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| World Home » Science & Technology » | Sat. Nov 22, 2008 |
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NASA-New Advances for Liquid-Fueled Rockets MIL/NASA, Oct 15, 2005. When you think of future rocket technology, you probably think of ion propulsion, antimatter engines and other exotic concepts. Not so fast! The final chapter in traditional liquid-fueled rockets has yet to be written. Research is underway into a new generation of liquid-fueled rocket designs that could double performance over today's designs while also improving reliability. Liquid-fueled rockets have been around for a long time: The first liquid-powered launch was performed in 1926 by Robert H. Goddard. That simple rocket produced roughly 20 pounds of thrust, enough to carry it about 40 feet into the air. Since then, designs have become sophisticated and powerful. The space shuttle's three liquid-fueled onboard engines, for instance, can exert more than 1.5 million pounds of combined thrust en route to Earth orbit. You might assume that, by now, every conceivable refinement in liquid-fueled rocket designs must have been made. You'd be wrong. It turns out there's room for improvement. Led by the US Air Force, a group consisting of NASA, the Department of Defense, and several industry partners are working on better engine designs. Their program is called Integrated High Payoff Rocket Propulsion Technologies, and they are looking at many possible improvements. One of the most promising so far is a new scheme for fuel flow: The basic idea behind a liquid-fueled rocket is rather simple. A fuel and an oxidizer, both in liquid form, are fed into a combustion chamber and ignited. For example, the shuttle uses liquid hydrogen as its fuel and liquid oxygen as the oxidizer. The hot gases produced by the combustion escape rapidly through the cone-shaped nozzle, thus producing thrust. The details, of course, are much more complicated. For one, both the liquid fuel and the oxidizer must be fed into the chamber very rapidly and under great pressure. The shuttle's main engines would drain a swimming pool full of fuel in only 25 seconds! This gushing torrent of fuel is driven by a turbopump. To power the turbopump, a small amount of fuel is "preburned", thus generating hot gases that drive the turbopump, which in turn pumps the rest of the fuel into the main combustion chamber. A similar process is used to pump the oxidizer. Today's liquid-fueled rockets send only a small amount of fuel and oxidizer through the preburners. The bulk flows directly to the main combustion chamber, skipping the preburners entirely. Full Story: http://www.universetoday.com/am/publish/new_advances_liquid_rockets.html?14102005
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