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Five years ago today, the NASA X-43A scramjet-powered flight research vehicle reached a record speed of over 6,600 mph (Mach 9.68).  In doing so, the X-43A broke its own record speed of Mach 6.83 (4,600 mph) and became the fastest airbreathing aircraft of all time.

In 1996, NASA initiated a technology demonstration program known as HYPER-X.  The central goal of the HYPER-X Program was to successfully demonstrate sustained supersonic combustion and thrust production of a flight-scale scramjet propulsion system at speeds up to Mach 10.

Also known as the HYPER-X Research Vehicle (HXRV), the X-43A aircraft was a scramjet test bed.  The aircraft measured 12 feet in length, 5 feet in width, and weighed close to 3,000 pounds.  The X-43A was boosted to scramjet take-over speeds with a modified Orbital Sciences Pegasus rocket booster. 

The combined HXRV-Pegasus stack was referred to as the HYPER-X Launch Vehicle (HXLV).  Measuring approximately 50 feet in length, the HXLV weighed slightly more than 41,000 pounds.  The HXLV was air-launched from a B-52 mothership.  Together, the entire assemblage constituted a 3-stage vehicle.

The third and final flight of the HYPER-X program took place on Tuesday, 16 November 2004.  The flight originated from Edwards Air Force Base, California.  Using Runway 04, NASA’s venerable B-52B (S/N 52-0008) started its take-off roll at approximately 21:08 UTC.  The aircraft then headed for the Pacific Ocean launch point located just west of San Nicholas Island.

At 22:34:43 UTC, the HXLV fell away from the B-52B mothership.  Following a 5 second free fall, rocket motor ignition occurred and the HXLV initiated a pull-up to start its climb and acceleration to the test window.  It took the HXLV 75 seconds to reach a speed of slightly over Mach 10.

Following rocket motor burnout and a brief coast period, the HXRV (X-43A) successfully separated from the Pegasus booster at 109,440 feet and Mach 9.74.  The HXRV scramjet was operative by Mach 9.68.  Supersonic combustion and thrust production were successfully achieved.  Total engine-on duration was approximately 11 seconds.

As the X-43A decelerated along its post-burn descent flight path, the aircraft performed a series of data gathering flight maneuvers.  A vast quantity of high-quality aerodynamic and flight control system data were acquired for Mach numbers ranging from hypersonic to transonic.  Finally, the X-43A impacted the Pacific Ocean at a point about 850 nautical miles due west of its launch location.  Total flight time was approximately 15 minutes.

The HYPER-X Program was now history.  Supersonic combustion and thrust production of an airframe-integrated scramjet had indeed been achieved for the first time in flight; a goal that dated back to before the X-15 Program.   Along the way, the X-43A established a speed record for airbreathing aircraft and earned several Guinness World Records for its efforts.   

As a footnote to the X-43A story, the HYPER-X Flight 3 mission would also be the last for NASA’s fabled B-52B mothership.  The aircraft that launched many of the historic X-15, M2-F2, M2-F3, X- 24A, X-24B and HL-10 flight research missions, and all three HYPER-X flights, would take to the air no more.  In tribute, B-52B (S/N 52-0008) now occupies a place of honor at a point near the North Gate of Edwards Air Force Base.

Posted in Aerospace, History

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