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Balloon Launch Discussion

Posted by: Monroe - Tue Jun 23, 2009 6:48 pm
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Balloon Launch Discussion 
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Space Station Commander
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Post    Posted on: Wed Jun 24, 2009 12:42 am
John
Thank you so much for that input. I have used the model A400 before in the California desert sampling steam ejected from the oil wells. Some of the low flow well's did not have enough condensables in them to effect this type of flow meter. This is a bellows type of meter correct? It was probably 30 years ago when I worked for Radian at that time doing EPA work for the gov. as a chemist (17 years old) that will get back to what Stew said about condensables in the flow I forgot these are sensitive to that. They are designed to not explode with combustible gas that really helps with Hydrogen.

Stew if we zigzag the flow thru the evaporator that system will work fine to remove almost all of the moisture. I do not know if the condensables are corrosive to alum. any free sodium hydroxide in the condensables would attack the evaporator.
If we had a gas chromatograph or access to one we could determine exactly what was going on with system. We probably need one anyway.

Monroe

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Post    Posted on: Fri Jun 26, 2009 9:51 pm
For the base system we fly 900 mhz maxstreams for command and control, 2 meter downlink only for backup position, a "spot" unit for post landing site verification and a two week carrier only beacon. Then each mission will is own set of transceivers depending on what is being tested or the project.

The team has left and I need to catch up. Rockoon flight tomorrow.


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Space Station Commander
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Post    Posted on: Sat Jun 27, 2009 6:07 am
John
Ohhh. I have been looking at the MaxSTreams thank you. 2-Meter back up makes a huge amount of since. Really appreciate that it will save us some time and heartache and more importantly money. Very best of luck with the Rockoon mission. I would love to see success. I am learning that every mission is really a success as long as everyone is safe and we learn something. We have a great group of guy's that are really putting in the effort and I'm sure any wisdom you share is more than welcome.
I have a small machine shop and small foundry if there's anything we can make for you let us know. That’s really all we can offer. I was wondering if you were heating your rockoon silo to aid in the stability of your propellant. I was told that you have to do that is that true?

Monroe
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Launch Director
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Post Re: Balloon Launch Discussion   Posted on: Tue Jun 30, 2009 4:42 pm
OK, here's a summary of our progress so far. I have made a set of tooling for cutting out balloon gores in a controlled, reproducible way. Imagine a plywood surfboard about 7' long by 1' wide and you won't be far off. Obviously, this is just a small scale prototype intended to test the process and method for making balloons, a 7' balloon won't be too impressive but it has the distinct advantage of fitting in my shop. The bottom table (the thing shaped kind of like a surfboard) is hollow in the middle and has little-bitty holes drilled all around the top, and a fitting on the bottom for attaching an air hose. Basically, you lay down a piece of plastic on it, turn on the vacuum (I'm using a shop-vac), lay down the plywood pattern in the actual shape of the gore on top of the plastic, clamp the pattern down, and then run a knife around it to cut out your gore. I've gotten that far with testing and it works very well. The vacuum holds the slick plastic down but lets you adjust it enough to smooth out wrinkles, it's just like an air hockey table in reverse.

I have started tests on sealing the seams with mixed results so far. Using the wood pattern itself as a guide, I run an iron around the seam, using a card-stock shield to keep the plastic from sticking to the iron. My first test stuck but didn't actually weld together except in a few places where apparently I was going slower. Some more experimentation is in order, but it looks like we are closing in on a viable method. Of course, it will be necessary to make some much larger tooling, and then we have to have a place to put it....

Stew

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Post Re: Balloon Launch Discussion   Posted on: Tue Jul 07, 2009 1:30 pm
> Open the press, turn off the vacuum, flip the new assembly over and fold the top sheet
> back away from the weld line. Mount a new sheet on the top board and repeat the welding
> process until all the gores are welded together. The toughest part is going to be designing
> the boards so that the partially assembled balloon can be folded flat and away from the
> weld line so the next weld can be set up. The final weld will also be tough, but I think it will
> all work and leave you with a spherical balloon folded flat on all it's gores ready for inflation.

That's pretty much exactly what I was thinking. You could assemble the balloon on the table one gore at a time, and the two being welded will lay flat against each other, although the rest of the balloon will assume a curved shape that will get increasingly awkward to deal with. Even with the final weld the two pieces being held should lay flat. Although, I actually hadn't thought of using another air table as the top, I was just using a flat pattern and clamping it shut. For more permanent/better tooling that would definitely be the way to go. It took me one afternoon with a jigsaw, drill, plywood, and wood glue to make the table, it's not particularly hard to do. You just need a bunch of clamps to hold it as the glue dries, or else screw it together instead.

Pegboard might have been easier than drilling about 80 3/32" diameter holes like I did, but one problem with pegboard is that the large holes will cause you to lose vacuum badly if a few of the holes aren't covered by the plastic. I chose the size and number of holes so that the total cross-sectional area of all the holes roughly equals the cross-sectional area of the hose on my shop-vac. It worked out nicely with 3/32" holes drilled every 2" around the perimeter, there aren't any holes in the middle. That way you still have good vacuum while you're lining up the sheet and the plastic is only covering some of the holes until you align it and get it smoothed down.

The construction was just three layers of plywood, a top, a bottom, and the middle hollow but with a plug in the middle to keep the whole thing from becoming concave when under vacuum. The holes are about 1/2" inboard of the gore pattern line, but I wish I'd but them closer, there tends to be a bit of wrinkling right there. I'm going to try to attach the pictures, we'll see how this turns out....

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