FLIGHT DEMONSTRATION WIND TUNNEL

For classroom demonstrations and student investigations
into the behaviour of fixed-wing aircraft and wing
performance during take-off, flight and landing.
The apparatus is an open-circuit wind tunnel with a model
aircraft suspended in the working section. The model is
supported by linkages that allow it to move vertically and
to pitch about the quarter chord point independently.
The working section is brightly illuminated and the aircraft
model is clearly visible through a large transparent
window. The operator flies the aircraft manually using a
control column and throttle. These are positioned directly
in front of the window and are arranged typically as found
in a light aircraft, providing realistic simulation of flight and
the effect of the control surfaces. To fly the aircraft, the
operator pushes the throttle lever forward to increase the
tunnel airspeed. When the airspeed reaches a certain level
the aircraft may be made to ‘take-off’ by drawing the
control column slowly back. A digital display shows air
velocity (pressure) in the working section, attitude, altitude
or lift force on the aircraft.
Air enters the working section through a flow straightener.
The throttle controls the air speed in the tunnel by
regulating an axial flow fan downstream of the working
section. The change in air speed in the wind tunnel
simulates the effect of increasing the change in air speed
of a real aircraft due to a change in thrust from the
propeller.
The control column is linked to the ?all-flying? tailplane of
the aircraft. Pushing the column forward or pulling it back
changes the angle of the whole tailplane. A scale on the
control column indicates the tailplane angle. The control
column differs from that of a normal aircraft in that it has
no lateral control of the aircraft: it has no rudder on the
tailplane and may only move up or down.
A locking control under the control column can lock the
angle of the tail plane to any setting.
Small tufts cover the port wing of the aircraft. These show
the direction and quality of airflow over the wing surface,
to show separation and stall. Using the optional Smoke
Generator (AFA10, available separately) enhances flow
visualisation.
An adjustable weight allows the student to set the centre
of gravity of the model to different positions from fore to
aft of the quarter chord point. A scale below the weight
indicates the position. This enables students to derive the
trim curves and identify the neutral point.
To find the lift characteristic of the aerofoil, students link
the aircraft to a load cell and vary the angle of attack.