# How do you make...ovals/football like shapes?

Discussion in 'Tips, Tutorials & Tools' started by gian7675, Jun 15, 2007.

1. ### gian7675Member

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Just wondering, can somebody here show me:

1.) how to make oval like shapes on paper/card?

The oval like shapes that I'm referring too is similar to a football shape or a fuel tank of a fighter jet.

2.) Now imagine that youhave the football shape now out of paper...my second question is how can you make a lontitudinal cut of the football...I also need half of the oval shape.

So what I need are 2 shapes...the full oval and the half oval

Can somebody please describe or much better show me the process?

Thanks!

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3. ### dansls1Member

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Well, there are really 2 methods - 'cones' or petals. The cones give the tip as a triangle, then just tapered tubes. The other is demonstrated very well in this tutorial.

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5. ### jleslie48Member

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I like the stacked cone approach::

6. ### gippolotMember

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This is the method I use.

Draw the oval, then divide it into the number of segments that you would like to use. Each segment will look just as though it has been cut from a cone.

I'll describe how to make the development of one segment.

Now comes the drafting part, making a development from your segment drawing.

Extend the sides of the segment upwards to form a triangle. This point is now the centre to be used to draw circles that will describe the development of the segment.

Now for the maths bit. I'll explain for those that haven't used any maths for a few years.

Measure the length of the base of the segment. In this case it is 81.

Next to work out the circumference the base of the segment will be.

Which is DIAMETER x PI. So here we have 81 x 3.142 which gives 254. You can use the pi value on your calculator, or 3.142 as the error will be far too small to matter.

Now draw in the circles using using the centre point.

Measure the large circle diameter, and calculate its circumference. For this we have 634.

The area enclosed by those two circles drawn will be the development of the cone, BUT, it needs to be cut down to size.

The final step is to calculate the fraction of area required. Use this formula.

CIRCUMFERENCE OF SEGMENT BASE / CIRCUMFERENCE OF CIRCLE x 360 degrees.

Now we have 144 degrees required to mark out the cone development

Here is the final result. Repeat for each segment.

Regards
Andrew