Davis notes that since Boeing is not bounded by the capabilities of an aircraft that already has been built, the company can tinker with the balance of what learning can be done on the ground and what must be done in high-cost flight hours.

What is unclear is just how much research and development funding Boeing plans to sink into its development before bidding a design to the Air Force. Significant financial pressure at the Pentagon is forcing the service to reduce its R&D spending as much as possible. Boeing may have to underwrite some of its design work, as it is doing with the KC-46A development, to balance out the cost of its design with that of one of the off-the-shelf options flying today.

Company officials declined to outline how far along they are in detailed design work and how much funding they are willing to put into their design for T-X.