Angle of Attack Indicator with Stall Horn

HCI Aviation is now producing an angle of attack indicator with built in stall warning for the homebuilder. In addition to the stall horn, a cockpit display indicates angle of attack on a multicolor LED (light emitting diode) vertical bar graph. Angle of attack information also assists the pilot in trimming for the best L/D in cruise flight. The display presents information coded in color. Normal cruise flight range is shown in green. Yellow warns of imminent stall, and red indicates a stalled wing. The LED display is self-dimming. Sensing cockpit illumination level, the display dims to insure that an over-bright indicator will not interfere with the pilot's dark-adapted vision.

At the limit of the yellow sector, the stall warning horn sounds. In addition to the audible horn, the stall tone is available to mix with radio/intercom audio so that a pilot wearing a headset can hear the warning.

The instrument operates on 12 volts, drawing less than 1/5 amp. Cockpit display is a vertical form 15/16" wide x 3 3Ú4" high. The wing-mounted pickup is a 1-3/8" diameter capsule, 9/16" long. Brackets and hardware are included for pilot or independent mounting. The airstream vane is 3Ú4" x 1".

A few words for the benefit of those who have had experience with flight-test alpha probes: The sensing element in this new probe is a non-contact optical encoder. It is therefore proof against humidity and vibration, which seriously degrade the performance and life of potentiometric angle of attack sensors.