PRODUCTS AND SERVICES
Various emerging trends have made it more
challenging to cool data acquisition units
(DAU) used in data acquisition systems (DAS)
for flight test instrumentation (FTI) applications.
Demand for higher performance, and more
compact, DAUs increases the density of heat
generating components, while also drawing
more power, further generating more heat.
Smaller chassis also contain less metal to draw
the heat away from inside the DAU. Another
challenge is the increasing use of composites in
modern airframes. Conduction cooling from a
DAU is less effective on composite airframes as
they are significantly less thermally conductive
than metal.
Good design strategies can mitigate these
cooling challenges. For the DAU module, a
large ground plane can help draw heat away
from components into a side rail system. To
optimize heat distribution around a chassis, a
solid chassis milled from a highly conductive
metal, such as aluminum, will minimize any
gaps that could lead to hotspots. Within the
chassis, a single voltage rail enables use of a
single hold-up capacitor. This reduces power
draw and ensures the DAU can handle common
supply voltage variances or interruptions.
Thermal monitoring on all DAUs can support
troubleshooting and data integrity assurance.
Curtiss-Wright’s Axon family provides an
example of a modern DAU that incorporates
these design strategies, resulting in a family of
DAUs that are the most powerful for their size
112 MARCH \\ AEROSPACETESTINGINTERNATIONAL.COM
DYNAMOMETERS WITH
CERAMIC TOP PLATES
COOLER DATA
ACQUISITION UNITS
FREE READER INQUIRY SERVICE
Curtiss Wright
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Kistler is introducing its new
piezoelectric dynamometer (9236A),
specifically designed to measure
micro-vibrations in satellite testing.
Featuring a ceramic top plate instead
of a steel plate, this new dynamometer
offers exceptionally high natural
frequency. Users can now measure
micro-vibrations up to 40% higher
frequencies than ever before. The
launch marks a major step forwards in
improving terrestrial observation.
Images of the earth captured by
satellites have to meet ever-increasing
standards of precision, so cameras
with higher resolution are required.
But enhanced resolution also
makes cameras more vulnerable to
micro vibrations.
Two approaches to solving this
problem have emerged — first,
dynamometers with higher natural
frequencies are used so that highfrequency
micro-vibrations can be
isolated more easily. Second, larger
dynamometers are deployed to
measure complete subsystems and
entire small satellites. Piezoelectric
dynamometers are the solution of
choice for measuring micro-vibrations
because they can handle static
preloads and measure dynamic forces
and moments with high resolution in
six axes. The dynamometer’s top plate
is usually made of steel and the larger
the dynamometer, the heavier the top
plate will be. However, increased mass
also means reduced natural frequency
and this effect cannot be compensated
by selecting sensors that are more
rigid. With the materials that are
currently in use, dynamometers have
clearly reached the limits of their
potential natural frequency.
After overcoming the difficulties
presented by such a brittle material as
ceramic, developers have perfected a
new design that offers outstanding
benefits — improved rigidity, lower
weight and a natural frequency of
2.6kHz. The new ceramic-top
dynamometer’s size remains
unchanged at 260 x 260mm and can
measure micro-vibrations across an
unprecedented measuring range from
-500N to 500N. The dynamometer’s
dimensions can be increased to
handle complete systems or small
satellites, so Kistler offers customers a
choice of two different sizes. \\
FREE READER INQUIRY SERVICE
kistler
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visit www.magupdate.co.uk/pati NOW!
and capable of being deployed without needing
forced cooling or additional heatsinks. \\
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