The Hangar

SentryRaven

06:21

Morning :)

Jay Carr

13:20

Anybody want to expalain to me why I keep asking questions where I can't completely understand the answer? I'm having a hard time judging who is right. I was going to jus follow the votes, but there's a huge debate...

12

Q: How do wings generate lift?

Just the basic question that every aviation enthusiast must be curious about: exactly how does a wing generate lift?

@DanHulme Who is more correct, you or Peter Kampf?

SentryRaven

You certainly picked an interesting topic...

Jay Carr

Well, it felt relevant to the stack you know...

And I do like physics, I just don't have a formal grounding in it, so I get confused sometimes.

SentryRaven

In many year's people will say: "Do you remember the start of scientific WW3?" - "Wasn't that caused by the guy who asked how wings generate lift?"....

3

Jay Carr

lolz, that seems quite likely at this point.

Farhan

@SentryRaven I did try to warn him ;)

Jay Carr

13:26

There is a correct answer though, right? Or is this kind of like gravity and all we can do is correctly figure out how a wing will work, but we don't know exactly how it does.

SentryRaven

Didn't succeed much there, did you? :D

Jay Carr

:-/

SentryRaven

@JayCarr It's science. There will be a correct answer at the time it's posted, which will be superseded once science finds a new theory or a new attempt to answer something...

I daresay, judging the way the boys are arguing in that question, we are probably somewhere in between of Answer A being correct and Answer B superseding A...

2

Jay Carr

To what are you assigning to A and what are you assigning to B? I assume A = Bernoulli and B = Flow turning?

SentryRaven

I for one believe this is still the most correct explanation, although my FI disagreed...

Jay Carr

13:29

You should just post that as and answer so I can accept it.

SentryRaven

Do not lead me into temptation...

Jay Carr

Oh come on, it's not like you could make me any more confused.

And I'm curious about this anyway. One of my favorite parts of history was historiography (or how our perception of history changes), this seems a bit similar.

SentryRaven

When I did my PPL, I learned it was Bernoulli. But I wouldn't say that this is and will remain the only possible answer. For now I am content that airplanes fly and make a nice hobby... if anybody asks why they fly I say magic and explain that there are different explanations, of which I only understand one currently.

Jay Carr

Fair enough

SentryRaven

If all fails, I can still claim I did my PPL at Hogwarts School for Wizardry and Witchcraft...

Jay Carr

13:34

lolz, yeah, that would help with the explanation of why you use that theory.

To be fair, NASA seemed pretty certain about flow turning, which makes me a bit more confident in them since they did, and do, help run the X-Plane program. I have to assume they know.

Farhan

@JayCarr Why don't you draft up your own answer which explains it to a layman?

Jay Carr

I might...

casey

@Farhan the problem with all of the misinformation with lift production is because people try to reduce it to be understandable to laymen and resulting explanation is no longer a good one. generally.

I'm disappointed to not see any complicated tensor equations in any of those answers

or even some actually writing the Bernoulli effect

something like $\frac{\partial\mathbf{u}}{\partial t} + \nabla (\frac{1}{2}q^2 + \int\frac{dp}{\rho} + gz) = \mathbf{u} \times \mathbf{\omega}$

Farhan

13:51

@casey So this principle isn't simple enough to be explained in simple words?

That's not hard to believe.

Jay Carr

14:20

So I guess the questions is if someone actually has the time and talent to write a succinct definition of how it works. Starting with the simpler bits and building into the more complex bits... Granted, that would have to be paired up with a more general question: is this site even the place for that sort of explanation?

Farhan

14:40

@JayCarr We do have a blog site :)

Jay Carr

@Farhan Does anybody read it? I don't think I've ever actually seen it before if I'm honest...

Federico

Concerning this: meta.aviation.stackexchange.com/questions/1641

http://aviation.stackexchange.com/a/16093/1467 && http://aviation.stackexchange.com/a/16092/1467

same user, two answers, double upvotes and the second answer was intended as edit of the first, result:
http://aviation.stackexchange.com/review/low-quality-posts/9264
the community thinks that everything is fine

I am confuse

DeltaLima

@Federico interesting

On the review panel it doesn't show the other answer

Federico

@DeltaLima should show my comment though, doesn't it?

