The Long Road to First Flight

Northrop-Grumman and the United States Air Force have commenced taxi testing of the B-21 Raider—the United States’ newest and most technologically-advanced, combat-capable stealth-bomber.

In addition to conceding the bomber “is conducting ground taxi activities,” a USAF spokesperson set forth: “Rigorous testing is a critical step in the B-21 flight test program. Extensive testing evaluates systems, components, and functionalities. This testing allows us to mitigate risks, optimize design, and enhance operational effectiveness.”

The most recent photos of the first B-21 depict the aircraft outside its hangar at Northrop Grumman’s facility at Air Force Plant 42 in Palmdale, California.  

Social-media sites dedicated to monitoring Plant 42—a storied and highly-secretive installation at which Lockheed-Martin and Boeing also have facilities and novel aircraft are the norm—have, since 23 October 2023, consistently reported “something moving” at Northrop’s end of the facility.

Taxi tests presuppose the completion of outdoor engine runs, and typically assess an emergent aircraft’s ground-handling qualities at slow and medium speeds. The commencement of high-speed taxi testing heralds the imminence of flight-testing.

An immense flying wing, the B-21’s expansive lifting surfaces render high-speed taxi testing a fiddly business. Excessive speed could easily precipitate an inadvertent first-flight—after the fashion of the YF-16, the machine that would evolve into the ubiquitous F-16 Fighting Falcon. During a series of 1974 taxi-tests, over-advancement of the prototype’s power-lever compelled the jet momentarily aloft.

Described as a production representative, the B-21 currently undergoing taxi-testing is one of six specimens of the bomber known to be in some stage of production. The aircraft are being built on production tooling, and the first examples ought not be considered prototypes; so stated Northrop Grumman aeronautics president Tom Jones at the Air & Space Forces Association (AFA) Air, Space, and Cyber conference in September 2023.

Mr. Jones asserted: “The jet that’s going to fly this year, for all intents and purposes, is a production jet. It’s got all the coatings, it’s got the mission systems, it was built using factory processes … with regular workers, by regular factory technicians, not engineers doing a bespoke first article.”

While the first B-21 to fly will be considered a “flight sciences” aircraft—which is to say an iteration of the bomber instrumented to collect data germane to all aspects of its performance—the B-21 contract calls for all test aircraft to be configured as operational models upon the conclusion of testing.

In January 2023, during the company’s quarterly earnings call, Northrop Grumman CEO Kathy Warden stated she expected the contract for Low-Rate Initial Production (LRIP) this year, but after first flight. At the company’s second-quarter call, Warden reported the first B-21 had completed its first “power on” test, thereby paving the way for engine runs and taxi.

During both calls, Warden cautioned the fixed-price nature of the LRIP contract, coupled with the inflation of recent years, essentially negated the possibility of the program showing an early profit. Warden added, however, that Northrop expected to receive a $60-million payment from the Air Force to mitigate inflation and hasten the aircraft toward first flight.

Air Force officials have repeatedly insisted the B-21’s inaugural flight will not be a media event. Rather, the service’s brass maintains the aircraft will fly when engineers and test-pilots determine the time is right—neither earlier nor later.

The B-2—the B-21’s predecessor—flew nine months after its rollout in 1988.

Rolled out of Northrop Grumman’s Palmdale, California plant on 22 December 2022, the B-21 Raider long-range, intercontinental, stealth, strategic bomber—according to Pentagon officials—will function as the cornerstone of America’s deterrence capability for decades to come.

In a 29 November 2022 statement, Northrop Grumman confided: The bomber “has … been designed as the lead component of a larger family of systems that will deliver Intelligence, Surveillance and Reconnaissance (ISR), electronic attack and multi-domain networking capabilities.”

The statement confirmed suppositions that the B-21 will rely on external support platforms or systems; although whether these are escort aircraft, bomber-launched vehicles, satellites, or some other technology remains unclear. In recent months, USAF officials have described the B-21 as an ISR node deep within enemy-controlled airspace.

A senior Northrop Grumman official confirmed the B-21 will be “a lot stealthier” than the B-2 and feature improvements in maintainability and reliability conducive to its operating continuously in full stealth mode. By contrast, the B-2’s low-observable surfaces require many hundreds of man-hours of maintenance between missions. The B-21 further improves on the B-2 by eliminating the so-called special tape that covers the latter aircraft’s airframe seams and panel lines, the Northrop Grumman official concluded. 

A Northrop Grumman spokesman stated: “To meet the evolving threat environment, the B-21 has been designed from day one for rapid upgradeability. Unlike earlier generation aircraft, the B-21 will not undergo block upgrades. New technology, capabilities, and weapons will be seamlessly incorporated through agile software upgrades and built-in hardware flexibility. This will ensure the B-21 Raider can continuously meet the evolving threat head on for decades to come.”

Referring to the Raider as a “digital bomber,” the Northrop Grumman spokesman added: “The B-21 uses agile software development, advanced manufacturing techniques, and digital engineering tools to help mitigate production risk” and “enable modern sustainment practices.”

Notwithstanding the persistence with which it is applied to the B-21, the term sixth-generation aircraft has yet to be clearly defined. Fifth-generation aircraft employ a high degree of stealth and sensor fusion for high degrees of situational awareness. How and to what extent sixth-generation aircraft might improve upon their forebears’ combat effectiveness remains to be seen.

Various descriptions of sixth generation being bandied about the defense industry suggest such aircraft would feature optionally manned capability—which the B-21 is meant to have—better situational awareness, better stealth, and the potential use of directed-energy weapons—among other possible attributes.

Of stealth, Northrop Grumman set forth that it is applying “continuously advancing technology, employing new manufacturing techniques and materials to ensure the B-21 will defeat the anti-access, area-denial systems it will face.”

Alluding to its work on the B-2 Spirit bomber, the YF-23 fighter prototype, the Tacit Blue stealth demonstrator and F-117 antecedent, the AGM-137 Tri-Service Standoff Missile, and presumed numerous additional classified programs, Northrop Grumman stated: “The B-21 benefits from more than three decades of strike and stealth technology. … It is the next evolution of the Air Force strategic bomber fleet, and a  visible and flexible deterrent.”

Noting that the B-21’s Raider appellation commemorates Doolittle’s Raiders—a squadron of B-25 Mitchell medium bombers commanded by then Lieutenant Colonel James H. Doolittle which carried out America’s first WWII offensive operation against Imperial Japan, Northrop Grumman asserted: “The actions of those eighty volunteers were instrumental in shifting momentum in the Pacific theater.” The company posited the Doolittle Raid served as a “catalyst to a multitude [of future achievements] in U.S. air superiority from land or sea.”

FMI: www.af.mil