Technically Speaking

Submitted by SvenS on Wed, 08/10/2005 - 04:29

If you're looking for a little realism in your writing, you may find this chart helpful:

Buoyancy Comparison

= Helium (He)=

Dia. Ft. Vol. l Lift gr. Lift Lbs.
1 14.83 15.2 0.03
2 118.62 121.7 0.27
3 400.34 410.9 0.91
4 948.96 973.9 2.15
5 1853.45 1902.2 4.19
6 3202.76 3287.0 7.25
7 5085.86 5219.7 11.51
8 7591.72 7791.5 17.18
9 10809.30 11093.7 24.46
10 14827.58 15217.7 33.55
11 19735.50 20254.8 44.65
12 25622.05 26296.2 57.97
13 32576.18 33433.3 73.71
14 40686.87 41757.4 92.06
15 50043.07 51359.8 113.23
16 60733.75 62331.8 137.42
17 72847.88 74764.7 164.83
18 86474.42 88749.8 195.66
19 101702.34 104378 230.12
20 118620.61 121741 268.40
21 137318.18 140931 310.70
22 157884.03 162038 357.24
23 180407.11 185154 408.20
24 204976.41 210369 463.79

= Hydrogen (H) =

Dia. Ft. Vol. l Lift gr. Lift Lbs.
1 14.83 16.5 0.04
2 118.62 132.3 0.29
3 400.34 446.4 0.98
4 948.96 1058.1 2.33
5 1853.45 2066.6 4.56
6 3202.76 3571.1 7.87
7 5085.86 5670.8 12.50
8 7591.72 8464.8 18.66
9 10809.30 12052.5 26.57
10 14827.58 16532.9 36.45
11 19735.50 22005.3 48.51
12 25622.05 28568.8 62.98
13 32576.18 36322.7 80.08
14 40686.87 45366.2 100.02
15 50043.07 55798.5 123.02
16 60733.75 67718.7 149.29
17 72847.88 81226.0 179.07
18 86474.42 96419.8 212.57
19 101702.3 113399.0 250.00
20 118620.6 132263.0 291.59
21 137318.2 153111.0 337.55
22 157884.0 176042.1 388.11
23 180407.1 201155.5 443.47
24 204976.4 228550.5 503.87

-Sven

Fri, 08/12/2005 - 04:40

Yousuck

What?

Fri, 08/12/2005 - 05:49

LutherVKane

It's a table for calculating buoyancy based on the diameter of a sphere. I remember performing a similar calculation many years ago as I explored my fascination with inflation. He's included 4 columns:

Diameter (in feet)
Volume (liters)
Lifting power (grams)
Lifting power (pounds)

Why is this useful? If you're writing a story in which a character fills with helium or hydrogen, a certain volume is required before flight is achieved if you want to keep the story believable. OR at least as believable as a story involving rampant inflation can be. In my experience, the best story minimizes the number of things about which the reader must suspend disbelief.

For example, the chart indicates that woman weighing 130 pounds would have to be inflated with helium to roughly 16 feet in diameter before she'd be large enough to leave the ground.

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Fri, 08/12/2005 - 16:49

doubleintegral

LutherVKane wrote:

For example, the chart indicates that woman weighing 130 pounds would have to be inflated with helium to roughly 16 feet in diameter before she'd be large enough to leave the ground.

Of course, that's assuming that the woman maintains the same weight. When I'm reading/writing stories, I don't generally think of a 16 foot wide inflated woman as weighing more than a few pounds.

That's just me, and it kinda defies the laws of physics. But then again, what doesn't?

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Wed, 08/17/2005 - 06:22

PopAShot

Also handy to know if the inflated person has a "passenger," nudge nudge, ;) ;) say no more.

So said 130 lb. woman would have to balloon out to two stories tall before she could take her 170 lb. beau for a joyride.

Interesting to add that while hydrogen has a notch more lifting power... it's also EXTREMELY flammable.

Wed, 08/17/2005 - 09:52

KorgFal

[quote Interesting to add that while hydrogen has a notch more lifting power... it's also EXTREMELY flammable.

That would be why they called it a Hydrogen Bomb back in the day... :P

Technically Speaking

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