NASA's X-43A Hyper-X Reaches Mach 10 in Flight Test
Aviation Week & Space Technology, 11/22/2004, page 24
Michael A. Dornheim
Edwards AFB, Calif.
Tests to continue with military, but NASA's role becomes unclear
Mach 10, But Now What?
A number of hypersonic-related programs are drawing confidence from the back-to-back successful flights of NASA's X-43A research craft that show scramjet operation at Mach 7 and Mach 10.
Last week's free flight at Mach 10 was especially important because it's difficult to test on the ground at that high speed. An early look at the data suggests that a series of 0.005-sec.-duration reflected shock tunnel runs did a very good job of predicting the flight, says Robert Bakos, vice president of ATK GASL in Ronkonkoma, N.Y.
Those two results--that the engine/ airframe combinations produced usable thrust, and that their behavior was close to analytical and wind tunnel predictions--should give a boost to other programs that haven't flown yet by increasing confidence in the validity of their designs, says Anthony Castrogiovanni, ATK GASL president. "Hopefully today's flight, showing it can be done twice, will trigger Defense Dept. interest," he said after the Nov. 16 test. ATK GASL, along with NASA Langley Research Center, was responsible for the X-43A "Hyper-X" design, and the company built the 12-ft.-long craft at its facility in Tennessee.
The first 12-ft.-long Mach 7 X-43A displays its lines during ground testing. Copper-colored engine is on bottom, and 800-lb. steel-colored slab of tungsten ballast at nose is surrounded by reinforced carbon-carbon leading edge. The Mach 10 version has more heat protection.Credit: NASA/TOM TSCHIDA
By having an integrated engine and airframe in free flight at operational conditions, Hyper-X has gone "orders" beyond what has been accomplished previously with scramjets, he says. Other tests have been mostly on the ground or, if in flight, fixed solidly to the front end of a booster rocket or were not an integrated vehicle.
Despite the apparent X-43A success, NASA has no funded scramjet follow-on program to capitalize on the new knowledge and retain the expertise. The three-flight Hyper-X program cost $230 million, and that would increase if it were all under the current "full cost" accounting system.
A team of officials from the Langley, Dryden, Glenn and Ames research centers are proposing a "modest but aggressive spiral development approach" of scramjet activities working with the Defense Dept. and universities, says Vincent L. Rausch, the Hyper-X program manager at Langley. Individuals working the final test showed frustration at having many years of work come to a halt as they finally obtained promising flight data. Rausch and others have proposed working toward a scramjet first stage for space launch (AW&ST Nov. 1, p. 56).
The Nov. 16 launch had been delayed several times, most recently on Nov. 15 when malfunctions required rebooting the X-43A computer twice. Each reboot took 40 min., pushing the flight beyond available range time and daytime landing requirements for the B-52B carrier aircraft of NASA Dryden Flight Research Center here. Dryden conducted the flight test, and it was the last research flight for the venerable "008" B-52B, which has been dropping test aircraft since 1959. Boeing Phantom Works did systems engineering, thermal protection, guidance, navigation and control design, flight control software and internal layout and structural design.
The X-43A was mounted on the front of a modified Orbital Sciences Pegasus launcher first stage. The stack, weighing 43,000 lb., was carried under the right wing of the B-52B and dropped westbound at 2:34 p.m. PST over the Pacific Ocean at 40,000 ft. from a point about 50 mi. off the southern California coast. The solid rocket motor took the stack up to the Mach 10 starting condition at 110,000 ft.
At 7-8 sec. after motor burnout, pistons pushed the X-43A forward away from the booster at Mach 9.8, and the X-43A's higher density made it pull ahead. Very little tipoff was observed at separation, unlike the Mach 7 flight on Mar. 27 that had noticeable tipoff, and drag and lift higher than expected (AW&ST Apr. 5, p. 28). Engineers learned from that and were able to correctly adjust for the faster condition.
The engine inlet was closed during the entire boost, but 2.5 sec. after separation the door opened downward to become the lower inlet lip. At 3 sec. after separation, the engine started firing at a speed of Mach 9.65 at 110,000 ft. with a dynamic pressure of 1,050 psf., or 557 kt. equivalent airspeed. It was still in a 2.1-deg. climb from the booster path.
The gaseous hydrogen fuel was on for 10-12 sec., says Randall Voland, the scramjet propulsion team lead at Langley. The first 4 sec. of firing included the pyrophoric chemical silane to ensure ignition, and the hydrogen ran at two flow rates to check different mixture ratios. The flow rates were repeated with silane off for comparison, and the flow then tapered down as hydrogen supply pressure ran low. The engine ran air-only for 8-9 sec. to check fuel-off characteristics, and at 21 sec. past separation the inlet door closed for the rest of the flight.
