Full models consist of a complete
replica of the object to be tested, with scales varying from 1:7 to
1:20. The most common scale is 1:12.
Full models are extremely suitable
for testing an object’s stability and control, resistance,
aeroelasticity and acoustics. Test objects comprise all types of
aircraft, vessels, trains and trucks, buildings and building components.
Depending on the type of test and
the tunnel to be used, DNW can accommodate aircraft models with a span
of e.g. 4.5 m in the 8 m x 6 m test section of its LLF in the Netherlands. The maximum model size for other tunnels is smaller, depending on the tunnel dimensions.
Support systems for models can vary
from dorsal and ventral stings to stings attached to the rear of an
object. In addition to providing the right type of support, the stings
are used as ducts for cables and compressed air flow. Selection of the
support system used depends on the test objective and required
maneuverability during tests, and is always selected in consultation
with the customer. The basic classification is:
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Dorsal sting support
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Simulation of take-off and landing conditions
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Ventral sting support
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Simulation in free air
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Rear sting support
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High-speed tests that require minimum interference with the wings
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Naturally, the stings have an effect
on the flow in the proximity of the support system. However, extensive
tests of aerodynamic effects of the support systems result in
correction factors that enable us to eliminate the introduced
interference.
The NWB
tunnel in Braunschweig, Germany, uses a high-precision Model
Positioning Mechanism (MPM) to simulate object maneuvers. This
mechanism can oscillate a model about its body axis or simulate
combined motions.