11-04-2009, 12:17 AM
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#11 (permalink)
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Quote:
Originally Posted by Frank Lee
Wing efficiency doesn't really enter into this.
The bottom line is, when lift is produced, drag is also produced. More lift > more drag.
Less lift > less drag.
*Whatever* angle of attack or airfoil design doesn't matter; the above holds true... unless you want to get funky and talk about undesireable situations like stalls and whatnot.
Keep in mind that "lift" can be in an up or down vector, depending on. For cars we tend to want "down".
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I beg to differ... wing efficiency has a great deal to do with the relationship between lift and drag. I am not saying that you can avoid drag when producing lift, but that some wings are able to produce far more lift for a given amount of drag than others.
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11-04-2009, 12:26 AM
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#12 (permalink)
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Moderate your Moderation.
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Quote:
Originally Posted by equation112
I beg to differ... wing efficiency has a great deal to do with the relationship between lift and drag. I am not saying that you can avoid drag when producing lift, but that some wings are able to produce far more lift for a given amount of drag than others.
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So you just admitted that there was no point in the interjection, right? I mean, IN REAL LIFE, in all situations, inducing any kind of aerodynamic lift, positive or negative, still induces drag, regardless of the relationship between them, as I stated before.
I'm sure in some abstract formula, you can design a shape on paper that will induce lift without any drag penalty at all. Hell, people have designed shapes that (on paper) can use pressure drag to propel a vehicle!
When you put it in real life situations, it degrades quickly...
Bernoulli went so far as to dictate that shape could induce lift based on air speed, and even elaborate that a shape could alter that lift based on flow principles.
Schools still teach Bernoulli's principle as the "end all be all" of wing lift, which is why I asked Hermie that question.
(On another topic - Did Bernoulli actually get "laws" status? Last I knew, it was a series of principles governing the application of shape-induced lift via the laws of fluid dynamics.)
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11-04-2009, 12:36 AM
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#13 (permalink)
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Quote:
Originally Posted by equation112
I beg to differ... wing efficiency has a great deal to do with the relationship between lift and drag. I am not saying that you can avoid drag when producing lift, but that some wings are able to produce far more lift for a given amount of drag than others.
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"more lift > more drag. less life > less drag"
I don't need to say any more.
Now, regarding the splitter... try it, I doubt it can hurt any and it just might help.
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11-04-2009, 12:52 AM
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#14 (permalink)
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Quote:
Originally Posted by Christ
So you just admitted that there was no point in the interjection, right? I mean, IN REAL LIFE, in all situations, inducing any kind of aerodynamic lift, positive or negative, still induces drag, regardless of the relationship between them, as I stated before.
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actually, you were the one to state:
Quote:
Originally Posted by Christ
Ok, so downforce is drag, first of all. In order to have zero gross drag, you need a neutral shape which produces no downforce, negative or otherwise.
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I am simply pointing out that lift and drag - while related - are not the same thing, and that drag is not dependent on lift.. it would be there even at a perfect 0 alpha/0 lift state.
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I take offense to the saying 'it isnt rocket science' to describe the relative difficulty of a given endeavour. Rocket Science is NOT hard... just EXPENSIVE
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11-04-2009, 12:56 AM
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#15 (permalink)
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Moderate your Moderation.
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Quote:
Originally Posted by equation112
actually, you were the one to state:
I am simply pointing out that lift and drag - while related - are not the same thing, and that drag is not dependent on lift.. it would be there even at a perfect 0 alpha/0 lift state.
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Neutral - ...of no particular kind, characteristics, etc or not causing or reflecting a change in something.
By the definition of neutral, a neutral shape would not induce drag, nor lift in any vector.
Are we done here?
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Last edited by Christ; 11-04-2009 at 01:29 AM..
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11-04-2009, 12:58 AM
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#16 (permalink)
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Quote:
Originally Posted by Frank Lee
Now, regarding the splitter... try it, I doubt it can hurt any and it just might help.
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I agree.
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I take offense to the saying 'it isnt rocket science' to describe the relative difficulty of a given endeavour. Rocket Science is NOT hard... just EXPENSIVE
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11-04-2009, 10:57 AM
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#17 (permalink)
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Wow what an argument...
All this talk of drag can be broken in to the three sub-categories.
Profile drag is from the shape of the airfoil. this seems to be what most of you are discussing. It seems that some of the points also are really thinking of surface friction.
Parasite drag applies to the original topic if we are not trying to create lift, negative or positive.
Induced drag is caused by angle of attack. This is the part the rest of you are discussing.
You most certainly can have "Real world" negative induced drag. (thrust from drag) Ask any helicopter pilot.
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11-04-2009, 04:23 PM
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#18 (permalink)
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aerodynamics - front splitter
Donno what it will do for mpg. There seem to be much agreement that it only changes handling characteristics at highway speed. I read somewhere that a splitter should stick out twice the distnace it is from the ground. So if you have 4 inches of clearance under the bumper, the splitter should stick out 8 inches. I can't seem to find that reference though.
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11-04-2009, 05:13 PM
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#19 (permalink)
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Moderate your Moderation.
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Quote:
Originally Posted by ncs
aerodynamics - front splitter
Donno what it will do for mpg. There seem to be much agreement that it only changes handling characteristics at highway speed. I read somewhere that a splitter should stick out twice the distnace it is from the ground. So if you have 4 inches of clearance under the bumper, the splitter should stick out 8 inches. I can't seem to find that reference though.
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Is that for maximum effect (to your recollection), or for any effect?
If I had to guess, I'd say it's probably just for maximum usable effect, where drag and downforce meet an equilibrium for a given angle. That is, of course, provided that it even makes a difference.
I know that splitters and canards usually are found hand in hand in most applications, and the canards are supposedly a good way to get some extra downforce while diverting air away from the tires' outside profile.
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11-04-2009, 10:25 PM
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#20 (permalink)
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wow!!! i didnt think such a question would stir so much debate. thanks for the info guys. i get the benefits of adding it... more or less i was asking if adding a splitter would create any disadvantages(as in mpg drop)?
as for creating an airdam... this is what i have going on
im going to try it for sure. we'll see how it goes
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