Vandenberg AFB Space Launch Complex 6

Clark’s completion of the retrofit of Space Launch Complex-6 (SLC-6) at Vandenberg Air Force Base for Boeing created a complex to accommodate the launch of a fleet of Boeing’s new Delta IV rockets on the site of an abandoned Space Shuttle facility in central California.

Elements of the project included a new 650-ton launch table, renovation & modifications to the 325-foot mobile service tower (MST), 270-foot tall mobile assembly shelter (MAS), and the 200-foot tall fixed umbilical tower (FUT). The MST features new moveable-multi-level access platforms and a new 50-foot tall addition on the roof to house the new 50-ton overhead crane. The FUT doubles in size, and has a new 180-foot tall lightening tower on top of the structure and two 90-foot long cryogenic fueling swing arms. Clark also constructed one of the first utilized fixed pad erector to be built in the United States. The erector is a bridge deck that is 165-foot in length and weighs 186-tons, a component that elevates the vehicle from its horizontal to vertical position in lieu of stacking the rocket sections in place.

Clark spent ten months building a 77 x 48 x 24-foot, 650-ton hollow, cathedral shaped structure off-site and outfitted it with a pre-assembled cryogenic utility skid. This structural steel monolith supports the Delta rocket on the launch pad and provides critical blast protection while supplying delicate fuel piping and electrical controls for liftoff. Vacuum jacketed piping and quick disconnect umbilical systems on the launch table supply super-cold liquid hydrogen (-430° F) and liquid oxygen (-360° F) fuel to the rocket.

Several key components of the rocket launch facility were manufactured off-site, and were required to fit together with minute tolerances. For example, the swing arm hinges on the rocket launch table, which were manufactured in Seattle, are 30 feet tall, 100 thousand pounds each and 30 inches in diameter. These hinges had to fit into hinge actuators, which were manufactured in Milwaukee, with the clearance between hinge pin and hinge actuator equal to less than 30 thousandths of an inch (half the width of a human hair). These pieces had to be assembled together onsite, 150 feet above ground.

To make sure that these pieces were manufactured to exact specifications, laser measurements were taken of each piece in both Seattle and Milwaukee. These exact measurements were used to ensure that once the pieces were fit together, the tiny tolerance limit could be met. Prior to delivery at the jobsite, the hinge actuators were shipped to the hinge pin manufacturing plant in Seattle for a “trial run”, resulting in a perfect fit.