# Did Slylock Fox get it wrong about helium balloons? **URL:** \ **Category:** Factual Questions\ **Created:** [March 27, 2006, 3:11pm UTC](https://boards.straightdope.com/t/did-slylock-fox-get-it-wrong-about-helium-balloons/350085 "2006-03-27T15:11:24Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![specie](https://avatars.discourse-cdn.com/v4/letter/s/ba9def/32.png) [@specie](https://boards.straightdope.com/u/specie)\ **Post date:** [March 27, 2006, 3:11pm UTC](https://boards.straightdope.com/t/did-slylock-fox-get-it-wrong-about-helium-balloons/350085/1 "2006-03-27T15:11:24Z")
Would a helium balloon do this? [Slylock Fox](http://i1.tinypic.com/sdn4mf.jpg) ---
**Author:** ![Frosted\_Glass](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/frosted_glass/32/3926_2.png) [@Frosted\_Glass](https://boards.straightdope.com/u/Frosted_Glass)\ **Post date:** [March 27, 2006, 3:14pm UTC](https://boards.straightdope.com/t/did-slylock-fox-get-it-wrong-about-helium-balloons/350085/2 "2006-03-27T15:14:50Z")
I was wondering if you could type out what the solution actually says. I tried to read it but the words were very hard to decipher. Thanks. ---
**Author:** ![drewbert](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/drewbert/32/15890_2.png) [@drewbert](https://boards.straightdope.com/u/drewbert)\ **Post date:** [March 27, 2006, 3:23pm UTC](https://boards.straightdope.com/t/did-slylock-fox-get-it-wrong-about-helium-balloons/350085/3 "2006-03-27T15:23:44Z")
> [@](#): > > Solution – As the balloon rises it will experience less and less atmospheric pressure causing the helium to expand. Since the balloon is already filled to its limit, it will burst. Sounds about right to me, as long as the balloon’s otherwise free to rise to any altitude (no tethers, conterweights, etc) ---
**Author:** ![GaryM](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/garym/32/241_2.png) [@GaryM](https://boards.straightdope.com/u/GaryM)\ **Post date:** [March 27, 2006, 3:23pm UTC](https://boards.straightdope.com/t/did-slylock-fox-get-it-wrong-about-helium-balloons/350085/4 "2006-03-27T15:23:49Z")
He’s got it right. If you look at the photos of old high altitude baloon launches, the baloon envelope looks as though it has little gas in it. But at altitude the envelope is nice and round. Look at this photo: [http://images.google.com/imgres?imgurl=http://www.photolib.noaa.gov/historic/nws/images/big/wea01126.jpg&imgrefurl=http://www.photolib.noaa.gov/historic/nws/wea01126.htm&h=1808&w=1184&sz=1359&tbnid=pjayo8VzZ-e1AM:&tbnh=150&tbnw=98&hl=en&start=36&prev=/images%3Fq%3Dhigh%2Baltitude%2Bballoon%26start%3D20%26svnum%3D10%26hl%3Den%26lr%3D%26c2coff%3D1%26sa%3DN](http://images.google.com/imgres?imgurl=http://www.photolib.noaa.gov/historic/nws/images/big/wea01126.jpg&imgrefurl=http://www.photolib.noaa.gov/historic/nws/wea01126.htm&h=1808&w=1184&sz=1359&tbnid=pjayo8VzZ-e1AM:&tbnh=150&tbnw=98&hl=en&start=36&prev=/images%3Fq%3Dhigh%2Baltitude%2Bballoon%26start%3D20%26svnum%3D10%26hl%3Den%26lr%3D%26c2coff%3D1%26sa%3DN) You can see the elongated envelope and the helium bubble at the top. ---
**Author:** ![chrisk](https://avatars.discourse-cdn.com/v4/letter/c/6de8d8/32.png) [@chrisk](https://boards.straightdope.com/u/chrisk)\ **Post date:** [March 27, 2006, 3:41pm UTC](https://boards.straightdope.com/t/did-slylock-fox-get-it-wrong-about-helium-balloons/350085/5 "2006-03-27T15:41:44Z")
> [@drewbert](#): > > Sounds about right to me, as long as the balloon’s otherwise free to rise to any altitude (no tethers, conterweights, etc) would also depend, I think, on whether the pressure force from the helium inside the balloon, unopposed by any air pressure from outside, is great enough to overcome the balloon material’s natural… tensile strength? Is that the right term?? If the balloon can take it, then it won’t pop, obviously. ---
**Author:** ![specie](https://avatars.discourse-cdn.com/v4/letter/s/ba9def/32.png) [@specie](https://boards.straightdope.com/u/specie)\ **Post date:** [March 27, 2006, 3:44pm UTC](https://boards.straightdope.com/t/did-slylock-fox-get-it-wrong-about-helium-balloons/350085/6 "2006-03-27T15:44:42Z")
No he’s got it wrong. And the reason is simple. Consider a zeppalin - Does it rise up and pop? No It will simply float to its equilibrium height and stay there. That’s what the balloon will do too. Noting is “pulling” it to greater and greater heights. It is floating. ---
