Access panels for the big fecking antennas hiding in the leading edges. Whether for EW systems or LPI radars. or both.
The leading edge is probably a suboptimal location for radar: there is minimal vertical room to shrink the beam vertically, which might result in suboptimal gain… EW antennas are definitely doable on the leading edge though, the F-35 has them.
 
They may be using the bypass air from the fan as a sheet of cooler air between the main nozzle and the upper surface and the hot core flow to help keep the upper surface somewhat cool, as opposed to completely "wrapping" the bypass air around the core flow. Also, it looks like the rear nozzles may actually be slightly higher than the rear deck of the wing, as far forward as they are, raising them up a bit from the rear surface. I also noticed the upper surface of the nozzle on the B-21 is a pointed facet, as opposed to the V-cut on the B-2 to maybe also help mixing the core and bypass flows to cool it faster? Those are just some guesses as to what they may be doing at the exhaust.
Boundary air may be farther down the inlet duct possibly?
It has, yes, along forward spar
Cove panels.
 
is it really a sensor/ towed decoy or some sort of UAP :)
It's a trailing cone. Standard for flight tests. It also has a Pitot tube as well as SS+AoA vanes on the forward-facing boom to probe the air in a rather undisturbed part of the flow. These devices are there to provide data for the calibration of the air data system (anemometry)
 

"Northrop Grumman says a previously undisclosed company-owned test aircraft has been sold to the U.S. Air Force as part of a production acceleration agreement for the B-21 Raider."
...
" It will not change the total number of B-21s that are part of the low-rate production phase of the program, Greene noted on the company’s first-quarter earnings call."
...
 
I would speculate (groundlessly) that it could be one of the three testbed CRJ-700s or the B-737 owned by the company and used for subsystem (such as radar) testing and integration. The B-2 program used an Air Force supplied NC-135A for that purpose.
 
I would speculate (groundlessly) that it could be one of the three testbed CRJ-700s or the B-737 owned by the company and used for subsystem (such as radar) testing and integration. The B-2 program used an Air Force supplied NC-135A for that purpose.

Could be.
Though the AW-article also states: "An Air Force spokesperson confirmed the B-21 purchase."
 
A ground test B-21 airframe repurposed as a flying article?

“To support the acceleration of aircraft deliveries, we agreed to sell an aircraft to the Air Force that was previously planned to be utilized as a company-owned test asset,” CFO John Greene said April 21.

This sounds like they built another B-21 airframe for Northrop testing and have sold it the Air Force to accelerate delivery.
 

 

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it's just me or AAFA has removed IMG_2644? strange - taking into account level of model sanitization...
 
Of course, the real joke would be if someone tried to pack a bunch of B-21s onto a Ford-class for a repeat of the Doolittle op.

What would be interesting is if the USAF and USN did a repeat of the early 1960s experiment where they had a C-130 Hercules land and take off successfully several times from a CV to see if it was feasible (It was) and do it with a B-21A.
 
It’s really weird… At first flight of the exact same aircraft, the exhaust region was either black or a very dark color.

And something is still required on the bottom.

View attachment 809147

Maybe there's a combination of heat-tolerant RAM, very efficient bypass mixing to get the plume as cool as possible, and airflow control over the surface to keep the exhaust gases separated and stood-off (even by a pretty minor distance) sufficient to keep surface temps reasonable. Definitely easiest to do on a platform that doesn't operate at high AoAs. Could bleed a little bit of bypass into a French drain type outlet combined with careful surface shaping.

Similar principle to the porous boundary cooling in turbine blades.

They may be using the bypass air from the fan as a sheet of cooler air between the main nozzle and the upper surface and the hot core flow to help keep the upper surface somewhat cool, as opposed to completely "wrapping" the bypass air around the core flow. Also, it looks like the rear nozzles may actually be slightly higher than the rear deck of the wing, as far forward as they are, raising them up a bit from the rear surface. I also noticed the upper surface of the nozzle on the B-21 is a pointed facet, as opposed to the V-cut on the B-2 to maybe also help mixing the core and bypass flows to cool it faster? Those are just some guesses as to what they may be doing at the exhaust.

I don't think there are any "main nozzles" on the upper surface. It seems likely that the dark areas on the trailing edge are the nozzles, possibly a fixed SERN type. This may be one of the innovations that will be used in the F-47 and F/A-XX also, though likely incorporating fluidic TVC there.
 
Or this picture could be modified.....Are we sure this is the real exhaust ?
Well this is not an official image, but an image taken by an outsider… So I believe there is no motive in modifying the image to show a fake exhaust setup.
Best to wait until Northrop releases the real exaust image I think.
On that note I think a picture of the real aircraft taken by an outsider is more reliable than any official image… Official images can be modified with all kinds of purposes.
 

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