DeltaLima

Not sure it did

Jay Carr

14:54

There, I selected the answer to that question (about how wings generate lift) in a controversial manner. I'm feeling fulfilled now... But honestly, I just felt like I got the best picture of what was going on from that particular answer. I'll keep an eye on the comments though, to see if there is any significant disagreement on the quality of the answer...

DeltaLima

I think the comment was there, I didn't notice it when I reviewed.

Farhan

15:10

@JayCarr I don't know how many, but some people do read it.

@Federico @DeltaLima The longer answer is older than the accepted answer.

I initially thought that the comment by mins triggered the user (who is new to SE) to write another answer explaining it further.

@DeltaLima The review panel/queue didn't show the shorter one because that user's first/earlier answer was already reviewed.

Federico

15:56

@Farhan I admit I have not checked the timestamps

Dan Hulme

17:21

Interestingly, both Peter Kämpf's and my answer have two downvotes

also, there's one thing thinking about lift has made me think of

is the circulation caused by the Kutta condition the reason a wing stalls if the alpha is too great?

Jay Carr

@DanHulme - I can't figure why either of yours would have any down votes... Other than there are a lot of people who are misinformed on how wings work, that might explain it a little bit...maybe. I wish people would leave comments.

Farhan

-1 for wrong explanation of Kutta-Joukowski theorem and flow turning. One should remember that flow turning is the effect of the lift (Which was created by pressure difference), rather than the cause of lift. — Victor Juliet 12 hours ago

This is one of the down votes on @DanHulme answer.

Victor himself has 3 down votes.

Jay Carr

@Farhan Sounds like we have a debate going there. Though I personally found @DanHulme responses fairly convincing.

Dan Hulme

that's because I cribbed them from the NASA website, as promised :-)

Jay Carr

What I really don't understand is how Peter Kampfs is voted down. He grounded it pretty well in basic fluid dynamics. I was really happy to see such a simple explanation of how molecules function in the given situation. It's why I picked his (though this is another situation where I wish I could combine two answers together. I think @DanHulme's part is pretty critical to understanding the whole thing.)

@DanHulme Fair enough ;)

Dan Hulme

17:31

annoyingly one dude posted a really good link as a comment and hasn't responded to my suggestion he post an answer

Jay Carr

Oh, and who would that be.

PS- I loved how one of your commentors (RononDex) used the fact that he's a physics student as the reason why he's right. Because, you know, you're answer was supplied by NASA, and Peter Kampf doesn't design wings for a living... (or some such)

Dan Hulme

yeah

I haven't the heart to break it to him that I did first-year physics at Cambridge and I still don't understand it fully

Jay Carr

lol, life will teach him. If not, he isn't paying enough attention.

Dan Hulme

av8n.com/how/htm/airfoils.html — BillOer 12 hours ago

Jay Carr

What do you think of Peter's explanation though? My first year of college was spent taking history classes so...yeah. Not super qualified.

Dan Hulme

17:36

My only complaint about Peter's answer is that it's a bit long and brings in molecules unnecessarily

I don't see anything factually wrong with it, for whatever that's worth

Jay Carr

Mmmm, I'd disagree with the molecules being unnecessary. I think if you get it in your head that there are bunches of little objects hitting the bottom of the wing and not that many hitting the top, it helps make it all make sense.

lol, that's more what I was after.

This could be another situation where the oddities of my own ability to understand certain analogies is playing into what works well for me and what doesn't.

Though I will take a crack at reading the paper you linked....

@DanHulme Do you know who wrote the document on av8n?

Dan Hulme

av8n.com/how/htm/author.html

casey

@JayCarr that question is generation a lot of "this is wrong, my way is right" type stuff, so the DV on all (but one) of the answers isn't exciting

also remember, it isn't your job to decide what is right and wrong, accepting just means you found a certain answer most useful, not that it is necessarily correct

Jay Carr

@casey I don't really think its exciting either, more troubling...

Dan Hulme

So, I had a colleague ask me a question today that I couldn't give a satisfactory answer to, and I might write it up.

