Artificial Storms at MSFC
Arm Farm Were Prelude to Real Saturn V Drama
Marshall Space Flight Center Historian
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
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
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
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
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
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.
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