CAMARILLO — Using less glamorous and less costly equipment, tiny American Rocket Co. plans to fly private payloads into space more cheaply than NASA, General Dynamics or the other giants of aerospace. The company plans its first private-enterprise space launch this July, which was scheduled after a successful test of its hybrid rocket engine last September. Amroc President George Koopman says the company, based 50 miles northwest of downtown Los Angeles, expects to have four or five paying customers for its first launch. Although the summer’s test flight will never reach orbit, it will be in a near-weightless state for three to four minutes. That is enough time for researchers interested in testing certain exotic materials. “The situation is getting so desperate, mainly because of NASA, that people are willing to come and include their valuable experiments even on the first flight of our vehicle,” Koopman said. Before the explosion of the shuttle Challenger, the National Aeronautics and Space Administration had nearly put major rocket builders out of the launch business. National policy excluded all other launch vehicles in favor of the shuttles. NASA offered shuttle rides into space at bargain prices that private companies couldn’t compete with. Expecting cheap prices from NASA, military planners, researchers and commercial interests built dozens of satellites and other payloads. But many of those payloads were left grounded when NASA’s space program fell short of predictions. NASA was pushed out of the commercial launch business in 1984 under the U.S. Commercial Space Launch Act, and three major players took over. General Dynamics with the Atlas, Martin Marietta with the Titan and McDonnell Douglas with the Delta were ready to launch into space with the capacity to carry at least 4,000 pounds. But smaller firms like Amroc are building launches to carry smaller payloads. Other competitors in space include Space Services Inc. of Houston, run by former astronaut Deke Slayton; Conatec of Maryland, headed by NASA veteran Gene Kadar; Orbital Services Corp. of Virginia, and E Prime Aerospace of Florida. “We’re trying to build a delivery truck,” Koopman said. The company is building a hybrid rocket that uses liquid oxygen and solid polybutadiene, which is artificial rubber, as fuel. Conventional rockets use either a solid propellant that is a fast-burning mixture of fuel and oxidizer or burn liquid fuel and liquid oxidizer. A hybrid rocket compares to a conventional rocket in the same way a diesel engine compares to a gasoline engine, Koopman said. Hybrids have the advantages of low cost, reliability and safety, Koopman said. “We have developed this technology and done what nobody has done before, and that’s make it work,” he said. “I’m trying to take that (success) . . . to Wall Street and convince them to continue to back us.” It is too early to tell what the ultimate success of Amroc and other upstart companies will be. Lawrence Harris, who follows aerospace issues for Bateman Eichler, Hill Richards in Los Angeles, said newcomers would have a hard time beating the big three rocket builders. But it is possible for a new rocket to be profitable, according to Wolfgang Demisch, first vice president of UBS Securities in New York. “To some extent, maybe the door is open to new approaches to take to kicking things up in the air.” Jim French, a former chief engineer for Amroc, said that while the major companies have the advantage of proven track records, small companies may be able to respond more quickly to new developments in the space launch field. “There is a potential, I believe, a tremendous potential, for small, low-cost satellites,” French said.