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  #11  
Old 11-05-2013, 10:39 AM
Eddie P's Avatar
Eddie P Eddie P is offline
 
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Paul, sorry, it was not a strong statement of intent, it probably came off the keyboard a little harsh and a bit un-intended. I like AOA, love it in fact, and use it all the time in my professional flying. However, I have heard a few guys mention a few things while hangar flying giving me the impression there are some guys that might not full understand how G loading works. That could be a problem in terms of how they might better be able to proactively manage their flight profiles. That's a training issue. I should have been a better word smith about how I stated that.

So AOA is good, we all can agree on that!
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  #12  
Old 11-05-2013, 10:43 AM
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Toobuilder Toobuilder is offline
 
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Quote:
Originally Posted by Neal@F14 View Post
When you're descending in a turn with the wing "unloaded" the stall speed is going to remain pretty low even with a steep bank angle.
Absolutely. There are so many variables that the OP might just as well ask "?how high is up?" A level turn is pretty easy to calculate, but this is a descending turn - and the vertical component is a HUGE discriminator in stall speed.

This has been discussed countless times here and always with the same result: A bunch of people take the ?AoA/fly the numbers? tack, while the rest go with ?practice/learn to fly?.

I predict this one is going to go the same way.
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  #13  
Old 11-05-2013, 10:46 AM
Eddie P's Avatar
Eddie P Eddie P is offline
 
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Quote:
Originally Posted by agirard7a View Post
Please corrected if I am wrong but decent angle
Should be irrelevant if you are maintaining constant
Speed.
You are right, if you are turning, you are NOT unloaded. Completely unloaded flight means ballistic, 0G flight like in an aggressive stall recovery or some random part of an aerobatic maneuver. Partially (relative) unloaded flight would be during some transition to a higher descent rate or reducing bank angle. You can see this with an AOA gauge while maneuvering. While we load and unload a little here and there during normal maneuvering, we are not (normally) in a constant state of unloaded flight in the pattern. A constant 600 FPM descent, stabilized approach with a 30 degree bank while turning to final is still 1.15G in the pants during that bank and turn and will still give you a 1.07*Vso stall speed until you are wings level where you go back to just Vso.

http://www.experimentalaircraft.info...ll-speed-1.php

PS - how high is up? That's relative

Last edited by Eddie P : 11-05-2013 at 10:49 AM.
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  #14  
Old 11-05-2013, 11:02 AM
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Neal@F14 Neal@F14 is offline
 
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Dan Rogers has a pretty good explanation on his acro website, including V-g stall graphs and formulas http://flyacro.us/SpinTraining.html
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  #15  
Old 11-05-2013, 11:02 AM
luddite42 luddite42 is offline
 
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Quote:
Originally Posted by agirard7a View Post
Please corrected if I am wrong but decent angle should be irrelevant if you are maintaining constant speed.
Correct, climbing or descending is irrelevant if you are maintaining a constant speed. If you are turning at a 45 degree bank with constant airspeed, your G-loading will be the same whether you are climbing, descending, or maintaining altitude. For those who say a descending turn is less loaded than a level turn, that assumes you are allowing the airspeed to increase.

Quote:
Originally Posted by Toobuilder View Post
This has been discussed countless times here and always with the same result: A bunch of people take the ?AoA/fly the numbers? tack, while the rest go with ?practice/learn to fly?.

I predict this one is going to go the same way.
Best summation so far. We will have truly turned a corner when all those flying farmer guys put AOA in their J-3's.

Last edited by luddite42 : 11-05-2013 at 11:08 AM.
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  #16  
Old 11-05-2013, 11:06 AM
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rmartingt rmartingt is offline
 
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Quote:
Originally Posted by Toobuilder View Post
This has been discussed countless times here and always with the same result: A bunch of people take the ?AoA/fly the numbers? tack, while the rest go with ?practice/learn to fly?.
I'd argue that the two aren't mutually exclusive. Having an AOA indicator within line of sight (or better yet, something like a HUD display with flight path vector vs. boresight) would make learning the relationship between AOA, speed, maneuvering, and performance a much faster process. These kinds of displays give a much clearer picture of what the airplane is actually doing, and once pilots know that, it's easier to correlate cues from their other senses. You could then remove the visual display if you want--though I'd personally see no reason to except for training.


