Northrop Grumman B-21 Raider (LRS-B)

It seems like the big question is the internal arrangement, namely engines and bomb-bay, as the dimensions of the latter define what weapons can be carried.
 
Considering the SFC of a low bypass military turbofan like the F135, it seems as if the USAF has bought what amounts to a medium or intermediate bomber. The B-21 is essentially the stealth equivalent to the old B-47 and a whole magnitude smaller and shorter ranged than the B-2. It makes sense if China is the new adversary and the target was simply to outrage the old H-6/Tu-16. If anything, the B-21 will require the USAF to move forward with more long term tanker capacity, hopefully in the form of a somewhat stealthy design that could be adapted to a longer range cruise missile carrier to eventually replace the B-52 or serve as a special forces transport.

Shifting back to a conceptual equivalent to a B-47 probably should have been debated by Congress. It’s a big move, possibly the right one, but it does raise questions over the relative costs of the range of platform vs the costs of refueling?

Doing some mental calculations, I think I’d rather see the B-21s based on Okinawa than Guam or even potentially Australia.
 
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TinWing said:
Considering the SFC of a low bypass military turbofan like the F135, it seems as if the USAF has bought what amounts to a medium or intermediate bomber. The B-21 is essentially the stealth equivalent to the old B-47 and a whole magnitude smaller and shorter ranged than the B-2. It makes sense if China is the new adversary and the target was simply to outrage the old H-6/Tu-16. If anything, the B-21 will require the USAF to move forward with more long term tanker capacity, hopefully in the form of a somewhat stealthy design that could be adapted to a longer range cruise missile carrier to eventually replace the B-52 or serve as a special forces transport.

Shifting back to a conceptual equivalent to a B-47 probably should have been debated by Congress. It’s a big move, possibly the right one, but it does raise questions over the relative costs of the range of platform vs the costs of refueling?
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What about the possible selection of a non-afterburning version of F135s means the B-21 is likely a intermediate bomber? The B-2 itself uses non-afterburning versions of the F110 military turbofan. The B-21's apparent size also indicates it is likely meant to be in a similar range class to the B-2. Indeed, speeches at the event highlighted that the B-21 would conduct global operations despite operating from bases in the continental US. Of course that will require some tanking, much the same as with the B-2, but I doubt they meant it would need much more tanking support if they specifically highlighted this.
 
Avimimus said:
steelpillow said:
aonestudio said:

Northrop, U.S. Air Force Roll Out the B-21 Raider | Aviation Week Network

The B-21 Raider was displayed at the company’s secretive Plant 42 complex about 34 years after a similar ceremony for its predecessor the B-2.
aviationweek.com aviationweek.com
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The question I ask myself now is, did Northrop Grumman secretly take forward all these long-known but also long-obscure aerodynamic features, or did their computers arrive at something they knew nothing of beforehand? Either way, the B-21 looks like becoming a major vindication of all those maverick forebears.
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That is quite the question. It'll keep me up at night for a bit :) How many decades before we can get an interview on the basic aerodynamics - three, four?
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It does look as if they got the B-2 right, for which great, indeed galactically vast respect to Irv, John, Steve and the rest of the gang.

We had a lot of great info on how the B-2 was done in the early 90s, but I'm afraid we may have to wait longer this time.
 
LowObservable said:
It does look as if they got the B-2 right, for which great, indeed galactically vast respect to Irv, John, Steve and the rest of the gang.

We had a lot of great info on how the B-2 was done in the early 90s, but I'm afraid we may have to wait longer this time.
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You say that but it was something like going on thirty years before the USAF released pictures of the B-2 refuelling in the air.
 
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NCQ said:
What about the possible selection of a non-afterburning version of F135s means the B-21 is likely an intermediate bomber? The B-2 itself uses non-afterburning versions of the F110 military turbofan. The B-21's apparent size also indicates it is likely meant to be in a similar range class to the B-2. Indeed, speeches at the event highlighted that the B-21 would conduct global operations despite operating from bases in the continental US. Of course that will require some tanking, much the same as with the B-2, but I doubt they meant it would need much more tanking support if they specifically highlighted this.
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I think it’s fair to say that the USAF was always going to produce a
Flyaway said:
You say that but it was something like going on thirty years before the USAF released pictures of the B-2 refuelling in the air.
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That pic wasn’t much of a surprise. Did anyone really think
that the B-2 aerial refueled all that much differently than any other aircraft? For all I know maybe that excessive secrecy might have lead the Kremlin to believe that the B-2 flew inverted during refueling?
 