The craft descended at an approximately constant dynamic pressure and conducted maneuvers at decreasing Mach numbers to compare aerodynamic characteristics against predictions. A Navy P-3 downrange received telemetry for at least 14 min. after separation, which is likely the point at which it hit the ocean after traveling about 850 mi. The craft sank and there are no plans to recover it.
The X-43A was controlled to about 1 deg. angle of attack (AOA) to meet design conditions for the engine run, but the AOA for lift to match weight was about 5 deg., Voland says. A higher angle would have increased drag but also increased shock wave compression and engine efficiency, and good performance is a balance of factors like these, he adds.
Project officials say early data show thrust was about the same as drag, as expected. They note that the X-43A derives from a Mach 10 cruiser design by McDonnell Douglas, implying that this level of "cruise" thrust is what was planned. However, given that the inlet was operating at an AOA that would not support the weight of the craft, countered by the X-43A being an unusually heavy test vehicle, it's hard to translate "thrust equals drag" into anything meaningful for an operational aircraft.
Nevertheless, 3.8 lb. of hydrogen were burned during the 10-12-sec. period at a bulk fuel/air ratio that was 20-30% richer than stoichiometric. Given uncertainties in the airflow, the mixture was intentionally fuel-rich to avoid lean-burning, Voland says. The speed of sound was about 680 mph., and flying at Mach 9.6 for 12 sec. covered 18.9 naut. mi., giving 5 naut. mi./lb. of hydrogen. Since hydrogen has about three times the specific impulse of kerosene, that translates into 1.7 naut. mi./lb. on jet fuel. Gross weight was 2,860 lb., or about the weight of a Cessna 182, which gets about 2 naut. mi./lb. on gasoline.
THE HIGHER SPEEDS compared with the last flight produced a real-gas stagnation temperature of about 5,500F and surface temperatures up to 3,600F on the nose, and heating rates twice as high. The prior flight had a peak of 2,600F on the wing leading edges. Thermal beefup included changing from hollow structure on the vertical tails to solid reinforced carbon-carbon leading edges. A hafnium carbide coating was added to leading edges, and the vehicle nose was made blunter for a more detached bow shock to reduce heating. Thicker thermal protection was used on the engine, and water cooling passages in the cowl leading edge were changed.
Engine height and flow lines were altered for the different shock wave pattern at Mach 10, and there is new controller software for the engine and airframe.
Ongoing programs that will be looking at Hyper-X results include Navy and Air Force efforts to make a fast strike missile that can cover 600 naut. mi. in 10 min., or an average speed of 3,600 KTAS or about Mach 6. An important difference from Hyper-X is that the military programs use essentially kerosene fuel, which is harder to burn than hydrogen but is much more dense. The Defense Advanced Research Projects Agency and the Office of Naval Research have a HyFly program that's set to flight test in 2005 a dual combustion scramjet engine integrated to an airframe that will free-fly in powered Mach 6 flight for about 30 sec. after being released from a booster.
The Air Force HyTech program plans to demonstrate a flightweight integrated scramjet in a ground test for several minutes next year. The engine will have fuel-cooled structure, and engineers will be checking whether it can survive the minutes of running required to meet the fast-strike goal, as well as performance and ease of operation. Part of the technology is to manage the cooling heat flow to crack the JP-7 fuel into desirable quick-burning gases like ethylene and hydrogen, Castrogiovanni says.
The flight test portion of HyTech is called Scramjet Engine Demonstrator, which may fly in 2008.
ATK GASL is working with Darpa and the Army on the ScramFire program to add scramjet boost to Army and Navy gun shells, from the 120-mm. Abrams tank round to a 5-in. naval shell. A solid propellant gas generator provides fuel for the scramjet. The idea is to have more impact velocity for the Army and extend the range up to 140 naut. mi. for the Navy.
Scramjet uses shock waves (red lines) to compress and decelerate flow to conditions that are still overall supersonic in the combustor. The isolator length is intended to prevent transient combustion pressures from disrupting the upstream shock train. The test ran at a low 1 deg. angle of attack to ensure the nose shock was not swallowed by the lower cowl, and a higher AOA would have been more efficient but riskier. At the prior Mach 7 test, the shock pattern had mostly dissipated at the combustor, but at Mach 10 the shock waves are lively throughout the engine.
