Balloons Lifting a House in "Up" is Realistic

[CoolTrainerTerry]

From WorstPreviews.com:




Pixar films have been accused of having unrealistic points in their stories, like Remy controlling Linguini by pulling his hair in "Ratatouille." But one thing that's not unrealistic is Carl Fredricksen's house being lifted by balloons in "Up."

In the movie, Carl ties 20,622 balloons to his house and flies to South America. Andrew Baird, president of the Balloon Federation of America, says that it's completely plausible for that many balloons to lift a house.

Given the fact that one cubic foot of Helium can lift 60 pounds, with even small, 1 x 1-foot balloons, Carl's rig has the capacity to lift about 618 tons — enough to lift about 150 Hummers. [via Popular Mechanics]






I'm...not too sure about the whole lifting 60 pounds thing.

 

[KYMickey]

From WorstPreviews.com:

Given the fact that one cubic foot of Helium can , with even small, 1 x 1-foot balloons, Carl's rig has the capacity to lift about 618 tons — enough to lift about 150 Hummers. [via Popular Mechanics]

I'm...not too sure about the whole lifting 60 pounds thing.

Don't be confused about the lifting 60 pound thing! Just look at all the little kids add get balloons and watch them fly away! Balloon vendors must have to wear awful heavy ankle weights to keep from flying away since they normally have at least 20 or 30 balloons!

Maybe a cubic foot of liquid helium can lift 60 pounds! But certainly a cubic foot of low pressure helium in a balloon can't lift that much, they probably can only lift a couple of ounces at most.

 

[dbenlee]

I think the 60 pound number is a bit off. I am a big fan of Mythbusters and a couple of seasons ago they tested the myth of a small child getting carried off by a bunch of balloons at a carnival. If I remember correctly, the child they used for demonstration weighed about 53 pounds and it took around 4000 helium filled balloons to be lift the child off of the ground. They also the stunt done by a guy in the Northwest (Oregon maybe?) of using weather balloons to lift a grown man in a lawn chair. It seems like they used 15 to 20 balloons for their test to lift Adam Savage about 75 to 100 feet. The guy they were copying, I think used, about 100 "large" helium balloons and stayed in the air for 8 or so hours and traveled about 200 miles.

With those numbers in mind, the 20,622 balloons in the movie would not have enough lift to lift a house. But, I'm sure it makes for a good movie!!

 

[micknpluto]

Its a cartoon. who cares.

 

[doconeill]

I think the number is WAY off...if they are talking standard temperature and pressure, helium has the lifting power of about 1 gram per liter. A cubic foot is the equivalent of a little more than 28 cubic feet. That means a cubic foot can only lift 28 grams.

I don't know if this math applies in this sense, but liquid helium I believe expands 1:754 as a gas, so a cubic foot of liquid helium expanded could lift about 21kg, which is about 46.3 pounds - a little more than 75% of the claim.

Here is the claim from Popular Mechanics.

 

[DVCconvert]

I'm...not too sure about the whole lifting 60 pounds thing.

That depends on the density of air and the density of the helium. For
simplicity's sake, let's say the air and the helium are at the same
temperature and pressure. In that case, four grams of helium will occupy
about the same volume as 28.5 gm/mole of air. To lift an object, you need for
the mass of the object + the mass of the helium to be less than the mass of
the air it displaces. Since any object you want to lift will probably have
a much greater density than air or helium, let's neglect its volume for
simplicity's sake (in other words, we'll neglect the mass of the air
displaced by the object, because it will probably be only a small part of
the mass of the air displaced by the helium and the object together). Then
we can say that you need the mass of the object + helium to be less than
the mass of the air displaced by the helium.

M + Mh < Ma,

where M is the mass of the object, Mh is the mass of the helium, and Ma is
the mass of the air displaced. Our shortcut of neglecting the volume of
the object just says that

Ma = (28.5/4)Mh,

that is, a given mass of of helium will displace (28.5/4) times its mass of air.

Knowing that 4 grams of helium occupies that same volume as 28.5 grams of
air, we can see that four grams of helium will lift almost 25 grams:

M + Mh < Ma
M + Mh < (28.5/4)Mh
M < (28.5/4)Mh - Mh
M < Mh [(28.5/4) - 1]
M < Mh (7.125 - 1)
M < Mh (6.125)
M < 4g (6.125)
M < 24.5 g.

