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Old Sep 25, 2012, 04:59 PM
Grad student in aeronautics
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Originally Posted by richard hanson View Post
One would think that in a model forum, the writer actually has some practical experience to back up their thoughts
Your belligerence is annoying. Can we just appreciate that we all have different backgrounds? Personally, I think that's what makes this forum great.
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Old Sep 25, 2012, 06:20 PM
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Originally Posted by richard hanson View Post
One would think that in a model forum, the writer actually has some practical experience to back up their thoughts
.
When I was getting my degree in Aeronautical Engineering, I also was flying toy airplanes with Frank Ehling, who could make just about anything fly because of his experience.
The difference between the textbook larnin' and the hands-on larnin' served me well for the next 55 or so years.
.
http://www.angelfire.com/indie/aerostuff/
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Old Sep 25, 2012, 08:56 PM
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Originally Posted by Sparky Paul View Post
.
When I was getting my degree in Aeronautical Engineering, I also was flying toy airplanes with Frank Ehling, who could make just about anything fly because of his experience.
The difference between the textbook larnin' and the hands-on larnin' served me well for the next 55 or so years.
.
http://www.angelfire.com/indie/aerostuff/
One of the top engineers I ever knew was a quiet modeler who could make a watch from a lump of iron -using a drill press.and a cabinet rasp.
He built a flying model of the Convair transport powered by two Super Cykes
-it had retracts - flaps inner oute fuselage shell all details etc..
all self taught . he did wind tunnel models for Convair - I have a small delta dart model he did for them.

He once told me all the airfoils they used were done by a guy with a great set of ships curves .-
He also had a great 32 roadster with a four banger ( -did 110 at the dry lakes ) this goes back a bit---
He taught me how things really flew - when I was 14--
I still.miss him - a no bs guy.
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Old Sep 26, 2012, 12:58 AM
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I've said it before and I'll say it again. Nobody is arguing against the "that-looks-about-right" method. Nobody says real-world experience is not important. Those who argue "real-world-experience" trumps book learning fails at logic completely because they fail to realize that those books, those research papers describe experiments done in the real world (where else could they have happened? Narnia?) and the results and conclusion of those experiments. Yes the real world experience trumps theorizing. Those papers cited are all real world experiences of real people conducting careful research of how things behave at very-small scales. The airfoils I posted were designed for wings of roughly 2 inches in span - much smaller than what most of us are flying. Yet you dismiss the research as "full scale"? Don't forget, honey bees are full scale flying machines as well.

Let's drop this stupid anti-intellectual tangent and go on the the really fun stuff: discussing how planform affects flight. That's what this thread was supposed to be. Let's not even discuss airfoils unless the specific planform under discussion is sensitive to airfoils (like tailless planks).

My feeling about people who dismiss research is best express by Richard Feynman:

Richard Feynman - Ode on a Flower (1 min 26 sec)
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Old Sep 26, 2012, 01:10 AM
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That guy has no idea what he's talking about. He's obviously never built a flower, let alone hundreds (or thousands) of flowers. I'm sure his theories are bogus and of no use in the real world (they must be if they challenge my "practical" observations). I bet he couldn't even sketch an accurate map of a cat.
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Old Sep 26, 2012, 08:28 AM
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Originally Posted by slebetman View Post
I've said it before and I'll say it again. Nobody is arguing against the "that-looks-about-right" method. Nobody says real-world experience is not important. Those who argue "real-world-experience" trumps book learning fails at logic completely because they fail to realize that those books, those research papers describe experiments done in the real world (where else could they have happened? Narnia?) and the results and conclusion of those experiments. Yes the real world experience trumps theorizing. Those papers cited are all real world experiences of real people conducting careful research of how things behave at very-small scales. The airfoils I posted were designed for wings of roughly 2 inches in span - much smaller than what most of us are flying. Yet you dismiss the research as "full scale"? Don't forget, honey bees are full scale flying machines as well.

Let's drop this stupid anti-intellectual tangent and go on the the really fun stuff: discussing how planform affects flight. That's what this thread was supposed to be. Let's not even discuss airfoils unless the specific planform under discussion is sensitive to airfoils (like tailless planks).

My feeling about people who dismiss research is best express by Richard Feynman:

http://www.youtube.com/watch?v=zSZNsIFID28
And as we examine an elephant -wearing blindfolds -we all see it differently-
A good friend n modeler does genome research - pure research-fascinating stuff - another flying buddy writes test papers for the top physics schools in the country- he also is one of the most practical hands on guys you could ask for-
Practical vs intellectual is really not the issue -
Practical application of theory, however is- at times- worth a few pokes with a stick to see how it holds up.
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Old Sep 26, 2012, 12:10 PM
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And as we examine an elephant -wearing blindfolds -we all see it differently
Yes, and that's exactly the problem I have with your posts. While the rest of us share experiences and knowledge trying to figure out how the whole elephant looks like. You keep insisting that the trunk is the whole elephant.

