A puzzler!

[rvmills]

'Sorry if I get what seems to be contentious in my responses; I don't mean to seem that way. I get a little perturbed when I find that someone gives me a mathematical or theoretical treatise to side-step the question at hand, so I try to show how the question is being avoided. It puts me in mind of the obfuscation that is the hallmark of a politician's reply to a question to which he doesn't want-to or can't answer. An honest response is usually something like "I've never thought about that before so I'll give it some thought and not just dismiss it off-hand." In reponding to my original query, Mel Asberry wrote that he thought that all of the lift was on the wing's bottom; at least he spoke his mind with no equivocation.

C'mon Paul, perhaps its not my role to say this...but I will anyway...I'd say that an apology with an explanation of why one says what they say (and how they say it) followed by a statement comparing fellow posters to politicians, is like saying, "ooops, sorry for the poke in the eye...now here's a poke in the other."

People are not skirting the question, they are offering their interpretations of known concepts (whether fact or theory or in between...I'm not going there in this post). Crazy thing is, you say they are dismissing your thought line, yet your thought line is a puzzle or riddle, and not a statement of a new hypothesis. So I'll ask a third time...what is your hypothesis on the original question. Previous queries on that (by me to you) are as yet unanswered. Your turn to avoid obfuscation.

Me thinks this thread may get the lock hung on it soon, for two reasons:
1. Mongo no like being poked in eye!
2. What aerodynamic or structural issue are we talking about now?

Remember, I like discussions with you, but Mongo no like having sand thrown in face, and won't step in sandbox if no stop...and Mongo think other Mongos feel same way.

The original noise model of the tropospheric effects on a radar wave, for our guidance computer, were developed strictly by fitting a polynomial curve to observed data and had absolutely no relationship to the real world. It was good in the middle, but like so many of these attempts, went squirrely at the ends. All it took to get a true model was to look at how the radar wave propagated through the air, and model that; simple and accurate. The same wth refraction correction. Astronomers use incredibly complex parameters in a curve fit that are chosen by some hieratical formula by the astronomical priests, but a simple model, based on measured physical properties, gives outstanding results.

OK, then please give us a simple model, based on measured physical properties, to evaluate and make comment on...

Now let me put forth a model. There's a plane with a hollow wing, joined only at the edges with no internal structure. The fuselage is joined to the top skin only. There's a giant man on the ground holding the plane up using both of his hands on the bottom skin, so that the weight of the plane is borne through his body to the ground. There is a tiny man inside the wing holding up the top skin, so that the weight on it passes through him to his feet on the bottom skin, and thence into the man holding it up on the outside. The little man's hands are pushing up on the top surface and his feet are pushing down equally on the bottom skin. Is he holding it up? Does the weight pass through him and the bottom skin and the giant?

I know you are having fun by asking the questions, but I have no idea what this model and question leads to, or how it relates to the original riddle. What are you asking? However, to be non obfuscative, I'll say that if the giant is already holding up the entire structure, then the push from the little man upon the top and bottom skins adds to zero net effect, and no additional weight is added to the giants hands (save the weight of the little man)(kinda like the air pressure inside a wing...net effect...zero...I think!).

But I'm providing an answer to a question that I can't fully place into context, so don't take it as a dismissal...I'm still trying to draw out the hypothesis. Can you hook a brudda up!?!

Cheers,
Bob

 

[PCHunt]

I don't think the trapped air inside a wing has any effect whatsoever on the lft being generated.

A solid wing still flies. Foam wings on models, for example. Another example that Paul might appreciate is a propeller. Very few propellers are hollow, most are solid. And they are rotating wings, and produce lift.

Now if the air leaks out into the airstream, then there would be an effect. Most racing airplane owners spend lot$ of time and Dollar$ to seal up all the leaks in the wing and airframe.

JMHO.

 

[Bob Kuykendall]

...The flow field over an airfoil or wing accelerates around the body as the result of a continuous distribution of pressure exerted on the fluid by the body. An equal and opposite reaction must occur on the body. This pressure distribution, acting everywhere normal to the body's surface, is what creates lift...

I think we're done here.

Bob K.

 

[roee]

You can't be serious...

'Sorry if I get what seems to be contentious in my responses; I don't mean to seem that way. I get a little perturbed when I find that someone gives me a mathematical or theoretical treatise to side-step the question at hand, so I try to show how the question is being avoided. It puts me in mind of the obfuscation that is the hallmark of a politician's reply to a question to which he doesn't want-to or can't answer. An honest response is usually something like "I've never thought about that before so I'll give it some thought and not just dismiss it off-hand."

That's nothing but further derision phrased in the form of an apology. Who's a politician here?

