AF41 - Experiment
FLIGHT DEMONSTRATION WIND TUNNEL

An open-circuit wind tunnel incorporating a suspended aircraft model with realistic controls for classroom demonstrations and student investigations into a variety of aircraft flight principles.

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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.

A variety of practical demonstrations, ‘hands-on’ flight simulations, and student investigations into the behaviour of fixed-wing aircraft and wing performance, including:

  • Practical investigation of longitudinal stability and control of the aircraft to demonstrate behaviour during take-off, level flight and landing.
  • Determination of the effect of speed on attitude for level flight and stall.
  • Measurement of the lift curve for the wing up to and beyond stall.
  • Students can adjust the centre of gravity of the model to alter its trim. They can then plot trim curves and determine the neutral point. - With Two-Pen Chart Recorder (AF41a, available separately):
  • Demonstration of phugoid motion in terms of altitude.
  • Short period oscillation due to sudden disturbance can be shown by the change of incidence. - With Smoke Generator and Probe (AFA10, available separately):
  • Visualisation of flow patterns past the aircraft’s aerofoil and tail-plane.
AF41A - Ancillary

A two-pen chart recorder for use with the AF41 Flight Demonstration Wind Tunnel.

AF10 - Base Unit

A fully mobile bench to provide basic airflow facilities to enable a wide range of practical airflow investigations. Suitable for demonstration, laboratory and project work at a basic level.

VDAS AF1300 - Base Unit

An open circuit suction subsonic wind tunnel with a working section of 300 mm by 300 mm and 600 mm long.

VDAS AF1600 - Base Unit

An open circuit suction subsonic wind tunnel with a working section of 600 mm by 600 mm and 1250 mm long. All instrumentation required to begin experimentation is included.

AF80 - Experiment

A floor standing suction type subsonic wind tunnel with smoke visualisation. It allows demonstrations and student investigations into the flow of air around a wide variety of different shaped models.