The aircraft were once controversial; before 9/11, their backers had to fight to deploy them against al Qaeda. But since then, the Predator drones have gone beyond surveillance to target and kill leading terrorists, and they are now widely deployed in Iraq and Afghanistan.

In early production today is a kind of Predator on steroids–the MQ-9 Reaper (seen above). Six times heavier than the Predator, the Reaper is capable of holding a payload of missiles and bombs equal to that of an F-16 fighter–and can linger in the same area for as long as 24 hours. Whereas Predators are called "killer scouts," the Reapers are dubbed "hunter killers."

So deadly and effective are the new drones that some military units plan to trade in their workhorse attack aircraft for them, according to a revealing story in Air Force Magazine.The Air Force has "provisional plans" to buy some 170 of the current Predators by 2010 and an additional 50 to 70 of the new Reapers by 2012, while retiring about an equal number of F-16s, the magazine reports.

Here's an artist's rendering of another remote-controlled drone, Boeing's Joint Unmanned Combat Air Systems X-45C. This model didn't fare as well–the Pentagon pulled the plug on it last year. But the basic design is still influencing development of remote-controlled projects for the Navy and Air Force, which include stealth-like features and adaptation for basing on aircraft carriers.

Photo credits: MQ-9 Reaper, U.S. Air Force

X-45C, Boeing Co.