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  • January 18, 2019, 08:00:09 AM

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Author Topic: Making an Elipse  (Read 659 times)

Online Motorman

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Making an Elipse
« on: January 08, 2019, 03:52:53 PM »
Hope this comes out clear enough.
There will be a sunny day and we will fly our airplanes.


Offline Mike Haverly

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Re: Making an Elipse
« Reply #1 on: January 09, 2019, 05:25:28 PM »
I don't know what your point is here.  I drew this on Corel, took about 10 seconds.
Mike

Offline Mike Haverly

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Re: Making an Elipse
« Reply #2 on: January 09, 2019, 06:33:05 PM »
Kidding, right?
Mike

Offline Paul Smith

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Re: Making an Elipse
« Reply #3 on: January 09, 2019, 08:10:09 PM »
Hope this comes out clear enough.

Where did the ordinate values come from? 
Were they "givens" from outside the lesson plan?
Paul Smith

Offline Paul Smith

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Re: Making an Elipse
« Reply #4 on: January 09, 2019, 08:11:28 PM »
I don't know what your point is here.  I drew this on Corel, took about 10 seconds.

But yours has a 50% high point.  We need to be able to get the high point at 25-30%.
Paul Smith

Online Motorman

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Re: Making an Elipse
« Reply #5 on: January 09, 2019, 09:02:11 PM »
I don't know what your point is here.  I drew this on Corel, took about 10 seconds.

It's a hobby, you can do it anyway you like.


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Offline Mike Haverly

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Re: Making an Elipse
« Reply #6 on: January 09, 2019, 09:18:56 PM »
But yours has a 50% high point.  We need to be able to get the high point at 25-30%.


It is indeed a hobby, make it like you want.  I was only demonstrating how easy it is to do with  plain Jane vector file software.  Do you like this one better?
Mike

Offline Dave Hull

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Re: Making an Elipse
« Reply #7 on: January 09, 2019, 11:03:44 PM »
Now give us one with a fore/aft of high point at 33% of root chord. (Representing the minor radii of both ellipses.)   I'd like mine with a 20" span and 4-1/2" chord. And a .dxf file for the laser cutter, and.....

Yeah, not all of us are hooked in with drawing programs or drafting software. Or don't have printers. So we do it the old fashioned way--we earn it. Oops, I meant we draw it with a pencil. And then fudge it with a sanding block until it looks right.

My latest has a semi-elliptical wing and tail. I-beamer. So far, so good.

Divot

PS--Zaic loved his elliptical glider wings. If you have his Model Glider Design handbook, he shows the simple development of such a dual elliptical shape derived from a circle. It is what engineers and draftsmen called descriptive geometry. No math needed.

PPS--What Paul was getting at is that the minor ellipse radius on the LE side should be, say 30%, and the TE side should be 70%, or Rm1+Rm2=chord; and Rm1=0.3*chord. So the overall wing shape is not formed by the equation of only one ellipse, but rather, is formed by splicing together two different ellipses. What you are showing in your second graphic appears to be a single ellipse with a major radius being 4x the minor radius, hence the 25% reference?
« Last Edit: January 09, 2019, 11:36:02 PM by Dave Hull »

Online Dennis Nunes

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Re: Making an Elipse
« Reply #8 on: January 10, 2019, 12:48:30 AM »
If you don't have a CAD/Drawing program, one can draw an ellispe by hand the old fashioned way.

https://www.wikihow.com/Hand-Draw-an-Ellipse

Or you can use the old string and pin method.

https://www.mathopenref.com/printellipse1.html


Enjoy,
Dennis
If at first you don't succeed ---- let someone else try it!  ;)

Offline Avaiojet

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Re: Making an Elipse
« Reply #9 on: January 10, 2019, 05:50:33 AM »
I designed this wing because I can.

There's everything in the drawing needed to build it also, AND it's in vector format for laser cutting all ribs.

Don't like the tip, just cut it off a bit like the Shark.

Tapers in thickness also.

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Offline Matt Spencer

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Re: Making an Elipse
« Reply #10 on: January 12, 2019, 07:56:25 PM »

Offline Dave Hull

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Re: Making an Elipse
« Reply #11 on: January 12, 2019, 11:42:01 PM »
I like the grommet idea. Might really work good with a Pentel mechanical pencil. Suggest you consider Spectra line for the string as it is far less stretchy and would improve accuracy.

For those that would use this method, but want perhaps less trial and error, there are equations that go with the foci as to where you stick the pins.

You can move the foci between drawing the LE and the TE in order to place the center of lift of each buttline on the spar at, say, 30%.


Dave

Offline Avaiojet

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Re: Making an Elipse
« Reply #12 on: January 13, 2019, 09:16:29 AM »
I like the grommet idea. Might really work good with a Pentel mechanical pencil. Suggest you consider Spectra line for the string as it is far less stretchy and would improve accuracy.

For those that would use this method, but want perhaps less trial and error, there are equations that go with the foci as to where you stick the pins.

You can move the foci between drawing the LE and the TE in order to place the center of lift of each buttline on the spar at, say, 30%.


Dave

I guarantee you, I did not use two pins and a piece of string to design my wing.
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I look at the Forum as a place to contribute and make friends, some view it as a Realm where they could be King.

"Ya gotta love it when a plane comes together."

Proverb 11.9  "With his mouth the Godless destroys his neighbor..."

"Perhaps the greatest challenge in modeling is to build a competitive control line stunter that looks like a real airplane." David McCellan, 1980.

Online Dan McEntee

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Re: Making an Elipse
« Reply #13 on: January 13, 2019, 01:14:48 PM »
I guarantee you, I did not use two pins and a piece of string to design my wing.

     And you would never build it either, so what does that prove? That you are good with an Etch-A Sketch?

    Type at you later,
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Offline Avaiojet

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Re: Making an Elipse
« Reply #14 on: January 13, 2019, 01:59:42 PM »
     And you would never build it either, so what does that prove? That you are good with an Etch-A Sketch?

    Type at you later,
    Dan McEntee

Congratulations,

I see you're going to finally start building.
Trump Derangement Syndrome. TDS

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Please visit my updated Website! www.cfcgraphics.com

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Alpha Mike Foxtrot.

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"No one has ever made a difference by being like everyone else."

Marcus Cordeiro, The "Mark of Excellence," you will not be forgotten.

I look at the Forum as a place to contribute and make friends, some view it as a Realm where they could be King.

"Ya gotta love it when a plane comes together."

Proverb 11.9  "With his mouth the Godless destroys his neighbor..."

"Perhaps the greatest challenge in modeling is to build a competitive control line stunter that looks like a real airplane." David McCellan, 1980.

Online Dan McEntee

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Re: Making an Elipse
« Reply #15 on: January 14, 2019, 05:17:54 PM »
Congratulations,

I see you're going to finally start building.

      Oh, I've built lots of stuff. Everything from free flight indoor rubber to R/C sail planes, to out door free flight and of course all sorts of control line models, stunt scale and speed. I've got a whole garage and basement full of airplanes, ask anyone that has been to my house. And you know what??? They all FLY!!  And I try to fly all of them as much as possible where time and weather permit.
  Type at you later,
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Offline Randy Powell

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Re: Making an Elipse
« Reply #16 on: January 15, 2019, 04:14:04 PM »
I rather liked Larry Cunningham's elliptical wing designer spread sheet, but that's just me.
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