Since the location of the Balloon Boy saga is about 60 miles north of our offices in Englewood, Colorado, we’ve received a number of phone calls and e-mails about the science of helium… specifically the lifting power of this inert gas. We decided to show our partners at KUSA and 9News.com what it would take to lift a 10 pound sack of potatoes.
[youtube width="560" height="344"]http://www.youtube.com/watch?v=AE65US7SwCM[/youtube]
According to news reports, the Jiffy-Pop-shaped balloon that captivated the world on Thursday as it floated across the state measured about 20 feet across and 6 feet tall, but it was easy to see that the balloon wasn’t fully inflated even at the time of lift off.
What is the lifting power of helium? For the sake of time and a more detailed explanation, here’s a simple data table that will give you an idea of what it would take to lift a person using a helium balloon. We’re assuming standard temperatures and pressures and no significant overpressure. Please note that we’re using “cubic feet” and “pounds” to match the English units that everyone is using in the news.
For reference purposes, you should know that a large tank of helium – the kind you find at a grocery store or party shop, holds approximately 250 cubic feet of helium. Based on the calculations below, you can see that 250 cubic feet will lift roughly 17 pounds. In our video test for KUSA 9News, we found that 250 cubic feet lifted about 8 pounds of potatoes, plus the string and the weight of the 45 large balloons (2.3 pounds). All in total, we lifted just over 10 pounds.
Balloon Volume Lifting Power
Diameter (ft) Cubic Ft Pounds
1 0.52 0.03
2 4.19 0.27
3 14.13 0.91
4 33.51 2.15
5 65.45 4.19
6 113.10 7.25
7 179.61 11.51
8 268.10 17.18
9 381.73 24.46
10 523.63 33.55
11 696.95 44.65
12 904.83 57.97
13 1150.42 73.71
14 1436.84 92.06
15 1767.25 113.23
16 2144.79 137.42
17 2572.60 164.83
18 3053.82 195.66
Why didn’t we lift the calculated weight of 17 pounds? As you can imagine, we’re working with lots of assumptions. The company supplying the helium told us that the larger cylinder holds about 250 cubic feet. Each red balloon held approximately 5 cubic feet of helium, and we were able to inflate just 45 balloons (that’s 225 cubic feet of gas). To top everything off, we lost 5 of our balloons during the test (a few pops and 3 into the sky). These are the results based on an impromptu science experiment with a single tank of helium.
Since most of use don’t have a giant, Mylar, flying muffin balloon the likes of the Heene family, we wanted to use something a little more common (big red balloons) to get an idea of the science behind the lifting power of helium.
For additional information about the lifting power of common gases, visit the University of Hawaii’s website. If you’re wondering more about the science of helium, the chemistry department provided this information…
Helium is mined, or more exactly drilled for. In the Oklahoma and Texas panhandles are natural gas wells that contain up to 4% or more Helium. This natural resource is very rare. The gas field must be encased in radioactive rock or no helium is produced. The alpha particle decay in the surrounding radioactive rock over millions and millions of years creates the helium. An alpha particle is just a helium nucleus. When it slows down and regains its two electrons, it becomes a helium molecule. Thus the radioactive rock makes helium, one molecule at a time, to accumulate in the same pocket as the natural gas.
In the 1930′s Germany asked the USA many times for helium for its Zepplins. The US was concerned that helium had other military uses and horded it as a strategic material. For this reason, the Hindenburg was still lofted with hydrogen on its last disastrous flight, instead of being converted to helium as Germany had been trying to do for years.
Helium is a natural byproduct of the liquefaction of the natural gas for pipeline shipment from these special gas fields. Helium liquefies at a much lower temperature than natural gas, close to absolute zero (4 degrees Kelvin). The volume left over after liquefaction is mostly helium ready to be stripped off and sold to the US Government Bureau of Mines. Few people seem concerned that this is a non-renewable and expendable natural resource, tied to very few gas wells in the world.