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Home > Articles & Tips > Actively
Stabilized Flying Wing Plank Project > AOA Sensor Alignment
[Courtesy of Helmut Lelke, hlelke "at" worldnet.att.net,
February 2002]
  
AOA Sensor Alignment and Test Flight Preparations
Preparation procedure steps for the first test flight:
1. Program elevator and aileron gains between to 50% and 60% respectively at
the transmitter.
2. The hall-effect sensor element may have an inherent output offset which has
be adjusted out. With AOA sensor vane pointed forward (the wrong way), null the
output of the AOA sensor by adjusting pot R3 to minimize the difference between
regulated 2.5V and U1-7 (see schematics).
3. AOA sensor gain should be adjusted to between 1.0 and 1.5 to start. Measure
the gain - don't guess.
4. Prepare for first test flights with a slightly forward CG setting. I
recommend a CG setting of ~27% if the final setting is expected to be farther
aft. The accuracy of all CG settings is vital. It is recommended that CG
calculations be based on the constructed model, not on the design plans. The
differences are generally significant. At this time, also prepare for a way to
back off to the final CG position in a couple or more increments (remove nose
weight incrementally until final trim CG and/or elevon deflection is reached).
5. Align AOA sensor mechanically to produce zero output at trim angle-of-attack.
Use your best guess to start.
6. Adjust elevator trim to slightly reflex position (with AOA sensor out of the
way - pointed forward) to account for the slightly forward CG at start. A
trailing edge rise of about an eight of an inch for a two inch wide elevon is
about right.
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