Sam Buchanan
been here awhile
Finally got around to trying something that had been on the to-do list for awhile. My RV-6 panel includes both a Dynon D10A and an LRI angle of attack indicator:
The LRI is a valued instrument that I use on every flight:
http://thervjournal.com/liftreserve.htm
Not only does it provide the info needed for max performance take-offs and landings, but the LRI is the backup instrument for landing in case the Dynon takes the day off.
The Dynon includes an AOA indicator that was designed for use with the Dynon AOA pitot probe. Even though the D10A AOA indicator is smaller than the LRI indicator, it does provide an audible alarm, something that many have mentioned as a shortcoming of the LRI.
Question for the day-----Will the Dynon AOA indicator work with the LRI probe?
Short answer........Yes!
This should be of great interest to folks flying the LRI and a Dynon. It is possible to retain the independent, non-electrical function of the LRI, and have an audible alarm without having to install the Dynon pitot mast. This also puts an AOA indicator in your EFIS instrument scan.
I inserted a tee in the low-pressure line of the LRI (the one that connects in the center of the gauge) and ran a hose to the AOA port of the Dynon. The LRI probe was not touched so calibration of the LRI was not disturbed. The question I needed to resolve was whether or not the Dynon had enough calibration range to accept the LRI low-pressure signal in a way that provided useful info on the Dynon AOA indicator. Instead of going through the entire set of stalls per the Dynon instructions, I did one flaps-up, power-off stall that corresponds to the red/white indicator on the LRI. My goal was to try to have the two AOA systems showing "matching" warnings that I was already accustomed to.
The Dynon calibration routine worked flawlessly. Some repeat stalls demonstrated the stability of the calibration, and several touch-n-goes also confirmed the Dynon/LRI combo was behaving in a similar manner to the LRI indicator. I am still very early in exploring the Dynon/LRI combo, but it appears this is a very attractive option for those of us with both systems. Since this is such an easy mod to perform, I encourage others who have these systems to try this and let us know how it works for you.
After pondering this for about, oh, five minutes, me thinks it might be a very simple project to build an AOA probe that would work with the Dynon. It would involve a second probe for those who aren't using the Dynon pitot probe, but could be fabricated from an extra Vans aluminum tubing pitot probe (or the home-made equivalent). An aluminum plug with a 1/16" diameter hole would be in the outboard end of the tube, and the lower end would be bent down/forward at a 45 degree angle instead of the customary 90 degrees. This would mimic quite closely the design of the low-pressure side of the LRI probe. Obviously some flight testing would be needed, possibly to adjust the probe angle, but basically the system is driven by ram pressure that increases as angle of attack increases. Hopefully the Dynon firmware would be able to accommodate the low pressure signals generated by the custom-built (!) probe.
The LRI is a valued instrument that I use on every flight:
http://thervjournal.com/liftreserve.htm
Not only does it provide the info needed for max performance take-offs and landings, but the LRI is the backup instrument for landing in case the Dynon takes the day off.
The Dynon includes an AOA indicator that was designed for use with the Dynon AOA pitot probe. Even though the D10A AOA indicator is smaller than the LRI indicator, it does provide an audible alarm, something that many have mentioned as a shortcoming of the LRI.
Question for the day-----Will the Dynon AOA indicator work with the LRI probe?
Short answer........Yes!
This should be of great interest to folks flying the LRI and a Dynon. It is possible to retain the independent, non-electrical function of the LRI, and have an audible alarm without having to install the Dynon pitot mast. This also puts an AOA indicator in your EFIS instrument scan.
I inserted a tee in the low-pressure line of the LRI (the one that connects in the center of the gauge) and ran a hose to the AOA port of the Dynon. The LRI probe was not touched so calibration of the LRI was not disturbed. The question I needed to resolve was whether or not the Dynon had enough calibration range to accept the LRI low-pressure signal in a way that provided useful info on the Dynon AOA indicator. Instead of going through the entire set of stalls per the Dynon instructions, I did one flaps-up, power-off stall that corresponds to the red/white indicator on the LRI. My goal was to try to have the two AOA systems showing "matching" warnings that I was already accustomed to.
The Dynon calibration routine worked flawlessly. Some repeat stalls demonstrated the stability of the calibration, and several touch-n-goes also confirmed the Dynon/LRI combo was behaving in a similar manner to the LRI indicator. I am still very early in exploring the Dynon/LRI combo, but it appears this is a very attractive option for those of us with both systems. Since this is such an easy mod to perform, I encourage others who have these systems to try this and let us know how it works for you.
After pondering this for about, oh, five minutes, me thinks it might be a very simple project to build an AOA probe that would work with the Dynon. It would involve a second probe for those who aren't using the Dynon pitot probe, but could be fabricated from an extra Vans aluminum tubing pitot probe (or the home-made equivalent). An aluminum plug with a 1/16" diameter hole would be in the outboard end of the tube, and the lower end would be bent down/forward at a 45 degree angle instead of the customary 90 degrees. This would mimic quite closely the design of the low-pressure side of the LRI probe. Obviously some flight testing would be needed, possibly to adjust the probe angle, but basically the system is driven by ram pressure that increases as angle of attack increases. Hopefully the Dynon firmware would be able to accommodate the low pressure signals generated by the custom-built (!) probe.
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