To use a bit of a simplified analogy for my see-then-feel vs. feel-to-see approach, imagine trying to learn how to buck rivets blindfolded, or learn your way around a room you have never been in before with the lights off. It's going to be a long and frustrating process, and wou will likely be drilling lots of rivets out or nursing sore shins.

Now, compare that to trying to do the same with the added benefit of visuals. Learning to buck rivets while you can see the bucking bar and the rivets is much easier; once you get used to doing it within sight it's easier to do it sight unseen. I'll bet 99% of us first learned to buck rivets we could see before moving on to the ones we couldn't. Similarly, even a few seconds' glance at a new room before turning the light out will help us navigate it much better, since we now have a mental map of the room and its major features on which we can place ourselves.
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  #17  
Old 11-05-2013, 11:07 AM
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agirard7a agirard7a is offline
 
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Eddie. My numbers where wrong and really
appreciate your input on this. I plan to put an
AOA in my plane. Most importantly however is having the knoweldge and understanding of these critical underlying factors.
Thanks.
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  #18  
Old 11-05-2013, 11:27 AM
penguin penguin is offline
 
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Quote:
Originally Posted by luddite42 View Post
Correct, climbing or descending is irrelevant if you are maintaining a constant speed. If you are turning at a 45 degree bank with constant airspeed, your G-loading will be the same whether you are climbing, descending, or maintaining altitude. For those who say a descending turn is less loaded than a level turn, that assumes you are allowing the airspeed to increase.
At small angles of climb and descent, yes. At larger angles engine thrust and gravity mean the wing has to work less hard. Draw a vector triangle and 'do the math'.

Pete

Last edited by penguin : 11-05-2013 at 11:30 AM. Reason: added quote
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  #19  
Old 11-05-2013, 12:15 PM
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flyeyes flyeyes is offline
 
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Quote:
Originally Posted by Ironflight View Post
Sorry Eddie, but the AoA is no more a crutch than the Airspeed indicator and a bunch of mental gymnastics to recalculate the current stall speed given the flight path, bank angle, gusts, etc, etc. The AoA does all of that compensation for you.

Ideally, we'd all be superior pilots who simply feel the airplane in the seat of our pants and never accidentally stall becasue we are one with the machine. That hasn't worked too well for a lot of dead folks over the last century.

If you want a reliable indicator of where the airplane is relative to the stall under all flight conditions, and you want that to be somethign other than your hind-quarters, AoA is the far superior instrument.
What he said.


The wing stalls (potentially causing a fatal loss of control) at the same AOA, independent of weight, density altitude, loading, bank angle, or any of a zillion other variables.

The only reason we have an "approach speed" is because it is a rough proxy for AOA. If you know your weight (or are flying an airplane where it doesn't vary much) you can pretty much calculate the airspeed where you will reach the critical AOA.

Bank angle really has nothing to do with stalling speed or "g-loading," except that you have to load the wing to maintain level (turning) flight and if you do the g-loading required can be calculated from the bank angle. This is independent of the airplane, and the exact same chart can be used for any aircraft.

It's possible to stall the airplane from level flight at any speed up to the maneuvering speed by loading the wing (pulling back on the stick). That's how snap rolls work, if you add some rudder at the same time so one wing stalls first.
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  #20  
Old 11-05-2013, 12:56 PM
Aryana Aryana is offline
 
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I think all the charts and numbers in the world combined with all the stall warning and AOA instruments don't hold a candle to some good old fashioned training in an aerobatic airplane if you really want to understand how an airplane stalls and spins at different attitudes/airspeeds.

I did mine in a Yak-52. My favorite part was accelerated stalls while banked over at 60 degrees, keeping it coordinated as best to keep it stalled. As soon as it goes out of coordination for a split second, it enters a spin. What a hoot.

I'd highly recommend it for anyone that has the opportunity. It sure helped me get a better "seat of the pants" feel for all the different airplanes I hop into now.
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