I was wondering if there was a way to have an indefinite flight using a lighter-than-air craft. I was planning on having an appropriate He-O2 mix to maintain an altitude of 100,000 feet, but I realized that all materials are porous to some degree. Is there any way that I can find a completely non-porous (as oxy-moronic as it sounds) material that can be used as an envelope for helium gas?
If not, is there any way that a hot-air balloon setup can be implemented (eg, solar panel-heater-balloon)? I realize that 100,000 feet is very cold and a heater probably wouldn't work at all, but out of sheer curiosity I was wondering if it could be done.
The reason I'm asking this is because I was interested in high-altitude weather ballooning and photography, then began to wonder... Plus, it would be helluva lot cheaper than a cubesat. :D
I'd appreciate any and all input!
Jack
ps -- attached are my doodles... I hope they help!
Replies
It seems to me that you can certainly get a helium balloon to 100,000 feet and that a solar nitrogen filled balloon could be made to work at lower altitudes, but it does not seem likely to me that a nitrogen balloon could be made to work at 100,000 feet.
The air is too thin and the nitrogen is never going to provide enough lift to overcome its own weight/mass at that altitude.
That having been said if you do manage to get a balloon to that altitude for an extended period of time, it is going to get blown all over the planet and there is pretty much nothing you can do to stop it from doing so.
Although the air is thin, air velocity tends to be pretty high at that kind of altitude.
Commercial flights are pretty much below 40,000 feet and most military planes don't go much above 50,000 feet.
The Blackbird holds the Airbreathing record at 85,000 feet (The U2 reportedly makes it to 90,000 feet), so not a lot of stuff (that isn't trying to shoot you down) is likely to fly past if you are at 100,000 feet.
Somehow, I would be wiling to bet that if you were even moderately successful in this venture the FAA and possibly the governments of several foreign countries would be seriously displeased.
I haven't admitted defeat! Actually, I kind of have. But if I come up with any ideas in the morning I'll be sure to post them. Also: what says peoples on the internal-cage idea?
First off, the FAA doesn't have a problem with high-altitude balloon (HAB) operations, as long as they don't violate the US Code of Federal Regulations Title 14 Section 101. I'm not a lawyer or an FAA official, so I'm not going to post a translation of what's being said, but I can tell you to look at sections 101.1-101.7 specifically for exemptions and operational restrictions. Note that it is possible to get waivers for stuff that falls outside of the specs... I've done it, and flown, but it wasn't fun to do.
Also, there are a lot of people who do HAB stuff as a hobby. The ARHAB page has links to most hobby HAB programs in the US. There is a yearly conference of HAB enthusiasts called the Great Plains Super Launch, and an associated email list, full of people who enjoy talking about their favorite hobby. Also, a number of universities have HAB programs as well; I was responsible for Taylor University's High Altitude Research Platform team for roughly 5 years; there's a link to that program on the ARHAB site, and a video that I put together can be found on youtube. Also, check out JP Aerospace and Space Data; both of which are highly-organized teams.
Some radio suggestions for you: the 900 MHz ISM band is awesome for these applications; FreeWave and Maxstream are two suppliers that I worked with, and both do a great job (FreeWave is much more expensive, but has better performance). Also, there are other opportunities on the ham bands (think what could be done with a repeater at 100k' - it's pretty cool, just coordinate with your local clubs/repeter coordinator).
Recovery via parachute is not difficult at all; look for high-powered rocket parachutes. At the weights that my team flew (no more than 12 lbs, in no fewer than 2 packages), 4-6' diameter chutes were perfect. Plus, deploying them is not hard, either; if the order of your system is (from the top) balloon -> load line -> parachute -> payload, the chute will be collapsed on the way up, and open on descent. At 100k', there isn't enough air to appreciably slow the chute (it inflates, but terminal velocity is extreme), but the rate of descent evens out as you get lower.
I believe that JP Aerospace did some experiments with propulsion, but they involved really big props to grab what little air exists up high (you're in a near vac at 100k'; low pressure testing of your systems can be helpful if you have access to a bell jar), and I don't recall if they were successful at all. However, in your area, there is generally a weak western flow above about 90k' in the summer (the dominant jetstream runs east), and some station keeping can be achieved by changing your altitude through layers of air - vent lift gas to descent, dump ballast to ascend.
I would encourage you to strongly consider including a small APRS system in your payload. Don't broadcast too often (to avoid the wrath of the APRS community), but if you transmit on one of the two national frequencies (depending on which direction you're predicting the payload to go; you're pretty close to the divide between the use of 144.39 and 144.34 MHz), you'll have the assistance of any APRS-equipped ham in tracking your payload.
Also, there have been some attempts by the HAB community to fly a trans-atlantic mission that I'm aware of, but they have all failed (one by only ~150 miles, if I recall correctly). Information on that project is here.
This is probably way more information than you were looking for, but hopefully some if it helps. If I can be of further assistance, feel free to let me know. I may be able to dig up some of the actual temperature / pressure data from some of my team's flights, too, if you're interested.
-D
Don't know if you're not cruising at flight altitude of commercial lines ==> NoNo
The winds up there are very different from the winds at ground level (speed / direction) --> how will you control position?
Pressure is very different from ground level, so you have to control that too!
Therefore I wonder if a balloon is the real solution to your problem.