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Old 11-27-2019, 05:04 PM
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Macy's Thanksgiving Day Parade balloons q.


What are they inflated with? They're pretty big, and if they were inflated entirely with helium it would not only be very expensive but generate more lift than is needed or wanted. Is dry nitrogen enough of a lifting gas to get them off the ground?
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Old 11-27-2019, 05:09 PM
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They use helium.
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Old 11-27-2019, 05:35 PM
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Nitrogen has a molecular mass of 28 grams per mole. Air is mostly nitrogen but the oxygen brings the average molecular mass of dry air to about 29. Since helium has a mass of about 4, it has about 25 times more lifting power than dry nitrogen. If helium provides more lift than needed, you could dilute with air to save money.
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Old 11-27-2019, 05:38 PM
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They're also heavier than you'd think, and they're being handled by dozens of people holding onto ropes.
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Old 11-27-2019, 05:47 PM
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They're also heavier than you'd think, and they're being handled by dozens of people holding onto ropes.
That doesn't sound right, the handlers are to control them as they have a huge surface area and the wind can really bounce them around. They're a little bit like big sails. It's not that they're heavy so much.
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Old 11-27-2019, 06:03 PM
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You can take this cite for what it's worth, but it says the big balloons take 12,000 cu. ft. of helium "which can lift up to 750 pounds."
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Old 11-27-2019, 07:05 PM
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The balloons themselves are heavy - probably 300-400 pounds.
The lift due to the helium is several hundred pounds, and when the anchor rope is removed from the guide truck, it takes 20 or more people to hold it down.
The Macy’s parade is one of the single largest consumers of helium in the world.

Cite.
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Old 11-27-2019, 07:25 PM
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Originally Posted by beowulff View Post
The balloons themselves are heavy - probably 300-400 pounds.
The lift due to the helium is several hundred pounds, and when the anchor rope is removed from the guide truck, it takes 20 or more people to hold it down.
The Macy’s parade is one of the single largest consumers of helium in the world.

Cite.
Did you just cite your own post?
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Old 11-27-2019, 07:32 PM
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Did you just cite your own post?
Yep.
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Old 11-27-2019, 09:58 PM
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Before the parade gets under way, you used to be able to wander by and see them being filled the day/evening before. Now it's also a major event and crowded as only a NYC event can be crowded. To hold down the balloons until launch date, they are covered with rope nets and big weights on the net... So they are pretty floaty. Keep in mind these are fairly thick vinyl, they make your beach ball look flimsy. The rope anchor points are made of some fairly thick, sturdy patches. yet, sometimes the balloons still tear. And they are solid enough to take down a lamppost instead of shredding.
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Old 11-27-2019, 10:08 PM
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In 1997 several of the balloons rose up in rebellion and attacked the crowd. One lady got a severe head injury and the NYPD was forced to disembowel several beloved childrens' icons on live television. Nowadays they keep a closer look on the wind forecast.
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Old 11-28-2019, 01:21 PM
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It occurs to me now that if most of the helium can be recovered from the balloons after the parade, the expense might not be as severe as I'd presumed. Still, if it wasn't for venerability's sake, the balloons ought to be replaced with something better designed.
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Old 11-28-2019, 05:51 PM
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It occurs to me now that if most of the helium can be recovered from the balloons after the parade, the expense might not be as severe as I'd presumed. Still, if it wasn't for venerability's sake, the balloons ought to be replaced with something better designed.
You would think it would be worth trying to save it, but at the end of the parade, the helium is simply released and it floats away (watch out, iPhone users!). I have a photo of the helium being released, and you can see the “wavering” effect in the air (just like “heat waves.”)
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Old 11-28-2019, 06:09 PM
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It occurs to me now that if most of the helium can be recovered from the balloons after the parade, the expense might not be as severe as I'd presumed. Still, if it wasn't for venerability's sake, the balloons ought to be replaced with something better designed.
How much do you want to spend on recovery equipment? Airgas, annoyingly, doesn't give web quotes to my zip code, but this price sheet from Oklahoma State University, detailing their purchasing prices for the gasses they buy, should be helpful: https://purchasing.okstate.edu/sites...520Summary.pdf

From it, dated 2018, they pay ~80 dollars for a 300 cubic foot container, pressurized to just under 3,000 psi. From that, figure out how much it costs to fill the balloons, and see if it would be worthwhile to try to recapture it. At a certain price, it would be. I guess they aren't quite there yet.
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Old 11-28-2019, 06:46 PM
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Hmmm. When the looming helium shortage was appearing in the news a lot, the Macy's Day organizers announced plans to recover the helium from the balloons:

https://cityroom.blogs.nytimes.com/2...in-the-bottle/

If that never worked out, it should be noted that even though the Macy's parade is a large single use, lifting applications only account for about 12% of helium use, from party balloons to filling blimps. By far the largest use of helium is in cryogenic applications, and MRI machines are the major user. They are supposed to be doing a much better job of recovering the helium these days.
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Old 11-29-2019, 04:58 AM
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...if it wasn't for venerability's sake, the balloons ought to be replaced with something better designed.
We're still working on antigravity sleds.
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Old 11-29-2019, 02:38 PM
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It's tempting to think that some mixture of hydrogen (cheap) and nitrogen could get the job done and also not be a fire hazard.
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Old 11-29-2019, 02:51 PM
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It's tempting to think that some mixture of hydrogen (cheap) and nitrogen could get the job done and also not be a fire hazard.
Doubtful, since hydrogen is flammable at concentrations as low as 4% in air.
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Old 11-29-2019, 04:19 PM
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Hot air balloons are lifted by nothing but air, heated by propane burners. And they have to carry the buburners, and propane, and humans aloft with them. Would it be possible to have a Macy's balloon tethered to a burner truck*, which heats up the air and blows it through a large tube going up into the balloon? Possibly the noise of such an arrangement would make it unworkable, though.

