Science: New Rocket Fuel

To roar farther and faster, rockets need a super-fuel with more bounce to the ounce. Most such concoctions are too volatile to handle. Last week Bell Aircraft announced success in taming one of them—liquid fluorine—which might boost rocket—payloads 70%. That would be enough to orbit U.S. satellites considerably bigger than Russia’s very heavy Sputnik III.

A rocket fuel combines a chemical that oxidizes and an ingredient that burns. The propulsive energy released is measured as “specific impulse.” Present combinations, e.g., liquid oxygen and kerosene, have a specific impulse of about 245 Ibs. Using liquid fluorine as the oxidizer instead of liquid oxygen would boost specific impulse to between 300 and 345 Ibs.

But fluorine, most tricky of the halogen series (others: iodine, bromine), is a nightmare to handle and hideously corrosive. To stay liquid, it must be kept at — 306° F., and if it merely touches water it will start a 5,000° F. explosion. Now Bell says it has actually harnessed this violence, even in small rocket thrust chambers. The chambers were specially designed laboratory chambers. Their metals are still classified, and so is the ingredient used with fluorine (possibly ammonia or hydrazine). Very special handling also involved unusual welding techniques, new storage tanks, refrigerated pipelines.

U.S. missilemen are unlikely to go to such trouble for some time, though the news last week gave thrust to Bell stock on Wall Street. Trouble is that using liquid fluorine would mean redesigning present ICBM engines, which run well enough on more placid fuels.