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 (1,100-pound) class to LEO.
The SpaceDev Streaker will use patented High Performance Mass FractionT 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. Those boosters will form the base of a family of SpaceDev propulsion products, including sounding rockets, strap-on boosters, targets, payload accelerators, and for other commercial and military applications.
On July 9, 2003, SpaceDev was awarded a Phase I Small Business Innovation Research contract by Air Force Research Lab to design and effectively begin the development of a small launch vehicle with a classical hybrid upper stage rocket. The SpaceDev Small Launch Vehicle is planned to responsively and affordably lift up to 1,000 pounds to Low Earth Orbit. The SpaceDev Small Launch Vehicle concept is based on a proprietary combination of technologies to increase the performance of hybrid rocket motor technology. Hybrid rocket motors are a combination of solid fuel and liquid oxidizer, and can be relatively safe, clean, non-explosive, and storable, and can be throttled, shut down and restarted. The original contract was valued at approximately $100,000, and was a fixed price, milestone-based agreement, which was completed in about one year.
The Phase II of this SBIR contract was awarded on September 29, 2004 and was worth approximately $1.6 million. The contract originally outlined the development and test firing of SpaceDev's large Common Core Booster for the SpaceDev Small Launch Vehicle but was subsequently changed to expand hybrid upper stage technology and explore aft stage injection technology. Congress awarded SpaceDev approximately $3.0 million in additional funding for this project, which became available in late 2005, and which we anticipate to expend in 2007. SpaceDev believes that there is additional interest by Congress to provide further funding to expand and accelerate the scope of the work; however, there can be no assurance that such work will be awarded to SpaceDev.
Liquid systems and solid systems are the two basic types of rocket propulsion systems that are generally used in the rocket industry. In a solid propellant system, solid rocket fuel and an oxidizer are mixed together and allowed to cure inside a rocket case to form a solid propellant material, which is then ignited in the rocket case. Upon ignition, pressure forms within the rocket case and gases are released through a nozzle to produce thrust. In a solid propellant system, the solid propellant burns uninterrupted until all the propellant is exhausted, which can be undesirable in certain circumstances. Solid systems can be quite complicated, and are subject to several requirements during manufacture in order to minimize safety risks during use. For example, the solid propellant must be crack-free, as propellant grains which contain cracks present a risk of explosive failure of the vehicle. Solid propellant systems can be inadvertently ignited by mechanical shock and static electricity. Consequently, the manufacturing process requires extreme safety precautions, which increases manufacturing costs.
In a liquid system, a liquid oxidizer is fed into a combustion chamber in combination with a liquid fuel. The oxidizer and liquid fuel are mixed in the combustion chamber, where they react to produce gases under high temperature and high pressure. The gases exhaust through a nozzle from the combustion chamber to thereby produce thrust. Although widely used, there are certain drawbacks associated with liquid propulsion systems. One such drawback is that the mixing of reactants requires a high performance pressurization system for the fuel and oxidizer, which can contributes to a high cost with respect to both money and maintenance. Like solids, a liquid system can also explode since the oxidizer and fuels can be inadvertently mixed together. Another drawback is that exotic--and therefore expensive--materials must be used for the various components of the system, which increases the monetary cost of the systems.
A hybrid system combines aspects of both liquid systems and solid systems in that one propellant is stored as a solid and another propellant is stored as a liquid. In a typical system, the solid material is used as the fuel and the liquid material is used as the oxidizer. A variety of materials can be used as the fuel, including Plexiglas (polymethyl methacrylate (PMMA)), high density polyethylene (HDPE), hydroxyl terminated polybutadiene (HTPB), etc. Nitrous Oxide is a commonly used as the oxidizer, although other oxidizers can be used.
Hybrid systems have characteristics that can be highly desirable for certain situations and uses. For example, a hybrid system generally has higher specific impulse than solid systems. Specific impulse is the change in momentum per unit mass for the rocket fuel. Thus, a hybrid system can generate a high level of "push" for each unit of fuel that is used. Another advantage associated with hybrid propulsion systems is the complete separability of the fuel from the principal oxidizer. This inhibits the potential for inadvertent ignition or catastrophic failure so that hybrid systems are inherently immune to inadvertent explosion. Yet another advantage is that hybrid systems have the ability to easily start, stop, and restart the combustion of the rocket fuel.
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