The US is planning to pour billions into a stealth programme that, by 2025, will see the US Air Force (USAF) replace its ageing fleet of stealth bombers with a new, highly advanced aircraft called the Long-Range Strike-B (LRS-B) heavy bomber.
In 2015, the Pentagon will be spending nearly $1bn on development costs for the new jet. Those costs are set to increase over the next five years with $1.6bn earmarked for the 2016 budget and $3.5bn for 2019.
In total, development of the new stealth bombers will cost nearly $12bn over five years, according to figures in the latest USAF five-year plan. Total costs for the programme beyond 2019 could top $55 billion, which makes it one of the Pentagon's costliest weapons projects.
The cost of one LRS-B heavy bomber is currently capped by the Pentagon at $550m, but that figure doesn't include research and development.
New bombers 'essential' for power projection
Nearly 100 bombers could eventually be built with the aim of replacing the USAF's fleet of B-1B Lancers and B-2 Spirits. The new bombers will fly alongside the last remaining B-52s, all 74 of them, until they too are replaced by another new-generation bomber.
"The next-gen bomber is absolutely essential to the future of US power projection," says Paul Scharre, project director for the 20YY Warfare Initiative at the Center for a New American Security. "A foundation for credible deterrence is the ability to strike someone, and the bomber will sustain that capability for the future.
"A new bomber is necessary because the integrated air defense systems of other states are becoming more sophisticated over time and the B-2 bomber's stealth will not be sufficient in the long run."
With ongoing problems in the F-35 programme, the most technologically advanced in USAF history, some question whether a next-generation bomber can indeed be built for half a billion dollars and not go over budget. You only have to look at previous programmes to realise this figure might be a little optimistic.
Each B-2 Spirit bomber, which the LRS-B will replace, costs an eye-watering $2bn after research, development and manufacturing costs are added up. At the time of its development, it was quickly realised that was too much money and production was stopped early. Out of a planned 132, only 21 B-2s were ever built.
For the time being, US defence officials are sticking to the $550m cap.
"Like many other defense programmes, staying on target cost-wise will require rigorous oversight from DoD and scrupulous attention to cost from the contractor," Scharre added. "But betting that it will go up is not a bad bet. It's also worth noting that $550m a copy doesn't include development costs, which will be in the billions."
Airforce-technology.com lists some of the world's best bombers operational today, based on range and payload capacity.
At that price, it's high stakes for whoever wins, or loses, the battle to manufacture the bomber. Three companies are in the running; aerospace giants Boeing and Lockheed Martin will bid together, while Northrop Grumman, the makers of the B-2, will also take part.
Northrop is seen to be at an advantage with its significant experience developing, manufacturing and sustaining the USAF's current stealth fleet.
While it has advantages, Northrop Grumman will be up against a consortium with a combined annual sales figure totalling nearly $130bn, compared with Northrop's $24bn. That makes the Boeing and Lockheed Martin partnership a formidable opponent when it finally comes to submitting their respective strike bomber bids.
Manned bombers over unmanned aerial vehicles
LRS-B is also a sign that the USAF has not given up on manned systems, despite significant advancements in unmanned technology over the last decade or so.
The advantages of using unmanned systems, namely performance advantages derived from removing the person from the vehicle and the ability to take additional risk, reduces with larger platforms, explains Scharre.
"At the size of a large bomber, on the order of nearly 400,000lb fully loaded, the weight of the two-person crew and their cockpit is negligible, maybe 1% of the total weight," he says.
"One of the advantages [of using unmanned systems] could be endurance, but B-2 pilots have flown for 40+ hours because having two pilots allows crew rotations. Moreover, a surveillance aircraft might have reason to stay aloft for days at a time, but a bomber's mission is to hit its targets then return home and get more bombs, so there isn't generally a need for long loitering over a target."
Still, it is likely the new bombers will be 'optionally manned', which means they can be flown as unmanned vehicles if commanders deem it necessary. Another challenge is the likely role they will play as nuclear bombers.
"The other, absolutely critical reason for having a manned version of the new bomber is that it will be dual-use, meaning it will also have a nuclear role in addition to conventional strike," says Scharre. "Putting nuclear weapons on an unmanned aircraft is just nuts."
Anti-access/area denial operations
Operationally, the LRS-B will be like the B-2 Spirit it is replacing. It will be deployed over countries with sophisticated anti-access/area denial (A2/AD) capabilities such as surface-to-air missiles and GPS jammers at their disposal.
When it comes to flying bomber missions in this environment, it seems current technology dictates that human pilots aboard stealth aircraft are a better option for military commanders than unmanned aircraft.
While the LRS-B is still on the drawing board, its development shows that the fiscally constrained US remains the world leader in advanced aerial bombers. No other country can match this capability; at least not yet. However, one project worthy of mention is Russia's next-generation bomber programme, designated the PAK-DA. That could see a new Russian bomber in the skies by 2025, around the same time as the LRS-B.
The era of the manned bomber is far from over.