- Few of the new B-21 bomber’s features have gotten as much attention as its unusual windshield.
- Its unusual shape and layout suggest minimal reliance on visual cues and a focus on defeating radar.
- Little is yet known about the B-21’s capabilities, but stealth has been a priority since the outset.
On December 2, the world got its first glimpse at America’s new stealth bomber, the B-21 Raider. Among the many details drawing the public’s attention, few stand out quite as much as its unusual windshield (or windscreens).
We’ve been tracking the comments we receive on stories and videos about the B-21 Raider since its unveiling and we have been trying to address the most frequently asked questions to the best of our ability. We have discussed why the B-21 is much more than an updated B-2 Spirit.
Today, we’re taking on the Raider’s unusual-looking cockpit and trying to better understand why its windscreens are so different from bombers of the past.
What’s the deal with the B-21 Raider’s windscreens?
The B-21 Raider’s unusual windscreen layout has been the subject of lots of discussions, but there has been very little in the way of formal statements regarding it. Like the B-2 Spirit before it, the B-21 uses four separate windscreen panels, but while the Spirit’s four windows look pretty ordinary, the B-21’s are downright exotic in comparison.
Using multiple separate windows in a curved structure like the B-21’s cockpit does make perfect sense, as a large, single-piece windscreen would be much harder to produce in volume.
The unusual shape of the B-21 Raider’s front two windscreens seems to prioritize visibility directly ahead and above the aircraft most of all. That makes perfect sense when you consider how important mid-flight refueling will be for its globe-spanning operations.
The unusual shape and layout of these windows may also suggest a minimal reliance on visual cues while flying, as well as the design’s emphasis on defeating radar detection. It’s important to remember that, once airborne, it’s not at all uncommon for pilots to fly entirely on instrumentation alone, with no need to peer out into the empty sky surrounding them. The windscreens on the B-21 will primarily be important during taxiing on the ground and mid-air refueling.
Windscreens can have a big effect on radar return
Seeing as there was discussion in the B-2’s development cycle about omitting a windscreen completely, it seems evident that in-flight refueling still requires some good old-fashioned eye-balling, but the rest of the windscreen’s design likely prioritizes stealth over visibility.
Glass windscreens and cockpits can have a pronounced effect on an aircraft’s radar return. This is most apparent in efforts like the first phase of the Air Force’s Have Glass F-16 treatments to reduce the F-16 observability by upgrading its windscreens.
The first stage of Have Glass included applying a thin layer of indium-tin-oxide to the fighter’s canopy to deflect radar, rather than allowing it to pass through the glass and reflect a return from the pilot’s helmet and the visible portions of the ejection seat.
All told, Have Glass stages I and II (the second of which included the addition of Radar-Absorbent Material to portions of the fighter’s body) reduced the F-16’s overall radar return by as much as 15%.
At this point, it’s impossible to say that the B-21’s windscreens are shaped in a way that minimizes their effect on the platform’s overall radar return, but it seems entirely likely that a bomber that has prioritized stealth from its onset would take stealth into consideration in all things — including in its windscreen design.