Jay Carr

17:44

And yeah, I understand that that is the way SE is designed to work. But since my general purpose is "understanding how this actually works", I tend to want the most correct answer. In this case though, both answers contained both ways of explaining flight, I just liked Peters analogy more.

@DanHulme Do it.

Dan Hulme

He asked what would happen if I were to accidentally overfly the local military aerodrome

I said the answer was probably "I'd get told off" but he thought they should shoot me down

casey

depends on the airspace overlying the base and how low you intend overflying it

Jay Carr

Oooh, that is an interesting one. I think there has been a question asked regarding restricted airspace, but it's not quite that specific.

Dan Hulme

yeah, the question is not really "what are the legal ramifications?" but "is there a military response?"

casey

I used to fly PAR approaches at a local base with students

the only rule was don't let the rubber meet the concrete

otherwise it was a low pass down the runway and onto the missed

if you flew through without talking, you'd probably just get talked to when you eventually land

Jay Carr

17:50

@casey Probably depends on the base though, right? And how active it is, or even what is stored at the base...

Dan Hulme

@casey PAR?

well, this one is active

if they wanted to intercept you, the fighters would be coming from there

casey

I doubt they'd scramble for a class D bust, regardless of what was on the ground

Farhan

Precision approach radar

Precision approach radar (PAR) is a type of radar guidance system designed to provide lateral and vertical guidance to an aircraft pilot for landing, until the landing threshold is reached. After the aircraft reaches the decision height (DH) or decision altitude (DA), guidance is advisory only. Controllers monitoring the PAR displays observe each aircraft's position and issue instructions to the pilot that keep the aircraft on course and glidepath during final approach. It is similar to an instrument landing system (ILS) but requires control instructions. One type of instrument approach that can...

casey

in any case, they wont shoot for that

Dan Hulme

they scrambled a few months ago for an airliner that had radio failure

oh, of course

casey

17:53

@Farhan yep, used to put sticky notes over most of the panel and let them bring us in

Dan Hulme

@casey well, that's what I said, and he was all, "It's a good job I don't work there, I'd just shoot you down"

Jay Carr

@casey - it is entirely possible I have been watching too many movies. I keep thinking if you did an approach to edwards (or some other place they fly top secret stuff), you might be in some serious trouble, regardless of if you touch down or not.

casey

@DanHulme to get shot at you need to be acting overtly malicious and posing a threat

e.g. taking off from runway 1 at DCA and not turning and not climbing. that allegedly will earn you a few rockets inbound

that is third hand info from a few crews I know that busted the DP at DCA and overflew the washington monument. They were supposedly told they only only reason they weren't considered hostile is that they maintained positive rate of climb

and there are missile batteries on certain rooftops in DC

Dan Hulme

there was a hoo-hah in the news before the 2012 olympics, because some blocks of flats in London allegedly got turned into SAM stations without first consulting the residents

Jay Carr

Did that turn out to be true?

casey

18:00

i'd bet the flaming debris of a blown up C172 would probably do more damage on the ground than the plane just crashing on its own

Jay Carr

Unless it had been packed with several hundred pounds of explosives.

Which would be better if they went off in the air...I'd say.

Not likely, admittedly.

casey

if thats the goal there isn't a lot of useful load in a 172 :)

Dan Hulme

TBH I think they courted the publicity to increase the deterrent factor

@casey I'd love to see the weight & balance calc for that flight

falstro

18:19

@casey yeah, same here, I've flown a PAR into Büchel air base. They had arresting cables across the runway, so touching down would probably have been a bad idea ;)

Farhan

@falstro How should I do it? Lollipops, doughnuts, plush toys, what's your weakness?

Shalvenay

23:11

re -- places like Edwards

I know offhand that Palmdale/Plant 42 won't draw a blink -- after all, that facility does double duty as Palmdale's airport. :p

Edwards itself is similar to most airbases in that you have to call the base up and get permission to land there -- the big downside to Edwards is its rather out in the middle of nowhere, so there just isn't much in facilities there.

also: you need (and will get) an airspace briefing for Edwards as part of getting PPR there

@DanHulme -- which airbase are you speaking of, specifically, btw? (the AIP docs for that base should have everything you need to know about landing there)

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