Escape Dynamics is developing the first single-stage-to-orbit, that uses external propulsion energy for launch, delivered from a ground-based phased array of microwave antennas.
According to the developer, he system designed to safely and efficiently beam flight-sustaining power to the spaceplane during the ascent and acceleration to orbital velocity.
Cost per launch can eventually be reduced to $150 per kg.
The energy is converted into thrust in a heat exchanger which absorbs microwaves into heat and couples the energy into the flow of hydrogen propellant. The heated hydrogen is exhausted through the nozzle creating thrust and accelerating the vehicle.
Our externally powered launch vehicles represent a revolutionary improvement in efficiency compared to chemical rockets used today. In a typical chemical rocket powered with combustion, approximately 90% of the initial mass is allocated to propellant and only 10% is split between useful payload and structure.
Externally powered engines designed by Escape Dynamics operate with specific impulse above 750s and propellant mass fraction below 72% (compared to almost 90% of chemical rockets) and for the first time enable reusable single-stage-to-orbit flight.
source Escape Dynamics