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05-10-2018, 05:42 PM
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been here awhile
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Join Date: Dec 2004
Location: North Alabama
Posts: 4,301
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Quote:
Originally Posted by Ed_Wischmeyer
And as for visual AOA displays, if you're too busy to look at the airspeed, why would you not also be too busy to look at AOA? And as for glareshield mounted displays, they can be okay if you actually look at them, but "cognitive capture" (related terms are inattentional blindness, tunnel vision and target fixation) means that you can look right past them if you're stressed and focused intently on the runway. Also, on an overly steep base to final turn, the AOA indicator could be so offset from where runway is in the canopy as to be ignorable in your peripheral vision.
When push comes to shove, and the pilot is so stressed / focused on the runway that cognitive capture means that he doesn't see a visual AOA indicator, and similarly doesn't hear a stall warning, what good are they? Evaluating AOA on a calm day, straight in approach is nigh unto worthless at best, deliberate falsification at worst.
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Naw...I don't buy any of that. I've been flying an analog LRI in the RV-6 for over 15 years and 1200 hrs and there is absolutely no issue with including the LRI in the normal visual landing scan. And my LRI isn't even on the glareshield:
(This photo is a few years old, the old GPS has been replaced by an iFly, and the transponder by the cool Stratus ESG ADS-B device. By the way, the LRI probe also runs the AOA indicator in the Dynon which provides an aural indicator)
If the pilot is so stressed out over landing that it is impossible to see any of the panel then some retraining is overdue. I have flown the LRI into a wide variety of landing scenarios and it has never failed to be my primary instrument in conjunction with a good visual scan. I have never been so busy landing the RV-6 that I didn't have time for the occasional glance at the LRI.
AOA is easier to fly in gusting conditions because it doesn't bounce around like airspeed indicators. Where it really shines is landing on short, tight strips where max landing performance is desired. If the pilot was to get stressed, this would be the time--but a scan trained with the LRI reduces stress, not increases stress.
I'm sure Ed is happy with his RV-8 as it is, but I find his objections to a good AOA to be invalid.
Last edited by Sam Buchanan : 05-10-2018 at 05:51 PM.
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05-10-2018, 05:48 PM
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been here awhile
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Join Date: Dec 2004
Location: North Alabama
Posts: 4,301
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Quote:
Originally Posted by rv7boy
Sticky needle? The gauge itself is just a Dwyer differential pressure gauge. I don't have the Dwyer catalog in front of me now, but I did buy one one time with the plans to build my own. There's nothing really fancy or exotic about the gauge except the Dwyer faceplate has been replaced with one with red and green background indicating "lift reserve."
Sorry I don't have the Dwyer part number but with a little research you could find one that has the correct range for this application.
P.S. A "little research" (2 minutes and three mouse clicks) and I found this. It's a Dwyer Series 2-5000 Minihelic II differential pressure gauge.
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There ya go. With a little patience, the Dwyer gauge bezel can be unscrewed, the needle gently pulled from the shaft, and the LRI dial face inserted in place of the generic Dwyer face. Instant LRI gauge!
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05-10-2018, 06:23 PM
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Join Date: Jan 2005
Location: Peshtigo, Wisconsin
Posts: 768
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Boy Sam, seeing your panel brings back memories of following your build. My 6A followed close behind, started in ?97 and finished in ?06.
I have an LRI as well (panel pic on the recent GRT/Hudly HUD thread) and I too have no issues with including it in a normal scan on landing. For example, I sneak a glance at it turning base to final.
__________________
Jeff Orear
RV6A N782P
Peshtigo, WI
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05-10-2018, 07:25 PM
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Join Date: May 2005
Location: Savannah, GA
Posts: 1,301
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Quote:
Originally Posted by Sam Buchanan
Naw...I don't buy any of that. I've been flying an analog LRI in the RV-6 for over 15 years and 1200 hrs and there is absolutely no issue with including the LRI in the normal visual landing scan...
If the pilot is so stressed out over landing that it is impossible to see any of the panel then some retraining is overdue. I have flown the LRI into a wide variety of landing scenarios and it has never failed to be my primary instrument in conjunction with a good visual scan. I have never been so busy landing the RV-6 that I didn't have time for the occasional glance at the LRI.
AOA is easier to fly in gusting conditions because it doesn't bounce around like airspeed indicators. Where it really shines is landing on short, tight strips where max landing performance is desired. If the pilot was to get stressed, this would be the time--but a scan trained with the LRI reduces stress, not increases stress.
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We disagree, of course -- but agreeably. :-)
I did not write, hint nor imply that looking at AOA was a problem as part of a normal visual scan. What I wrote was that instruments can and do get dropped when the scan breaks down due to a stressful situation, like those immediately preceding an inadvertent low altitude stall or spin.
When pilots have a stall/spin accident base to final, it's a pretty safe bet that they're focused on something other than the instruments.
Both and I another regular poster here have had wind shear encounters in which the aural AOA warning was not heard till after the event. And the literature is full of events in which aural sensing was first to be dropped in stressful situations.
And as for AOA not bouncing around like airspeed, that's easy to do -- just dampen the sucker within an inch of its life. From what I've read, AOA sensors are so inherently noisy that they have to be heavily damped. The trouble with heavy damping is that a damped signal tells you what was happening a little while ago, not what's happening right now. (Those of you who have studied first order lag filters will understand. Same for finite impulse response filters.) When I asked Garmin what their AOA algorithm was on the G3X so that I could understand exactly what it was telling me, their answer was, "proprietary."
