Engineers at MIT have successfully built and flown a first of it's kind plane with no moving parts. The plane is powered using "ionic wind", a principle first identified in the 1920s, to create enough thrust to propel it over a sustained flight. This creates a plane this is completely silent and does not rely on fossil fuels to fly.
“This is the first-ever sustained flight of a plane with no moving parts in the propulsion system,” says Steven Barrett, associate professor of aeronautics and astronautics at MIT. “This has potentially opened new and unexplored possibilities for aircraft which are quieter, mechanically simpler, and do not emit combustion emissions.”
The plane, which weighs only five pounds and has a five meter wingspan, has a fuselage containing lithium-polymer batteries. The front wings are strung with thin wires, acting as positively charged electrodes, while the back wings contain thicker wires acting as negatively charged electrodes. When the wires are energized they attract and strip the negatively charged electrons from the surrounding air, leaving behind newly ionized molecules. These new molecules are then attracted to the negatively charged electrodes on the back wings. This process creates a cloud of ions moving toward the back wings which creates a thrust propelling the plane forward.
From the MIT article: "About nine years ago, Barrett started looking for ways to design a propulsion system for planes with no moving parts. He eventually came upon “ionic wind,” also known as electroaerodynamic thrust — a physical principle that was first identified in the 1920s and describes a wind, or thrust, that can be produced when a current is passed between a thin and a thick electrode. If enough voltage is applied, the air in between the electrodes can produce enough thrust to propel a small aircraft."
Read more about flying a plane without moving parts at MIT.