Building an electronic Angle of Attack indicator

"bildan" wrote in message ...

The interest for me is a sailplane installation where AOA is a
performance issue in addition to a safety issue.

My glider can be flown at 1000 pounds up to 1433 pounds gross weight
and spends a lot of time in 2G turns thermalling. The AOA for minimum
sink is always the same but the airspeed at which that happens changes
a lot. The same thing with best L/D.

A very 'slippery' glider takes a while for the airspeed to settle down
after a pitch change. Flying to an exact AOA would be easier than
chasing airspeed.

An AOA indicator that shows minimum sink and maximum L/D as well as
stall would be quite useful.

Bill,

I tatally agree! It would also be nice to have the AOA measure units instead of degrees and be calibrated so to give the same readings for max L/D and Min Sink at all flap settings.

When I was flying A-6 Intruders 21 units of AOA was the Max Range value (best L/D) at all flap settings. I don't believe you can develop an effective unit for aircraft with flaps without integrating the flap setting into the system. This requires knowing the performance curve for each setting in order to calculate a single Max L/D (Max Range) indicator reading and a single Min Sink (Max endurance) indicator reading.

This isn't as simple of a problem as some seem to think it is.

Wayne
HP-14 with flap settings from -5 to +90.
http://www.soaridaho.com/Schreder

On May 14, 7:30*pm, "Wayne Paul" wrote:
"bildan" wrote in ...

The interest for me is a sailplane installation where AOA is a
performance issue in addition to a safety issue.

My glider can be flown at 1000 pounds up to 1433 pounds gross weight
and spends a lot of time in 2G turns thermalling. *The AOA for minimum
sink is always the same but the airspeed at which that happens changes
a lot. *The same thing with best L/D.

A very 'slippery' glider takes a while for the airspeed to settle down
after a pitch change. *Flying to an exact AOA would be easier than
chasing airspeed.

An AOA indicator that shows minimum sink and maximum L/D as well as
stall would be quite useful.

Bill,

I tatally agree! *It would also be nice to have the AOA measure units instead of degrees and be calibrated so to give the same readings for max L/D and Min Sink at all flap settings. *

When I was flying A-6 Intruders 21 units of AOA was the Max Range value (best L/D) at all flap settings. *I don't believe you can develop an effective unit for aircraft with flaps without integrating the flap setting into the system. *This requires knowing the performance curve for each setting in order to calculate a single Max L/D (Max Range) indicator reading and a single Min Sink (Max endurance) indicator reading.

This isn't as simple of a problem as some seem to think it is.

Wayne
HP-14 with flap settings from -5 to +90.http://www.soaridaho.com/Schreder

Yes, there would have to be additional hardware/software to do it with
flaps. But, as long as the AOA system knew what flap setting was
being used, it could still display AOA data for that flap polar. Of
course, a continuously variable system like yours could be
complicated.

To simplify the system, min sink is only of interest at thermalling
flap settings and best L/D only at zero flap. (I'm guessing if you
are in negative flap, you're not interested in flying at best L/D.)

Also, the newer airfoils have made non-flapped gliders just about as
good as flapped ones so the flap issue may be becoming moot anyway.
It could be that a glider without flaps but flown with the precision
possible with an AOA indicator might not be at much of a disadvantage.