The question of how do you adjust target AOA for reported winds and gusts remains unanswered. Sure, you can keep lowering the nose to keep the AOA down for the gusts you've already encountered, but that's reactive, not proactive.
And I never wrote, hinted nor implied that an LRI would increase stress, so I feel no obligation to reply to that statement.
Calm, benign wind conditions, go for it. I will agree that training is the solution to stressful situations, but more than the kind of training that's fashionable now. If the EAA Founder's Innovation Prize judges ever get over their fascination with gadgets, I'll explain all this at Oshkosh.
But it's nice that we both have safety as a primary objective.
__________________
RV-9A at KSAV (Savannah, GA; dual G3X Touch with autopilot, GTN650, GTX330ES, GDL52 ADSB-In)
Previously RV-4, RV-8, RV-8A, AirCam, Cessna 175
ATP CFII PhD, so I have no excuses when I screw up
2020 dues slightly overpaid
Retired - "They used to pay me to be good, now I'm good for nothing."
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05-10-2018, 07:34 PM
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been here awhile
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Join Date: Dec 2004
Location: North Alabama
Posts: 4,301
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Quote:
Originally Posted by Ed_Wischmeyer
We disagree, of course -- but agreeably. :-)
I did not write, hint nor imply that looking at AOA was a problem as part of a normal visual scan. What I wrote was that instruments can and do get dropped when the scan breaks down due to a stressful situation, like those immediately preceding an inadvertent low altitude stall or spin.
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The whole point of AOA is avoid getting into an inadvertent low altitude stall or spin........
Oh well, I just know the thing is very useful and it is my primary instrument for pattern operations (benign and especially otherwise) and I consider it a huge enhancement to safety. If someone chooses not to use AOA...that be ok with me.
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05-10-2018, 07:39 PM
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Join Date: May 2005
Location: Savannah, GA
Posts: 1,301
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Quote:
Originally Posted by Sam Buchanan
Naw...I don't buy any of that. I've been flying an analog LRI in the RV-6 for over 15 years and 1200 hrs and there is absolutely no issue with including the LRI in the normal visual landing scan. And my LRI isn't even on the glareshield:
If the pilot is so stressed out over landing that it is impossible to see any of the panel then some retraining is overdue. I have flown the LRI into a wide variety of landing scenarios and it has never failed to be my primary instrument in conjunction with a good visual scan. I have never been so busy landing the RV-6 that I didn't have time for the occasional glance at the LRI.
AOA is easier to fly in gusting conditions because it doesn't bounce around like airspeed indicators. Where it really shines is landing on short, tight strips where max landing performance is desired. If the pilot was to get stressed, this would be the time--but a scan trained with the LRI reduces stress, not increases stress.
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Good answers, but none of them address the points I was trying to raise:
* The point is not whether AOA works when you have time to look at it, the point is whether AOA visual indicators work when a pilot is in a stressful situation when the whole visual scan breaks down, such as those situations that lead to low level loss of control. The case of a pilot being stressed in nominal conditions was not what I (intended to) address. By the way, visual stall warning indicators are no longer certifiable in FAR 23;
* For what I've read of AOA sensors, the raw data they provide is so noisy that that they have to be heavily damped. The flip side of damping is that a damped signal inherently has lag, meaning, it tells what was going on a short while ago rather than what's going on right now. I asked Garmin what their AOA algorithm was on the G3X so that I could understand what it was telling me, and their response was that the algorithm was proprietary;
* The question of how to adjust AOA for forecast winds and gusts, before you encounter those gusts, remains unaddressed;
* I never wrote, hinted nor implied that an LRI would increase stress, so I will not address that canard;
The good news is that we agree on making safety a priority.
__________________
RV-9A at KSAV (Savannah, GA; dual G3X Touch with autopilot, GTN650, GTX330ES, GDL52 ADSB-In)
Previously RV-4, RV-8, RV-8A, AirCam, Cessna 175
ATP CFII PhD, so I have no excuses when I screw up
2020 dues slightly overpaid
Retired - "They used to pay me to be good, now I'm good for nothing."
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05-10-2018, 08:19 PM
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been here awhile
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Join Date: Dec 2004
Location: North Alabama
Posts: 4,301
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Well, Ed....it appears you definitely believe in redundancy..... 
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05-10-2018, 08:28 PM
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Join Date: May 2005
Location: Savannah, GA
Posts: 1,301
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Stupid internet... I typed in the first response and it didn?t show up in the forum. So I retyped it. Now they?re both there. Grrr.
I need a Typing Reserve Indicator or something.
Grrrr.
__________________
RV-9A at KSAV (Savannah, GA; dual G3X Touch with autopilot, GTN650, GTX330ES, GDL52 ADSB-In)
Previously RV-4, RV-8, RV-8A, AirCam, Cessna 175
ATP CFII PhD, so I have no excuses when I screw up
2020 dues slightly overpaid
Retired - "They used to pay me to be good, now I'm good for nothing."
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05-11-2018, 10:01 AM
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Join Date: Sep 2006
Location: Reno, NV
Posts: 19
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Thanks RV7boy! I'll check it out and see what I can do.
I appreciate the efforts and the commentary on AOA / LRI type devices. Ours is mounted on the glareshield and has been a useful reference in our scan.
Happy flying!
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05-11-2018, 04:59 PM
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Join Date: Aug 2014
Location: Bowie MD
Posts: 886
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So is the LRI guy (InAir Instruments Inc) still doing this, or is it a defunct co? I'm total for steam next to electric, and been looking for an AOA in this vein for my build.............
__________________
Mani
Busby MustangII (FoldingWing) Pending DAR.
Don't be a hater; I'm a cousin with thin wings! 
N251Y (res)
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