Rotary Rocket plans to begin test flights of the Roton atmospheric test vehicle (ATV) by the end of next month, with first orbital flights scheduled for the final quarter of 2000.
Details of the test schedule were revealed at the roll-out of the Roton ATV from the company's newly completed building at Mojave, California, on 2 March.
The vehicle, which has an adapted Sikorsky S-58 four-blade rotor system attached to its nose cone, is being developed as a reusable, low-cost, single stage to orbit vehicle.
For its initial flights, the Roton will be powered by small hydrogen-peroxide rockets mounted in the rotor blade tips. These will be used to lift the vehicle off the ground for a few feet during the first six weeks of tethered hover tests. Then, in a three-month programme, the "bunny hops" will be increased in altitude and duration, with the eventual goal of flying as high as 10,000ft (3,050m).
The work is intended to confirm the basic handling qualities and control system of the Roton, which will use the rotor to slow its descent after re-entry, and to control its landing with an autorotation descent from 28,000ft.
Three ATVs are scheduled to be built. The 17.1m-diameter rotor is expected to be able to lift the 19.2m-tall vehicle at up to 4m/s (2,400ft/min), but it is limited to less than 5min powered flight time using 1,360kg (3,000lb) of 85% peroxide fuel. The maximum rate of descent is expected to be 12m/s and best glide speed is estimated at about 40kt (75km/h).
The full-up, space-capable, prototype test vehicle (PTV), which is due to be rolled out in the first quarter of 2000, will be powered by a Roton rocket engine now in the final stages of design. The Jet-A fuelled engine will produce about 545,000lb (2,425kN) thrust, and have a thrust-to-weight ratio of 83. Unlike more conventional, hydrogen-fuelled rocket engines, the Roton unit is designed for a life of up to 100 flights.
Part of this longevity is expected to result from the unusual basic design of the engine, which uses centrifugal force to generate high propellant flow pressures, rather than the usual array of small internal turbopumps.
Slightly offset rocket nozzles will cause the entire base of the vehicle to spin at several hundred revolutions a minute during launch. The resulting force will drive a single-stage centrifugal pump at the engine's core.
In the production version, 96 small rocket combustion chambers will be arranged in a circle on the base of the Roton-C vehicle. Like the linear-aerospike rocket motor being developed for the Lockheed Martin X-33, the Roton engine will use an altitude-compensating nozzle to adjust the exhaust gas flow automatically to the ambient atmospheric pressure.
The first full run of the initial test version, which has 72 chambers, is due to take place at the end of this year.
Rotary Rocket is seeking to raise a further $120 million over the next 18 months to continue the programme to the PTV stage. The company has raised about $30 million to date.
Source: Flight International
