Faster than a speeding bullet ...

It is -- literally -- faster than a speeding bullet.

The supersonic combustion ramjet, or scram-jet, currently being designed at the University's Aerospace Research Laboratory is expected to fly at 3,700 miles per hour, nearly twice a bullet's speed.

The University is working in conjunction with the Virginia Space Grant Consortium, which includes researchers at Virginia Tech, Old Dominion University, Hampton University and the College of William & Mary.

At that speed, the five-hour plane ride from Charlottesville to Los Angeles could be cut down to about 40 minutes, according to Aerospace Research Laboratory director Christopher Goyne. Also, Goyne added, the scramjet speed would make it feasible for him to return home to his native Australia for a long weekend.

Nearly everyone is familiar with the idea of supersonic flight. Phrases like "sonic booms" and "breaking the sound barrier" have long been integrated into our cultural consciousness. However, the idea of so-called "hypersonic flight," flight at least five times the speed of sound -- or Mach 5 ­-- is only beginning to be tested.

Several scramjets have been flight-tested around the world. The most well-known of which is the Hyper-X, designed by NASA, which reached a speed of Mach 9.6. The fastest regular jet engines have only achieved speeds of around Mach 3.

Scramjets are able to achieve speeds that far exceed that of traditional jets because of their alternative design.

A scramjet differs from a traditional jet because it contains no rotating components. Unlike a regular jet engine which uses a compressor in its combustion chamber, a scramjet uses the speed of the aircraft to compress air, which has a supersonic speed throughout.

The scramjet is also different from a rocket in that it uses oxygen from the air for combustion, rather than carrying heavy loads of oxygen for combustion in tanks.

For this reason, Goyne said, the scramjet is more efficient than both a rocket and a traditional jet engine.

However, because the air flowing through a scramjet must be greater than the speed of sound throughout, a scramjet cannot simply take off from rest. Instead it requires a staging vehicle -- usually a rocket to accelerate the scramjet to a supersonic speed. The lowest functioning speed of the University's scramjet design is around Mach 4, Goyne said.

Since a scramjet uses air for combustion, the range of altitudes it is able to fly in is limited. These limitations give scramjet designers the problem of the mythical Greek Icarus.

"The trick is, if you fly a scramjet too high you run out of air and if you fly it too low there is too much friction," Goyne said.

Another difference in a scramjet's design is that it often lacks wings. According to Goyne, wings are unnecessary to create lift in a scramjet.

"If you go fast enough, almost anything will fly," Goyne said.

The opportunities presented by this kind of speed are varied. Scramjets could be used for commercial shipping, travel, military maneuvers or as space transport vehicles.

Goyne said he believes scramjet technology will be widespread in the coming years.

"We're very close to seeing scramjets routinely used," he said.

The Aerospace Research Laboratory's scramjet project is known as Hy-V, the "Hy" standing for hypersonic, and the "V" standing for both Virginia and the Roman numeral five, which is the Mach number the scramjet hopes to attain.

Here at the University there are 10 undergraduate students working on the project, mainly second-, third- and fourth-year Aerospace Engineering majors. Around the commonwealth, there are around 50 students.

"We have undergraduate students working side-by-side with aerospace professionals," Goyne said. He added that they hope to expand the project with more funding.

"We hope to have graduate students working on the project soon," Goyne said.

Researchers are planning a flight test for the scramjet in 2009. At that time they will launch the scramjet in a rocket provided by NASA at NASA Wallops Island on the Eastern Shore of Virginia.

In the planned test, the scramjet is projected to reach a speed at or near Mach 5.

On the ground, the designers are able to test the scramjets in the Aerospace Research Laboratory's hypersonic wind tunnel, which can simulate Mach 5 conditions.

According to Goyne, this is one of only a handful of hypersonic wind tunnels around the country, and the only one that can stay on for several hours. Most hypersonic wind tunnels can only be operated for a few minutes.

The flight test will also test the validity of the conditions created by the hypersonic wind tunnel.

The 10 undergraduate students working on the scramjet have the opportunity to participate in cutting edge aerospace research.

"Working on the scramjet has been an amazing experience," third-year Engineering student Libby Croft said. "I've really learned a lot."

In addition to the educational value of working on this project, students are able to appreciate the many opportunities presented by the idea of such flight speed.

"Being involved in this sort of research really helps direct more attention to the field and increase the level of publicity and funding," third-year Engineering student James Thompson said.

Thompson added that unlike many scientific fields, scramjet research is really something that the general public finds interesting.

"People are amazed at it," Thompson said. "It's really a sexy science"

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