X51 Cruise Missile Hypersonique
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X51 Cruise Missile Hypersonique
par Jeannot Dim 21 Mar 2010, 01:42
[url=http://www.aviationweek.com/aw/generic/story.jsp?id=news/awst/2010/03/22/AW_03_22_2010_p58-210968.xml&headline=U.S. Hypersonics Could Hinge On X-51 Tests&channel=awst][Vous devez être inscrit et connecté pour voir ce lien] Hypersonics Could Hinge On X-51 Tests&channel=awst[/url]U.S. Hypersonics Could Hinge On X-51 Tests
Hypersonic proponents worldwide will eagerly watch two long-awaited technology demonstrations starting with the imminent first flight attempt for the X-51 Waverider, to be followed within a month by the first flight of the Falcon HTV-2 hypersonic test vehicle.
Successful flights for both are seen as critical to proving the practicality of hypersonic technology for high-speed weapon, reconnaissance and space-access applications. The X-51 is a Mach 6+vehicle powered by a hydrocarbon fuel-cooled scramjet, and could perform the longest duration air-breathing hypersonic flight in history. The HTV-2 is an unpowered hypersonic glider aimed at gathering rare performance data.
Researchers say success in at least one of the four planned X-51 flights, the first of which could come as soon as Mar. 18, will reinforce the case for follow-on development. The HTV-2 will be boosted on a Minotaur IV Lite from Vandenberg AFB, Calif., to an impact near the Reagan Test Site at Kwajalein Atoll in the Marshall Islands. A launch is planned within an 8-day window—Apr. 20-27.
Preparations for the first flight of the X-51, a joint effort involving the Air Force, Pratt & Whitney Rocketdyne and Boeing, are now complete, says Boeing X-51 program manager Joe Vogel. “The vehicle is ready to go and we’re ready to make it happen.” Originally expected to fly in late October 2009, the test has slipped mainly because of availability of the B-52H carrier aircraft that will launch the X-51 over the Pacific.
Two captive-carry tests were flown in December and January, the second of which “threaded the eye of the storm” through successive weather fronts to fly out over the Point Mugu, Calif.-controlled test range, from which the X-51 will be launched at 50,000 ft. “We can’t fly on a rainy day,” adds Vogel. That is not because of weather; it is done to control test parameters.
Two test vehicles are complete with “just close-out work to do,” Vogel says. The remaining pair, which may have updated guidance software to test possible hypersonic navigation, will be ready “in the next couple of months. We’ve got a lot of confidence it’s going to work as we hope it will,” he adds.
The flight of the Lockheed Martin-built HTV-2 is the first of two planned from Vandenberg. April’s flight, originally due in May 2009, will be followed by a second later this year to evaluate cross-range maneuvering capability and the thermal protection system. The ability of the GPS/INS-guided navigation system to acquire signals through plasma will also be vetted.
The HTV-2 program will be the first beneficiary of an upgrade to the Air Force’s Hypervelocity Wind Tunnel 9 in White Oak, Md. Following a 14-month refurbishment to install a new control system and instrumentation, an HTV-2 model is being used for initial runs of the facility, capable of conducting aerodynamic and aerothermal tests at speeds up to Mach 14.
“Instead of using the traditional 7-deg. cone, we chose the HTV because the complexity of its 3D geometry drives the physics and provides the perfect testbed for us to look at hard problems,” says Dan Marren, director of the White Oak site, which is part of the USAF’s Arnold Engineering Development Center. “After they fly, they’ll come back here to understand what they see in flight.”
Refurbishment has upgraded the facility to a fully digital control system for increased test accuracy, but the biggest change is a new suite of advanced instrumentation that enables the tunnel to be used to investigate the physics of hypersonic flight. Marren says Tunnel 9 had been used mainly to test systems close to being fielded, such as the Theater High-Altitude Area Defense interceptor.
The facility is the highest-pressure wind tunnel in the world, he says, operating at up to 30,000 psi. and temperatures up to 3,500F. The 5-ft.-dia. test cell uses electrically heated nitrogen as the working fluid. Unlike hypersonic shock tunnels, which only run for milliseconds, Tunnel 9 can run at Mach 14 for 1 sec. at high pressures and 15 sec. at low, allowing the model to be moved during a run, changing angle of attack, for example.
The tunnel can replicate the boundary-layer physics of hypersonic vehicles, enabling investigation of the transition between laminar and turbulent flow and the resulting increased heating. The new instrumentation will be key in these investigations.
