blimp coming soon! but need help

i have restarted the blimp project and it will be coming soon....i hope. i need to know how many cubic feet of helium does it take to lift 1 pound (16 ounces). also need to know if mylar will melt to. please respond

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Kiteman8 years ago
Sun Gear (author)  Kiteman8 years ago
i thought i needed 16 cubic feet
You do - a sphere three feet across holds just over 14 cubic feet. Then you need to lift the weight of the balloon itself, so at least 16 cubic feet would be sensible. If you have more lifting capacity than you need, you can always add ballast to adjust the blimp's flight (angle as well as buoyancy). If you don't have enough lifting capacity, it's a lot harder to shave weight off your load.
Sun Gear (author)  Kiteman8 years ago
oh how long and how wide does cylinder have to be to hold 16 cubic feet
Volume of a cylinder is Pi x radius2 x length.

A cylinder 2 feet wide, five feet long, will have a volume of Pi x 1 x 5 = 15.7 cubic feet.

I'll let you work things out from there - working in feet instead of metres is making me grit my teeth, and I had a filling 5 hours ago.
Sun Gear (author)  Kiteman8 years ago
ok is 2 ft radius or diameter
Two feet is the diameter, making the radius one foot. Thus, r2=1.

Sheesh, Kiteman! Feet aren't that bad! It's furlongs and fathoms and gills and leagues and chains and rods and links and drams and hogsheads and minims and pecks and bushels and barrels and hundredweights and board-feet that are confusing.
Let's not forget English "stones" LOL
actually weight in stone isn't hard, it's 2.2lbs to a kilo, 14lbs to a stone. thereby to change from metric to imperial you take (weight in kilos)*2.2 / 14
Um, yeah, I have that memorized now (until I go to another page *sigh* ) the difficulty is not that it is hard, but it's unfamiliarity
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