It's OK if just knowing the trunk is good enough for you. But don't keep telling others who want to know more: "who cares about that, it's all trunk!".
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Old Sep 26, 2012, 12:27 PM
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For toy airplanes, "That looks about right" works perfectly when following other successes.
Getting into the math of flight really doesn't matter to the yank-and-banker flyer.
If performance is the goal, then having to know something about moments and profiles etc will make itself obvious.
Otherwise... It looks good, it'll fly.
Show us your work.
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Old Sep 26, 2012, 12:33 PM
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Originally Posted by Sparky Paul View Post
For toy airplanes, "That looks about right" works perfectly when following other successes.
Getting into the math of flight really doesn't matter to the yank-and-banker flyer.
If performance is the goal, then having to know something about moments and profiles etc will make itself obvious.
Otherwise... It looks good, it'll fly.
Show us your work.
Nonetheless, this forum is about modeling science and the thread asked "How does the shape of the wing affect its performance?" With this in mind, I don't think the OP wants to hear "if it looks about right, it will probably fly ok." He probably knows that already.
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Old Sep 26, 2012, 12:42 PM
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I have no problem with the TLAR method, and indeed, its probably how I do most of my designs, but, if we had always continued to go with that as our sole driver, because for the most part, it was "good enough", then we would not be where we are, and our models would have remained unchanged. We progress because people want to do something more than "good enough", and spend a lot of time and expertise doing so, and we all reap the benefits to a greater or lesser extent.

Take someone like Mark Drela as an example, who has done masses of work, research and experiment in model design. He didn't have to, some might consider that there was no need because "good enough" was ok for most sport flyers. But, those quests for ultimate performance, in a competitive setting perhaps, filter down to us "sport flyers" in the end.

So, we progress by a combination of trial, error, observation and calculation, but all driven in the end by the desire to "do better" rather than stay as we are.

Quote:
Otherwise... It looks good, it'll fly.
The point is, why? We can't always just take these things as eternal verities, sometimes we need to look a bit deeper and understand what makes things work the way they do, thats how we move forward.

Some things, just don't conform to the TLAR method, because what looks right depends on where you are standing. Our judgement of what "looks about right" is informed by our knowledge and experience, and we have to get that from somewhere. Nature vs Nurture in aerodynamics? Very much so, which is why doing something radically different is difficult, because that requires us to step away from all that we think we know, and trust in a different set of principles. Some of which may be based on theories which push us in an altogether different direction and make us feel uncomfortable.

We then have the choice, to follow the theory to wherever it leads, or to say "that doesn't look right to me" and stay in our comfort zone, where "TLAR" is bound to work, because it is based on historic success (or otherwise).

Thats where military technology comes to the fore, the leaps we have made, and the benefits we enjoy on the back of those leaps, were gained by "TLAR" absolutely NOT being good enough. Do you believe that an F-22 looks the way it does simply because it looks pretty neat? It looks the way it does because thats what our current understanding of physics leads us to believe that design to be the best solution to a design specification. So for that design process, TLAR had no place.

We could have done better, we could DO better, the limitations are not always aerodynamic. Designers in 1914 probably knew that a forest of wires and bracing probably wasn't doing much for aerodynamics, but limitations imposed by materials technology and manufacturing meant that was what they used.
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Old Sep 26, 2012, 12:47 PM
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Originally Posted by Sparky Paul View Post
Show us your work.
Well if you insist (says the man who likes to show off )

This is my latest project:


And some of my older projects:



As you can see, I'm also a fan of flat plate airfoils:



ok.. I think that's enough for now. Sorry for the thread hijack but I couldn't resist

Almost all my work (except for that giant green flying wing) is based on pure guesswork - what looks right is probably right. But I like to read up on the literature - not necessarily doing the calculations mind you, just understanding the conclusions - so that I can make better, more informed guesses.
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Old Sep 26, 2012, 01:19 PM
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Originally Posted by slebetman View Post
Yes, and that's exactly the problem I have with your posts. While the rest of us share experiences and knowledge trying to figure out how the whole elephant looks like. You keep insisting that the trunk is the whole elephant.

It's OK if just knowing the trunk is good enough for you. But don't keep telling others who want to know more: "who cares about that, it's all trunk!".
Not really - I have done the entire elephant over the years - I just am not keen in theory with no practical example for modelers
My models? here are a few - all scratch built except the EDGE
I don't know if my homemade airfoils were optomized but they seemed to bring home a fair amount of hardware for the pilots ---
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Old Sep 26, 2012, 01:37 PM
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Originally Posted by slebetman View Post
Well if you insist (says the man who likes to show off )

This is my latest project:


And some of my older projects:



As you can see, I'm also a fan of flat plate airfoils:



ok.. I think that's enough for now. Sorry for the thread hijack but I couldn't resist

Almost all my work (except for that giant green flying wing) is based on pure guesswork - what looks right is probably right. But I like to read up on the literature - not necessarily doing the calculations mind you, just understanding the conclusions - so that I can make better, more informed guesses.
.
Nice fleet.. any one else?
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Old Sep 26, 2012, 03:16 PM
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I just am not keen in theory..
And that's perfectly fine. Just don't put down others who like discussing the theory.

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Originally Posted by richard hanson View Post
..with no practical example for modelers
You may not have noticed but all the theories presented in this thread so far are practical examples for modelers. I don't know what's more practical than people describing their experience building gliders, rubber powered planes, pylon racers etc. Or research papers describing the design of micro UAVs.
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Old Sep 26, 2012, 03:27 PM
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And that's perfectly fine. Just don't put down others who like discussing the theory.



You may not have noticed but all the theories presented in this thread so far are practical examples for modelers. I don't know what's more practical than people describing their experience building gliders, rubber powered planes, pylon racers etc. Or research papers describing the design of micro UAVs.
All the theories ?
I really don't agree
there are both good useful ones and others which do not hold up in actual practice
No surprise to me - This is the same as it has always been in these forums - all of em
I don't expect people to agree with me all the time and I don't think they should get agitated because I don't agree with them.
I like your little models - they look like a lot of fun
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