Sky Ramp Technology - Information on sky ramp technology and its applications. Rotational Slingshot Catapult - Provides a space enthusiast's view of the possibility to use alternative means for propulsion of spacecraft. Space Launcher: Pylon Turn Wing Concept - An hypothetical alternative space launch system. Hypersonic Waveriders - Hypersonic flow theory and applications to waveriders and other hypersonic flight vehicles. Nasa X-Planes - Provides a centralized location for information on NASA X-aircraft. Also provides links to photos, fact sheets, line drawings and movie clips. Experimental Rocket Propulsion Society - A LEO launcher development by a group of space enthusiast. Features engine and vehicle designs, project descriptions and membership information. Space Vehicles - Vehicle Designs - A list of projects under way today and some significant projects of the past for orbital and sub-orbital flights.