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I'm interested to know what it would take to get a hot air balloon, with a 600lb load, to 30,000 feet. Is this cheaper than flying a plane with a similar load to the same altitude?

If a special balloon is needed, what is the cost of that balloon compared to the typical recreational hot air balloon? What is the quantity and cost of fuel necessary to make it to that altitude, and hover for a few minutes prior to descending?

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    $\begingroup$ How do you intend to breathe at 30,000 ft. (higher than Mt. Everest)? How will you stay warm at -70F (-60C)? $\endgroup$ – abelenky Nov 2 '18 at 19:24
  • $\begingroup$ @abelenky That's not the subject of this question, but presumably with breathing apparatus and a specialized suit. It's not anything ground breaking. People have flown balloons well over 60,000+ feet before. $\endgroup$ – M28 Nov 2 '18 at 19:30
  • $\begingroup$ If you just want to get a view , you can always send a camera up for almost nothing! msn.com/en-au/video/watch/… $\endgroup$ – quiet flyer Nov 2 '18 at 19:31
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    $\begingroup$ 4 passengers and equipment are likely to weigh a bit more than 600 lbs. 150 lbs/person including life support? $\endgroup$ – Dan Pichelman Nov 2 '18 at 19:44
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    $\begingroup$ "Its not anything ground breaking"?? I can only find 17 manned balloon flights above FL300 in all of history. Most of them were backed by the Air Force or other well funded government agencies. All of them required custom, purpose-built equipment. 5 balloonists died during various attempts. $\endgroup$ – abelenky Nov 2 '18 at 20:09
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A Hot Air Balloon should be able to reach 30,000 ft just fine as according to Wikipedia the world record altitude for Hot Air Balloons is 69,852 ft. Besides the necessary survival gear for the occupants (Pressurized oxygen and environment suits) a special propane tank would be needed as according to wikipedia:

However, if the liquid propane in the fuel tanks is too cold (0 °C/32 °F or less) it does not generate sufficient vapor pressure to adequately feed the burner(s). This can be overcome by charging the fuel tanks with inert gas such as nitrogen or by warming them, with electric heat tapes for example, and insulating them against the cold.

Another thing to consider is that you would need special permission from the FAA to go into Class A airspace which goes from 18,000 to 60,000 feet MSL. Usually only IFR rated aircraft can fly in this airspace. The FAA may require you to fly with a radio and/or transponder if you do get the permission to fly in this airspace.

I do not know how much propane would be required as I don't fly Hot Air Ballons but it would probably depend on the outside air temperature (less fuel in colder air).

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  • $\begingroup$ [citation needed] Wikipedia fails to mention something. The problem with propane tanks freezing isn't from outside air temp. What makes them freeze is the propane itself flashing to vapor. This is called the "latent heat of vaporization". Propane tanks right here on the ground will ice up from being drawn down quickly. $\endgroup$ – Harper - Reinstate Monica Nov 2 '18 at 22:56
  • $\begingroup$ This doesn't seem to answer the question about costs specifically, although indeed there are other practical things to think about $\endgroup$ – Pondlife Nov 3 '18 at 3:07
  • $\begingroup$ Interesting point about the limitations of regular propane/propane tanks as a fuel source.. I'm looking specifically for how expensive it is though, to estimate cost efficiency compared to other forms of flight. $\endgroup$ – M28 Nov 5 '18 at 15:33
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    $\begingroup$ 32F is not the limit on propane tanks. We have people in this area who launch them somewhat routinely in temps of 10F. The vaporization temperature of propane is -44F. To compensate for vaporization energy, one can carry more tanks, or use tank heaters. For high altitude flights, gas balloons are more common. $\endgroup$ – mongo Dec 3 '18 at 12:53
  • $\begingroup$ Of course, once you get above FL600, the airspace changes back to class E. $\endgroup$ – Sean Feb 21 '19 at 4:14

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