http://www.dsti.net/Information/News/59346
X-51A“乘波者”創造新記錄
2010-05-28
【據英國《飛行國際》2010年5月27日報導】 5月25日早晨，X-51A“乘波者”（Waverider）在加利福尼亞海域上空創造了超燃衝壓發動機最長飛行時間記錄——140秒，此前的記錄是NASA X-43創造的12秒。Point Mugu海軍空戰中心的指揮控制臺由於丟失遙感信號而終止了此次飛行。
X-51A專案由空軍研究實驗室、DARPA和NASA聯合主管。據空軍實驗室X-51A專案經理Charlie Brink透露，Edwards空軍基地第419飛行測試中隊兩名飛行員駕駛的B-52H母機將這架X-51A搭載至49 500英尺（15 088米）的高空，並於當地時間10:10釋放。
Brink稱初步資料表明與B-52H的分離後，固體火箭推進器點火，將X-51A加速至4.8馬赫。推進器在65 000英尺的高度按計劃與飛行器分離，超燃衝壓發動機隨即點火工作。飛行器進一步在70 000英尺的高度加速至5馬赫，展示出令人滿意的導航和控制功能。
提到該專案的原目標是飛行300秒並達到6馬赫時，Brink透露，飛行器利用自身動力飛行了大約140秒時，工程師“發現一些感測器出現異常”。發動機仍然繼續工作，但與地面連接的遙感信號則中斷了，控制人員按要求（遙感信號丟失超過3秒鐘）啟動了自毀程式。
儘管飛行時間沒有達到預期目標，但測試組仍然對結果感到滿意。Brink表示工程師將仔細評估試驗資料以為本財年的剩餘工作做好準備。在吸取了這次飛行的經驗教訓後，項目組可能將在10月或11月繼續展開下一次飛行試驗。（中國航空工業發展研究中心 廖孟豪）
http://www.flightglobal.com/articles/2010/05/27/342468/pictures.html
DATE:27/05/10
SOURCE:Flight International
PICTURES & ANIMATION: X-51A Waverider reaches Mach 5 in 140s scramjet flight
By John Croft
US Air Force and Boeing researchers on 26 May took a leap towards harnessing hypersonic vehicles for space access or weapons applications with the longest-ever supersonic combustion ramjet-powered flight, off the southern California Pacific coast.
The Boeing Phantom Works-built X-51A Waverider achieved 140s burn of its Pratt & Whitney Rocketdyne-built air breathing scramjet engine and accelerated to 70,000ft (21,350m) and Mach 5 before controllers at the Point Mugu naval air warfare centre sea range terminated the mission because of a loss of telemetry.
The previous longest scramjet burn in a flight test was 12s in a hydrogen-based engine in the NASA X-43.
The X-51A was carried to about 49,500ft under the wing of a Boeing B-52H before release. Four seconds later an Army Tactical Missile solid rocket booster accelerated the X-51 to about M4.8 before it and a connecting interstage were jettisoned.
Air Force Research Laboratory X-51A programme manager Charlie Brink says preliminary data shows that the separation from the B-52H was "phenomenal" and the solid booster light was "perfect". At 65,000ft the booster separated from the vehicle as planned, followed by the start of the scramjet engine with an ethylene mix and switchover to JP-7 fuel.
While the programme had a goal for a 300s flight to M6, Brink says that at roughly 140s of powered flight, engineers "started noticing some anomalies with some sensors". The engine continued to run, but the telemetry stream to the ground was interrupted, requiring controllers to activate the self-destruct function.
Despite the shorter flight, the team was exhilarated over the results. "Up until 140s, everything was working textbook, per calculations", says Joe Vogel, Boeing's X-51A programme manager.
In M5-plus hypersonic flight, heat and pressure make conventional turbine engines impractical. A scramjet's great advantage is the ability to capture and burn oxygen in thin atmosphere, rather than having to carry it in a large tank like other rockets. Not having to carry the oxidizer needed for combustion means more payload capability.
Brink says engineers will review data for the rest of the fiscal year and the programme is likely to pick up with flight tests in October or November, incorporating any required lessons learned from the 26 May flight.
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