Special paint on the model is viewed via thermal imager to determine surface temperatures. The HTV-2 tests will be the first time this is used on a model that changes pitch during a run, Marren says. New sensors measure both pressures and frequencies to determine the state of the boundary layer, while focused Schlieren imaging is correlated with the pressure measurements to look closely at the boundary layer and see what is causing the transition to turbulent flow.
Data from the first run of the refurbished Tunnel 9, on Mar. 4, were “outstanding,” says Marren.
Dernière édition par Jeannot le Dim 21 Mar 2010, 01:48, édité 1 fois
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Re: X51 Cruise Missile Hypersonique
par Jeannot Mer 26 Mai 2010, 22:57
Premier vol réussi du X-51A !
[Vous devez être inscrit et connecté pour voir ce lien]Boeing: Hypersonic scramjet sets record in first flight
In its first flight attempt, the X-51A WaveRider Wednesday completed the longest supersonic combustion ramjet-powered flight in history, flying nearly three and a half minutes at a top speed of Mach 5, according to Boeing.
The unmanned aerial vehicle was released from a U.S. Air Force B-52H bomber off the southern California coast around 10 a.m. and flew autonomously for more than 200 seconds, powered by its Pratt & Whitney Rocketdyne supersonic combustion ramjet motor, transmitting telemetry data to ground stations, Boeing said in a news release.
"Something then occurred that caused the vehicle to lose acceleration. At that point, the X-51A was terminated as planned."
Despite the something that occurred, Boeing and Air Force officials touted the test.
"The technology proven today is something The Boeing Company has worked on for the past seven years," Alex Lopez, vice president of Boeing Phantom Works' Advanced Network & Space Systems, said in the news release. "It is thrilling to be a part of history and advance hypersonic science to the next level. Boeing is looking forward to transitioning the technology to operation in the near term, but for now, we are exhilarated."
Charlie Brink, X-51A program manager with the Air Force Research Laboratory at Wright-Patterson Air Force Base, Ohio, said: "We are ecstatic to have accomplished many of the X-51A test points during its first hypersonic mission. This gives us huge confidence. We built four test vehicles to get a successful flight, and we hit many of our goals right out of the gate, the first time around."
Four seconds after being released at approximately 50,000 feet, a solid rocket booster accelerated the X-51A to about Mach 4.5 before it was jettisoned. The X-51A's engine ignited on a mix of ethylene and JP-7 jet fuel and after a short period ran exclusively on JP-7 jet fuel, reaching an altitude of about 70,000 feet.
Joe Vogel, Boeing director of Hypersonics and X-51A program manager, said the test "sets the foundation for several hypersonic applications, including access to space, reconnaissance, strike, global reach and commercial transportation."
The team will review the data from today's test before scheduling additional flights with the three remaining test vehicles, which do not have recovery systems, Boeing said. X-51A is a collaborative effort of the Air Force Research Laboratory and the Defense Advanced Research Projects Agency, with industry partners Boeing and Pratt & Whitney Rocketdyne.
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Re: X51 Cruise Missile Hypersonique
par Jeannot Mer 02 Juin 2010, 11:30
Le premier vol a tout de même eu quelques soucis et la vitesse atteinte ne fut pas celle qui était espérée.
[url=http://www.aviationweek.com/aw/generic/story.jsp?id=news/awst/2010/05/31/AW_05_31_2010_p27-230271.xml&headline=X-51A Team Eyes Results Of Scramjet Flight&channel=awst][Vous devez être inscrit et connecté pour voir ce lien] Team Eyes Results Of Scramjet Flight&channel=awst[/url]X-51A Team Eyes Results Of Scramjet Flight
Following the longest flight yet by an air-breathing scramjet engine, the X-51A Waverider team is waiting to see whether the largely successful first launch of the hypersonic demonstrator will unlock funding for further development of the technology.
The X-51A was launched over the Pacific on May 26, achieving scramjet ignition and acceleration, but the engine ran for only 200 sec. rather than the 300 sec. planned, and the vehicle reached around Mach 5 instead of accelerating beyond Mach 6. When it began to slow down and telemetry was lost, the flight was terminated and the vehicle destroyed, says Charles Brink, U.S. Air Force Research Laboratory (AFRL) program manager.
“We were 95% successful,” he says, adding that the cause of the slow acceleration and short duration is not yet known. Three more X-51As have been built, but their flights are on hold because delays in flying the first vehicle have consumed most of the available funding. The team hopes the flight’s success will unlock new sources of funding and allow tests to resume in 2011.
