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Why rockets fly better with jelly

发布时间:2019-03-08 02:16:01来源:未知点击:

NEXT month, the US Army will launch a missile fuelled by a toothpaste-like gel, instead of the usual solid fuel. The gel will improve control over missiles, allowing them to reach targets at great distances and perhaps even attack several objects along their flight path. The faster a rocket goes, the more fuel it burns. So an ideal fuel-efficient missile would go relatively slowly for most of its journey, only increasing its speed when close to the target. But this can’t be achieved with current missiles, because it is extremely difficult to change the rate at which solid fuels burn. “With a solid, the only thing you could do is light it and go,” says Jerrold Arszman, propulsion technology manager for the Army’s Future Missile Technology Integration project. “You turn the thing on, it does what it’s going to do and then that’s it.” On the other hand, it’s easy to change the rate at which a missile burns a liquid fuel—just pump less fuel into the engine and it slows down. But liquid fuels are dangerous. If a shell fragment punctured a liquid-fuel tank, for instance, the resulting leak and puddle of fuel present a huge risk of explosion. The gel fuel will prove safer than liquid fuels, but could still be pumped into the engine at different rates. The space shuttle uses solid rocket boosters to aid its liftoff—so the new gel fuel could make its way into space applications,