Operational Methodology - uAvionix AV-30-E Pilot's Manual

The following provides a description of how the derived Angle of Attack
(AoA) operates and presents the corresponding AoA information to the
pilot.
One of the main advantages of an AoA system is that it can provide an
early indication of a stall, bringing enhanced awareness to the pilot.
However, the AV-30-E system is supplemental in nature and
does not replace the functionality provided by the aircrafts
existing stall warning system.

11.1 Operational Methodology

Angle of attack is determined by comparing aircraft pitch to the aircraft
flight path angle through the air. In level flight this directly corresponds
to the angle at which the wing is intercepting the body of air
surrounding the aircraft, with correlates to the current AoA.
Pitch is determined by the precision internal AHRS and flight path
angle is determined by air-data based airspeed versus vertical speed
measurements.
As an example of this relationship, during a climb, if the pitch angle is
10 degrees up, and the aircrafts flight path through the air (forward
airspeed and vertical speed) is also 10 degrees up, the equivalent
AoA is 0 Degrees. If, however, the pitch angle is 10 degrees up, and
the aircrafts flight path through the air is only 5 degrees, this
corresponds to a positive 5 degree AoA.
UAV-1004233-001, AV-30-E Pilot's Guide
Pitch Angle = AHRS Measured Pitch
Flight Path Angle = ADC Vertical Speed / Indicated Airspeed
Figure 35 – AoA Computation
40
Pitch Angle
Flight Path
Angle Of Attack
Level Ref
Revision A