An electric aircraft runs on electric motors rather than internal combustion engines, with electricity coming from fuel cells, solar cells, ultracapacitors, power beaming,[22] or batteries. Currently, flying electric aircraft are mostly experimental prototypes, including manned and unmanned aerial vehicles.
Rocket engines[edit source | editbeta]


Bell X-1 in flight, 1947
In World War II, the Germans deployed the Me 163 Komet rocket-powered aircraft. The first plane to break the sound barrier in level flight was a rocket plane – the Bell X-1. The later North American X-15 broke many speed and altitude records and laid much of the groundwork for later aircraft and spacecraft design. Rocket aircraft are not in common usage today, although rocket-assisted take offs are used for some military aircraft. Recent rocket aircraft include the SpaceShipOne and the XCOR EZ-Rocket.
Ramjet and scramjet engines[edit source | editbeta]


Artist's concept of X-43A with scramjet attached to the underside
A ramjet is a form of jet engine that contains no major moving parts and can be particularly useful in applications requiring a small and simple engine for high-speed use, such as with missiles. Ramjets require forward motion before they can generate thrust and so are often used in conjunction with other forms of propulsion, or with an external means of achieving sufficient speed such as a parent aircraft or catapult. The Lockheed D-21 was a Mach 3+ reconnaissance drone that was powered with a ramjet which was launched from a parent aircraft such as the Lockheed A-12. A ramjet works by using the forward motion of the vehicle to force air through the ramjet without resorting to turbines or vanes. Fuel is added and ignited, which heats and expands the air to provides thrust.
Scramjet aircraft are still in the experimental stage. A scramjet is a supersonic ramjet and aside from differences with dealing with internal supersonic airflow works like a conventional ramjet. This type engine requires very high initial speed in order to work. The NASA X-43 is an experimental unmanned scramjet that set a world speed record in 2004 for a jet-powered aircraft with a speed of Mach 9.7, nearly 7,500 miles per hour (12,100 km/h) at an altitude of about 118,000 feet (36,000 m)