* Of course, that would use up a fair amount of propane during the parade -- still not good for then environment. Not having a parade at all would be best, environmentally; but we're not willing to give that up anytime soon.
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Old 11-29-2019, 05:20 PM
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I've been in, or rather, carried under a hot air balloon. They are enormous. Bigger than the Macy's parade balloons. Not sure such balloons would be able to fit between the buildings and other obstacles along that route.
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Old 11-29-2019, 07:22 PM
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Originally Posted by RioRico View Post
We're still working on antigravity sleds.
I was thinking more along the lines of something better than pressurized vinyl as a support structure. Maybe a semi-rigid shell made of lightweight materials like Kevlar that could distribute the load forces from wind more evenly between the people controlling the balloon.
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Old 11-29-2019, 10:59 PM
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You can take this cite for what it's worth, but it says the big balloons take 12,000 cu. ft. of helium "which can lift up to 750 pounds."
That's total lift; minus 400 lbs of balloon (fabric) weight means only 350 lbs of 'free' lift; sounds about right because as the balloon rises it's also lifting up the weight of the fabric.


Quote:
Originally Posted by Lumpy View Post
I was thinking more along the lines of something better than pressurized vinyl as a support structure. Maybe a semi-rigid shell made of lightweight materials like Kevlar that could distribute the load forces from wind more evenly between the people controlling the balloon.
Doubtful it could be lighter than fabric only.
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Old 11-30-2019, 10:15 PM
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Originally Posted by Broomstick View Post
I've been in, or rather, carried under a hot air balloon. They are enormous. Bigger than the Macy's parade balloons.
But under TT-Bonham's proposal the balloon has to lift only itself - no basket, and people, burners & fuel all stay on the ground.
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Old 12-01-2019, 03:25 AM
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I'm not sure how well it would work with, essentially, piping the hot air up to the balloon.

That said - even lifting "just itself" the balloon is going to be huge because hot air isn't as efficient a lifting gas as helium.
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Old 12-01-2019, 08:28 AM
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Sure, hydrogen is flammable, but then, most things humans make are flammable. Nobody's aghast at making things out of, say, wood. Even pure hydrogen is acceptably safe, as long as you don't do anything stupid like make the envelope out of thermite.
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Old 12-01-2019, 01:39 PM
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Sure, hydrogen is flammable, but then, most things humans make are flammable. Nobody's aghast at making things out of, say, wood. Even pure hydrogen is acceptably safe, as long as you don't do anything stupid like make the envelope out of thermite.
Hydrogen is not only flammable, it's among the leakiest substances known. Extraordinary precautions are required to use it; to float balloons in a public parade simply isn't going to fly (no pun intended).
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Old 12-01-2019, 03:02 PM
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Hydrogen is not only flammable, it's among the leakiest substances known. Extraordinary precautions are required to use it; to float balloons in a public parade simply isn't going to fly (no pun intended).
Chronos (or Stranger On A Train, whenever he comes back) would know this, but wouldn't even a modest portion of one balloon's worth of hydrogen, mixed with atmosphere and ignited, be enough to shatter a lot of the windows along the parade route?

That strikes me as a bad thing.

Last edited by Gray Ghost; 12-01-2019 at 03:02 PM.
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Old 12-01-2019, 03:07 PM
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Originally Posted by Tim@T-Bonham.net View Post
Hot air balloons are lifted by nothing but air, heated by propane burners. And they have to carry the buburners, and propane, and humans aloft with them. Would it be possible to have a Macy's balloon tethered to a burner truck*, which heats up the air and blows it through a large tube going up into the balloon? Possibly the noise of such an arrangement would make it unworkable, though.
A hot air balloon flys because it's roughly 100° degrees above ambient air temp. This is accomplished via a 12-15,000,000 BTU burner. A small passenger hot air balloon is 77,000 cu ft, or (for size comtparison a basketball is 1 cu ft). Sure, they could be smaller w/o the weight of humans, baskets, tanks, & burners but not having the burner on board but having that air pumped in means one heckuva large fan. In a real hot air balloon if it gets too hot/we start rise when we don't want to, we merely pull the vent line in the top of the balloon to let some of the hot air escape. The further the pilot is from that point, the tougher micro control would be; I fear an oscillating ride of too high (straining the handlers) & then hitting them in the head if too much hot air is released.


Quote:
Originally Posted by Lumpy View Post
Hydrogen is not only flammable, it's among the leakiest substances known. Extraordinary precautions are required to use it; to float balloons in a public parade simply isn't going to fly (no pun intended).
Hydrogen can be dangerous when filling but should be stable once in the balloon. A small leak would go up, into the atmosphere, away from people. However, a terrorist standing on a balcony on CPW with a flaming arrow could end that balloons trip in a hurry. I don't see NYPD ever allowing this.
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