Here’s how the legendary B-2 bomber’s stealth actually works

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Air Force crew chiefs inspect on a B-2 Spirit bomber at Whiteman Air Force Base, July 12, 2012.

  • Only 21 B-2s were ever built, and they reportedly have a stealth profile similar to that of a large bird.
  • Because it’s so hard to spot, it can be a first-wave attacker, clearing air defenses and opening paths for less stealthy aircraft.
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The B-2 Spirit is one of the most clandestine and rare planes in the world.

Only 21 were ever built, and they reportedly have a stealth profile similar to that of a large bird despite their 170-foot wingspan. And they’re invisible to many infrared seekers, despite four large engines.

Here’s how engineers made a massive plane with large engines nearly invisible to systems designed to detect threats exactly like the B-2.

The B-2’s stealth profile is the result of extensive computer testing that wasn’t possible before its design. While the F-117 and B-1 were stealth aircraft, they were designed by nerds with slide rules and minimal computer modeling because the technology and the computers necessary simply didn’t exist.

But when it was time to design the B-2, the all-powerful nerds had super computers and leveraged them to create a model that had no flat surfaces with which to reflect radar directly back to the sensor. While a machine with no flat surfaces is harder to manufacture, the increase in stealth was deemed worthy of extra costs.

If the B-2 were flying directly toward the radar, most of the waves would actually be reflected 90 degrees away from the receiver, giving the radar operators next to nothing to work with.

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A B-2 takes off at Nellis Air Force Base in Nevada, January 28, 2014.

But of course, the flying wing would lose most of its stealth if the engines were mounted outside of its high-tech form. So the engines were mounted inside with special openings for intake and exhaust that, again, would not reflect radar waves back to the dish.

That exhaust opens its own can of worms. After all, aircraft can be tracked by their infrared signatures, if only from relatively close ranges. So, the B-2 needed tech that would let it diffuse or mask its infrared emissions at ranges as short as possible.

It has a few (mostly classified) systems to help with this. The exact shape of the exhaust helps a lot, but it also cools its exhaust and mixes it with the outside air to create a final exhaust that is at nearly the same temperature as the air flowing into the intake.

This greatly frustrates pursuing missiles and fighters, but obviously still leaves it vulnerable if someone spots the plane and talks fighters into the vicinity to hunt it.

Except the B-2 has another trick up its sleeve that makes even that less likely. It’s actually extremely quiet, so much so that people at sporting events with B-2 flyovers have reported being able to speak to one another as the plane flies past.

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Anyone who has worked with most other jets knows that you can typically hear them before you see them, often by a matter of hundreds of feet. It’s the sound that lets you know to look for the plane, but the B-2’s tiny acoustic signature means that most observers on the ground won’t know there’s anything in the sky to look for.

Combined, this makes the B-2 a plane with little radar observability, that’s too quiet for most people on the ground to notice it flying nearby, and it gives off little heat, frustrating missiles and fighters sent to down it.

All of this still requires good pilots and planning. Determined defenders could use low-frequency radar waves and skilled fighters to hunt down a B-2 following a too-populated or well-defended route. But the last element of B-2 stealth comes from good intelligence, allowing pilots and planners to send the bombers in through relatively undefended routes or through routes the B-2 can defeat.

Because that’s a big part of the B-2’s mission. It’s not supposed to act as the primary bomber in most circumstances. It’s a first-wave attacker, clearing the air defenses on the ground and opening “alleys” for less stealthy aircraft.

Ideally, they get a picture of the air defenses they will attack from reconnaissance aircraft like the RC-135 and are then able to dismantle them piece by piece.

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A B-2 takes off from Nellis Air Force Base, June 1, 2017.

But the B-2 can and has been sent against other targets, including bunkers in Iraq housing command and control elements during the invasion of that country. This is particularly useful when planners need to eliminate a target too early in the timeline to dismantle the air network first.

After all, if an enemy commander shows himself at a rally in the capital during an air campaign, you aren’t going to wait for the B-2s to finish opening the air corridors, you’re just going to send in B-2s to the final target (or you send B-1s if the B-2s can’t get there in time). You can get the radars later.

And that’s what’s so great about the B-2. While the plane costs more dollars per hour of flight than many others and carries fewer bombs than planes like the B-52 and B-1, it can hit targets that few other platforms can, largely because of its amazing stealth.

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Rare, close-up video shows a B-2 stealth bomber preparing for takeoff

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A US B-2A bomber and a Dutch F-35A conduct aerial operations in support of Bomber Task Force Europe 20-2 over the North Sea, March 18, 2020.

  • This rare video shows how the B-2 Spirit’s control surfaces move during pre-flight checks.
  • Such tests are done after start-up and during taxi to make sure the surfaces can move freely.
  • See more stories on Insider’s business page.

In March last year, three US Air Force B-2 Spirits, belonging to the 509th Bomb Wing and the 131st Bomb Wing, Whiteman Air Force Base, Missouri, operated from RAF Fairford, UK, as part of Bomber Task Force Europe 20-2 deployment.

From there, the stealth bombers carried out a variety of missions across northern Europe, including one that saw the B-2s fly toward the Arctic, over Iceland.

As usual, their stay in the UK also provided a great opportunity for local aviation enthusiasts and spotters to get some cool in-action photos and videos of the tailless aircraft.

To that respect, the clip below is particularly interesting. Posted by “Saint1 Aviation Vids” Youtube channel, that includes many great videos of B-2s, B-52s and U-2s, it shows B-2 #82-1068, “Spirit of New York,” as it carries out pre-flight checks on its control surfaces before departing RAF Fairford.

Similar tests are conducted after start-up and during taxi in order to assess that the surfaces are not obstructed or limited and can freely move.

The video shows the movement of the split rudders and elevons that on the B-2 are installed along the trailing edge of the plane. Since the aircraft has no vertical fin, the split rudders and the elevons are used to control the aircraft rotation along the vertical/yaw axis, whereas pitch and roll are controlled by means of (mid and inboard) elevons. The split-rudders also act as speed brakes.

Unfortunately, the clip doesn’t provide a clear view of the Spirit’s peculiar exhaust and the wedge-shaped flap in the middle of the trailing edge, the GLAS (Gust Load Alleviation System), that looks like the aircraft’s beaver tail and counters the rolling impact or resonance to smooth out the ride of the B-2 in turbulent conditions and extend the aircraft’s fatigue life.

Air Force test data finite elemental analysis (FEA) modeling suggest the B-2 will remain structurally sound to approximately 40,000 flight hours. This analysis also revealed that the rudder attachment points at the B-2’s wingtips are the highest structural stress areas and will be the first to fail.

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