THERE鈥橲 a new way to fire spacecraft into orbit鈥攁 giant spurt of air
and water.
Amateur rocketeer Scott Taylor鈥檚 Hydro Pneumatic Accelerator (Hypacc) should
be capable of launching objects as big as the space shuttle into orbit without
using huge amounts of rocket fuel. Hypacc will instead use the immense pressure
of water at depth to provide the necessary initial lift, says Taylor.
鈥淚鈥檓 not a rocket scientist and I know there must be thousands of wackos out
there all pushing their ideas,鈥� Taylor told 快猫短视频. 鈥淏ut I鈥檓 just trying
to establish if there鈥檚 anything to this idea.鈥� So far, the reaction has been
fairly positive, he says.
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In Taylor鈥檚 scheme, the spacecraft
(see Diagram) sits at the bottom of a very
long silo that is almost entirely submerged in the sea and acts like the barrel
of the gun. 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. 鈥淭he rising volume of water provides a constant force
and pressure onto the compressed air, which propels the shuttle capsule,鈥�
explains Taylor.
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. A 10-metre-wide barrel 1 kilometre long would be capable of launching a
mass of 10,000 tonnes, the equivalent of five space shuttles. 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.
鈥淏esides being a major civil engineering project, this could only ever launch
very small payloads,鈥� he says. When factors like friction and air resistance are
taken into account, he doesn鈥檛 believe there will be enough thrust.
Taylor says that although the speed is nowhere near the 29,000 kilometres per
hour escape velocity required, it does mean that the craft would be travelling
at immense speeds when it reaches sea level鈥攁t which point the on-board
rockets are fired. This would be a considerable advantage over an entirely
rocket-based launch. For example, only 1 per cent of an Ariane 5 rocket鈥檚 mass
is its payload. Most of the rest is fuel and 60 per cent of this is in the
boosters, which are jettisoned anyway.