The system will perform a series of ground tests that will ultimately qualify the engine for flight. After the ground tests, the same engine will be integrated into the Demonstrator 3 rocket that will perform a suborbital space flight up to an altitude of 120 km above the New Mexico desert. It will be the first ever flight of a linear aerospike engine and the first ever space flight of an aerospike engine.
Based on the results from these tests the company then intends to build a single-stage-to-orbit small rocket that they hope to fly by 2018.
Go to the company’s news website here to see some good images of the engine and the aerospike nozzle. It does not look like any typical rocket engine. If this effort is successful it will as significant a technological improvement to rocketry as SpaceX’s recovery and reuse of its Falcon 9 first stage.