'One small step' for man, one massive rocket project for engineers

"A 10% upgrade is significant in engineering terms," said Biggs, a bearish, bespectacled man of 75. "A factor of 10 puts it in a whole new universe."

Big problems

The sheer "bigness" brought on a series of problems, said Biggs, who went to work at Rocketdyne in 1957, fresh out of the Army. The engine was so noisy that engineers had to move it to Edwards Air Force Base in the desert for testing.

A key problem was the start-up. "They had a design for the starting sequence," Biggs said in an interview. "I did the analysis and told them it was no good. The rocket would probably blow up."

Biggs' solution was to slow down the launch sequence. That gave the Saturn V its characteristic feline look, as it seemed to crouch and gather itself for five seconds after ignition before lifting off the launch pad.

The next problem -- and the biggest -- was combustion instability. The F-1's central chamber was so large that the fuel and oxidizer mixed at different rates in different places, causing the mixture to slosh around, which set off tremors that, unless stopped, shook the engine apart. The problem lingered for two years, Biggs recalled.

D. Brainerd Holmes, then head of NASA's Office of Manned Spaceflight, urged engineers to consider scrapping the design altogether.

As it turned out, Soviet scientists were running into the same problem on their moon rocket, the super-secret N-1. Their solution was to discard the idea of using a few large engines on the first stage, substituting 30 smaller engines. But that created problems too, such as synchronizing all those motors.

While other problems, some political, hampered the Soviet program, "it was mostly materials science" that defeated that nation's efforts to reach the moon first, Launius said. "They just didn't have the capability to make their engines work."

After 15 redesigns, including changing the way the fuel and oxidizer were fed into the engine and the installation of baffles to regulate flows, Rocketdyne was finally able to tame its huge engine. "One day, it was suddenly stable," Biggs said.

Next up was a problem with the impeller on the liquid oxygen pump. Individual blades that stirred the fuel and oxidizer kept breaking off and starting fires that burned out the pump. "We had a half-dozen blowups," Biggs said.

"I'm not sure we ever solved that one," he said. "We made some design changes, and the rate of failures began to go down."