speed to
avoid stall. Moreover, helicopters do not lose their agility at low speeds and
are even able to hover motionless.
The rotor provides lift as well as
propulsion. However, the rotating wing unit not only provides the hovering
ability. It also causes dynamical challenges. The blades are non-uniformly
stressed during forward flight by the superposition of the forward motion of
the helicopter and the rotation of the blades. Therefore, helicopter flight
mechanics have to consider not only the actual hull dynamics but also the
dynamics of the blades, which perform additional motions, called flapping,
lagging and blade torsion.
These motions cause, among others, a number
of aeromechanical problems. Helicopters have, in addition, a moderate
travelling speed compared to rigid-winged aircraft, which reduces their
transport performance. Therefore, the institute currently deals with the
following issues:
Analysis of higher
harmonic control (HHC) / individual blade control (IBC)
Active Blade Control
using IBC / HHC
Blade angle feedback
control
Reconfiguration of
helicopters
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