An easier way to look at this is to note that since four grams of helium displaces 28.5 grams of air, the "payload" for the helium is 28.5 g - 4 g = 24.5 g.

On a per gram basis, this means that one gram of helium will lift a payload (including the mass of the balloon) of (24.5 g payload)/(4 g helium) = 6.125 g payload /g helium. You can also see this in the above derivation if you just figure the mass of helium to be 1 g instead of 4 g.

So, to lift 1000 grams (1 kg), you need about 163 grams (~0.16 kg) of helium:

M < Mh (6.125)
M/(6.125) < Mh
Mh > (1000g)/ (6.125)
Mh > 163.3 g.

How much volume of helium is this? It depends on the temperature and
pressure. Neglecting the volume of the object to be lifted becomes a more
serious error as it becomes a larger fraction of the total volume. Under
normal conditions (ambient temperature and pressure), this is a small error.


HTH

 

[Pluto Region1]

Thanks for posting the Popular Mechanics link. I have to agree with those above that reply, "it's a cartoon." Whatever happened to people using their imaginations? That is what you're supposed to do here. Pixar is taking a "plausible premise" and expanding it to a full concept for the film. One can imagine that if enough balloons were tied to the house, it MIGHT work. Remember, I said "one can can imagine." I think it was a nice premise tho for Popular Mechanics article though. I was unaware of all these balloon attempts. For people to criticize Pixar over their plots, this is kind of ridiculous. What about Monsters Inc., or Bug's Life or any of the other competing studio cartoon films - all these films deal in imagination - which is something these adult critics seemed to have lost.

 

[doconeill]

Thanks for posting the Popular Mechanics link. I have to agree with those above that reply, "it's a cartoon." Whatever happened to people using their imaginations? That is what you're supposed to do here. Pixar is taking a plausible premise" and expanding it to a full concept for the film. One can imagine that if enough balloons were tied to the house it MIGHT work. Remember, I said "can imagine." I think it was a nice premise tho for Popular Mechanics to provide an overview of the various balloon enthusiasts' attempts. For people to criticize Pixar over the plots, this is kind of ridiculous. What about Monsters Inc., or Bug's Life or any of the other competing studio cartoon films - all these films deal in imagination - which is something these adult critics seemed to have lost.

I'm not criticizing Up or Pixar at all. I'm criticizing a statement from a magazine that should have known better.

 

[CoolTrainerTerry]

I agree, it is a cartoon. I just thought it was an interesting article. In fact, in one review I read, they said that the movie was bad because it was unrealistic. They must not like any movies since most of them aren't realistic. It's a movie, made for pure enjoyment.

 

[KYMickey]

I think we all realize it's a cartoon, we're just refuting the title of this thread that says it's realistic! While I tried to do it by example several others have gone through the complete scientific analysis. It's a fun movie no matter how you look at it but we also need to be sensible in our thoughts.

 

[P.I. Squirrel]

From WorstPreviews.com:




Pixar films have been accused of having unrealistic points in their stories, like Remy controlling Linguini by pulling his hair in "Ratatouille."

Suuuuurre. Talking rat is A-OK, but controlling a human by pulling his hair is 'unrealistic'.



Given the amount of helium required to get a blimp off the ground, I find their reasoning of the ability to lift a house doubtful. The problem with the balloons lifting the house is not so much the lifting power of helium. To me, the bigger issue is how a house is not made to be supported from the top. It would fall apart before it ever got off the ground.

Up next, whether three sharks can hold a 'Fish Eater's Anonymous' meeting.

 

[M-I-C-K-E-Y]

What's also a weeeee bit unrealistic is that a rather slow-moving gent managed to fill 20,622 balloons overnight. Let's give him a full 12 hours to pull off this amazing plan. He would have had to fill, knot, string and secure a balloon every two seconds...for that entire time. He also needed time to lug the heavy, empty helium tanks to the curb!!

Realistic? Nope! Fun, amazing, absolutely a "grin from ear to ear" film...YES!!