a research excitation flight system was
recently flight tested at nasa's dryden
flight research facility
a nasa f-16xl aircraft served as a test
bed
this exciter is unique because it is a
self-contained lightweight
excitation system which can easily be
strapped onto a variety of aircraft
it is intended to be used in flight
flutter testing to help improve data
quality
and flight test efficiency
the system consists of a fixed vein with
a rotating slotted cylinder at the
trailing edge
the slotted cylinder rotates and the
flow is ultimately deflected upward and
downward
this results in a periodic lift force
which is imparted to the aircraft at
twice the cylinder's rotational
frequency
the exciter vane is controlled by the
pilot in the backseat of the f-16xl
aircraft who sets the parameters for the
test
data is telemetered to the spectral
analysis facility where it is monitored
in real time
here response from the wing tips are
monitored to find frequency and damping
trends
as functions of mach number and dynamic
pressure
the wing can be seen responding to the
exciter veins input sweeping from 5 to
35 hertz
data is analyzed in the computer showing
the aircraft's natural frequencies
test points were taken between mach 0.6
and mach 1.7 at an altitude of 30 000
feet
the variables in the different frequency
sweeps were linear or logarithmic sweeps
brain time length varying force
amplitude and dwelling on a certain
frequency
this exciter system has shown it can
provide high quality data and improve
flight test efficiency
with minimal interface to aircraft
systems future testing will continue to
provide insight into using this system
as a safer more effective flight flutter
testing system for today's flight
research
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