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The Roton was a launch vehicle design for a cone-shaped single-stage-to-orbit (SSTO) fully reusable manned spacecraft. Championed by Gary Hudson and was to be built by the startup Rotary Rocket, Inc (rotaryrocket.com).
The projected price to orbit was to be $1000 per kg of payload; less than 1/10 of the current price; although payload was limited to 3 tonnes.
The company intended to use a unique rotating annular aerospike engine; the engine and base of the launch vehicle would spin at high speed to pump fuel and oxidizer to the rim by centrifugal force. The entire base of the vehicle was designed to act as a truncated nozzle; and later in the flight double as a reentry shield. The engine had a projected ISP of ~355 seconds; which is very high for a LOX/Kerosene engine; and a thrust:weight ratio of 150; which is extremely light.
The vehicle was also unique in planning to use a helicopter-style rotors for landing, rather than wings or parachutes; this concept allows giving controlled landings (unlike parachutes), whilst being 1/5 the weight of fixed wings. The rotor blades were powered by peroxide tip rockets to permit pinpoint landings. Worryingly the rotor blades were to be deployed before reentry and some questions were raised about whether the blades would still be present at landing.
Reentry was to be achieved utilising the base as a water cooled reentry shield. This is potentially a good way to survive reentry; particularly for a very lightweight vehicle such as the Roton was to have to been.
The company also designed and pressure-tested a unique exceptionally lightweight, and yet strong, composite LOX tank, which survived a test plan which involved being pressure cycled and ultimately being deliberately shot to test its ignition sensitivity. This composite construction was actually a world first.
A full size, 64-foot (20 m) tall, atmospheric test vehicle was built which successfully flew three test flights in 1999, proving the rocket-rotor concept, but in early 2001, the venture ran out of funds and closed down.
Author Tom Clancy provided some financial support to the company among many others.
The timing of the venture was unfortunate, the Iridium fiasco was coming to a head, and the whole space industry was feeling the pinch. Engine development ceased in 2000 (reportedly 2 weeks before a full scale test was due), and ultimately the vehicle did not attract sufficient funding, failed to secure launch contracts and Rotary Rocket was forced to close.
Whether the full-up vehicle would have worked is anyone's guess. However the company had backup plans for boosters in case the vehicle didn't quite have enough performance to reach orbit; and given this, there's no reason that it couldn't have successfully launched payloads to orbit.
Some of the engineers that worked there have since set up other rocketry ventures, notably XCOR Aerospace. The atmospheric test vehicle was intended to reside in a helicopter museum near San Diego, California; however an attempt to move it there via helicopter failed due to aerodynamic problems and it currently still resides in Mojave.
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