Hi guys,
So I have been using a Hwoyee 3000 balloon filled with 6.37 m3 of helium. I had a tank pressured @ 200 bar = 9,1 m3 of helium.
I have used 140 bar= 6,37 m3.
The payload was 2200grams.( nacelle + radar reflector + cord+sealing silicone+duct tape)
Sticking those numbers into an online calculator used by most balloonists you should have got around 4.6m/s ascent rate and the balloon should have been exerting about 3.5 kg of pull, so even with some rain it should have still gone up (you'd have needed over a kilogram of water on the balloon for it to not go up).
How were you measuring the gas put into the balloon? It sounds a bit like this was based on the amount of gas you put in, if that's the case the meters on most helium cylinders are not known for being particularly accurate so it's very possible the balloon was underfilled. The most common way of measuring you've got enough gas is to measure the neck lift. This will give a decent gauge of whether there's enough gas and would account for differences in pressure, weight of rain etc.
If you havn't I'd suggest reading my earlier post:
Here's the post with my thoughts about the Balloon Launch, sorry it's another long one...
I have concerns that this payload will overheat (you've got a lot of heat generating electronics), I'm also wondering how you're going to achieve the transactions at 30km (and that you'll know you've reached 30km). Internet connectivity above a few km is very difficult (even at 1km it will be a challenge).
I'm usually keeping an eye on the IRC channel if I'm around so drop by and we can talk about the details if you want (I'd prefer that this is a success rather than another failed balloon launch due to the years of experience out there being ignored).