On Sep 3, 2011, at 7:24 AM, Dominic Pflaum wrote:
Another idea may be to counteract gravity by filling the balloons with a certain amount of helium.
They had a partial helium mix ... it's not as easy as I thought to make them neutrally buoyant and they only stay that way for about 2 hours. For various reasons, most of the documentation was shot *after* they had lost some lift ...