# Aspect Ratio & MAC



## Zipper730 (Mar 15, 2018)

I'd almost swear I read you can find the MAC from the aspect ratio: If so what's the formula to determine this?


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## XBe02Drvr (Mar 16, 2018)

Zipper730 said:


> I'd almost swear I read you can find the MAC from the aspect ratio: If so what's the formula to determine this?


Apples and oranges multiplied by qumkwats equals Kiwis. Do a little research instead of asking us to do it for you. Why would you want to calculate that? In the real world all that data is available from charts and graphs and tables for any sweptwing aircraft out there. And MAC is really only necessary for sweptwing aircraft. Straight wings just use chord line.
Cheers,
Wes


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## fubar57 (Mar 16, 2018)

XBe02Drvr said:


> Apples and oranges multiplied by qumkwats equals Kiwis. Do a little research instead of asking us to do it for you. Cheers,Wes



Good luck with that


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## Zipper730 (Mar 16, 2018)

XBe02Drvr said:


> Do a little research instead of asking us to do it for you. Why would you want to calculate that?


I was thinking of practicing some art and making some drawings that have at least some accuracy in them

https://courses.cit.cornell.edu/mae5070/AeroBackground.pdf

This useful? What's that long f like thing?


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## XBe02Drvr (Mar 17, 2018)

Zipper730 said:


> I was thinking of practicing some art and making some drawings that have at least some accuracy in them
> 
> https://courses.cit.cornell.edu/mae5070/AeroBackground.pdf
> This useful? What's that long f like thing?


It's the calculus symbol for an integral. Conceptually it's kind of like imagining a wing, let's say, chopped into an infinite number of cordwise slices then taking whatever value you wanted to measure (lift maybe?) for each slice, added them all up, and thus derived your desired value for the entire airfoil. Simple, huh? You've just been treated to all I understand about integral calculus. Any more questions, ask one of the numerous engineers on this forum. Told you it isn't easy.
Cheers,
Wes


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## pbehn (Mar 17, 2018)

Zipper730 said:


> I was thinking of practicing some art and making some drawings that have at least some accuracy in them
> 
> https://courses.cit.cornell.edu/mae5070/AeroBackground.pdf
> 
> This useful? What's that long f like thing?




That f like thing is a mathematical symbol, if you google mathematical symbols you get this.
Mathematical symbols list (+,-,x,/,=,<,>,...)

There you can see the f like thing denotes an integral, if you google integral you get this.
Integral - Wikipedia

No, there isn't an easy way to do it.

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## Zipper730 (Mar 17, 2018)

Basics and Symbols: Feel free to correct me as I suck at math, though largely written so I can just go to this page and cut & paste.

∫ = Integral, some calculus thing that has to do with x's and y's that I have no real grasp of...
dx, or dy = related to integrals, d being an infinitely small slice of x, or y, whatever that be...
_f_ = function of
b = wingspan
b/2 = half-span
c = chord
croot​ = The chord at the wing-root
ctip​ = The chord at the tip
c(y) = a slice at a specific area of the wing's chord, wherever that be
Λ = lambda, measures intervals, and also means wingsweep
Λ0​ = Wing sweep at the zero chord?
_ρ_ = Rho; densities as in air density

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## pbehn (Mar 18, 2018)

Zipper730 said:


> Basics and Symbols: Feel free to correct me as I suck at math, though largely written so I can just go to this page and cut & paste.
> 
> ∫ = Integral, some calculus thing that has to do with x's and y's that I have no real grasp of...
> dx, or dy = related to integrals, d being an infinitely small slice of x, or y, whatever that be...


Zipper, if you dismiss calculus you are living in the world of the Pilgrim Fathers, before Newton and Leibniz. Unless you understand that f thing and that calculus thing you cannot understand what any equation with a square or cubic function in it actually means or does. Having stated that you don't understand it and have no intention of learning anything about it I cant understand why you keep asking questions, unless endlessly asking questions is an end in itself.


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## Zipper730 (Mar 18, 2018)

pbehn said:


> Zipper, if you dismiss calculus you are living in the world of the Pilgrim Fathers, before Newton and Leibniz.


