SpaceX successfully launched the worlds most powerful rocket, a towering behemoth known as the Falcon Heavy that tore through the sky with the thundering force of 18 Boeing 747 jetliners.

Lifting off at 3.45 p.m., on Tuesday from the same launch-pad that sent the crew of Apollo 11 to the moon, the rocket sent up a mountain-sized plume of smoke and a rattling roar across Florida's Space Coast, where thousands gathered to watch, reports The Washington Post.

The mission represented the first test of the massive rocket, powered by 27 engines in three first-stage boosters that are estrapped together.

The maiden flight also marked the first time a privately financed venture ever attempted to launch a rocket so powerful that it was capable of hoisting a payload out of Earth's orbit.

As a promotional stunt, SpaceX founder Elon Musk loaded the Falcon Heavy with his own cherry-red Tesla Roadster carrying a spacesuit-clad mannequin named "Starman" in the driver's seat.

Musk said he planned to send the convertible, built by another one of his companies, into an orbit around the sun that would take it near Mars.

SpaceX topped off the launch by successfully landing two boosters on land, setting off twin sonic booms on their return. A third first-stage, the so-called centre core, crash landed at sea.

"I'm still trying to absorb everything that happened because it seemed surreal to me," The Washington Post quoted Musk as saying.

"I had an image of a giant explosion on the pad with a wheel bouncing down the road and the Tesla logo landing somewhere. But fortunately that's not what happened. The mission seemed to have gone as well as possible."

If SpaceX can fly the Falcon Heavy reliably, the rocket could prove useful to the Pentagon for lifting national security satellites and to NASA for helping its human exploration goals.

The company has said that the rocket is capable of hauling more mass farther than any existing rocket - an estimated 140,000 pounds to low Earth orbit, and nearly 40,000 pounds to Mars.

After the launch, SpaceX broadcast a live stream from the Roadster in space using the three cameras mounted to the vehicle.

In addition to carrying a plaque with the names of 6,000 SpaceX employees, the car also transported a data storage device containing Isasac Asimov's classic Foundation science fiction trilogy.