186Views25Replies

# blimp coming soon! but need help Answered

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

Tags:

## 25 Replies

Sun Gear (author)2008-02-28

i thought i needed 16 cubic feet

Kiteman (author)2008-02-28

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)2008-02-28

oh how long and how wide does cylinder have to be to hold 16 cubic feet

Kiteman (author)2008-02-28

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)2008-02-28

ok is 2 ft radius or diameter

CameronSS (author)2008-02-28

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.

Goodhart (author)2008-02-28

Let's not forget English "stones" LOL

killerjackalope (author)2008-02-28

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

Goodhart (author)2008-02-28

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

killerjackalope (author)2008-02-28

Yeah lbs does the same to me, also american money can befuddle me now and again, we have 20p pieces no 25p pieces...

Goodhart (author)2008-02-28

Is your 20p like 1/5th of a (what) pound ? 25 cents is 1/4 of a dollar (100 pennies in a dollar), but I see how that could be disheartening anyway.

killerjackalope (author)2008-02-28

just seems odd when adding up...

Goodhart (author)2008-02-28

I understand. I know I had difficulties trying to figure the price of things in Canada, when the currency was the same, but the values were different *sigh*

killerjackalope (author)2008-02-28

Ah the simple complications of life...

CameronSS (author)2008-02-28

That's Imperial...All of mine are official measurements that are part of the US system.

Vernors-No problem. Math with a purpose is actually fun. Arbitrary equations in a classroom that mean nothing aren't as much fun.

Well, except for the equation ei*pi=-1. That's a cool enough equation that it gets to be fun.

Goodhart (author)2008-02-28

as can fooling about with: c2=e/m
;-)

Sun Gear (author)2008-02-28

thanks sometimes to much math makes me go insane

Goodhart (author)2008-02-28

Then wouldn't it have been easier to just work it out in meters and then convert ? :-)

Sun Gear (author)2008-02-28

i don't know meters that well but i know feet and in the U.K. the use meters in U.S> they use feet

Goodhart (author)2008-02-28

Yes, what I was say to Kiteman was that if he had difficulty doing the math in base 12 (inches in a foot), then he could use meters and then just convert the answers in the end, which is what you were looking for anyway.

Sun Gear (author)2008-02-28

if i post this instructable should i message you to let you know

Sun Gear (author)2008-02-28

crap back were i started but thanks this will help

Sun Gear (author)2008-02-28

finally all the stress of getting materials is gone I'm soooo happy

Sun Gear (author)2008-02-28

i just looked at the links and amassed that i need a lot less helium