The first widely adopted drone aircraft for the U.S. Air Force was the Predator. The aircraft originally designed to be a pure reconnaissance vehicle that could fly and loiter in an area for up to 20 hours at altitudes up to 25,000 feet without putting a pilot in harm's way.

Eventually the military got the idea to arm the Predator with Hellfire missiles so that the aircraft could engage targets. The Predator has been a major success for the Air Force, however, the sun is setting on the drone. The Air Force has purchased its final batch of 268 Predators from General Atomics with the last one expected to be delivered by February 2011 reports Wired.

As the Predator drones are removed from service for various reasons, they will be replaced with a new and more capable drone aircraft called the Reaper. The Reaper is a much more capable drone aircraft and was designed for the start to be able to perform in both surveillance and attack roles.

The Reaper is able to fly at around 50,000 feet and flies twice as fast as the Predator with a maximum speed of 260 knots and a cruise speed of 150 to 170 knots. Perhaps the biggest improvement for the Reaper is in its ability to carry a variety of weapons. The Reaper will be able to carry the Hellfire AGM-114 missile and GBU-12/GBU-38 precision bombs. The Predator was only capable of carrying the Hellfire missile. The Reaper also has more electrical power onboard allowing the aircraft to have more sophisticated sensors.

The Air Force already owns 57 Reaper drones and wants another 272 of them. How fast the additional Reapers come into the fold will depend on budgets approved by Congress.

The Air Force is also already looking towards the replacement of the Reaper with a faster aircraft called the Avenger. The Avenger is jet-powered allowing it to be much faster than the Reaper.