The US Air Force has launched the competitive phase of the classified long range strike bomber by issuing a request for proposals, with Northrop Grumman and a Boeing/Lockheed Martin team poised to compete for a contract to develop and build 80-100 aircraft over the next two decades.

Details of the air force’s requirements for the new bomber are classified, and service officials are unlikely to provide more updates until a scheduled contract award in the second quarter of 2015.

“It will be an adaptable and highly capable system based upon mature technology,” says secretary of the air force Deborah Lee James.

Air force officials also have said the new bomber, also called the LRS-B, will enter service as a manned aircraft with a target unit price of $550 million. As the first new US bomber launched since the Northrop Grumman B-2A, the LRS-B is expected to replace a fleet of 76 Boeing B-52H and possibly a portion of the supersonic Rockwell B-1B fleets. A fleet of 20 B-2As will remain in service and complement the LRS-B.

The request for proposals has been highly anticipated by the competing teams as the largest new business opportunity in the aerospace sector for at least another decade.

“We look forward to industry’s best efforts in supporting this critical national security capability,” James says.

Both competing teams have already been jockeying to secure political support and to reduce costs. In May, Northrop announced that it would base the LRS-B engineering centre in Melbourne, Florida, if it wins the contract, with the state providing a package of tax credits.

Meanwhile, the California state legislature passed a new bill in June offering $400 million in tax credits to a subcontractor who builds a new strategic military aircraft for the air force in the state, which is expected to benefit Lockheed if its team wins the air force contract. The bill’s language appears to exclude a prime contractor, such as Northrop, from the same benefit.

The competition comes several years after the air force began developing concepts for a B-52 replacement programme.

A congressional researcher, Jeremiah Gertler, issued a report on 2 July that suggests that billions may already have been invested by the air force in the early development phase of the contract.

Gertler cites air force budget documents showing a more than 10-fold increase in spending on the LRS-B programme from Fiscal 2013 to 2019, with annual outlays rising from $259 million to $3.45 billion. Such a profile may imply that early production could begin by the end of that range, Gertler says.

Classified budgets may have already paid for “significant” development work on the LRS-B, Gertler says.

“If there has in fact been considerable prior development, the air force will be challenged to construct a truly competitive RFP,” Gertler says. “Whichever competitor may have done the bulk of any such preliminary LRS-B development is likely to have an advantage in the production contract.”