A rendering of the upcoming B-21 stealth bomber the USAF's first new heavy bomber in over 3 decades Northrop Grumman

A new runway, a massive hangar and a flurry of unusual activity at the Area 51 in the Nevada desert, are fueling rumours that the US Air Force (USAF) is using the secret base to test and develop its upcoming B-21 Raider.

The B-21 Raider, which is currently reportedly under development, is the first new heavy bomber that the US is working on over the past 30 years, notes a report by Popular Mechanics (PM). The B-21 bomber is shaped similar to the B-2 stealth bomber and is reported to cost around $550mn (£411mn) per aircraft. Its long list of abilities, or what could be expected of the bomber once it is ready, could make it a formidable addition to the already strong American arsenal.

The B-21 Raider is believed to have drone capabilities in addition to its pilot mode, it could also be used to deliver nuclear bombs as well as have a star-trek like invisibility cloak feature. Apart from a few other details, including a few mock-ups on design and shape, there is not much known about the Raider. At one point of time, there were even rumours that the US President might be shifting from the 747 Air Force One jet to a B-21 Raider.

The PM report notes that the USAF wants to build at least 100 Raiders to replace their current fleet of B-52H Stratofortress and B-1B Lancer bombers.

A post by the Aviationist notes that recent activity around Area 51 could possibly point out to it being used to test or develop this secret project. The Nevada Test and Training Range (NTTR), the official name of Area 51, has new construction on site, according to the post. Satellite imagery shows a new runway that does not have any rubber marks on it, meaning it is freshly laid out. New facilities and hangars have also reportedly appeared at the site.

A new U-shaped taxiway, a roadway, and a very large hangar have been spotted at the site, notes the PM report. The new hangar is estimated to be about 250 by 275 feet and is a lot larger than what the USAF's current stealth bomber, the B-2 Spirit, needs. Aviationist concluded that this can only mean that the B-21 is being developed at this restricted site.

Trucks carrying an F-117 fuselage and an F-16 at the site as well as reports of "bearded military-aged men" taking buses into the Nevada desert have further sparked speculations about the unusual activity around the Area 51.

The B-21 Raider is expected to be operational in the 2020s.