**Author:** ![N9IWP](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/n9iwp/32/3154_2.png) [@N9IWP](https://boards.straightdope.com/u/N9IWP)\ **Post date:** [March 27, 2006, 3:52pm UTC](https://boards.straightdope.com/t/did-slylock-fox-get-it-wrong-about-helium-balloons/350085/7 "2006-03-27T15:52:25Z")
Actually Zeppelins are designed to have not enough lifting gas to float. (that is, slight negative bouyancy) The remaining lift is from the engines. A balloon will expand as the atmospheric pressure goes down. Brian ---
**Author:** ![Fear\_Itself](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fear_itself/32/19637_2.png) [@Fear\_Itself](https://boards.straightdope.com/u/Fear_Itself)\ **Post date:** [March 27, 2006, 4:08pm UTC](https://boards.straightdope.com/t/did-slylock-fox-get-it-wrong-about-helium-balloons/350085/8 "2006-03-27T16:08:42Z")
> [@specie](#): > > No he’s got it wrong. > And the reason is simple. > Consider a zeppalin - Does it rise up and pop? No > It will simply float to its equilibrium height and stay there. > That’s what the balloon will do too. > Noting is “pulling” it to greater and greater heights. It is floating. That’s not what the [manufacturer of high altitude weather balloons](http://www.aerostar.com/aerospace/high_altitude_balloons.htm) says: > [@](#): > > Burst Panel: A rectangular piece of film that is slightly weaker than the surrounding balloon envelope material. It is located at the top of the balloon to assure a rapid deflation of the balloon at burst altitude. Balloons without a burst panel can deflate more slowly and take longer to reach the ground. [http://www.aerostar.com/pdf/Aerostar\_sounding\_balloon\_performance\_curves.pdf](http://www.aerostar.com/pdf/Aerostar_sounding_balloon_performance_curves.pdf) > [@](#): > > Sounding balloons are designed to rise until bursting. The bursting > height is determined by the amount of helium in the balloon and > the full volume of the balloon. The amount of helium is commonly > referred to as the Gross Inflation (GI). For most flights: > GI = (payload wt + balloon wt) \*1.2 ---
**Author:** ![chrisk](https://avatars.discourse-cdn.com/v4/letter/c/6de8d8/32.png) [@chrisk](https://boards.straightdope.com/u/chrisk)\ **Post date:** [March 27, 2006, 4:13pm UTC](https://boards.straightdope.com/t/did-slylock-fox-get-it-wrong-about-helium-balloons/350085/9 "2006-03-27T16:13:06Z")
> [@specie](#): > > No he’s got it wrong. > And the reason is simple. > Consider a zeppalin - Does it rise up and pop? No > It will simply float to its equilibrium height and stay there. > That’s what the balloon will do too. > Noting is “pulling” it to greater and greater heights. It is floating. Well, a zeppelin also has a noticeable counterweight on it - ie the passenger compartment. 🙂 ---
**Author:** ![CC](https://avatars.discourse-cdn.com/v4/letter/c/f1d935/32.png) [@CC](https://boards.straightdope.com/u/CC)\ **Post date:** [March 27, 2006, 4:23pm UTC](https://boards.straightdope.com/t/did-slylock-fox-get-it-wrong-about-helium-balloons/350085/10 "2006-03-27T16:23:22Z")
FWIW, for many years, my science classes launched helium balloons to track wind direction, patterns, etc. We often filled them quite full and often, when they were returned, they came back shredded. I think this meant that they had burst after they had risen to a certain height. We noted that the balloons that were filled the most were the ones that were most likely to be returned shredded. (Careful record keeping being a hallmark of good experimental technique). ---
**Author:** ![specie](https://avatars.discourse-cdn.com/v4/letter/s/ba9def/32.png) [@specie](https://boards.straightdope.com/u/specie)\ **Post date:** [March 27, 2006, 4:25pm UTC](https://boards.straightdope.com/t/did-slylock-fox-get-it-wrong-about-helium-balloons/350085/11 "2006-03-27T16:25:45Z")
Ok, another example. The can of helium never floats at all. Its equilibrium point is at ground level. And there are plenty of balloons the morning after a celebration that are cruising halfway up the wall or nearly on the ground. [And what about this guy?](http://i1.tinypic.com/sdp5i0.gif) ---
