SpaceX's Falcon Heavy rocket is poised to blast off Tuesday afternoon from Florida's Kennedy Space Center with a cherry-red sports car on top.

It's the long-awaited first test flight for the rocket.

Once it soars it will become the world's most powerful rocket in use today.

The Heavy is equipped with three boosters and 27 engines designed to provide about 5 million pounds of thrust.

SpaceX chief Elon Musk has his Tesla Roadster on board.

Musk - who also heads up the Tesla electric carmaker - says he wanted to add some dramatic flair.

Usually there are things like steel or concrete slabs or mundane experiments on test flights.

SpaceX is targeting a long, oval orbit around the sun for the car.