I know everybody is concerned about whether my angle of attack PRO model by Jim Frantz worked as it should on Friday when I had my accident in N27RM.

 

I just got off the phone with Jim, and learned some things I should have known.  Maybe you will all benefit from this info, I learned the hard way.

 

My angle of attack gave me an oral warning when I felt the aircraft should fly.  In light of the terrain ahead of me and now two conforming instruments; i.e. airspeed AND angle of attack, I elected to abort. 

 

The angle of attack worked the way Jim designed it.  Contrary to what I had been used to in jets where an angle of attach sensor on the airframe talked to the angle of attack system which was a completely independent system from the airspeed system, and therefore a great backup with blocked or malfunctioning pitot, on a prop plane, one cannot design a system like this.  Jim’s system relies on both wing loading and pitot and static inputs.  The cockpit indicator gives an indication of angle of attack from the computer which analyzes wing loading and airspeed.  The output from the computer goes to both the oral warning system and the cockpit indicator.  With blocked pitot, the angle of attack will give an oral warning no matter what the actual ground/air speed is, as well as show an unacceptable angle of attack on the cockpit angle of attack indicator.

 

So, in the future for all of us, with blocked pitot, your sport or pro model angle of attack will not be reliable. Jim asked me to post this for all to read.

 

Hope I quoted him correctly.

 

Ron