into the cabin means you just can't have them. instead, there's a suggestion that passengers will have virtual screens, which should make up for the lack of a real view. well, that's where hybrid technologies come in — aircraft which look like a conventional airliner gas engines on the wings but with an additional electric fan behind the tail. this is a concept known as boundary layer ingestion. now, boundary layer ingestion is a technology which is aimed at taking the flow that forms over the surface of an aircraft, the flow that's on the surface is what usually forms the wake behind an aircraft and causes the drag. the idea we have is to have a fan that's wrapped around the back of the fuselage and so itjust ingests all of this parasitic flow at the back of the aircraft and takes that in and reenergise it and turns it into useful thrust.