Karmy Flying Adventures

Well, during this year’s annual inspection I decided to install an AOA system. I got the AOA sport from Advanced Flight Systems. The install took about 2 full days when mixed in with my inspection tasks. It was a good time to do it since I had all the inspection panels opened up anyways. First came the wing ports. 2 small holes are drilled in the last bay of the wing and some tubes connected and routed back to the panel. The only hard part about this was reaching in the inspection holes on the wing to route the tubes. It would help to have small arms!

Next came the AOA brain box install. I decided to mount it with some velcro on the rear sub panel behind the other instruments. This proved to be a fine locaiton, however as the years go by it seems like things are filling in behind there. Not much room left for more toys to be installed. You can see the CPU box and tubes hooked up in the picture. Another job was to figure out a way to detect the flap position as the AOA needs to know when you have lowered the flaps. The best way ended up being to make a slip ring out of UHMW plastic that I attached to the flap torque tube. You can also see the microswitch that was installed to sense the rotatio of the tube. With all of the remote sensors installed and wires / tubes run back to the CPU, it was time for the display indicator. As the primary purpose of having an AOA is to get your head outside the cockpit and really add some safety to flight at the edges of the envelope I decided to create a custom mount. I first tried to make an aluminum box to house the light bar, however I could not get it to work out to my satisfaction, so I fabricated a fiberglass enclosure. I simply made a male plug out of wood, waxed it, and layed up the fiberglass. After some sanding and filling, etc… this is the result. I think it worked out great. It’s just large enough to hold the LED light bar for the AOA display.

I then installed it on the glareshield directly in the line of sight. This gives easy visibility without ever taking your eyes off the runway when on final.

So how does it work you ask? Well, after flying my RV9A for 550 hours I was not really sure that I needed an AOA. I was told by my friend Jim that it would really be usefull and he really sold me on the safety of flying by AOA when in critical phases of flight. So here we go. I took off and got the unit calibrated. Initally you need to do a few manuevers to get it all setup. A zero G push over, and some slow flight with flaps up and down takes care of it. I then few a few approaches with it. Each one worked great just flying with 2 yellow lights lit all the way to the ground. You arrive in the right place, right time, right speed, right AOA, ready to land. So far so good.

Now the real test was the next day when flying to the EAA meeting. This time of year that means night flying. So as I approached Thun field, I had been flying with the panel lights turned off. As I got setup on the aproach and capture my 2 yellow lights, a quick cross check with AS indicated an expected airspeed value, so I continued the aproach and landing never once turning on the panel lights, or looking anywhere but out the front and at the AOA. Perfect night landing, most likely one of my best landings. Hum, there must be something to this navy carrier AOA stuff.

I’ve taking it up for accelerated stalls at high G, unusual attitudes, etc and it always gives plenty of warning just before the plane let’s go into the stall. In short you can’t fool AOA, it really is what keeps you in the air. So I say it’s a great success. I think this will provide much safety over the years.