CAPE CANAVERAL -- An experimental aircraft expected to fly 10 times the speed of sound is set to begin tests next month above the Pacific Ocean.

If it works, NASA could finally have the blueprint for a spacecraft that takes off and lands like an airplane.

It also could lay the groundwork for superfast missiles that scream to their targets several times quicker than current models.

"[It would be] the same kind of shift as the jet engine over the propeller engine," Hyper-X Program Manager Vince Rausch said Wednesday.

The 12-foot- (3.7-meter-) long shovel-shaped aircraft relies on a revolutionary engine called a scramjet for its hypersonic speed. Instead of using a metal turbine to compress air, the aircraft's high speed forces air into the engine where it is mixed with fuel and burned.

A scramjet uses the surrounding air instead of carrying its own oxidizer like the space shuttle and other rockets. This saves tremendous weight while still allowing the speed necessary to reach orbit.

The scramjet has one moving part, but only works at very high speeds. By comparison, the record-setting X-15 rocket plane reached almost Mach 7 in the 1960s. The unmanned X-43 will not start its engine until it hits Mach 7.

To get there, it will ride a winged Pegasus rocket dropped from a B-52. NASA used the same B-52 to drop manned X-15s, which held speed records until the space shuttle flew in 1981.

The $185 million X-43 program will fly three tests this year, each with a different aircraft. The first will be a 10-second scramjet burn at Mach 7 followed by a fast glide and splashdown in the Pacific. The last is targeted to reach Mach 10, or more than 2 miles (3.2 kilometers) a second.

Engineers have been studying the scramjet technology since the 1950s. Studies have been limited to wind tunnels and computer simulations to overcome the control problems for such an aircraft.

"We've done what we can and now we need to go fly and see what happens," said Joel Sitz, who manages the X-43 project at Dryden Flight Research Center in California.

More ambitious test aircraft would follow the X-43 in a path that researchers hope leads to a manned spacecraft around 2025.

Rausch estimated a manned version of the X-43 would weigh about 1.1 million pounds (498,960 kilograms) to start a mission carrying 25,000 pounds (11,340 kilograms) to Space Station Alpha. The shuttle weighs 4.5 million pounds (2 million kilograms) at liftoff.

"If you can operate like an airplane, you should be able to get your safety up and your flexibility up and your costs down," Rausch said.