Page 13 - Nov 2015 Volume 9, Number 11

including the latest innovation from Aspen Avionics. Unique among the lower-cost offerings, the Aspen AOA software integrates into the Evolution EFD 1000 PFD and MFD and requires no vanes, special pressure sensors, or component displays. Instead, the system leans on airspeed, temperature, altitude, pitch, and acceleration information provided by the EFD 1000’s ADC and AHRS, along with some simple weight and V-speed parameters unique to the aircraft. And rather than measuring AOA to determine CL, the Aspen product calculates the coefficient directly. Ironically, angle of attack, in the sense of relative wind and wing chord, does not play a direct role in the calculation. This 100% software upgrade retails for around $1,900 – a bargain compared to the big airplane products. But the question begs, does the system really work?In pursuit of an answer, we purchased the software upgrade for the installation in our 1944 G44 Widgeon. We chose the Widgeon not only to redeem its namesake but because, like most airplanes built before 1950, the Widgeon has no stall warning device whatsoever. Furthermore, the airplane, a complex, heavy piston twin amphibian with a symmetrical wing and flaps, promised to test the full envelope of support offered by Aspen. Our Widgeon already benefitted from a single Aspen Evolution PFD, so, in theory, the installation would require no more than a download and memory card reprogramming. Inreality, the installation process required starting with a version of Evolution base software that was compatible with the unlocking software used to enable the AOA functionality. It turns out some versions (ironically, the newer ones) were not recognized by the unlocking software, a problem that has since been corrected. Once this was sorted out, our avionics technician was able to successfully complete the installation.After installation comes calibration. First, information, including the aircraft’s “near” cruise speed (80% Vno), max gross weight, short field approach speed, basic empty weight, and calibration weight (the weight of the aircraft as loaded) is entered into the system. Next, the pilot must fly three different aircraft configuration/Northeast Air Inc. Half Page4/C AdJANUARY 2016TWIN & TURBINE • 11Flaps DownCL1.5 1 0.5-10 -5 0 5 10 15 20AoA [deg]2 Flaps Up 1.5CL1 0.5-10 -5 0 5 10 15 202-0.5AoA [deg]