BUSINESS FEATURE
Massive Hangar Supports Out-of-this World Mission B Jim ad By Jim Ladesic ich Pre-engineered metal building to house largest aircraft ever built
The largest aircraft ever built will be based at a 103,256-square-foot hangar completed earlier this year at the Mojave Air & Space Port in Mojave, Calif. Burt Rutan, a legend in the aviation fi eld, designed the twin-fuselage be- hemoth that will serve as the air-launch carrier for multi-stage rockets on commercial aerospace mis- sions. Paul Allen, the co-founder of Microsoft and an aerospace enthusiast, has fi nanced Stratolaunch Systems as a startup venture with headquarters in Huntsville, Ala. The company could someday domi- nate the commercial aerospace industry, just as Allen and Bill Gates achieved during the meteoric growth of Microsoft. Wallace & Smith General Contractors, based
in Bakersfi eld, Calif., completed the hangar earlier in 2013, and a neighboring 88,000-square-foot manufacturing and assembly facility in 2012, where the unique aircraft is being built from hybrid com- posites combined with major sections from two retired Boeing 747-400s that will be stripped of their engines, landing gear and electronics for use in the unique plane. The assembly building and the following larger
hangar were awarded as separate design-build con- tracts. CBC Steel Buildings, a division of Nucor, based in Lathrop, Calif., supplied the custom-engineered and fabricated structural framing, standing seam metal roof and metal wall panel systems.
CBC builder earns project referral “We had built several projects at the Mojave airport where we earned a solid reputation for quality and performance,” says Paul Cooper, a vice president with Wallace & Smith General Contractors, Ba-
30 METAL CONSTRUCTION NEWS December 2013
kersfi eld, Calif. “In 2006, [Mojave-based] Scaled Composites, now part of Northrop Grumman [Corp., Falls Church, Va.], was referred to us as a reliable contractor to build two facilities that included the earlier building to manufacture this aircraft.” “Conceptual discussions began in 2006,
but were shelved in 2009 just prior to obtaining permits,” Cooper refl ects. ”The owner came back to us in June 2011 and had us bring everything back on line in a fast-track schedule that enabled us to start construction on December 15 of that year. We had an excellent design-build team and CBC really supported us in refi ning the engineering and meeting delivery schedules. This enabled us to complete the hangar $500,000 under budget and two months ahead of an already challenging schedule without lost-time injuries.” “The savings stayed with Stratolaunch
Systems,” Cooper notes. The two contracts were awarded separately
and involved the same California-based project team led by Wallace & Smith. On the design side, the team included Engle & Co. Engineers, Bakersfi eld, which served as engineer of record. Teter Architects & Engineers, Fresno, Calif., were the project architects. B.D. Compton, Santa Rosa, Calif., provided the steel erection for the 88 truck- loads of heavy-steel trusses, roof and wall cladding systems that were hauled 300 miles at night under police escorts to the project site from the CBC plant in Lathrop. The metal building manufacturer’s building in-
formation modeling (BIM) system was a valuable tool for interacting throughout the coordinated design development, fabrication, delivery and
erection sequence for the 1,500 tons of fabricated steel components.
Large parts of the story The building is confi gured as an inverted-T footprint with the 148- by 462-foot dimension on the larger entry side established by the aircraft’s 385-foot wingspan. A contiguous 135- by 212-foot extension at one side accommodates the tail of the twin-bodied aircraft when parked inside the cavernous hangar. The CBC MS-24 standing seam metal roof
system extends from the 57-foot eave height in a double-slope condition of 2 1/4 inches on 12 inches that steps to a 1/2-inch on 12 inches double slope 30 feet below the 100-foot-high ridge. The space that receives the twin tails of the aircraft has a uniform 1-inch in 12 inches slope from the 66-foot eave to the 72-foot-high ridgeline. Baymarr Constructors, Bakersfi eld, served
as the concrete subcontractor for the foundations and fl atwork. The foundations are 20 feet wide, 7 feet deep and 56 feet long, with 300 cubic yard of concrete poured for each of the main footings. The fl oor construction has varied depth sections from 15 inches at center to 9 inches at each side to 6 inches at the outer wall lines. The fl oor’s varied plane—and different section thicknesses—are necessary to carry the loads from the 1.3-million- pound aircraft. Each section slopes slightly toward cast-in-place trench drains to capture any release from the dual fi re protection systems. The hangar’s wall system consists of 12
18-foot-wide truss columns with I-beam diago- nal bracing that create six frame lines. The rafter trusses were fabricated as 40- to 50-foot-long by
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