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Until yesterday I thought the B2 looked advanced still to this day. Now the spirit looks like a 1981 corvette by comparison. Lots of big swoopy features.

Reading posts this morning is seeing cooler minds jumping in.

No it's not the size of a cirrus business jet. Yes it's likely the same or more volume than the spirit. No it's not too small for MOP or alcms. There's definitely enough volume there for aams plus it's payload.

Surprised they jumped full in on synthetic vision for the crew. The windscreen is obviously there for refueling and taxi and that's about it. Never thought they would go for 2 big twins versus 4 smaller engines. Yeah I know reliability is good but still, stuff happens. Losing 25% of your power is better than 50% when stuff does happen.
 
NCQ said:
TinWing said:
Considering the SFC of a low bypass military turbofan like the F135, it seems as if the USAF has bought what amounts to a medium or intermediate bomber. The B-21 is essentially the stealth equivalent to the old B-47 and a whole magnitude smaller and shorter ranged than the B-2. It makes sense if China is the new adversary and the target was simply to outrage the old H-6/Tu-16. If anything, the B-21 will require the USAF to move forward with more long term tanker capacity, hopefully in the form of a somewhat stealthy design that could be adapted to a longer range cruise missile carrier to eventually replace the B-52 or serve as a special forces transport.

Shifting back to a conceptual equivalent to a B-47 probably should have been debated by Congress. It’s a big move, possibly the right one, but it does raise questions over the relative costs of the range of platform vs the costs of refueling?
Click to expand...
What about the possible selection of a non-afterburning version of F135s means the B-21 is likely a intermediate bomber? The B-2 itself uses non-afterburning versions of the F110 military turbofan. The B-21's apparent size also indicates it is likely meant to be in a similar range class to the B-2. Indeed, speeches at the event highlighted that the B-21 would conduct global operations despite operating from bases in the continental US. Of course that will require some tanking, much the same as with the B-2, but I doubt they meant it would need much more tanking support if they specifically highlighted this.
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Any gains in SFC by going from four F110 derivatives to 2 F-135s won’t be all that significant. However, the B-21 will have a much higher thrust to weight ratio, not a surprise because it’s a twin and needs a higher ratio for engine out scenarios and it also shouldn’t surprise anyone that the B-2 was extremely underpowered. Look at the relative size the airframe, the B-21 will most definitely have a MTOW that is around 2/3 that if B-2, maybe less. More than a B-47, though. Even factoring half the payload and lower structural weight, the B-21 will definitely have a shorter range than the B-2. Like I said, this is more of an intermediate or medium ranged bomber. A big shift in doctrine. I don’t have a problem with that as America probably would have survived the Cold War just fine with updated, B-47 sized bombers.
 
rooster said:
Surprised they jumped full in on synthetic vision for the crew. The windscreen is obviously there for refueling and taxi and that's about it. Never thought they would go for 2 big twins versus 4 smaller engines. Yeah I know reliability is good but still, stuff happens. Losing 25% of your power is better than 50% when stuff does happen.
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How does asymmetric thrust work when you are a flying wing? Sounds like flat spin to hell if you just do the default.
 
rooster said:
Until yesterday I thought the B2 looked advanced still to this day. Now the spirit looks like a 1981 corvette by comparison. Lots of big swoopy features.

Reading posts this morning is seeing cooler minds jumping in.

No it's not the size of a cirrus business jet. Yes it's likely the same or more volume than the spirit. No it's not too small for MOP or alcms. There's definitely enough volume there for aams plus it's payload.

Surprised they jumped full in on synthetic vision for the crew. The windscreen is obviously there for refueling and taxi and that's about it. Never thought they would go for 2 big twins versus 4 smaller engines. Yeah I know reliability is good but still, stuff happens. Losing 25% of your power is better than 50% when stuff does happen.
Click to expand...

It's a bit Victoresque. "Like trying to land your house while peering out through the letterbox."
 
LowObservable said:
rooster said:
Until yesterday I thought the B2 looked advanced still to this day. Now the spirit looks like a 1981 corvette by comparison. Lots of big swoopy features.

Reading posts this morning is seeing cooler minds jumping in.

