The Air Force's premier killer drone could get a lot more dangerous, if the flying branch agrees to upgrades proposed by the robot's manufacturer. California drone-maker General Atomics has figured out ways to nearly double the flight time of the camera-, missile- and radar-equipped MQ-9 Reaper by adding fuel pods, longer wings and stronger landing gear. With all three enhancements, a Reaper's endurance jumps from 27 hours to a whopping 42 – almost two days of continuous flying, which makes a big difference now that the Air Force is scaling back its drone buys.

The upgrade, which is just a company proposal so far, boosts what is already the MQ-9's biggest advantage over traditional aircraft such as the F-16. Manned warplanes' flight times are limited by a wide range of factors, but especially the endurance of their human pilots. A typical F-16 sortie lasts just a couple of hours. With no pilot on board, the $30 million MQ-9 can fly until it runs out of gas. In enhancing the Reaper, General Atomics focused on expanding and stretching the 'bot's fuel load.

The company is offering three related upgrades, although it's not saying how much they cost. One adds a new 88-foot-span wing, replacing the existing 66-foot wing. The longer wing boosts lift and improves fuel efficiency. Plus, Reaper users can add two new fuel pods in place of some of the drone's weapons, each carrying a hundred or so gallons of gas. Both upgrades mean more weight on the airframe and require new heavy-duty landing gear that can support the nearly six-ton weight of an improved Reaper.

The new wing, fuel pods and landing gear can be installed by company reps at the Reapers' forward bases in Afghanistan, East Africa and elsewhere. Since the Reaper made its combat debut in Iraq in 2007, the Pentagon has steadily expanded the territories the killer drone patrols. The CIA, the U.S. Border Patrol, the U.K. and Italy also operate Reapers.

It's not hard to see why General Atomics wants to boost the MQ-9's flight time. The enhancements reflect "customers’ emerging needs," said Frank Pace, president of General Atomics' airplane division. To save money, the Air Force has decided to cut its Reaper purchases in half, to just 24 a year. But the flying branch still wants to be able to keep up to 85 killer drones in the air at all times.

Today, that takes two drones on the ground for every one in the air. Getting more flight time out of each aircraft means fewer are needed overall, as the increased endurance buys time for mechanics to fix, refuel and re-arm the robots that aren't flying. When you've got two days to prep the next drone, there's less need for spares.

Moreover, the upgraded Reaper could partially replace the Global Hawk spy drones that the military recently decided were too expensive to maintain. The MQ-9 will never fly as high as the 11-ton Global Hawk, but with the proposed changes, it might fly as long as the larger 'bot.

For now the extended-range Reaper is just a company proposal. The Air Force has not said yet whether it wants the upgrades – or if it can afford them.