Airbus has developed a concept under which the engines of a rocket’s first stage would separate from the booster after burn out and glide back to a runway landing for reuse.
Details are contained in a patent application titled, Simplified Reusable Module for Launcher. Media reports say the company has been working on the project, which is code named Adeline, since 2010 and has conducted demonstration flights. The system could be used on any rocket, including the Ariane 6 that is now under development.
United Launch Alliance has a similar plan under which engines would separate from the Vulcan booster and be recovered in mid-air by an aircraft. SpaceX is working on recovering the first stages of its Falcon 9 and Falcon Heavy boosters for reuse.