U.S. Air Force Reveals New B-21 Design Details

Credit: U.S. Air Force

A newly released Northrop Grumman B-21 picture offers the first clear view of both of the bomber’s unique air inlets. 

The image, which the U.S. Air Force published March 7, reveals for the first time that the inlets are shaped like sideways teardrops. 

The designers appear to have positioned a bulbous inboard section to ingest the boundary layer of air flowing over the leading edge of the wing.

If viewed from above, the inlet also appears to be L-shaped, with a right angle placed at roughly one-third of the inlet length. Both sides sweep forward from the right angle, with the outboard section at roughly two-thirds the length. 

The B-21 also is designed with a pair of indentations above the engine nacelles on either side of the aft fuselage. The openings may be slits for supplemental inlets or exhausts. Alternatively, they could be apertures for sensors or communications. 

Several stenciled markings appear on the wings and fuselage. The symbol for Northrop’s advanced projects division appears on the right wing, as viewed from the cockpit. The roundel of the U.S. Air Force is shown on the left wing. Along the right side of the fuselage aft of the cockpit appear three more unit logos, but the details are not visible. 

The image appeared in a presentation by Gen. C.Q. Brown, the Air Force chief of staff, who addressed the Warfare Symposium in Aurora, Colorado. 

The Air Force first revealed the B-21 during a Dec. 2 ceremony at the Northrop factory in Palmdale, California, but carefully obscured views of the inlet from the crowd and live footage. The aft section of the aircraft still has never been shown to the public, nor has the identity and quantity of the engines on the bomber been disclosed. 

The B-21 is still scheduled to fly this year, but Air Force officials do not offer more details. “It will fly when it’s ready,” Andrew Hunter, the assistant secretary of the Air Force for acquisition, technology and logistics, told the symposium audience on March 7. 

Air Force officials have consistently said the bomber’s development has gone generally to plan, and that certain aspects of the program have proceeded faster than similar advanced aircraft in the past. 

The B-21’s mission system recently demonstrated that it could detect, target, track and destroy a target in simulations, Gen. Thomas Bussiere, the commander of Global Strike Command, said at the symposium. Although no further details were released, Bussiere’s remarks suggest the B-21 may be further along than the Lockheed Martin F-22 and F-35 at the same stage of development. Neither aircraft began testing the mission systems onboard until at least three years after first flight. 

“The capabilities and technology integrated into that weapon system is second to none,” Bussiere said. “It will be the most advanced strike platform ever designed or built on the planet.”

Steve Trimble

Steve covers military aviation, missiles and space for the Aviation Week Network, based in Washington DC.


It is hard to follow that description. Generally, boundary layer splitters, ingesters, extend along the whole dimension of the inlet along the body lateral to it (F-4 a nice example) or ventral in this case. (As an aside, it is the flow aft of the leading edge that produces most of the energy loss, especially if it goes turbulent). Assuming for a moment the article has it wrong, then would the peculiarities of the shape be mainly the product of stealth requirements rather than BLC? Could the BL be handled internally within the duct? As a digression would it be possible for Journalists to bring a pocket radar to get a preliminary estimate of radar stealth while at a roll out or other function? Bernard Biales
While an interesting idea, I'm sure both NG and USAF would not look kindly upon anyone foolish enough to attempt such a trial.