Balloonists Prepare For Another Altitude Record Attempt

EyesWideOpen writes "Determined to break the current altitude record of 34,747 metres (114,000 ft) Colin Prescot and Andy Elson will try again this year to take a giant envelope to a height in excess of 40,000 metres (130,000 feet). The balloonists have made previous attempts at the record and are hoping to use what has been learned so far, as well as a wider zone in which their QinetiQ 1 balloon can fly off southwest England, to be successful this year. To perform radiation and micrometeoroid experiments Prescot will try to fly a solar-powered propeller-driven plane (with a mounted camera) in the stratosphere. June to September is the proposed launch window."

This is easy

[Tuxinatorium]

Just fill a huge, thin balloon 1/50 full of hydrogen, and it will rise until the pressure is 1/50 that of sea level, and then start to leak, but probably keep on rising as long as the bag and stuff are lighter than the weight of that volume of air at 1/50atm. Hydrogen is always going to be 1/7 the density of air at any pressure, so it shouldn't be much of a problem to get a balloon into the upper stratrosphere and beyond.