Rick Newlands 2013 -
I’m plumping for a hydrogen balloon (erk! you all cry: remember the Hindenberg!) The Hindenburg disaster was caused by the airship’s metal skeleton breaking up in very strong winds which punctured the bags carrying the hydrogen. A big build-
Most of the passengers and crew got away safely, but the fire was captured on camera, and the newspapers went quite nuts, proclaiming that hydrogen was terribly dangerous. So much so that nobody uses hydrogen anymore for manned balloons or airships. (What didn’t help was that the black and white camera film of the time picked up infra-
Most other balloonists use helium, even though it doesn’t lift so well so you need a bigger balloon. All of the World’s helium comes from one large cave in America that happens to have captured a lot of radioactively-
As it happens, the UK has experience of large balloon projects. Yes, the Qinetiq One enormous helium balloon burst upon inflation, but that was caused by manufacturing defects in the balloon canopy: easily rectified with better quality control.
The balloon will be launched in the north of Scotland, possibly from a quarry or from a boat, at sunrise when the winds are light.
For the mechanics of launching a large balloon see the Red Bull Stratos site.
A rocket fired from a balloon is known as a rockoon system (which sounds like a cartoon character!)
To get the ¾ tonne of spacecraft plus fuelled booster to 35 Km up requires a big balloon.
To get the estimated 710 kg of payload to 35 Km altitude, the balloon will require approximately 102 kg of hydrogen or 226 kg of helium, which at 35 Km results in a balloon of 69 or 72 metres diameter. The balloon fabric alone will weigh 597 or 643 kilograms.
I need to keep the Equivalent (indicated) airspeed during rocket ascent really low as I’m going up with my body sideways to the flow (or rather, the capsule around my body) which could get really draggy. If I start the rocket ascent from a height of 35 kilometres up (115 thousand feet) then the maximum Equivalent airspeed during ascent is a paltry 55 knots.
(An Equivalent airspeed of 55 knots is that much higher actual (True) airspeed at high altitude that produces the same magnitude of aerodynamic force as if the craft really were doing only 55 knots at sea-