The North American XB-70 Valkyrie is rolled out at Palmdale, Calif. Designed to fly at three times the speed of sound and at altitudes above 70,000 feet, the XB-70 is originally planned as a manned bomber, but funding limitations allow for only two aircraft, to be used strictly for testing and research.
The rate of building B-21 bombers would speed up if the fiscal 2026 defense budget passes. But it remains unclear how much capacity would be added, and whether the Air Force would simply build the bombers faster, or buy more.
