So far, the reaction has been fairly positive, he says. Beneath this, separated by a valve, is a chamber filled with compressed air. Opening a vent equalises the pressure above and below the valve, allowing it to be released. The chamber is open-bottomed so water rushes in from below and discharges up the barrel. The air expands rapidly as it tries to equalise with atmospheric pressure, pushing the rocket ahead of it.
Water rushing up the barrel increases the thrust.
The final exit speed at the mouth of the barrel depends upon the diameter and length. The force of the air, says Taylor, would enable the vehicle to exit the barrel at speeds in excess of 1000 kilometres an hour. But Barry Moss, a space launch expert at Cranfield University has his doubts. When factors like friction and air resistance are taken into account, he doesn't believe there will be enough thrust. This would be a considerable advantage over an entirely rocket-based launch.