No it's not the size of a cirrus business jet. Yes it's likely the same or more volume than the spirit. No it's not too small for MOP or alcms. There's definitely enough volume there for aams plus it's payload.

Surprised they jumped full in on synthetic vision for the crew. The windscreen is obviously there for refueling and taxi and that's about it. Never thought they would go for 2 big twins versus 4 smaller engines. Yeah I know reliability is good but still, stuff happens. Losing 25% of your power is better than 50% when stuff does happen.
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It's a bit Victoresque. "Like trying to land your house while peering out through the letterbox."
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You know if the RQ-180 lands itself, then at some point somebody had to suggest it was perfectly reasonable to assume the B-21 could be excpected to do the same.
 
shin_getter said:
How does asymmetric thrust work when you are a flying wing? Sounds like flat spin to hell if you just do the default.
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The same way you do it with any aircraft. You make sure you have enough control power in yaw to handle the asymmetric thrust. Considering the engine thrust lines are just offset from the aircraft center line and yaw control is near the tip of the wings, I can assure you the engineers made sure they have enough control volume to handle this situation.
 
Sundog said:
shin_getter said:
How does asymmetric thrust work when you are a flying wing? Sounds like flat spin to hell if you just do the default.
Click to expand...

The same way you do it with any aircraft. You make sure you have enough control power in yaw to handle the asymmetric thrust. Considering the engine thrust lines are just offset from the aircraft center line and yaw control is near the tip of the wings, I can assure you the engineers made sure they have enough control volume to handle this situation.
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Not just control volume, but excess thrust on the surviving engine. The drag rudder must compensate not only for the drag of the other side, but also for the asymmetric thrust. For example if the centre of drag of a half-wing is at say 30% span and the rudder at 90%, then it must add a third of normal thrust to even up the drag, while if the rudder is four times further out than the engine, it must add drag corresponding to a quarter of the already-increased engine thrust. All this adds a very significant amount of drag, adding to the surviving engine thrust already at 200% normal. It adds up to almost 3 times normal thrust for the engine, at any given airspeed. Speed and range suffer severely; it is not a nice thing to happen far out over the battle zone. The B-21 may be a bit more optimally laid out than this example, but the issue is still substantial.
 
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Does white paint point to anything? Perhaps operating altitude?

Then again, one can sometimes read about U-2 and rq180 being black and white, respectively, because of their high altitude mission. Which Is a bit conflicting. I mean, which one is it? Is it better to be painted white or black at very high altitude?
 
totoro said:
Does white paint point to anything? Perhaps operating altitude?

Then again, one can sometimes read about U-2 and rq180 being black and white, respectively, because of their high altitude mission. Which Is a bit conflicting. I mean, which one is it? Is it better to be painted white or black at very high altitude?
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Something like ceramic RAM and probably surfaces removed before it was unveiled.
 
steelpillow said:
Sundog said:
shin_getter said:
How does asymmetric thrust work when you are a flying wing? Sounds like flat spin to hell if you just do the default.
Click to expand...

The same way you do it with any aircraft. You make sure you have enough control power in yaw to handle the asymmetric thrust. Considering the engine thrust lines are just offset from the aircraft center line and yaw control is near the tip of the wings, I can assure you the engineers made sure they have enough control volume to handle this situation.
Click to expand...
Not just control volume, but excess thrust on the surviving engine. The drag rudder must compensate not only for the drag of the other side, but also for the asymmetric thrust. For example if the centre of drag of a half-wing is at say 30% span and the rudder at 90%, then it must add a third of normal thrust to even up the drag, while if the rudder is four times further out than the engine, it must add drag corresponding to a quarter of the already-increased engine thrust. All this adds a very significant amount of drag, adding to the surviving engine thrust already at 200% normal. It adds up to almost 3 times normal thrust for the engine, at any given airspeed. Speed and range suffer severely; it is not a nice thing to happen far out over the battle zone. The B-21 may be a bit more optimally laid out than this example, but the issue is still substantial.
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I understand all of that. My point is the engineers designed it to be able to handle that situation, they aren't idiots. It has to be considered in any aircraft design.
 
Rolead said:
So is this flyable or just a mockup similar to Checkmate, hard to tell really.

Robert
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It's the first flyable aircraft and has many of the operational systems in it already. It will, however, be retained as a flight test vehicle for it's life. The rest of the test flight fleet that follow it will eventually become operational aircraft.
 
