By mating modern lightweight avionics with new-generation ultralight turbine engines, Bye hopes to create a "sportscar for general aviation" capable of speeds up to Mach 0.92, just shy of supersonic. In 2000 he put together a company, Aviation Technology Group, to design, build, and market the Javelin. But few aircraft start-ups manage to endure the Federal Aviation Administration's lengthy, expensive testing and certification process for production aircraft. If the Javelin does, its most serious competition will come from the many military surplus jets on the market (you can pick up a reconditioned Czech L-39 Albatross for about $500,000). But military jets are expensive to maintain and are subject to extensive restrictions. They can't, for instance, be used commercially or to carry passengers.