**Author:** ![Fear\_Itself](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fear_itself/32/19637_2.png) [@Fear\_Itself](https://boards.straightdope.com/u/Fear_Itself)\ **Post date:** [March 27, 2006, 4:32pm UTC](https://boards.straightdope.com/t/did-slylock-fox-get-it-wrong-about-helium-balloons/350085/12 "2006-03-27T16:32:25Z")
> [@specie](#): > > Ok, another example. The can of helium never floats at all. Its equilibrium point is at ground level. And there are plenty of balloons the morning after a celebration that are cruising halfway up the wall or nearly on the ground. > And what about this guy? But you do admit that at least some balloons burst when the reach a certain altitude, right? ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [March 27, 2006, 4:55pm UTC](https://boards.straightdope.com/t/did-slylock-fox-get-it-wrong-about-helium-balloons/350085/13 "2006-03-27T16:55:32Z")
> [@chrisk](#): > > would also depend, I think, on whether the pressure force from the helium inside the balloon, unopposed by any air pressure from outside, is great enough to overcome the balloon material’s natural… tensile strength? Is that the right term?? The original statement says the balloon is already “filled with as much helium as it can possibly hold without bursting.” I think that implies the balloon is already stretched to the limit, or the pressure across the balloon is at the breaking point. Any gain in altitude is equivalent to putting more helium in the balloon (in terms of stresses on the balloon), so it would burst. But it _is_ possible to design a balloon that reaches a stable altitude. You need to make the balloon out of a tough, inelastic (doesn’t stretch) material that can withstand some pressure difference. Then you need to make it _very slightly_ positively buoyant. If you do this, the balloon with rise a little bit and the pressure outside decreses, but the balloon volume remains constant (because it’s inelastic). At some altitude the surrounding air will not be dense enough to provide lift, and the balloon will stabilize at that altitude. Such balloons are called “super-pressure balloons” and there are some projects to make it work, but it’s extremely difficult. > [@specie](#): > > Ok, another example. The can of helium never floats at all. Its equilibrium point is at ground level. If you had a metal can holding as much helium as it can without bursting, and took it up a mountain, it too would burst. ---
**Author:** ![BubbaDog](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bubbadog/32/333_2.png) [@BubbaDog](https://boards.straightdope.com/u/BubbaDog)\ **Post date:** [March 27, 2006, 5:09pm UTC](https://boards.straightdope.com/t/did-slylock-fox-get-it-wrong-about-helium-balloons/350085/14 "2006-03-27T17:09:04Z")
> [@specie](#): > > Ok, another example. The can of helium never floats at all. Its equilibrium point is at ground level. And there are plenty of balloons the morning after a celebration that are cruising halfway up the wall or nearly on the ground. > [And what about this guy?](http://i1.tinypic.com/sdp5i0.gif) Not following your logic here. Are you referring to the helium _tank_ ? If so, the tank holds compressed helium, has less dependence on atmosphere to maintain stability and is very heavy. In any case, my vote is that the Skylock situation is essentially correct. The balloon maintains its strength with the help of the atmospheric pressure. If it is on the brink of failure, as stated in the comic strip, and the outside pressure drops, it should burst. I’ve worked with the same principle while SCUBA diving. We used a tire innertube to float a sunken powerboat. We attached a deflated innertube on a two foot tether to the boat at a depth of 50’ and filled the tube about 25% volume. Then two divers physically “pulled” the boat up slowly. As the boat got closer to the service, the tube expanded and the divers efforts were relaxed. At a certain point the tube had enough bouyancy to raise the boat on its own. When the tube broke the surface of the water it was fully inflated. We towed the tube and the “sunk less deep” boat towards shore and then muscled the boat by hand when we got it into 4 ft’ shore depth. ---
