Aerospace and Mechanical Engineering
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Wind Tunnels Angle of Attack Measurements

Computerized AOA measurements on both Tunnels

These measurements are provided by US Digital T7-1 inclinometers, which is shown below. They have RS-232 serial interfaces that are connected to Aaxeon LS100 serial to Ethernet interfaces. The wind tunnel programs (bdtunnel and crtunnel) then read them over the local network.

T7 Inclinometer

Note that zero from the T7 indicates that the sting is horizontal. How this relates to your model depends on its particular mounting arrangement.

T7 Specifications

  • Solid state technology - no moving parts
  • Field programmable (zero, sign, range and filter time constant)
  • Full 360° range
  • Temperature compensated from 0°C to 70°C
  • ±0.1° accuracy (bias)
  • 0.01° resolution
  • 8 Hz Bandwidth maximum (filtering time constant is set to 1000ms for our installations)
  • Noise (precision) with 1000ms filtering: 0.005° Standard deviation, 0.011° 95% confidence interval

CR tunnel AOA Indicator: Angle Cube

An AngleCube (shown below) digital level has been attached to the mechanism for the sting on the large Closed Return (CR) wind tunnel. It shows absolute angle of the sting relative to level (0.0 degrees).

AngleCube with power button marked


Press the LEVEL button (marked with arrow above) to turn on the display. Use the bottom crank to adjust the sting angle. Note that the display updates slowly, so you will have to stop turning the crank and wait to read the current angle. The small up and down arrows on both sides of the display indicate the direction (sign) of the angle.

Do not use the ZERO function, as its setting is lost when the AngleCube goes into power saving mode.

Level, 0.0 degrees, is when the sting itself is level and parallel to the bottom of the tunnel. This may not be what you want to use for zero degrees on your model depending on how it attaches to the sting. Add or subtract a constant angle from the readings to account for this.

The AngleCube accuracy is ±0.2 degrees.

Last Modified: 2012-06-11 at 11:41:58 -- this is in International Standard Date and Time Notation