The first in a series of bonding milestones was achieved in early December with the bonding of XB-1's right-hand fuselage in Boom's hangar. Successful bonding along XB-1's BL0 splice (from the aircraft nose all the way to the aft pressure bulkhead behind the cockpit) took 2 1/2 hours to cure at 150°F (65°C).

Fuselage is an aircraft's main body section. Think of it as a long tube. In a typical commercial aircraft, the fuselage encompasses sections for passengers and cargo, as well as the crew. In XB-1, the fuselage is more streamlined and includes the cockpit.

Every time an aircraft part is bonded, it must be cured within eight hours. Boom team members rehearse the process several times to ensure that when bonding begins, they can work quickly and efficiently together, with no surprises.

What's BL0? BL0 ≠ butt-line zero. It's a vertical reference plane down the center of an aircraft. Measurements to the left or right are made from BL0. XB-1's forward fuselage is split into 3 sections: left and right halves (along BL0), and upper.

The next step in the bonding process was the bonding of XB-1's cockpit and nose landing gear into the fuselage skin, which was accomplished in late December.