SkyView AOA and L/D Max

madb1rd

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Dec 8, 2007
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Does anybody know where in the AOA display is reflecting L/D Max being flown? L/D Max varies but not substantially with respect to AOA so knowing this gives one a good baseline for max range along with a few other things like best glide.
 

Dynon

Dynon Staff
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SkyView's AOA algorithm doesn't pin L/D max to a consistent spot from calibration to calibration. A way to determine that could be to put the aircraft in a configuration that is L/D max (ie, best glide), and then note where your AOA indicator is.
 

cbretana

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Jul 10, 2019
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Generally, when I calibrate the AOA system, I try to set it up so that the AOA tone starts at L/D max and increases ( as AOA increases), to become a steady tone just below max AOA. Then you can use the onset of the uscillating tone as an L/D max indication.
 

HFMan

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Aug 28, 2019
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Generally, when I calibrate the AOA system, I try to set it up so that the AOA tone starts at L/D max and increases ( as AOA increases), to become a steady tone just below max AOA. Then you can use the onset of the uscillating tone as an L/D max indication.
That would drive me crazy... starting to get a tone at L/D max? The difference between my L/D max and stall speed is a relatively large span, and would mean that during my entire approach starting several miles out I'm getting an AOA tone. I would not want to be your co-pilot in this setup.
 

cbretana

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Jul 10, 2019
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The volume is controllable. and the information about what your aircraft is doing aerodynamically is incredibly informative. It saves me from putting my eyeballs in the cockpit (to check airspeed), for numerous other reasons... Without looking at any other instruments, I can tell, just from the sound in my headset if I'm operating the aircraft at optimum aerodynamic AOA for glides, climbs, and most critically, for approaches. And if I'm not, I can immediately and easily adjust my back pressure (the AOA), (without focusing on any cockpit instrument), and get instant aural feedback.
How many times do you look at the airspeed indicator? Without even touching on the fact that for almost everything we use the airspeed for, it's actually the AOA that's really the critical important parameter, imagine not having to do that, being able to keep your eyeballs on what's happening outside the aircraft, instead of what's going on on your instrument panel.

In the General Aviation community, unfortunately, we have established and propagated the idea that the only thing AOA is useful for is to let you know when you have stalled the aircraft. That was, and is a mistake. AOA is the primary aerodynamic parameter for everything affecting how the aircraft performs.
 

HFMan

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Aug 28, 2019
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I don't focus on any instrument- long ago during a BFR my CFI challenged me to not remain focused on airspeed on approach- rather look out the window and 'feel' the airplane through pitch angle, throttle, visual sink rate, wind noise, etc. It's amazing how much better pilot you become if you fly the airplane, as opposed to fly the numbers. I don't want AOA tones at any time other than when approaching a stall- otherwise they would be a distraction and almost become a nuisance, to the point of being dangerous. To each his own, and I respect your opinion, but I also suspect you are in a very distinct minority with regard to AOA tones.
 

cbretana

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Jul 10, 2019
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Except for very simple GA aircraft, most aircraft today have artificial feel systems such that you cannot "feel" the aircraft, as you describe, at least not directly. As to your comment about being in the minority, surely you are not saying <grin> that you simply take a poll before deciding what to think? I flew high performance jets in the service, and the aircraft I flew had a system in it that did more or less exactly what I describe above. and we used it for many, many things. It was far from being a distraction. The below is from the Operations Manual for the F-4E Phantom II.

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Nevertheless, as you say, every one should be respected, (although I'm not so sure that every opinion deserves the same consideration!)

Regards to you, sir.
 
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