The team also adopted Lockheed’s backbone approach so they wouldn’t have to come up with their own packaging solution. The backbone is an internal structure intended to help manage the packaging challenges and to manage the location of the center of gravity for the spacecraft particularly during reentry into the earth’s atmosphere. “The main difference,” says Kirsch “is that the CCM integrated the backbone system into the primary load bath, and in addition incorporated lobes in the floor between the webs of the backbone, whereas the Orion crew module backbone was nonstructural. Because composites can easily accommodate complex shapes, such as the lobes, it has the potential for a mass savings over a non-lobed shape. Additionally, integrating the floor to the backbone provided an external hard point for the heatshield to interface with, allowing for a more structurally efficient heat shield design. This was one of the knowledge bites we were able to feed back into the Orion program, dropping approximately 1,000 pounds,” he says.
The team also collaborated with experts to refine joint production. “We collaborated with the Air Force Research Laboratory, Lockheed Martin, and Northrop Grumman, and tapped into their experience with the F-35 joint strike fighter by adopting a 3 dimensional woven perform—aptly named for its mathematical Pi symbol shape—called a Pi-joint,” Kirsch explains. The Pi-joint looks like an inverted Pi symbol. The continuous fibers from the composite materials give the Pi-joint its strength, making a very robust and easily manufactured orthogonal joint. Additionally, the team was able to leverage the Pi experience and rapidly develop a four-sided variation, called a cruciform, to enable the orthogonal intersections of the backbone webs.