Old Reliable

The old-reliable Model A Ford of transportation to the high atmosphere is the Nike rocket motor. Like the old Fords, some of the Nike rockets flown at the Poker Flat Research Range near Fairbanks are vintage-class vehicles. As they emerge from packing crates, they display markings showing manufacture dates as far back as the early 1950's.

Nike rockets originally were mass-produced for military purposes, the prime use being for ground-to-air flights against aircraft. They are no longer manufactured. Some years ago NASA and other civilian agencies acquired the remaining several hundred Nikes for scientific rocket flights.

A Nike rocket is used mostly as the first stage of a two-stage vehicle intended to carry 80- to 300-pound payloads to altitudes ranging from 60 to 200 miles. If the system falls to work properly, the fault usually is in the performance of the newer second stage and almost never with the old military surplus Nike.

At launch a Nike weighs in at about 1300 pounds, is 16 inches in diameter and is 12 feet long. Hotter than any dragster, the Nike goes from 0 to 1600 mph in less than 4 seconds flat. Then, it has risen a mile high and is nothing more than a hollow tube with fins, all its fuel being spent. A few seconds later the Nike ends its first flight--also its last--by crumpling into the ground a few kilometers downrange from the launch site. By then the burning of its separated second-stage motor has increased the vehicle speed to about 4500 mph. That speed enables the second stage and its attached payload to coast to an altitude of 150 miles.

The fuel of a Nike is a rubbery black solid formed from a liquid poured into the steel rocket shell and cast into place leaving a star-shaped central hole extending the full length of the motor. An ignitor at the front end initia tes burning that almost immediately extends to the confining nozzle at the rocket's rear. Burning proceeds from the central hole outward toward the rocket case; at any instant the remaining unburnt fuel helps shield the case from the hot gases inside.