NASA Podcasts

Historic Recordings: KSC Report 4, Mobile Launcher Swing Arms
Interview with Brad Downs
1967
 
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Sound of rockets engines firing

LAUNCH COMMENTATOR:
"Five... four..."

NARRATOR:
KSC Reports... a weekly coverage of events at the National Aeronautics and Space Administration's John F. Kennedy Space Center.

Sound of rocket

NARRATOR:
Almost every visitor to Kennedy Space Center's Launch Complex 39 expresses amazement at the sheer size and complexity of the launch facilities required to send man to the moon. The most massive structure of all is the Vehicle Assembly Building, with nearly 130 million cubic feet of volume. Inside the VAB someday not too far in the future, work may be in progress on several moon rockets at the same time. The moon rockets themselves, metal monsters 365 feet tall, three times more powerful than any previous American launch vehicle, dwarf the hundreds of technicians swarming about at various levels during the assembly and checkout work. These Apollo Saturn V launch vehicles are put together on mobile launchers that provide a platform from which the rocket will lift off for space, and a tower carrying fuel lines, power cables and control circuits, known as umbilicals, because they service the rocket and spacecraft in a manner similar to that of biological umbilicals. The umbilical lines are carried to the vehicle on service arms that bridge the gap between tower and vehicle at nine different levels. Brad Downs, the NASA section chief for the service arms says most visitors don't realize how large these arms are.

DOWNS:
The service arms are 40 to 45 feet in length. The main structure is five feet wide, and they're about eight feet high. In other words, you can walk through the center of the service arms and not bump your head. At the end of these service arms are extension platforms that allow the mechanics and technicians to have access to the inside of the vehicle through hatches in the side. The longest of our service arms is about -- counting everything , the hinges, the environment chamber on the end -- the command module access arm is 85 feet from end to end. It's as big as many bridges were not too long ago. I guess you could say that one is a bridge, couldn't you, a bridge to the moon?

NARRATOR:
The command module access arm used by the flight crew to board their spacecraft is one of four service arms that will be disconnected from the vehicle shortly before the countdown for launch approaches zero. The remaining service arms stay connected until the flight actually begins. Then, all connections must be broken and the service arms swung back out of the path of the rising rocket.

DOWNS:
Well, when the engines ignite, we're still connected with five service arms. The engines come up to speed, the readouts required by the blockhouse are all satisfied, and hold down release occurs. The vehicle is now permitted to fly. Since it has an excess of thrust, it does. It lifts off the launch pad. And we have a switch -- two switches in fact, bearing in mind the need for redundancy -- at the base of the vehicle that tells us that this vehicle has gone. At this point, you need never expect it to return. There's no way to grab it and hold it back to the pad or anything, it's going to fly from here on, so these service arms that are still connected must have an extremely high degree of reliability. These two liftoff switches measure that the vehicle has traveled three-quarters of an inch. They give a signal to the service arms to perform their function. If these two switches should fail us, two more switches come in at 22 inches of rise off the pad. These fire additional equipment and additional circuits to guarantee that the service arms retract.

NARRATOR:
Within four to six seconds, the umbilical lines must disconnect, and the five service arms weighting as much as 40,000 pounds each, swing back out of the way. As many as four different ways to perform each vital swing arm function have been incorporated in the design to insure success when the time comes to break the ties that had nurtured this bird, and it goes roaring triumphantly into the sky atop a tail of fire. LAUNCH COMMENTATOR:
"Five...four..."

Sound of rockets engines

NARRATOR:
This has been KSC Reports... a weekly coverage of events at the National Aeronautics and Space Administration's John F. Kennedy Space Center.

Sound of rockets engines

 
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