Just when you thought you had the competition cornered, you hear footsteps behind you. And it isn't just another gutsy rival spoiling for a fight. It is a gang of heavily financed and better-equipped companies. Now who is trapped?

Until recently, tough antitrust laws discouraged most big companies from collaborating. But last year, Congress passed legislation designed to encourage them to join forces for research and development. For small enterprises, this raises the frightening prospect of competition from groups of companies with far greater resources to pursue new products.

Bobby Inman, president of the most celebrated of such consortia, Microelectronics and Computer Technology Corp., argues that small companies needn't worry. "Small companies can band together, too, if they want," says Inman. "They've already got the mechanism for doing that." He says that consortia are likely to choose projects "on an investment and technology scale that small businesses cannot afford." He also predicts that many new consortia will include small business members.

Charges that consortia serve only the interests of big business are "pure bunk," Inman declares. "Consortia," he adds, "are absolutely necessary when you look at the slide we've experienced in creating technologies."

Inman says that all companies will benefit from consortia because the United States will be a stronger international competitor. The 53-year-old admiral, who spent 30 years in government, cites the example of Japan, which has successfully subsidized consortia in such industries as automobiles and television. "Consortia are how we keep competitive in the international market," Inman says. That will be little consolation to small companies here at home that find themselves working on the same new product as a wealthy group of rivals.