Darpa is working with the Australian HyShot team to make a Mach 10 flight test next year, again using a powered engine attached to the nose of a booster rocket (AW&ST May 24, p. 13).
Instead of trying for an essentially impossible goal like the defunct National Aero Space Plane program's attempt at single stage to orbit, "the overall focus now is on affordable experiments," Castrogiovanni says.
I wonder if the real purpose of the program is to develop a hypersonic terminal cruise reentry vehicle. I mean, suppose as a way of defeating normal anti-ballistic missile defense of using a highly menuverable Reentry Vehicle carrying a nuclear warhead. The vehicle reenters the earth's atmosphere at a point, say 1000 km from the target area, and then uses a menuverable hypersonic cruise phase to manuver to the desired attack point. By coming in low and hot (below ABM or space based defense cover) but above normal air defenses, this could provide a means to deliver a highly lethal payload to knock out enemy defenses in preperation for an attack.
Hmmm...if this is so, then I can think of only one "former" enemy with the technical means to achieve ABM defense: Russia [the North Koreans can't do this--the Iranians are still somewhere at phase one ballistic missile stage. China perhaps, but they don't seem credible as they are only thought to possess 20-50 ICBM's.] The Russians have just announced that they will field a new type of "unusually accurate" ballistic missile. And who would they be shooting them at? Maybe the Cold War isn't quite as "Over" as we would all like to think.
But the Russian economy is in such tatters, that even if they succeed in developing such an RV, they will not be able to field them in great numbers. IMO, this is just propaganda intended more for internal consumption, to keep the generals happy and thinking that they're still in charge of a superpower....
I would only differ slightly on the technical details -- for the type of maneuverable RV you describe, I don't think you need a scramjet -- a hypersonic waverider-type vehicle, unpowered, would do the trick quite nicely (I believe that Nazi rocket scientists had the same idea over half a century ago).
The Russians have however tested missiles with nose-mounted scramjets. I believe those were meant to be developped into intercontinental missiles with below-horizon approach trajectories -- not all that different from FOBS, fractional orbital bombardment system.
Its just unfortunate that the Putin gov't thinks it necessary to make these ridiculous financial sacrifices to the military, when their economy can so ill-afford it. Who knows, maybe they won't even give them adequate funding to make much development progress, never mind deployment..... Anyway, I'm not too concerned about it. As long as we're making good progress in the "megatons to megawatts" program of converting Russian nuke warheads (or even just surplus fissile materials) to commercial nuclear fuel, I think we're on a generally correct track.
Agreed on the "Megatons to Megawatts" program--better to illuminate cities with the light of a million lightbulbs than the "Light of a Thousand Suns!"
Menuverable RV's could be a way to develop hypersonic missiles. I think the US Air Force was looking at something like this years ago for the Mach 7 regime--a long range missile capable of 100nmi+ intercepts--something akin to the US Navy's Pheonix missile only more menuverable.
I think the whole notion of a NASP (National Aerospace Plane) is pretty much bunk--I don't think Concorde ever did become profitable during its whole 30 year lifetime.
I think the primary value of the X-43A was to verify which set of Computational Fluid Dynamic Model Parameters most closely matched the test flight. In this way--they were verifying the validity of their "Digital Windtunnel" probably for bigger programs that have yet to be disclosed. If you have to spend a billion dollars on a flight prototype (because no windtunnels exist that are big enough and powerful enough for the test)--you want to atleast be somewhere in the ball park, instead of driving around in the dark wondering where the field is....
Hmmm -- might you be refering to the HyFly program ?
Aviation Week & Space Technology09/02/2002
New Powerplant Key To Missile Demonstrator
STANLEY W. KANDEBO/NEW YORK and WASHINGTON
Darpa and the Office of Naval Research are betting on a dual combustion ramjet that can operate up to Mach 6.5
The Defense Advanced Research Projects Agency and the U.S. Navy plan to air-launch a powered, prototype hypersonic missile off the coast of California in late 2004 as part of a technology development and validation effort that eventually could lead to the procurement of a production version of the weapon later in the decade.
Dual combustion ramjet was fully integrated into this uncooled, nickel-alloy "missile" body and successfully run using hydrocarbon JP10 fuel. The tests were conducted in NASA Langley's 8-ft. high-speed wind tunnel under simulated speeds of Mach 6-6.5 and at angles of attack of 0 and 5 deg.
