Artificial Storms at MSFC Arm Farm Were Prelude to Real Saturn V Drama

Envision the scene -- the director gives the cue -- huge towering structures sway back and forth blasted by torrential rains and hurricane force gales.

One generation might imagine a scene created by Cecil B. DeMille. Another might think of Steven Spielberg.

Not many would think of a back lot at the Marshall Space Flight Center in the mid-1960s, a site that Center Director Dr. Wernher von Braun and his employees called the "Arm Farm."

Today thousands know the Center for its role in developing the huge Saturn rockets that lifted humans to the surface of the moon in the late 1960s. Some also know about the unique facilities the Center developed to handle the task of testing, building, and launching the Saturn V. The Arm Farm, officially known as the Random Motion/ Lift-Off Simulator was one of those unique facilities.

In addition to designing the actual Saturn V vehicle that would carry humans into space, engineers at Marshall had to make sure that the space-bound vehicle would safely and quickly disconnect from a complex array of service cables and feed lines carrying electrical power, propellant, and other elements.

These cables and propellant lines were supported by giant mechanical arms weighing up to 52,000 pounds each and hinged to an umbilical tower taller than the Saturn V vehicle itself. The arms also served as access routes and work platforms for technicians making last minute changes and repairs to the rocket.

The swingarms had to be in place during final countdown, but in the last moments before launch they had to be retracted out of the way to permit the rocket to rise. There was always the possibility, however, of some trouble after the swingarms had been disconnected. For instance, the holddown mechanism would release the rocket only after all five engines of the first stage produced full power. If this condition was not attained within a few seconds, all engines would shut down. In such a situation, unless special provisions were made for reattachment of some swingarms, Launch Control technicians would be unable to safe the vehicle and remove the flight crew from its precarious perch atop the Saturn V.

This made it imperative that the swingarm mechanisms be thoroughly tested long before launch day ever arrived. Instead, however, of trying to completely conduct such an aggressive test program on site at the Kennedy Space Center, NASA decided to replicate a portion of the Kennedy Center at Marshall. There the detachment and reconnection of various arms could be tested under brutally realistic conditions.

The 18-acre swingarm facility built at Marshall had more than a half dozen arm test positions and one position for testing access arms used by the Apollo astronauts. On the Arm Farm extreme environmental conditions (such as a launch scrub during an approaching Florida thunderstorm) could be simulated.

Each test position had two elements -- a vehicle simulator for duplicating motions during countdown and launch, and a section duplicating the launch tower. The vehicle simulator duplicated the portion of the vehicle skin that contained the umbilical connections and personnel access hatches. Driven by a hydraulic servo system, the vehicle simulator produced relative motion between the vehicle and tower.

Some of the simulators were equipped with elevators that duplicated the lift-off of the vehicle. The elevators moved upward for about eight feet to simulate the "breaking" of the umbilical connections at lift-off.

Tower simulators duplicated that portion of the umbilical tower where the umbilical swingarm and the equipment required to retract the arms during launch were located. Cryogenic liquids were pumped through the lines at various positions to give technicians a realistic look at the equipment after it had been chilled down.

Artificial rain was blown by aircraft propellers against the swingarms and their interconnect plugs while the simulated portion of the vehicle was moved back and forth, left and right, simulating the swaying motion that the towering rocket would display during a storm.

Marshall's Alex McCool, a direct participant in the Saturn V program at the Center recalled the critical nature of the testing performed at the Arm Farm. "There was no way in the world we could have flown the Saturn V without this type of ground support equipment and the associated testing," McCool said.

The scenes that the Marshall engineers and technicians created at the Arm Farm were dramatic. But theatrics were completely incidental to the real task of gathering technical and engineering data in advance of the real drama -- launching the mammoth Saturn V launch vehicle from the Kennedy Space Center in Florida.

Back to Top