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Beyond Supersonic

HyperSoar plane could cross Pacific in two hours, but would take passengers in and out of weightlessness repeatedly. Designer says most of the needed materials exist today, though engine is still in development.


LIVERMORE, Calif. — Imagine the convenience of traveling 10 times the speed of sound. You could make it from Los Angeles to Tokyo in two hours, to New York in 30 minutes.

A new design for a hypersonic plane has made this scenario a little less fanciful, a little more feasible. Dubbed HyperSoar, the plane would be capable of far outpacing current aircraft of supersonic capability--defined as one to five times the speed of sound. Go above Mach 5 and the rating jumps to hypersonic.

The man behind the concept is Preston Carter, an aerospace engineer at Lawrence Livermore National Laboratory. By linking advances in engine technology and aerodynamics with theories in flight pattern dating back to World War II, Carter came up with a design that is capturing the imagination of the public as well as those in the industry.

Not only would the plane get from point A to point B in record time, says Carter, but--size and weight being equal--a HyperSoar plane could carry twice the load of a Boeing 747-400. HyperSoar could also be used to launch other vehicles into space.

"It's a very good airplane," Carter said, "but it's one heck of a good launch vehicle. We could put payloads into space at three to five times the efficiency of anything we've got now."

Still, Carter acknowledges that the idea of HyperSoar as a plane might hold more glamour for the public. But this allure would be tempered by a flight plan that calls for taking the passenger from weightlessness back to gravity force every two minutes for the entire course of the trip.

HyperSoar would take off just like a typical airliner. The plane would "skip" above the atmosphere to 200,000 feet, then descend to 115,000 feet before starting up again.

Why skip? Jason Speyer, professor of mechanical and aerospace engineering at UCLA, says the skipping, known technically as a periodic trajectory, helps deal with a longtime bane of supersonic flight: heat. The faster an object flies through space, the more it slows and compresses the air around it. The more the air is compressed, the hotter it gets.

"If [the plane] stays in the atmosphere, you are constantly absorbing heat," Speyer said. "With periodic motion, you go outside the atmosphere."

Because HyperSoar would spend up to two-thirds of its time in space, heat could dissipate, giving the plane a needed cool-down period.

Passengers would feel the pull of gravity weakening to zero as the plane rose into space. The engine would shut off during the crest of the wave, and for about 100 seconds, everything inside the plane would be weightless.

As the plane descended, gravity would take hold again at about 1.5 Gs, the same force one might feel at the lowest point in a child's swing. The engine would start up again to help boost the plane out of the atmosphere, and the cycle would start again.

In one skip, the plane could travel 250 miles. Going to Asia? Get ready for 24 more skips.

People With Weak Stomachs: Beware

Those with weak stomachs might be cringing at the plane's trajectory, but Carter thinks many people would be willing to tolerate the unconventional flight path if it meant valuable time saved. "I would ask, do you want an hour and 50 minutes between L.A. and Tokyo and maybe getting airsick, or a 12-hour flight" on a conventional jet, Carter said.

The plane's shape would increase lift by taking advantage of the same aerodynamic principles that generally increase drag at high speeds. The sharp leading edges of a "waverider" plane such as HyperSoar would give the vehicle lift from the high-pressure air behind the shock wave created by breaking the sound barrier, said Mark Lewis, associate professor of aerospace engineering at the University of Maryland and a consultant on the HyperSoar project.

In addition, the velocity, as the plane descended into the atmosphere, would provide enough lift to actually reverse the flight path and create the "skip." On each cycle, the HyperSoar's engines would turn on for a quick boost, keeping the bounce going and extending the plane's traveling distance.

Carter said most of the materials needed to withstand the heat and pressure of hypersonic flight exist today. But what may ultimately make or break the HyperSoar concept, experts say, is the success of its engine, which is still in development.

So-called ramjet engines are used in today's fastest manned plane, the SR-71 Blackbird of the U.S. Air Force, capable of traveling three times the speed of sound. Air flows into the engine, where it is compressed, mixed with fuel and shot out the back for thrust.

"Scramjet"--supersonic combustion ramjet--engines work similarly but for speeds higher than Mach 6. Scramjets would be used for the Hyper X, another hypersonic research vehicle that is being developed by Boeing.

However, George Orton, manager of hypersonics at Phantom Works, Boeing's research and development unit in St. Louis, said scramjets are not yet operational in an airplane.

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