Angle of Attack: True or False
- Thread starter birdus
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In fact, I dropped it right from the CG, which is the state the aircraft is in if there is zero relative wind. Yet, it dropped straight down and did not rotate toward the heavy side even a little bit.
There is nothing to provide leverage to cause a rotation unless there is relative wind - aerodynamic force. Half the plane (from a mass perspective) is on the left side of the cg and half the plane is on the right side. Gravity simply cannot cause the plane to change pitch, until you add another relative force. And that relative force will be exceeding the critical angle of attack (because you are falling straight down)
There is nothing to provide leverage to cause a rotation unless there is relative wind - aerodynamic force. Half the plane (from a mass perspective) is on the left side of the cg and half the plane is on the right side. Gravity simply cannot cause the plane to change pitch, until you add another relative force. And that relative force will be exceeding the critical angle of attack (because you are falling straight down)
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So comical. I say hold the handle and you say I'm wrong if you hold the HEAD. You don't internet well. LOL
I give up. Your desire to avoid learning something is stronger than my desire to teach you something. Enjoy your ignorance.
What is my ignorance? You completely flipped around my post to say something the exact opposite then claim I can't learn anything new. Helps if you read correctly. Only point you've made here is about the objects in a vacuum. Nobody disagrees. I fully expect you to read this post totally backwards as well. LOL
I made my points quite clear in three posts above. I can't make you understand them.
No you didn't. You totally flipped my thought experiment, restating it backwards. I fear for your piloting abilities if you don't know the difference between the head and handle of a hammer. But once you have this concept down, you can then learn screwdriver use.
The fact that you can't see how my reversing your thought experiment proves that your experiment didn't prove what you tried to prove with it is what is actually scary.No you didn't. You totally flipped my thought experiment, restating it backwards. I fear for your piloting abilities if you don't know the difference between the head and handle of a hammer. But once you have this concept down, you can then learn screwdriver use.
I also said a great many other things that you ignore. Showing that you are not even attempting to understand what I'm saying. You're only trying to prove you are right.
You tried to prove that the hammer hitting heavy side down shows you were right, but in fact, it does nothing of the sort - which my reversing of your experiment shows clearly.
If you are not a troll you scare me. I believe you are a troll, and should be ashamed of yourself.
Get a life.
Okay then. It's settled. A forum thread is a terrible thing to use as a basis of your knowledge on this subject.
zaitcev
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Pete Zaitcev
With some qualifiers, yes (well behaved airplanes, not flying upside down, etc.). Stick position controls the AoA - and vice versa. And the best part is, people wrote about it in books in 1944! 75 years later we still have pilots who fail to understand how it works.
I highly recommend you read "Stick and Rudder". The author spends chapters discussing these types of topics in great detail. Just get used to calling the elevator "flippers"
donjohnston
Pattern Altitude
This guy must be a lot of fun at parties.
dmspilot
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A stall does not result in zero lift. The nose drops in a stall due to the location of the CG relative to the center of lift, i.e. due to gravity.
dtuuri
Final Approach
It would still drop if the wings fell off at the stall. (Hint: Think, "Bombs away!")
dmspilot
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Just because the relative wind is 0 for an infinitesimal period of time doesn't mean anything. The airplane doesn't get suspended in mid air. Not sure what you're trying to prove with the whole vacuum thing, it's irrelevant. I agree with the premise that no pitch change will occur when the relative wind is 0, but that premise does not lead anywhere.
I was responding to the assertion, nothing more.
Tantalum
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Still false.
If the correlation were direct then we would not need stall indicators in our airplanes nor would there be a market for angle of attack indicators, we could simply color the shaft on the yolk different shades of green to orange to red with the red region being the critical angle of attack, IE, stalled region. Clearly after 100 years of aircraft engineering not a single manufacturer has decided to do that. Please dispel this notion that the stick position controls angle of attack
Referencing a 75 year old book that refers to lift as "bouyancy" is dubious. That's a great book, but we've learned a lot since 1945.. so "massive" grain of salt
All the elevator controls directly is what kind of force up or down is being placed on the tail of the aircraft
dmspilot
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Gotcha, sorry.
