Design and Feature Analysis of the B-21 Raider Stealth Bomber

The maiden flight of the B-21 Raider stealth bomber on November 10, 2023 in Palmdale California, has attracted attention. Even though the B-21 flight procession was carried out secretly, the video recording from Matt Hartman has opened the veil that had been tightly closed about the B-21 Raider. 

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And thanks to Matt Hartman's video footage, we can now gauge some of the features Northrop Grumman may have installed in the B-21 Raider design.

From the first flight of the B-21 Raider, what is considered to have the highest information value is the appearance of the fuselage which allows for an in-depth analysis of details of the B-21 Raider that were previously unknown. 

Quoted from theaviationist.com (11/11/2023), the following are several suspected devices that may have been installed on the B-21 Raider. As seen in the photo above, Wonwoo Choi, writer at theaviationist.com, revealed several devices on the B-21 Raider, such as the radar atimeter, air data probe arrays, luneburg lens, retractable navigation lens and thermal coating.

In addition to the lower fuselage, the side of the B-21 Raider during taxii tests confirmed that the bomber had one secondary air intake door above each nacelle. 

On the B-2, the semi-hidden engine has a secondary intake hatch that opens during takeoff to provide sufficient airflow. While the B-2 had two doors per nacelle for its four engines (General Electric F118- non afterburning), the B-21 Raider appears to have only two doors total.

Nacelle refers to the covering structure that protects an aircraft engine, especially a jet engine. The nacelle is usually located at the front or bottom of the aircraft wing and is designed to channel air through the aircraft engine. This nacelle also protects the engine from weather elements and provides good aerodynamics.

While it is possible that the air intake split into two from one opening to accommodate two engines, it is more likely that the single entrance indicates that there was only one engine in each nacelle. Although more evidence must be reviewed before making any reasonable conclusions, it appears that the B-21 was a twin-engine bomber.

The radar reflector or Luneburg lens, pictured here is mounted between the landing gear. Since stealth aircraft do not usually appear on radar, they tend to fly with their radar reflectors on unless low detection is required. Moreover, on prototypes like this, it is rare to see an aircraft without a radar reflector because the actual radar again tends to be a closely guarded secret.

Due to the aircraft's difficult to observe nature, its pitot tube and static probe were also unconventional in shape. Almost identical to the setup found on the B-2, the B-21 also uses three sets of four air data probes located in the nose and nose of the aircraft.

Although any aircraft requires a set of pitot tubes and static ports to measure airspeed, altitude, and vertical speed, they tend to be in free flow for accurate measurements. However, having a conventional pitot static tube would be detrimental to the stealth aircraft's radar capabilities.

B-21 RAIDER FIRST FLIGHT 11-10-23 #RAIDER33 #B21Raider pic.twitter.com/3tEKudqDiw

— Matt Hartman (@ShorealoneFilms) November 10, 2023

Therefore, the B-2 uses a series of flush-mounted static ports and data correction to mimic the role of a conventional pitot tube. Because the location of the air data probe is at an angle to the local air flow, there tends to be multiple sets of sensors in common to account for inaccuracies in measurements. In this case, the B-21 appears to have nearly the same arrangement of its air data ports as the B-2.

Just like on the B-2, a darker shaded line can be seen extending down the rear of the Raider. This appears to be a thermal coating applied to areas in direct contact with the engine exhaust.

It should be noted that Very Low Observable (or “stealth”) technology does not only refer to low detection from radar, but also across other spectrums including the visible and infrared spectrum. Therefore, efforts were made to reduce detection of B-21s in the arena through gray paint schemes and thermal coatings.

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While the central weapons bay (internal weapons bay) has two sets of doors that swing open, the secondary weapons bay appears to open with a single door. As can be seen from the described drawings, the two sets of secondary gun emplacements will have a smaller width and length compared to the primary emplacements.