Not surprisingly, there hasn't been any news on the development of Hypersoar since the concept was unveiled in 1999. Given the current state-of-the-art scramjet technology and the fact that the X-51 is the first hypersonic air-breathing aircraft to demonstrate sustained hypersonic flight (beyond 12 seconds), maybe the Lawrence Livermore National Laboratory will go back to the Hypersoar concept and build its own technology demonstrator for an air-breathing, hydrocarbon-fueled hypersonic plane to test the feasibility of hypersonic passenger flight. The trouble is, there is no infrastructure for fueling a hypersonic aircraft with methane or any other hydrocarbon, and hypersonic flight requires the use of a combined cycle turboramjet engine to accelerate to Mach 3.7 (at which the turbine is shut down and the pilot turns on the throttle to ignite the scramjet so that the plane can fly to Mach 5.9).