**Author:** ![Critical1](https://avatars.discourse-cdn.com/v4/letter/c/3e96dc/32.png) [@Critical1](https://boards.straightdope.com/u/Critical1)\ **Post date:** [March 27, 2006, 5:27pm UTC](https://boards.straightdope.com/t/did-slylock-fox-get-it-wrong-about-helium-balloons/350085/15 "2006-03-27T17:27:07Z")
yeah but what if it was a helium balloon that was on a \* Treadmill???\* sorry couldnt help it since thats where this conversation appears to already be headed…of course it would burst, and not even that long after getting off the ground since its already near its burst point. ---
**Author:** ![jjimm](https://avatars.discourse-cdn.com/v4/letter/j/ba8739/32.png) [@jjimm](https://boards.straightdope.com/u/jjimm)\ **Post date:** [March 27, 2006, 5:36pm UTC](https://boards.straightdope.com/t/did-slylock-fox-get-it-wrong-about-helium-balloons/350085/16 "2006-03-27T17:36:06Z")
I think **specie** is mixing up buoyancy with expansion. Though related, in this case they’re separate issues. One is the weight of the object vs. the “negative weight” of the gas. The other is the volume of the gas at a given altitude. In the cartoon, it’s a given that the non-rigid container has positive buoyancy in air. So the issue is will the gas necessarily expand as it rises? Yes. Is the container non-rigid? Yes. Is the container infinitely expandible? No. Therefore at some point it will burst. ---
**Author:** ![VunderBob](https://avatars.discourse-cdn.com/v4/letter/v/839c29/32.png) [@VunderBob](https://boards.straightdope.com/u/VunderBob)\ **Post date:** [March 27, 2006, 5:41pm UTC](https://boards.straightdope.com/t/did-slylock-fox-get-it-wrong-about-helium-balloons/350085/17 "2006-03-27T17:41:41Z")
A fabric based balloon is somewhat porous, and will leak the helium before going through a pressure failure. This will happen, despite any coatings applied to the fabric to counter the porosity. This is a requirement of man-rated helium balloons. Weather balloons and the high altitude jobs are made from a monolithic plastic or mylar film and those will burst. Latex (toy balloons) are porous, but often will burst because of molding flaws. Oh, and a tank of helium sitting on the ground is not neutrally bouyant. It has a net force acting up on it from the surface that holds it in place. ---
**Author:** ![garygnu](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/garygnu/32/2924_2.png) [@garygnu](https://boards.straightdope.com/u/garygnu)\ **Post date:** [March 27, 2006, 6:03pm UTC](https://boards.straightdope.com/t/did-slylock-fox-get-it-wrong-about-helium-balloons/350085/18 "2006-03-27T18:03:51Z")
The only thing I can think of that could “save” the balloon is Charles’s Law. As the temperature decreases as it goes up, the volume of the helium would have to decrease. However, I don’t think it would be enough to counteract the decreasing pressure of the surrounding air. ---
**Author:** ![panamajack](https://avatars.discourse-cdn.com/v4/letter/p/47e85d/32.png) [@panamajack](https://boards.straightdope.com/u/panamajack)\ **Post date:** [March 27, 2006, 6:34pm UTC](https://boards.straightdope.com/t/did-slylock-fox-get-it-wrong-about-helium-balloons/350085/19 "2006-03-27T18:34:56Z")
Can we just all decide that Slylock is being an ass? His mouse friend is desperately trying to grab the rope while Slylock stands there, arms folded, taunting him. The rope’s easily within his reach but he lets poor mousy jump and strain. Max knows that when the balloon bursts, the camera’s going to come crashing down, maybe on him. And it’s big enough to probably kill him. The least Slylock could do is grab the rope and just remove the camera. After all, all he’s going to do is encourage Count Wierdly to fill the balloon properly next time. ---
**Author:** ![bup](https://avatars.discourse-cdn.com/v4/letter/b/6bbea6/32.png) [@bup](https://boards.straightdope.com/u/bup)\ **Post date:** [March 27, 2006, 7:15pm UTC](https://boards.straightdope.com/t/did-slylock-fox-get-it-wrong-about-helium-balloons/350085/20 "2006-03-27T19:15:40Z")
> [@panamajack](#): > > Can we just all decide that Slylock is being an ass? Oh hell yeah. Arrogant bastard. Profile much, Fox? He rounds up Shady Shrew and Count Weirdly all the time, then looks for evidence of wrongdoing. And, like with most blowhards, Slylock has been wrong, too. He just happened to be right this time. [Next page](https://boards.straightdope.com/t/did-slylock-fox-get-it-wrong-about-helium-balloons/350085.md?page=2)