How Hypersonic Planes Work

By: Kevin Bonsor

Taking Flight

The X-43A attached to the Pegasus booster rocket
The X-43A attached to the Pegasus booster rocket
Photo courtesy NASA

As mentioned before, scramjet-powered aircraft don’t carry oxygen onboard. That means that they can’t lift off like conventional spacecraft. The X-43A requires a booster rocket to get it up to a hypersonic speed, at which point it is released and sent flying on its own. This rocket boost is necessary for the scramjet engine to work.

Here’s a rundown of how the X-43A test flights work:


  1. The X-43A is attached to a Pegasus booster rocket.
  2. The X-43A and booster rocket are carried up to about 20,000 feet (6,000 m) by a customized, B-52 aircraft.
  3. The B-52 releases the launch vehicle.
  4. The booster rocket accelerates to a speed of approximately Mach 5 and flies to an altitude of about 100,000 feet (30,500 m).
  5. The X-43A separates from the booster rocket and flies under its own power and preprogrammed control.
  6. The X-43A flies over the ocean for a few minutes before splashing down.
Image courtesy NASA

NASA officials say that the scramjet engine would be a major step forward for NASA and would arguably provide a safer, more flexible, less expensive way to get people and cargo to space.

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