tary Rocket needed over $100 million for development, but managed to raise only $30 million, and so ceased trading in 2000.
The photo on the left is of the Roton ATV (Atmospheric Test Vehicle) that was rolled out of its Mojave hangar facility in March 1999. This vehicle made 3 successful piloted test flights, demonstrating the feasibility of the rotor-assisted landing.
In 1984, British Aerospace proposed the HOTOL horizontal takeoff single-stage-to-orbit reusable launcher. The concept featured a new type of airbreathing rocket engine that would have burned compressed air rather than liquid oxygen up to a speed of Mach 5. HOTOL was studied in great detail both by BAe and the ESA Winged Launcher Configuration study.
The concept eventually gave way to Interim HOTOL in the early 1990s, a British/Russian joint proposal which replaced the (technologically risky) airbreathing rocket motor with existing Russian RD-0120 engines. The vehicle would have been launched piggy-back from a Russian Antonov 225 aircraft. Alan Bond, the inventor of HOTOL's airbreathing propulsion system, later refined the concept as SKYLON, above.
The Space Ship Xperimental was a modified version of the Phoenix VTOL rocket, used by Max Hunter to help persuade the US government to fund VTOL research, ultimately leading to the DC-X project. It is described in "Halfway to Anywhere" by G Harry Stine.
This is a design for a 2-stage HTOL launch vehicle produced initially by the company MBB in Germany (see " Sanger: An Advanced Launcher System for Europe"). The first stage would use air-breathing rocket engines (which have not yet been developed) to reach approximately Mach 6, at which the upper stage would separate and use rocket engines to reach orbit. Piloted versions of the upper-stage have been designed to carry 36, 40 and 44 passengers.
The " X-33" was announced by NASA in 1995 as an unpiloted, reusable VTOHL rocket test vehicle. It was expected to fly to speeds reaching Mach 13, with test flights starting in 1999.
The plan was very soon after scaled back to reach only Mach 8, and then cancelled in 2001 after NASA's entire budget of more than $1 billion had been spent, leaving it several $billion short of having a flight vehicle. (Article)
A supposedly commercial follow-on to the X-33 demonstator. However, the proposer, Lockheed-Martin Corp, had stated that the satellite and government launch markets for which it was designed were not large enough to make it a viable business venture, and so it has expired with the X-33.
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The [an error occurred while processing this directive]X-34[an error occurred while processing this directive] was announced as an unpiloted, reusable [an error occurred while processing this directive]HTOL[an error occurred while processing this directive] rocket test vehicle to fly first in 1999, eventually reaching Mach 8. The main objective was to provide a flight-test vehicle for the NASA developed 'Fastrac' engine and some other hardware. Having overrun the original $100 million budget by 30%, NASA's request for an addition $200 million was turned down and the project was scrapped in 2001 before any flights were performed. (Article)
By contrast, the piloted, reusable [an error occurred while processing this directive]HTOL[an error occurred while processing this directive] rocket-test-vehicle, the X-15, reached Mach 6.6, flying successfully 199 times in the 1960s.
"Spaceplanes" that take off like an aeroplane and fly to orbit have been a dream of some space engineers and science fiction writers for decades. Expendable [an error occurred while processing this directive]SSTO[an error occurred while processing this directive] [an error occurred while processing this directive]VTOL[an error occurred while processing this directive] vehicles are simple to design using existing components (see "A Single-Stage-to-Orbit Thought Experiment"). By contrast, reusable [an error occurred while processing this directive]SSTO[an error occurred