Solid Triumph

In the rolling hills of Santa Clara County, 60 miles southeast of San Francisco, a man-made volcano erupted. A brilliant flame spewed 200 ft. in the air, and a screaming roar rolled across the country, knocking birds to the ground and shaking a helicopter that hovered a mile away. The eruption was over in less than two minutes, but its reverberations would shake more than helicopters. This was the first test of United Aircraft Corp.'s big, new solid-fuel rocket engine, and it was completely successful. Partisans of solid fuel will cite it proudly in claiming for solids a bigger role in the U.S. space effort.

Steered by Injections. U.A.C.'s 120-in. engine is a monster: 75 ft. tall, it weighs 250 tons, and each of its five cylindrical segments contains more rubbery propellant* than an entire Air Force Minuteman. While it burns for nearly two minutes, it gives 1,000,000 lbs. of thrust, three times as much as that of an Atlas. It is steered by injections of liquid nitrogen tetroxide into the white hot gas stream through valves in the sides of the engine's nozzle.

Inevitably, the 120's success reopened the long squabble among experts over the merits of solid fuel and liquid fuel in rocket-engine design. In the desperate effort to produce very large boosters such as those the Russians have, the National Aeronautics and Space Administration several years ago committed the civilian space program to rockets powered by kerosene and liquid oxygen, and its present hopes are pinned on a liquid-fuel engine called the Fl, which North American Aviation, Inc. has been developing for five years. It is a big, impressive machine, which will generate 1,500,000 lbs. of thrust; but though F-1 has completed many successful full-power tests, once in a while it "burns rough," shaking itself with destructive oscillations. No one seems to know what causes this dangerous instability or how to prevent it. Some think the problem is inherent in any liquid-fueled engine of that size.

Interested Spectator. Last week's successful test of the U.A.C.'s engine went far to justify the claim of those who have always argued that solid-fuel rockets can be increased in size much more easily than engines that burn liquids. Solid fuels, in fact, have been the backbone of U.S. military missile power ever since the success of Polaris and Minuteman. Built for the Air Force, the U.A.C. 120-incher is part of Titan III, which will consist of Martin Marietta Corp.'s liquid-fueled Titan II rocket, already operational, with two of the new solid-fuel boosters to help it into space with 2,000,000 Ibs. of thrust.

Titan HI has no definite military mission. The Air Force hopes to use it to launch Dyna-Soar, its controversial steerable satellite that (it is hoped) will be able to maneuver freely in orbit and land where it will. Another Air Force hope for Titan III is MODS: an inhabitable satellite ten feet in diameter with a crew of two or three men.

The dazzling success of the 120 may in the end also give it and its bigger solid-fuel relatives a nonmilitary space job. At last week's test a keenly interested spectator was Democratic Representative George Miller of California, who is chairman of the powerful House Space Committee. Obviously impressed, he said he would try to persuade Secretary of Defense Robert McNamara to give more support to the 260-in. solid-fuel rockets that Aerojet-General Corp. and Thiokol Chemical Corp. are trying to develop with meager funds. If the favored F-1 liquid engine falters, they may yet come to NASA's rescue with their many millions of pounds of thrust, and boost the first Americans to the moon.

* Made of powdered aluminum, ammonium perchlorate and synthetic rubber.

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