Space Development Company ------------>  Sierra Nevada Corp.


American Rocket Company (Amroc) has planned two orbital launchers. Aquila-21 uses two H-1800 strapons on one central H-1800 stage , a United Technologies Orbus-21 second stage and an Amroc U-75 rocket in the third stage. Aquila-31 uses three instead of two strapons H-1800.

The design of the H-1800 has a planned average vacuum thrust of 1,003 kN, and average vacuum Isp design goal of 2724 N*s/kg. The nozzle of the engine DM-01 is fixed, with thrust vectoring by LOX injection through the side of the silica-phenolic nozzle. Each of the H-1800 motors weighs 36.97 tons fully fueled, with 9.98 tons of HTPB propellant and 22.00 tons of oxygen. The U-75 is a Amroc hybrid rocket using self-pressurizing pressure-fed nitrous oxide (N2O) as the oxidiser.
Aquila-21 will lift 0.907 tons into LEO from Vandenberg. The first suborbital test was scheduled for 1995.
A first test-vehicle
SET-1 (Single Engine Test) with a H-1500 stage (324 kN thrust) is failed in 1989.
Amroc went bankrupt in the summer of 1995.

"James C. Bennett, a principal in US hybrid rocket research and development, co-founded Space Enterprise Consultants in 1980, and Arc Technologies, Inc., later known as Starstruck, Inc. Starstruck successfully conducted a sea launch of its Dolphin rocket on August 3, 1984 with a thrust of 175.00 kN using HTPB and LOX. This Dolphin launch produced two notable firsts: the first flight of a privately developed large launch vehicle in the US, and the first flight of a large hybrid rocket. In 1985, Mr. Bennett co-founded American Rocket Company (Amroc), which tested engines up to 324.00 kN, and unsuccessfully launched the SET-1 sounding rocket on October 5, 1989, which failed for reasons unrelated to the hybrid motor. Amroc folded in 1995, but SpaceDev acquired rights to Amroc's hybrid technology in 1999, and continues to develop hybrid technology."
"Starstruck (formerly ARC Technology, a predecessor to Amroc) developed the hybrid fueled (polybutadiene and liquid oxygen) Dolphin. It was also launched from a floating launch cannister at sea. One successful suborbital flight was made 03.08.1984, but the project ran out of money, as it was backed entirely with private funds, which did not suffice for further development."

Liftoff Thrust
: 155.00 kN. Total Mass: 7,500 kg. Core Diameter: 1.07 m. Total Length: 15.50 m. Narrative: Single stage vehicle.


In August 1998
Space Development Com. (SpaceDev), the world's first commercial space exploration company, acquired exclusive rights to intellectual property including the three patents originally issued to American Rocket Company (Amroc) for their hybrid rocket motor technology. In addition, SpaceDev acquired exclusive possession of and access to a large quantity of Amroc engineering documents, plans, designs, test results, manufacturing data, and other materials related to the rocket motors and Amroc launch vehicles.
The USAF Research Laboratory awarded a contract to SpaceDev to design and develop a low cost small launch vehicle, dubbed
Streaker. The hybrid vehicle will offer quick response launches of payloads in the 500-kilogram (1,102-pound) class to LEO.

The SpaceDev Streaker will use patented High Performance Mass Fraction hybrid common core boosters that will equal the performance of solid rocket motors and some liquid rocket motors while remaining safe, responsive and affordable. The rocket motors burn HTPB (tire rubber) and Laughing Gas (nitrous oxide), and will be augmented by existing technologies to produce performance significantly above traditional hybrid motors.
SpaceDev has signed a lease to expand its fabrication and test facilities and to begin constructing portable, high tech rocket motor test support equipment in anticipation of test firing new rocket motors that SpaceDev is developing for its low-cost expendable small launch vehicle called SpaceDev Streaker.
Under an Air Force Research Laboratory contract, SpaceDev will begin development of the SpaceDev Streaker Hybrid Upper Stage rocket motor. This motor is expected to produce approximately 20,000 pounds of thrust, in contrast to the 15,000 pounds of thrust produced by SpaceDev's hybrid rocket motor technology for Paul Allen's SpaceShipOne.
In addition, the Company plans to boost overall performance of this upper stage motor using new techniques and refining current techniques that go beyond that of traditional hybrid motors.
The additional SpaceDev facility will be located in Poway, California. It will add approximately 11,000 square feet of fabrication space in which we will construct rocket motor development equipment that will be highly adaptable and mobile.

A test stand will be designed to support the 20,000 pounds of thrust produced by the Hybrid Upper Stage motor, and the 120,000 pounds of thrust expected to be produced by the SpaceDev Streaker Small Common Booster motor.

SpaceDev design for a restartable hybrid propulsion space tug or upper stage. The MoTV was the SpaceDev Maneuvering and orbital Transfer Vehicle. It used a hybrid motor based on HTPB for fuel and N2O (nitrous oxide) as an oxidizer. Features included: Total impulse could be controlled by burn length (significant advantage over solids); oxidizer could be used for cold-gas attitude thrusters (for steering); could be used for multiple burns.

SpaceDev currently plans to use variations of both the Hybrid Upper Stage and the Small Common Booster motors in "
SpaceDev Dream Chaser, along with Large Common Boosters in the orbital version of SpaceDev Dream Chaser. The reuseable, piloted, sub-orbital space ship that could be scaled up to safely and economically transport passengers to and from low earth orbit, including the International Space Station. The SpaceDev Dream Chaser would be piloted and take-off vertically, like most launch vehicles, and is designed to glide back for a normal horizontal runway landing.

The sub-orbital SpaceDev Dream Chaser is derived from an existing X-Plane concept, will have an altitude goal of approximately 160 km (about 100 miles) and will be powered by a single, high performance hybrid rocket motor, under parallel development by SpaceDev for the SpaceDev Streaker, a family of small, expendable launch vehicles, designed to affordably deliver small satellites to low earth orbit. The SpaceDev Dream Chaser will use motor technology being developed for the SpaceDev Streaker booster stage, the most powerful motor in the Streaker family. The SpaceDev Dream Chaser motor will produce approximately 100,000 pounds of thrust, about six times the thrust of the SpaceShipOne motor, but less than one-half that of the 250,000 pound thrust hybrid rocket motors developed several years ago by the American Rocket Company (Amroc).

SpaceDev selected for V.G. SpaceShip engine
Scaled Composites, developers of the SpaceShipOne (SS1) reusable suborbital spacecraft, announced that they had selected SpaceDev to provide the propulsion system for the vehicle. SpaceDev was in competition with another company, Environmental Aeroscience Corporation (eAc), to build the hybrid propellant engine that will be used to boost SS1 onto a suborbital trajectory once it its released from its White Knight carrier aircraft. Both SpaceDev and eAc had successfully tested their versions of the engine, using nitrous oxide and hydroxy-terminated polybutadiene (HTPB), or rubber, as propellants.

2014 change of motor
In May 2014, Virgin Galactic announced a change to the hybrid motor to be used in SpaceShipTwo, and took the development effort in-house, terminating the contract with Sierra Nevada and halting all development on the first-generation rocket motor for SpaceShipTwo.

Virgin Galactic says it's switching from a rubber-based solid fuel to a plastic-based fuel for the motor. The new motor would now use thermoplastic polyamide (i.e., nylon) as the solid fuel component of the propellant.
The plastic fuel was projected to have better performance and was expected to allow SpaceShipTwo to make flights to a higher altitude.