The proposed Mach 6 missile would be carried by surface ships, submarines and aircraft initially to combat highly mobile, time-sensitive surface targets like mobile Scud launchers. Eventually, the weapon also could be used against hardened, buried and heavily defended targets, according to U.S. Navy officials.
The four-year HyFly (hypersonic flight) demonstrator project evolved from existing Navy hypersonic efforts and from Darpa's ARRMD, or affordable rapid-response missile demonstrator.
HyFly has existed as a Darpa/Office of Naval Research (ONR) program only since February, but the project has made substantial gains since its formal creation. First and foremost among them was the successful completion in late July of a series of free-jet wind tunnel tests that exercised the proposed weapon's hydrocarbon-fueled dual combustion ramjet (DCR) at hypersonic speeds, with the powerplant fully integrated into a flight-representative aero-shroud or missile body.
During the trials, the nominally 168-in.-long, 19-in.-dia., uncooled, full-scale hypersonic missile body and its integrated DCR powerplant were tested over a speed range of Mach 6-6.5 and at angles of attack of 0 and 5 deg. The tests were run in the 8-ft. high-speed wind tunnel at NASA Langley Research Center. The nonflight-weight missile, which was constructed primarily of nickel alloys, was fitted with a working, dual combustion ramjet engine running on liquid JP10 hydrocarbon fuel to verify the powerplant's installed operability at realistic hypersonic flight conditions, said Darpa's Preston Carter,HyFly program manager.
Engineers measured a net positive thrust with the engine, which has exactly the same flowpath as anticipated for a flightworthy engine. This powerplant, and the flight-weight engine will differ, however, in materials of construction.
"The tests were successful, and we met or exceeded our projected performance and operability goals," Michael E. White said. He is program area manager for advanced vehicle technologies at The Johns Hopkins University Applied Physics Laboratory. APL originated the DCR concept, and it is a lead technical adviser for the HyFly development team.
The Navy expects to deploy production hypersonic missiles on surface ships, submarines and aircraft. The Mach 6-class weapon would have a 400-600-naut.-mi. range.
NEXT ON THE AGENDA is running the test "missile" at USAF's Arnold Engineering Development Center (AEDC) near Tullahoma, Tenn. Those tests, which will begin later this month and run through November, will examine missile and DCR operability in the low-speed, Mach 3.5-4.0 flight regime. Researchers will use the same nonflight-weight "missile" as was employed in the earlier studies at NASA Langley.
Once those tests are complete, the missile design team will refine its concepts with the wind tunnel data it has collected, and begin work on a flight-weight configuration for the weapon. Testing of a flight-weight missile, fitted with a flight-weight powerplant, should get underway at AEDC's Aerodynamic and Propulsion Test Unit (APTU) in early 2004. Long-duration missile tests will take place at that time, with tests running as long as 5 min. The Air Force is currently upgrading its existing facilities to accommodate the extended, high-Mach testing.
Direct-connect combustor tests at APL's Avery Laboratory hypersonic wind tunnel complex also are supporting the hypersonic missile project. According to university officials, more than 150 tests have been conducted with this rig to examine the operating characteristics of a full-size DCR combustor. The tests, which are focused on the DCR's Mach 3-6.5, 85,000-95,000-ft.-altitude operating regime, began in 2000 and will continue to run for "some time."
THE DUAL COMBUSTION ramjet was invented by the APL in the early 1970s. The DCR differs significantly from both a pure ramjet and a supersonic combustion ramjet of the type being jointly pursued by Pratt & Whitney, the Air Force and NASA.
Ramjets typically operate in the Mach 3-5 flight regime. In flight, air entering the powerplant is compressed by the engine inlet and slowed to subsonic speeds to raise the pressure and temperature so that combustion can occur. Fuel is added to this subsonic air, and the mixture is ignited. Combustion products are then allowed to accelerate through a converging/diverging nozzle at supersonic speeds, generating thrust. Above Mach 5, the inefficiencies associated with slowing the air for mixing and combustion are large and result in a loss of net positive thrust.
In contrast, a supersonic combustion ramjet, or scramjet, begins to operate at flight speeds of around Mach 4-4.5 and, theoretically, can continue to operate up to about Mach 25. In this powerplant, supersonic air entering the engine inlet is mixed with fuel under supersonic conditions, ignited and expanded to create thrust. But getting the fuel-air mixture to ignite when mixing time is less than 1 millisec. is extremely difficult. Early scramjet researchers used highly reactive fuel additives to enhance the mixing and combustion process, but these chemicals can't be used on board ships or submarines because the materials are highly toxic. Researchers also have used hydrogen as a scramjet fuel, but that element's high volatility makes it hard to handle safely, ruling it out for shipboard use.
