| Here's the DIY AOA I call the Bacon Saver, named by my late friend and ex-P-39 pilot Marty Haedtler, an early EAA Director when Najeeb Halaby was head of the FAA. in the early 1960s. I put on my Model W, on the Jake and Magnum, on the Dragonfly, the Mitchell B-10/O'2, and now on our Lancair 235/320. Anyone can make one, or I'll make one for you for $200. plus shipping. It uses a stainless shielded ball bearing with 1/8" bore, a counterbalanced vane, and mounts 20% of the local wing chord ahead of the leading edge, outside the propblast, and close enough to be in the pilot's left field of vision. It is simple and self-contained, mechanical, no electrics. It's just a wind vane that tells you what the AOA of the wing is, no matter what. I calibrate it by doing some stalls while watching where it is poijnting at the break, and then mark the angle with automotive pinstriping tape... mark a second mark AOA for best rate of climb, or whatever angle you want. The actual angle in degrees is irrelevant. It was reassuring when I took off once and the pitot line pulled off. Just flew the AOA. Also makes steep turns on final no-sweat. I can fly a few degrees below stall AOA in any attitude, any airspeed, temp or turbulence. IMHO the AOA with lights are only accurate usually to about 3 or 4 degrees and don't tell you how far above -- above -- stall you are, where as the little Bacon Saver tells you exactly to what angle to pitch the wing down to recover from a stall, for minimum altitude loss. Mine's mounted into a tube I bonded to the rib at the end of the wing stub, removable with a taped-on 3/32 flush rivet through the tube. Any questions or suggestions are welcome. Make one yourslef, and get an AOA on your plane, and take the sweat out of slow flight or high AOA flight. Terrence L235/320 N211AL
Posted for Jeff Peterson
< jeffreyb.peterson@gmail.com>: If you are interested in homebuilt angle of attack systems you might want to read this
thread on rec.aviation.homebuilt http://groups.google.com/group/rec.aviation.homebuilt/browse_thread/thread/bc8acb7472d0698e/dfc062e386e86a01?hl=en&lnk=gst&q=angle#dfc062e386e86a01 I
was surprise how many people are interested in the subject. before building your own it pays to look at the variety of
commercially available system out there. Two that use differential pressure systems are Advanced Flight Systems
and Alpha Systems. and several efis units now include some kind of AOA. I have not flown with any of
these but have collected a few opinions: The audio beep output of the Alpha is very effective...gives continuous feedback during any
high AOA operation, but with eyes outside. The Alpha LED display looks cheap and clumsy (my opinion). The AFS unit is cumbersome to
set up in the cockpit and requires probes built in to the wing. The AFS Pro display looks quite nice but is also pretty
large. I did breadboard my own design which has heartbeat audio feedback, and a smaller display that
either of either these units. I plan to use the Dynon heated Pitot/AOA probe. My own work is not well enough along for me
to post schematics. I will post, if I get it working well. Cheers, -- Jeff
Peterson LNC2 N273CK
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