PYRAMIDAL
BALANCES
Small Pyramidal Balances
AEROLAB Small Pyramidal balances are designed for
subsonic tunnels with a test section up to two feet in height. As
shown in the photograph, the model is mounted on a strut which is
adjustable in angle of attack. The diagonal members (if extended)
would meet at a point inside the model at the intersection of the
balance's Pitching, Yawing and Rolling Moment Axes. This minimizes
the moment transfer between the balance axes and the model c.g.
axes.
The components are separated by the mechanical linkage so exact
component readings are provided in the electrical readout without
reference to calibration curves or tables. The individual components
are sensed by strain gauge load cells which are specially designed
and calibrated to provide and exact integral ratio (such as 1:1
to 2:1) between the component readout and the component load.
The model positioning system is built into the balance system with
drives in angle of attack and angle of yaw. Digital angular readout
to the nearest tenth of a degree. Motorized operation is optional.
Overhead view of small pyramidal balance
Close up of small pyramidal balance
Detailed picture of small pyramidal balance stepper motor
Close up of small pyramidal balance
Small pryamidal balance mounted in an AEROLAB 20"x28" Wind Tunnel
Top view of Small Pryamidal Balance
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Large Pyramidal Balances
Large Pyramidal Balances may be supplied for test sections of any
size or (subsonic) speed. They employ a turntable and a three-strut
mounting. Since air loads on the lower “live” turntable
are measured by the balance, an upper turntable, the "fairing"
turntable is installed in the floor of the wind tunnel to shelter
the live turntable. The system is designed to permit adjustment
of the distance between the struts to accommodate various models
or to permit single or two-strut mounting. Windshields are attached
to the fairing turntable to reduce wind loads on the support struts.
Particularly on the larger models, the fairing and the live turntables
may have individual motorized drives which are synchronized with
each other. These are accompanied by remote control and remote readout.
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