Darpa/ONR hypersonic missile demonstrator has a nominal 168-in. length and 19-in. diameter. At front, left, is James Keirsey, inventor of the dual combustion ramjet, with others from The Johns Hopkins University Applied Physics Laboratory.
To overcome these problems, Pratt & Whitney, working with the Air Force and NASA, is developing a scramjet powered by conventional, unadulterated, liquid hydrocarbon fuels such as JP7. To accomplish this, they direct the liquid fuel through the scramjet's walls and use the heat generated by supersonic and hypersonic flight to "crack" the JP7 into "lighter," more volatile components. These gaseous components are then introduced into the supersonic airstream and ignited, producing thrust (AW&ST June 24, p. 95).
APL's dual combustion ramjet is yet another way to obtain hypersonic speeds. In this powerplant, supersonic air ingested through one inlet is slowed to subsonic speeds, mixed with a conventional hydrocarbon fuel in a fuel-rich environment and ignited, as in a ramjet. To break through the ramjet's operating speed limitations, though, the expanding combustion products are then mixed with supersonic air entering through a second inlet and are more completely burned in a supersonic combustor. According to APL researchers, the DCR has an operating threshold of about Mach 3, and a maximum operating speed of about Mach 6.5.
Observers of the Navy and Air Force hypersonic programs note that there are some significant differences between the two. First and foremost is application. The USAF/NASA effort is aimed at satisfying propulsion requirements for reusable platforms as well as one-time-use weapons, while the Navy is fixed on developing a powerplant exclusively for hypersonic missiles. This means the USAF system probably will have levels of complexity and redundancy that are unnecessary for a single-use weapon.
And--since the Navy's hypersonic missile will be carried by surface combatants and submarines--a whole host of Navy-unique restrictions has to be considered. For example, missile size is a critical issue.The weapon needs to fit into the vertical launch systems of surface ships, into the canister launch systems of submarines, and under the wings of the F/A-18 Hornet. That imposes strict limits on the weapon's length and diameter. Taking this one step further, it means that even the most fundamental aspects of weapon design, such as the missile's shape, must be closely scrutinized.
Navy officials say that the heat-absorbing, hydrocarbon-fueled scramjets being pursued by the Air Force tend to be rectangular in cross section, and notional Air Force hypersonic missiles are likely to have a shovel-nosed, wave-rider or lifting-body shape. They also say that a naval weapon needs to be virtually tubular to fit into the launch equipment already in use on ships and submarines, and that the uncooled, axisymmetric shape of the DCR is a good fit with this requirement.
Navy officials also say that since the threshold speed of a future missile's hypersonic propulsion system largely determines the length and size of its solid rocket booster, the powerplant that can operate at the lowest possible speed would likely be the best for them, because it would require the smallest booster. They note that in this respect, the DCR also is a good match because it has an operating threshold of about Mach 3, versus Mach 4-4.5 for the scramjet.
Navy officials are quick to point out, however, that they are not knocking the scramjet. It is, they observe, simply a matter of different propulsion systems satisfying different requirements.
Navy plans for the hypersonic missile call for full-scale wind tunnel tests of a flight-weight demonstrator missile in early 2004. These will be followed by 11 flights of a full-scale demonstrator version. The first three trials will essentially be drop tests and rocket booster demonstrations. The missile will fly under its own power using its DCR during the final eight trials.
Several flights of a subscale, liquid-fueled, DCR-powered version of the missile mounted on a sounding rocket also are anticipated. Performed by Allied Aerospace, they'll be made about six months prior to the first full-scale demonstrator flight.
"The subscale flights will help us develop scaling data so we can design DCR-powered weapons of different sizes," White said. "These subscale tests can be seen as risk reduction too, but they're not critical to the full-scale demonstrator flights."
Full-scale flight tests using an F-4 launch aircraft will be conducted in the Pacific Missile Test Range off Point Mugu, Calif. The first of the airborne tests should prove that the unpowered demonstrator can safely separate from carrier aircraft.
THE SECOND AND THIRD missile tests should show that the demonstrator's off-the-shelf, solid-propellant rocket can accelerate it to the DCR's Mach 3 operating threshold. The tests also are aimed at verifying that once expended, the booster--formerly used in the SLAT (supersonic low-altitude target) effort--will separate from the missile as planned.
