Even if it were too messy to use for the outer construction, it might be interesting to use it only for those components that are most temperature sensitive, such as the battery. This would also solve the battery dislodging problems you had with your first flight.
I'm wondering if anyone is creating a stereolithography machine capable of printing structures using materials designed for insulation such as polyurethane/polystyrene foams and silica aerogels (R-value ~10.0.
I'm also curious if using stereolithography to print honeycomb structures in a vacuum would be a good way to produce vacuum insulated structures (AFAIK R-values of 30 to 50 should be possible.)
In a flight like jgc's, the latex balloon expands until it pops. There are other balloons which can float at a steady altitude. One of these is called a "Zero-pressure Balloon." This balloon operates with a valve on the bottom. The helium will expand until it reaches this valve, then spill out. When the balloon loses helium, it loses lift. The valve will tend to dump helium until the balloon reaches neutral buoyancy. These balloons are so named because the pressure at the valve is the same as the ambient atmospheric pressure.
Another type of balloon is called a "Superpressure Balloon." These balloons maintain altitude by pressurizing internally. Unlike latex, these balloons stop stretching at a certain altitude. As soon as the balloon stops expanding, it maintains a constant volume. Buoyancy is based on the volume of fluid displace, so a pressurized balloon maintains the same altitude.
I work with a group of hackers attempting to cross the Atlantic Ocean using a Zero-pressure balloon. (http://www.whitestarballoon.com). A group of radio amateurs actually beat us to the punch (http://www.arrl.org/news/amateur-radio-balloon-flight-crosse...), their crossing was involved a large quantity of luck. We seek to develop systems and methods for engineering balloons capable of traversing large distances safely and reliably.
(PS: I am aware the Kármán line actually has to do with aerodynamic lift (and therefore may not really be applicable to lighter than aircraft). It just chose it because it's the commonly accepted "edge of space")
The Japanese currently hold the world altitude record (among all professional and amateur balloons), IIRC. Their balloon was 3.4 micrometers thick, 60,000 m^3 of helium. They reached 53 km.
I imagine you'd get more lift with hydrogen.
I expect to see an increase in the number of hydrogen-filled balloons as helium prices rise in the next few years.
How would you do that? Once it is in the air isn't it at the mercy of the air currents (can you control the altitude?). Then is it a matter of analyzing and predicting the flow of air currents and the weather?
Japanese for example attempted to send balloons over the pacific that were intended to drop on US and start forest fires.
They even claimed one human victim.
We can drop ballast to maintain altitude, but we don't have any other control. As a result, we must wait for the winds.
(You can see an example prediction feed here: https://twitter.com/WSBFlightPath Cryptic, but it's meant for the launch team).
The Japanese balloons were examples of exquisite analog engineering. The Army made a great video documenting their construction and operation (available here: http://www.archive.org/details/gov.archives.arc.13084).
One question. Did you choose the video cameras based on size or are did you assess the quality too? I've seen some pathetic 'HD' videos from cheap cameras before but things seem to have progressed a lot over the last couple of years.
The ones I am using are what he called #16: http://www.chucklohr.com/808/C16/index.html
On #highaltitude, what were the highest altitudes others have achieved?