As we referenced earlier today, the Air Force's X-51A Waverider hypersonic test vehicle is now two-for-two when it comes to test flights being cut short.
On June 13, the Waverider was dropped from a B-52 at 50,000 feet and it was successfully boosted by a rocket to Mach 5 where its scramjet engine ignited on ethylene. Things went wrong when it tried to transition to the deliberately tough to ignite JP-7 jet fuel (originally developed for the SR-71 Blackbird). Apparently, the JP-7 wouldn't light despite several attempts to do so and the craft glided itself into the Pacific Ocean in the waters of the Navy's Point Mugu test range off the California coast.
From an Air Force announcment on the "less than successful flight test":
According to Charlie Brink, the Air Force Research Laboratory's X-51A program manager, AFRL, Boeing and Pratt-Whitney Rocketdyne engineers are reviewing the large amount of telemetry data collected during the test flight to identify the cause of the anomaly.Last year's test flight saw the scramjet ignite but a manufacturing flaw led to hot engine gas seeping into the airframe after it had flown for143 seconds at a max speed of Mach 5. The gasses fried the aircraft's control and telemetry circuits; cutting off communication with test controllers whereby range safety officials hit the kill button causing the craft to self destruct. That flight was supposed to last 300 seconds and engineers hoped the vehicle would reach Mach 6.
"Obviously we're disappointed and expected better results," said Brink, "but we are very pleased with the data collected on this flight."
"I am extremely pleased with the AFFTC and Point Mugu's support and execution of this complex flight test mission as they provided us every opportunity for success in this endeavor," said Brink. "We have attempted two scramjet experiments now where one successfully lit, and one did not."
"We will continue to examine the data to learn even more about this new technology," he said. "Every time we test this new and exciting technology we get that much closer to success."
Boeing and Pratt & Whitney Rocketdyne built four X-51A flight test vehicles with the program goal of reaching Mach 6 in hypersonic flight. The next flight is tentatively schedule for fall 2011.
This week's flight was originally slated for late March but was scrapped at the very last minute due to unknown issues with the test range.