This is a combination air/space craft (similar to the Space Shuttle and U.S. NASP) proposed by the British Aerospace Corporation in 1984. It is designed to be a reusable single-stage-to-orbit vehicle. Hotol does use a launching trolley though.
The aim of the Hotol, like NASP and the Hermes programs, is to reduce significantly the cost of launching hardware into space, perhaps, by a factor of five or more.
The Hotol concept uses a hybrid engine designated RB545. Hotol's goal is to place 14,000 to 16,000 pounds of payload into low Earth orbit. It is to have a launch weight of about 500,000 pounds and cost $4-5 million per flight.
The Sanger space plane is designed to reduce the cost of putting payloads and people into space. It is a two stage concept rather than a single-stage-to-orit design.
The first stage engines are airbreathing turbo-ramjet types. The second stage has two alternate configurations: a reusable HORUS (Hypersonic Orbital Reusable Upper Stage) for manned missions, and the expendable stage CARGUS (Cargo Upper Stage) for heavy payloads (up to 15 tons).
The design of Sanger is for a standard aircraft runway without special launch assisting provisions. The first stage turbojet engines boost the Sanger to 10 kilometers through Mach 1 with full thrust and afterburner. At Mach 3.5 and 19.5 km altitude, the ramjet propulsion (continued)propulsion system takes over and increases the altitude to 24.5 kilometers and speed to Mach 4.4. A period of cruise commences to avoid sonic booms over populated areas then the ramjet accelerates the vehicle under full power to Mach 6.6 and altitude 30 kilometers. The second stage LOX/LH2 propulsion rocket is then ignited, taking the second stage to orbit.
The planned performance is two to four Mg of payload using the CARGUS stage for launches to Space Station Freedom with personnel. Performance without personnel would place 15 Mg in LEO. This in turn would translate to placing 2600 kg into GEO with the appropriate transfer stage. Both the first and second stages are reusable, returning to Earth and landing on conventional runways.
