Decided to cut down the header tank. It just didn't fit well, and seemed too large/heavy for it's mounting location. New total length is just shy of 19 inches with 8 inches in diameter.

Volume of a cylinder = 2 x pi x R x length, so 2 x4 x pi x 18= 452.38 cubic inches/ 231 (cu in per gallon)= 1.96 gallons.

When my warning light comes on, I will have one gallon remaining, or 12 minutes at 5 gal/hr.

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Comment by Steven Winn on February 29, 2012 at 8:50pm

You guys are absolutely correct, Thanks!

So, I should have 2 gals remaining when the light comes on. If I reduce power to 4 gals/hr (should be no problem), I should have FAA required 30 minutes reserve upon low fuel warning. Now if the weight and balance works out, I'm set (this does have me concerned).

The tank appears to be made from dead soft .060 aluminum. I will confirm this, and if different will post findings.

Comment by Bill McWethy on February 29, 2012 at 7:03pm

Actually your getting the equations for area of a circle and circumference of a circle mixed up.  The area is pi x r squared.  So the volume of a cylinder is pi x r squared x length.  So if the tank is 8" in diameter and  18" long the volume would be (pi x 4 squared x 18)/231 = 3.9 gallons

Comment by Ken Ryan on February 29, 2012 at 7:01pm

Steven, the formula for volume of a cylinder is:

Pi time "R-squared" time height so:

3.14 X 16 X 18 = 904 = 3.9 gallons

Can you tell me the material thickness of your tank? Thanks!

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