The hammer will fall in what orientation you drop it in. If you let go unevenly, it will begin to rotate and will continue to do so indefinitely. With enough height the heavy end will rotate back up again and the hammer will land sideways (flat) with the heavy end on the opposite side of where it started.
birdus
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Actually, it’s not that the book is wrong, it’s that you have to read “the rest of the story” to get the context.
Tantalum
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Oops! My bad. I saw that this thread had devolved a little bit so I admittedly only skimmed it briefly
Fair enough. But that passage was already taken somewhat out of context to build a point
it is an interesting thought exercise none the less, and not nearly as inane as the aircraft taking off on a treadmill thing.. or "will the truck weigh less if the birds carried within it start flying around inside of it"
dtuuri
Final Approach
Not false. What do move when you need to change your AoA? The throttle? Rudder? Ailerons? Seat back? Angle of attack is controlled by the stick, any other control is just a bit player.
Sacrilege!
Tantalum
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Maybe I'm the one being pedantic here then, but it certainly influences it and is the primary thing impacting it, but "control" implies a direct correlation, hence my earlier point that if that were true you wouldn't need angle of attack indicators and stall horns, etc.. you could just paint the yoke with a red area as your stall zone
Also, notice that rudder controls yaw, not degrees of heading deflexion, and turning the yoke left or right controls bank and roll, not a specific bank angle
Lachlan
En-Route
After reading this thread, at least, uh, those parts that were readable, I have discovered that my little airplane came from the Cessna factory with an AoA indicator built in! I had no idea that the YOKE was an AoA indicator until I perused this horrible, awful, terrible, awesome thread!!!
This seems a bit dubious. I can change my angle of attack with trim, throttle/power, aileron and rudder not just elevator.
Granted the trim is a secondary elevator control and the aileron's are controlled by the stick so the stick is still being used to control AoA when using ailerons but if the stick/elevator were the only means by which you control the angle of attack, then trim would do nothing and it would also be impossible to spin an airplane since only 1 wing has fully stalled in a spin.
Rudders, ailerons, throttle, trim may all play a much smaller part than the elevator in determining angle of attack but they do play a part beyond just being a bit player.
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Lachlan
En-Route
Has anyone considered the point that lift counteracts gravity, so everyone is right? This thread is special.
Just wanted to say that airspeed can be very high in a stall, and will be in a sustained stall. If you ever hold a stall for a proglonged time you can very well double your standard stall speed while still in the the stall
dtuuri
Final Approach
Load factor varies as the square of the increase in stalling speed, so doubling the stalling speed would cause 4 'g's.
dtuuri
Final Approach
Not sure what you're thinking of here. In a spin, one wing's stalled but the IAS may read higher, is that what you're referring to? If so, that might be due to location of the pitot and static ports.
dtuuri
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birdus
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Devolved a little bit? Ha, ha. I never could've imagined wanting to talk about angle of attack would result in people trying to beat each other to death with hammers.
Tantalum
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PoA hot topics (aviation related) are:
-parachutes and single engine planes
-someone saying something other than a Bonanza is the best all around airplane
-claim aerodynamic facts about the Mooney reverse tail
-high wing vs low wing
-retractable gear.. is the cost / complexity worth the speed gain
-posing a ridiculous medical question: "I'm a healthy guy but I do have a meth addiction and I have 3 felonies, how can I get my medical?"
-angle of attack (see, this earned you an "A$$ raped" remark by one of the other posters only a few posts in!)
-innocently ask really any question, then when the consensus is not what you wanted, freak out (like when someone wanted to do a 1,500 mile cross country as a student pilot for the first solo XC)
birdus
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In his defense, I think he was just concerned (in advance) about my well being.
Ooh! I'm all in favor of great adventures! I'll have to track that one down. Of course his instructor never signed off on it (I suspect) and so no great adventure occurred.
[EDIT: Found it! Should be an exciting read!
][EDIT: Read the whole thing. BRUTAL!!! Sounds like a smart and accomplished guy. Hopefully, he's up and flying.]
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