The Economist magazine had recent coverage of R-Jet Engineerings orbiting combustion nozzle (OCN) engine.
To ease its entry into the market, R-Jet reckons OCN engines could be used first as generators to produce electricity or to power an unmanned drone. With operating experience, the engines could then migrate to airliners.
R-Jet Engineering, has been developing a gas turbine engine that intends to improve fuel efficiency and cut harmful greenhouse gas emissions by more than 20 percent. The new engine has fewer components, half the size of a conventional jet engine of the same power and is lighter weight than conventional engines. It also significantly cuts operation and maintenance costs.