In any case, your response is bunk. There have been plenty of well thought out posts in this thread put forth by knowledgeable and astute folks (and I'm not just speaking of myself, but many others) who presented well reasoned arguments, poking holes in your hypothesis and the validity of its underlying premises. It is you who have dismissed these without reason. In fact, reading some of your retorts, I question whether you had even thoroughly read many of these posts before cavalierly shooting them down. I can't speak for others, but for me, I left this discussion when it became apparent to me that it was actually not a discussion at all, but rather just a platform for you to grandstand. You've shown no willingness to have your own ideas put under scrutiny, and you've shown personal contempt toward those who have done so. I suggest that if your objective is to seek adulation, you should find a dumber audience.

Now let me put forth a model. There's a plane with a hollow wing, joined only at the edges with no internal structure. The fuselage is joined to the top skin only. There's a giant man on the ground holding the plane up using both of his hands on the bottom skin, so that the weight of the plane is borne through his body to the ground. There is a tiny man inside the wing holding up the top skin, so that the weight on it passes through him to his feet on the bottom skin, and thence into the man holding it up on the outside. The little man's hands are pushing up on the top surface and his feet are pushing down equally on the bottom skin. Is he holding it up? Does the weight pass through him and the bottom skin and the giant?

As for your giant man / tiny man analogy... If you go back and re-read post #69 (assuming you actually read it the first time), you'll see that I've already described this phenomenon, and how the air pressure inside the wing -- "the tiny man" -- can influence the distribution of forces between different parts of the wing. Others have described this too in different terms. But again, it must be made perfectly clear that this variable only affects how forces are distributed across the wing structure. It does not affect total lift, and is not the phenomenon responsible for the fact that a wing can generate lift.

I'm not writing this for the benefit of the original poster, but rather for other forum members who are actually interested in the exchange of ideas.

 

[Ironflight]

OK, Moderator stepping in here. I've pretty much ignored this thread since it was clear that the OP wasn't going to bother giving an answer to his riddle, but now that I took a look, it is annoyingly close to derision. I have receieved several PM's syang "enough is enough".

Ellipse, baiting the audience into an argument is not the way the game is played here on VAF. As I understand it, you're not an RV builder or flyer, right? That makes you a bit of a guest. Play nice, provide the answer to your riddle, or yup, as predicted by a number here, it'll get locked. We encourage sharing knowledge, not playing "I am smarter than you, and I am not going to tell you why" games.

Respect for each other folks - that's what works here!

Paul

 

[elippse]

I'll be happy to step up and give my analysis of what supports an airplane in flight. First off, I must say that air, as long as it is above absolute zero, contains energy in the form of molecular velocity, what we refer to as temperature. That is why the propagation velocity of air is related to its absolute temperature; it is how fast, based upon the average speed in a particular direction of the molecules, that a disturbance can be carried along. I need to emphasize this point because whether air is just in the atmosphere surrounding the airplane or is carried along internally with it, it still has energy which can be utilized to generate a force; it doesn't suddenly become inert when it is in the plane. This force was utilized in the thin stainless steel balloon construction of the Atlas missile to transfer unbalanced aerodynamic and inertial loads throughout the skin. That's why I wrote the post which shows why the rubber sealing strip is installed wrong and gets pushed out by the air in the wing.

As far as I'm concerned, the tiny man-giant man model shows all too well how the loads are transferred from the surfaces to the ground below. These two men make up a rigid structure that supports the weight on the top surface all the way to the ground.

The giant man is the air below the wing pushing up from the ground to the wing's bottom surface harder than the weight of the air above the wing is pushing down on it; that should be patently obvious. In the same way, the tiny man inside the wing, pushing up on the top surface while standing on the bottom surface, is the air within the wing which is pushing up on the top surface bearing the load while pushing down on the lower surface which is being held up by the air below it.
So basically what this says is that the air within the wing does pretty much the same job that would be done if the wing were solid; it solidifies it!

 

[Flying Scotsman]

"The giant man is the air below the wing pushing up from the ground to the wing's bottom surface harder than the weight of the air above the wing is pushing down on it"...

This would cause a constant acceleration upward, rather than level flight.

 

[szicree]

Don't forget gravity is also pushing down.

 

[Flying Scotsman]

I think the proper formulation is that "giant man" (that sounds silly even typing it) is pushing up with a force equal to the weight of the plane (including the air *in* the wing) + the weight of the air above the wing.

Need some graphics in these posts, so you could draw the vectors .

 

[rv7boy]

Amen!

Well said, Paul. You have expressed many of the same feelings I have had. I have deliberately stayed out of this discussion. Thanks for taking the time to step in.
Don

OK, Moderator stepping in here. I've pretty much ignored this thread since it was clear that the OP wasn't going to bother giving an answer to his riddle, but now that I took a look, it is annoyingly close to derision. I have receieved several PM's syang "enough is enough".

Ellipse, baiting the audience into an argument is not the way the game is played here on VAF. As I understand it, you're not an RV builder or flyer, right? That makes you a bit of a guest. Play nice, provide the answer to your riddle, or yup, as predicted by a number here, it'll get locked. We encourage sharing knowledge, not playing "I am smarter than you, and I am not going to tell you why" games.

Respect for each other folks - that's what works here!

Paul