No, I wasn't... I just wanted to have the symbology available and a sort of glossary readily available on a forum I'm on so often.


> Unless you understand that f thing and that calculus thing you cannot understand what any equation with a square or cubic function in it actually means or does.


I never took calculus... just to be clear, I don't object to learning. From what it looks like the upper and lower numbers seem to be related to coordinates...


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## pbehn (Mar 18, 2018)

Zipper730 said:


> No, I wasn't... I just wanted to have the symbology available and a sort of glossary readily available on a forum I'm on so often.
> I never took calculus... just to be clear, I don't object to learning. From what it looks like the upper and lower numbers seem to be related to coordinates...


Your reply clearly showed you had not opened and read the link I posted. Differentiating a squared equation gives its gradient, when that gradient is zero it is at a limit which yields useful information. Any straight line on a graph has a gradient "m" it will normally cross a square function curve at two points, the area between the line and the curve also reveals important information, while the point on the curve with the same gradient as the line (a tangent) reveals other important information as does the difference between that line and any line parallel to it. 

In other scenarios values approach a certain value but never reach it, or as x approaches a fixed value y tends to infinity, all these reveal important information depending on the subject


This may sound vague because they are principles which can be applied to aircraft design, bomb aiming, banking, computing, medicine sociology....... in fact any where you see x to the (n) or root(n) x.


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## Zipper730 (Mar 18, 2018)

pbehn said:


> Your reply clearly showed you had not opened and read the link I posted.


So the integral is a gradient so if the top is 1 and the bottom is zero it's a gradient of 0 to 1 or 1 to 0? Do you always work in 1/5's? Or others? I'm looking at the wiki-page


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## pbehn (Mar 18, 2018)

Zipper730 said:


> So the integral is a gradient so if the top is 1 and the bottom is zero it's a gradient of 0 to 1 or 1 to 0? Do you always work in 1/5's? Or others? I'm looking at the wiki-page


Zipper you must have been a straight A student and much loved by your teacher. I clearly stated "differentiate" in the link you will read that integration and differentiation are opposites, but both equally useful.

A gradient in a car or on a graph is a rate of change, on a flat road mathematically speaking as x changes (when you drive on a flat road) y doesn't change at all ( you don't go up or down). On a 1 in 4 hill for every four units you go forward you go one unit upwards, this can also be represented as 25%. On a square or cubic function the gradient is never 1, it may get ever closer to it but at the point that it is 1 then y is at infinity, the x value that "y" tends to infinity can also be important.

In terms of driving a car, it is a wall.


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## Zipper730 (Mar 19, 2018)

XBe02Drvr said:


> You've just been treated to all I understand about integral calculus. Any more questions, ask one of the numerous engineers on this forum. Told you it isn't easy.


Who should I contact?



pbehn said:


> Zipper you must have been a straight A student and much loved by your teacher.


Depends on the subject...


> I clearly stated "differentiate" in the link you will read that integration and differentiation are opposites, but both equally useful.


Sorry about that


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## XBe02Drvr (Mar 19, 2018)

Zipper730 said:


> Who should I contact?


Zipper, you spend plenty of time on this forum, so by now you should have formed some opinions about who is knowledgeable about the quantitative aspects of aircraft performance and who is not. Go to their profile pages and see if they identify themselves as engineers.
On second thought, don't do that. It's kind of an imposition to ask an engineer to wear the hat of an elementary level mathematics teacher. (Kudos to pbehn!) There's got to be a "Calculus For Dummies" book out there; there's a "For Dummies" book for every other topic under the sun. Try that.
On the other hand, there's got to be at least a hundred people in this world who've managed to live successful lives without ever mastering calculus. A few of them have even managed to survive in the world of aviation. There's hope yet!
Cheers,
Wes

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## Zipper730 (May 16, 2018)

This could be useful for anybody... it's an integral calculator that also includes a blow by blow
Integral Calculator • With Steps!
Since most of us learn math not just by being told the formula but seeing the professor or teacher actually walk us through a formula...


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