Flight tests in which the DCR will be exercised are expected to begin late in 2004 and extend through early 2006. "We'll start by making short-duration, lower speed flights at about Mach 4 and then push up to longer range flights that reach peak speeds of Mach 6," White said. Nominal launch conditions for the demonstrator will be Mach 0.85 and 35,000 ft. Cruise conditions are Mach 6 at 90,000 ft. Flight tests also will be used to show that the demonstrator can dispense submunitions.
"We won't guide the submunitions, but we will demonstrate that we can dispense them from the right point in the sky," Gil Graff said. He is a program manager for weapons technology and HyFly deputy program manager at the ONR. Evolving plans now indicate that as many as three submunition-dispensing trials may be performed.
At the conclusion of the flight tests, "we should have demonstrated--in flight--everything necessary for a production weapon, including the materials, propulsion system and guidance equipment," White said. Guidance for the demonstrators and any production weapons will be GPS-based. Future weapons also may carry a communications link so they can be retargeted in flight.
Ship- and submarine-launched production weapons probably would be about 256 in. long and weigh around 3,800 lb., including an expendable, or "tandem," solid rocket booster, while an air-launched weapon would weigh approximately 2,300 lb. and be about 183 in. long. All proposed production configurations, unlike the demonstrators, also will have a "slip-in" solid rocket motor that fits within the body of the missile and is jettisoned once expended. Missile length, without the tandem and "slip-in" boosters, is 168 in. "Slip-in" booster development is not actively being pursued at this time because it could divert resources from the critical DCR effort, officials said.
The range of a ship-launched weapon would be about 600 naut. mi., while air-launched weapons would have a 400-naut.-mi. range. The payload of each will be "in the hundreds of pounds."
Two sets of inlets would be located circumferentially about the weapon's nose. One set will direct air into the DCR's gas generator, or ramjet combustor, while the other will port air to the DCR's supersonic combustor.
Production weapons would be fabricated primarily from titanium. "Darpa's ARRMD program demonstrated the key materials and fabrication techniques that will be used to produce this weapon," Graff said. In fact, in 1999, Precision Cast Parts made a single-piece titanium casting that would be the main body of this weapon, officials said.
As for the DCR, it will rely on ceramic matrix composites from "tip to tail," and a flight-weight engine will probably have fewer than 10 parts total, according to Adam Siebenhaar, HyFly chief engineer at propulsion contractor Aerojet.
BOEING'S PHANTOM WORKS is lead contractor for the HyFly effort and was awarded a four-year, $92.4-million contract in May to design, test, develop and produce the flight demonstrators, with most of the work being conducted in the St. Louis area. Boeing plans to hold its preliminary design review in January 2003, and to follow this with the critical design review in September 2003, John Fox said. He is Boeing's HyFly program manager.
Aerojet has a $43-million contract from Boeing to develop and manufacture 14 flight-test DCRs for the demonstrator missile project. Six of the powerplants will be used for ground tests, while the balance will be used in test flights. Aerojet said it was selected for the HyFly program because it has broad experience with solid- and liquid-fuel rockets and with airbreathing propulsion.
"Bringing this to bear in the area of air-breathing hypersonic propulsion is one of our unique strengths," Charles Beaudry, Aerojet's HyFly program manager, said.
NASA counts some $426 million in earmarks--unrequested spending ordered by Congress--in its $16.2-billion appropriation for Fiscal 2005 (see p. 37). Much of that money must be spent on pork-barrel projects in the $500,000 to $1 million range, but one $25-million item keeps alive a program that was killed just as it was starting to pay off. Inserted by members of Congress from Tennessee, where the X-43A scramjet testbed was built, the earmark directs the agency to continue work on the proposed X-43C follow-on that would be larger than the X-43A and use hydrocarbon fuel instead of gaseous hydrogen for a much longer burn time. NASA intended to scrap its hypersonic research effort after the second X-43A test, conducted this month.
Dual combustion ramjet was fully integrated into this uncooled, nickel-alloy "missile" body and successfully run using hydrocarbon JP10 fuel. The tests were conducted in NASA Langley's 8-ft. high-speed wind tunnel under simulated speeds of Mach 6-6.5 and at angles of attack of 0 and 5 deg.
The Navy expects to deploy production hypersonic missiles on surface ships, submarines and aircraft. The Mach 6-class weapon would have a 400-600-naut.-mi. range.
Darpa/ONR hypersonic missile demonstrator has a nominal 168-in. length and 19-in. diameter. At front, left, is James Keirsey, inventor of the dual combustion ramjet, with others from The Johns Hopkins University Applied Physics Laboratory.
