This is more efficient than the hot gas which provides the thrust in a conventional rocket.

ECONOMIST: A large asteroid sweeps by Earth. Where are the others?

When ignited in a test pit the rocket, called the B4, produced a thrust of about a quarter of a tonne and behaved exactly as predicted.

BBC: Hybrid success for British rocket

The two-stage Falcon 9 rocket uses nine engines to generate 855, 000 pounds of thrust, and is capable of carrying more than than 7, 000 pounds of cargo.

FORBES: Live Feed: SpaceX's Resupply Mission To The International Space Station

But then ignition gets going and at full blast the jet and the rocket will each provide about half of the 210, 000 newtons (47, 000 pounds) of thrust needed to break the record.

ECONOMIST: The land-speed record

To invest wisely in the likelihood that originators can capitalize on a string of fads through creativity and experimentation is very different from investing in one hot rocket that goes straight up with full knowledge that gravity will send it back down with equal and opposite thrust.

FORBES: Don't Fear the Fad