How Tennis Shoes and Tug-of-War Toppled the Mighty Saturn V
The Saturn V 500F rocket rolls out of the Vehicle Assembly Building (VAB) on May 25, 1966 at NASA's Kennedy Space Center in Cape Canaveral, Fla.
Credit: NASA.

The year was 1966 and NASA was testing its first fully-assembled, 36-story tall Saturn V moon rocket at its launch facilities in Florida. Despite the threat posed by a hurricane and a ruptured fuel line, the trials with the sky-scraping booster had gone well and it came time to separate the Saturn into its five stages in the voluminous Vertical Assembly Building that had been erected for that very purpose.

But NASA engineers had another idea: though the 363-foot (110-meter) tall rocket had been analytically designed to be structurally stable, they saw the opportunity to gather some real world data about how the booster would react to vibrations imparted by wind and other outside forces.

So, they proposed to set the Saturn swaying. And what better way to do that than to exert force on the tower by having one group lie on their backs and push with their feet while another pulled a rope tied to the opposite side?

Really, what possibly could go wrong?

Setting the stage for Saturn

The first Saturn V rocket was never destined to launch to the Moon, let alone leave the ground.

Assigned the designation SA-500F, the full-size but not flight worthy rocket was designed for use as a facilities demonstrator. Before NASA could launch a Saturn V, the agency's engineers and technicians needed to test the equipment that would be used to assemble, transport and prepare the booster for liftoff.

On May 25, 1966, 500F made its first trip out to the pad atop a crawler transporter (the same pad and crawler are still in use today by the space shuttle). Testing continued successfully throughout the summer, only interrupted by a series of minor problems.

On June 8, the Saturn V was rolled back into the Vertical Assembly Building (VAB) temporarily as Hurricane Alma moved close to the Florida coast. As the winds remained below critical levels, the ground crew expressed surprise by the order to return the rocket to its shelter. The general consensus among workers was that the center's director, Kurt Debus, had called for the roll back as an opportunity to practice a maneuver not yet tried.

Ray Byrd, a Boeing mechanical systems engineer for the Saturn V's first stage, remembers spending a lonely night monitoring pressures in the rocket as it was returned to the VAB. There were concerns related to maintaining the integrity of the stack were the pressures to fall. Byrd sat alone on the crawler beneath the booster as it swayed in the driving rain and high winds.

Another Boeing engineer, Art Scholz, was stationed as an observer in a cab on top of the mobile launcher platform, where he reported measured wind velocities. Byrd recalls the fear in Scholz's voice as he called back during gusts.

Byrd, Scholz and the 500F made it safely inside the VAB that evening and two days later, on June 10, the rocket returned to the launch pad for further fuel loading tests.

During propellant loading trials on Aug. 19, an 18-inch (46-cm) liquid oxygen (LOX) feed line ruptured, dumping 800,000 gallons (three million liters) of fuel from the storage tank at the pad. The loss of propellant caused the inner shell of the LOX storage tank to collapse inwards 16 feet (4.8 meters). Re-pressurization of the tank popped it back out again.

Testing with the rocket was completed at the pad and on Oct. 14, it was brought to the VAB to be destacked. There were tentative plans, never realized, to reassemble SA-500F and repeat the facilities checkout operations at the other Saturn launch pad, 39-B, the following summer.

Tennis shoes and tug-of-war

What happened next may never have been known -- let alone believed -- had a long-lost film clip not surfaced...

Continue reading at collectSPACE.com to learn the outcome of the 'Tennis Shoe Test' and to watch the video.

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