Designed as a single-stage-to-orbit ( SSTO ) reusable winged launch vehicle, it was to be fitted with a unique air-breathing engine, the RB545 called the Swallow, to be developed by Rolls Royce.

Aerospike engines have been studied for a number of years and are the baseline engines for many single-stage-to-orbit ( SSTO ) designs and were also a strong contender for the Space Shuttle Main Engine.

Rotary Rocket, Inc of Mojave, California, was a rocketry company headquartered in a facility at Mojave Airport that developed the Roton concept in the late 1990s as a fully reusable single-stage-to-orbit ( SSTO ) manned spacecraft.

It is intermediate between a three-stage-to-orbit launcher and a hypothetical single-stage-to-orbit ( SSTO ) launcher.

With reference to a reusable launch system this approach is often proposed as an alternative to single-stage-to-orbit ( or SSTO ).

The X-33 would flight-test a range of technologies that NASA believed it needed for single-stage-to-orbit reusable launch vehicles ( SSTO RLVs ), such as metallic thermal protection systems, composite cryogenic fuel tanks for liquid hydrogen, the aerospike engine, autonomous ( unmanned ) flight control, rapid flight turn-around times through streamlined operations, and its lifting body aerodynamics.

Through the use of the lifting body shape, composite liquid fuel tanks, and the aerospike engine, NASA and Lockheed Martin hoped to test fly a craft that would demonstrate the viability of a single-stage-to-orbit ( SSTO ) design.

The RS-2200 was to power the VentureStar single-stage-to-orbit vehicle.

VentureStar was to be a single-stage-to-orbit vehicle, launching vertically but returning as an airplane.

The engine has been designed to achieve single-stage-to-orbit capability, propelling the proposed Skylon launch vehicle.

* single-stage-to-orbit, a vehicle that reaches orbit without jettisoning hardware

An advantage of such a system over single-stage-to-orbit is that the entire mass of the spacecraft is not carried into orbit.

The first stage of the Titan II had the mass ratio required for single-stage-to-orbit capability with a small payload.

The STV would be single-stage-to-orbit aircraft, similar to Lockheed's X-30 and the UK's HOTOL proposals of the 1980s, with capability for in-flight refueling, and an expected speed of 6, 000 mph ( Mach 8. 5 +).

Many designs which use a very small boost at the beginning of their flight are referred to as single-stage-to-orbit.

VentureStar was a proposed single-stage-to-orbit reusable launch system by Lockheed Martin.

However, Cole is able to put them on another path-a privately constructed single-stage-to-orbit spacecraft at Edwards Air Force Base, disguised by the simple and effective method of its designer, Gary Hudson, declaring it nonfunctional.

* The Treehawk-A single-stage-to-orbit spaceship, which transports personnel, such as Lieutenant Hiro, to the Spacehawk.

Rockets with as many as five stages have been successfully launched, and there have been designs for several single-stage-to-orbit vehicles.

The project's creators, The Lunar Resources Company, However it is not known how economically feasible this would have been since low cost access to space ( possibly involving single-stage-to-orbit or two-stage-to-orbit vehicles ) had yet to be developed.

The ultimate goal for an SSTO vehicle would be airliner-like operations.

If an SSTO vehicle were combined with reliable systems and lower maintenance design of a more automated nature, it could greatly reduce operational costs.

On the other hand, an SSTO vehicle needs to lift its entire structure into orbit.

Careful studies have shown that some dense fuels ( for example liquid propane ) exceed the performance of hydrogen fuel when used in an SSTO launch vehicle by 10 % for the same dry weight.

Some designs for SSTO attempt to use airbreathing jet engines that collect oxidiser and reaction mass from the atmosphere to reduce the take-off weight of the vehicle.

A rocket stage is not a complete launch vehicle, but this demonstrates that an expendable SSTO was probably achievable with 1962 technology.

The Apollo Lunar Module was a true SSTO vehicle, albeit on the moon.

The unmanned DC-X technology demonstrator, originally developed by McDonnell Douglas for the Strategic Defense Initiative ( SDI ) program office, was an attempt to build a vehicle that could lead to an SSTO vehicle.

In the cases of a single stage to orbit ( SSTO ) vehicle or suborbital vehicle, the mass fraction equals the propellant mass fraction ; simply the fuel mass divided by the mass of the full spaceship.

The rocket equation says that an SSTO vehicle needs a high mass ratio.

In 1996 NASA selected Lockheed Martin Skunk Works to build the X-33 VentureStar prototype for a single stage to orbit ( SSTO ) reusable launch vehicle.

There have been various approaches to SSTO, including pure rockets that are launched and land vertically, air-breathing scramjet-powered vehicles that are launched and land horizontally, nuclear-powered vehicles, and even jet-engine-powered vehicles that can fly into orbit and return landing like an airliner, completely intact.

For rocket-powered SSTO, the main challenge is achieving a high enough mass-ratio to carry sufficient propellant to achieve orbit, plus a meaningful payload weight.

For air-breathing SSTO, the main challenge is system complexity and associated research and development costs, material science, and construction techniques necessary for surviving sustained high-speed flight within the atmosphere, and achieving a high enough mass-ratio to carry sufficient propellant to achieve orbit, plus a meaningful payload weight.

Although an SSTO rocket might theoretically be built, margins would be likely to be very thin: even comparatively minor problems could mean that the craft may fail to achieve the necessary mass-fraction to reach orbit with useful payload.

The fuel used is orders of magnitude cheaper, and, if a single stage to orbit design SSTO avoided some of this refurbishment, costs would drop, although this could require more repairs.

There are two approaches to Single stage to orbit or SSTO.

Future orbital spaceplanes may take off, ascend, descend, and land like conventional aircraft, providing true single stage to orbit ( SSTO ) capability.

An SSTO craft would not require external fuel tanks or boosters to reach low-earth orbit.

Some SSTO vehicles simply use very high pressure engines which permit high ratios to be used from ground level.

Its supporters argue that, since each stage may have a lower mass ratio than an SSTO launch system, such a system may be built without approaching as close to the limitations of its structural materials.