You don't hear much about the new F-35 fighter-bomber. But it regularly passes all it's milestones on it's way to active service in 2009. Some 3,000 are expected to be built. Roughly the same size as the F-16, it's far more capable. But aside from being stealthy and on time, the F-35 is also likely to be one of the last major manned combat aircraft built in large quantities. The reason is cost and need. During World War II, major combat aircraft were built in enormous numbers. Some 37,000 Il-2 Stormovik's were built, at a cost of about $100,000 (in current dollars) each. U.S. warplanes were more expensive. Each of the 15,575 U.S. P-51s cost about $500,000 each. By the time the Korean war came along, the aircraft were getting more expensive. The F-86 jet fighters cost about $1.2 million each and 6,200 were built. By the 1960s, things were really getting expensive. Each of the 5,000 F-4s built cost over $20 million. It's replacement, the F-16, saw only 3,500 built. The more expensive (up to $40 million) F-15 saw far fewer built (1300). The Russians built 10,000 Mig-21s from the 1950s to the 1980s (and China continues to build a copy). The Russians were always flexible is quoting a price for MiG-21, but in the 1990s the Indians were making licensed copies for about $800,000 each. Unfortunately, the MiG-21 has a miserable combat record and even the Indians are finally wising up to that angle. So what comes after the 3,000 F-35s? Combat UAVs. There will still be human pilots up there, but more and more they will be flight leaders for hordes of combat droids. These are a lot cheaper than manned aircraft, and will be built in much larger numbers. A successful combat UAV design will probably see 5,000 copies built. Considering that the U.S. Air Force was only about to built 21 of the B-2 bomber (at over a billion bucks each) and is scraping to get 500 F-22s built (at $200 million, or more, each.), 5,000 combat UAVs looks comforting, and affordable.