The Air Force Flight Test Center at Edwards AFB, Calif., had been criticized because of repeated delays caused by the availability of the B-52 launch aircraft, but Brink praises the test team for “putting us on point” for the May 26 launch.
The X-51A booster-and-cruiser “stack” was released by the mother ship at around 50,000 ft. and Mach 0.8. The stack separated cleanly and the booster ignited as planned, taking the vehicle to Mach 4.8, where the cruiser separated and executed a planned roll maneuver.
After slowing to Mach 4.73, ethylene was used to ignite the scramjet, which then transitioned to JP-7 hydrocarbon fuel. The X-51A began to accelerate, but slower than expected—up to 0.15g instead of the projected 0.22g. “We were seeing higher temperatures in the back of the engine bay, but have no idea why,” Brink says.
After reaching around Mach 5, the vehicle began to slow. When telemetry was lost, range safety officials decided to terminate the flight by destroying the vehicle.
The flight was the first using a hydrocarbon-fueled scramjet in which the fuel is used to cool the engine, and the heat is used to crack the fuel so that it will burn when injected into the supersonic flow. The thermal equilibrium achieved allows the engine to operate indefinitely, for as long as there is fuel.
NASA’s scramjet-powered X-43A reached Mach 9.7 in 2004, but its hydrogen-fueled, copper heat-sink engine ran for only 10 sec., then melted.
“The preliminary information shows the engine performed very well,” says Curtis Berger, director of hypersonics for the scramjet’s manufacturer, Pratt & Whitney Rocketdyne. “First time out of the box we achieved the most critical things: lighting on ethylene, transitioning to ethylene and JP-7, getting the JP-7 to condition, going on to JP-7 [alone] and running for 200 sec.” There was fuel remaining when the vehicle was destroyed.
The flight control software “performed perfectly, and this vehicle is completely unstable in all directions,” says Joe Vogel, Boeing program manager. “There is no smoking gun, but we will figure out what the issue is and fix it.” Possibilities could be a seal or actuator failure, or a miscalculation of drag at the lower-Mach “pinch point” at which the flight was conducted.
What happens next will depend on funding. Four identical flights were planned, but because the first was largely successful, it is possible the test objectives could be expanded for the second and subsequent vehicles. Brink says Boeing has proposed modifying the software to demonstrate waypoint guidance, which would be a further step toward proving the technology for application to a long-range strike missile.
Brink says the decision to stand down the next three flights was made to conserve the remaining funds, which run out in July.
“We moved to stretch out the program to maintain the critical skills to October/November,” he says. AFRL does not have any more funds available this year, but Brink is hopeful money will become available is Fiscal 2011. “The success may open other coffers,” he says.
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Re: X51 Cruise Missile Hypersonique
par Jeannot Mer 15 Juin 2011, 22:40
Le deuxième vol du X-51 hypersonique s'arrête prématurément
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Second X-51 hypersonic flight ends prematurely
Second X-51 hypersonic flight ends shortly after scramjet ignition
The second flight of the hypersonic [Vous devez être inscrit et connecté pour voir ce lien] X-51 waverider ended prematurely due to an inlet unstart. The aircraft made a controlled crash into the Pacific Ocean off the California coast on 13 June. The crash is a setback to the revolutionary aircraft program.
After what the US air force described as a 'flawless' flight to the launch point aboard the B-52 mothership, the X-51 was successfully boosted to M5.0 by a rocket booster. The Pratt & Whitney Rocketdyne scramjet engine successfully ignited using its initial fuel, ethylene. During the immediate transition to JP-7, the conventional fuel that makes X-51 unique, an inlet unstart occurred. A subsequent attempt to restart and reorient to optimal conditions was unsuccessful.
An inlet unstart, according to [Vous devez être inscrit et connecté pour voir ce lien], occurs when the shock wave moves too far out front of the air inlet, causing a momentary lapse in airflow to the engine. Scramjet engines depend on extremely precise shock wave movements and engine airflow to function. No wind tunnel can move air at hypersonic velocities, making hypersonic testing extremely difficult.
"Obviously we're disappointed and expected better results," said air force program manager Charlie Brink, "but we are very pleased with the data collected on this flight."
"We will continue to examine the data to learn even more about this new technology," he added. "Every time we test this new and exciting technology we get that much closer to success."
In its first flight, on 26 May, 2010, the X-51 experienced a similar inlet unstart about 110s after the scramjet ignited; the engine recovered successfully, and the flight continued until 143s, when an unrelated seal in the engine failed.
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