What I haven't been able to determine, is where are the egress panels? Does the flight crew sit more under those side windows? Are those the panels that get blown off for ejection? Because I don't see anything on the top between them for egress.
 
Hmmm. I *think* I grok the side windows.

If I'm not mistaken, the egress panels drove the shape of the side windows...
 
steelpillow said:
Sundog said:
shin_getter said:
How does asymmetric thrust work when you are a flying wing? Sounds like flat spin to hell if you just do the default.
Click to expand...

The same way you do it with any aircraft. You make sure you have enough control power in yaw to handle the asymmetric thrust. Considering the engine thrust lines are just offset from the aircraft center line and yaw control is near the tip of the wings, I can assure you the engineers made sure they have enough control volume to handle this situation.
Click to expand...
Not just control volume, but excess thrust on the surviving engine. The drag rudder must compensate not only for the drag of the other side, but also for the asymmetric thrust. For example if the centre of drag of a half-wing is at say 30% span and the rudder at 90%, then it must add a third of normal thrust to even up the drag, while if the rudder is four times further out than the engine, it must add drag corresponding to a quarter of the already-increased engine thrust. All this adds a very significant amount of drag, adding to the surviving engine thrust already at 200% normal. It adds up to almost 3 times normal thrust for the engine, at any given airspeed. Speed and range suffer severely; it is not a nice thing to happen far out over the battle zone. The B-21 may be a bit more optimally laid out than this example, but the issue is still substantial.
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Shifting the exhausts closer to the centerline could be a measure to mitigate yaw. Or combine the two exhaust into one central one? However, it may take a long time until we get a look at the rear end.
 
VTOLicious said:
Shifting the exhausts closer to the centerline could be a measure to mitigate yaw. Or combine the two exhaust into one central one? However, it may take a long time until we get a look at the rear end.
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Structurally simpler and lighter as well to keep all the volume and mass (including engines) nearer centerline.
 
flateric said:
Judging from taxiway plate size thiz cat iz rly smal with ~120 ft/36 m wingspan
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A lot of experienced aviation reporters were there to look at it and they've been fairly unanimous that it didn't look like it was that much smaller than B-2. It's also hard to picture how you supposed to cram two USAF pilots, with their critical gear like individual charcuterie boards and a table for mid-mission canasta tournaments, into a cockpit as small as your image would indicate.
 
flateric said:
Judging from taxiway plate size thiz cat iz rly smal with ~120 ft/36 m wingspan
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I think you've got it too small. Judging by the lines in between concrete panels on the ground at both their reveals the width between each main landing gear leg is only very slightly narrower on the B-21 than it is on the B-2. At least, that's the way it looked to me.

Check out how the landing gear line up with the panels on the ground in these two pictures:

B2_bomber_initial_rollout_ceremony_1988.jpg
FjBYvObVQAENCV4

Main landing gear to main landing gear on the B-2 is almost exactly three panels across, and for the B-21 it's just a bit less than three panels.
 
CiTrus90 said:
Edit: actually, I think you can still see one thing from the side windows. If it's day or night.
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Given the HMDs can see stuff through the plane, are windows even needed for landing? In dense fog windows are useless anyway. We all remember Die Hard 2 right?
 

Sundog said:
What I haven't been able to determine, is where are the egress panels? Does the flight crew sit more under those side windows? Are those the panels that get blown off for ejection? Because I don't see anything on the top between them for egress.
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Look at Overscan's highly detailed pic. It looks as if its a one piece design... Targa top.
 
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Hard to tell the engine arrangement from that angle. I thought it might at least be more clear if it was an F135 based powerplant or not. Still seems more likely than not. It certainly seems large enough to carry one B-2 sized bomb bay at the minimum and I believe LRSO is slated to be carried internally, so I think GBU-57 is still on the table. Wasn't there a USAF statement that indicated 30,000lb payload a year or two ago? But all in all I think most of the "smaller B-2 with a single tail" predictions were vindicated. I don't think we have a wingspan even yet, but it at least weighs in light enough for a single axle landing gear.
 
Slicknick said:
flateric said:
zaphd said:
I decided to do some pixel counting on the photos.

I used the B-2 photo in front of that hangar posted by Maro Kyo (post#3164) to estimate that the hangar door is roughly 8.7m high.
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I doubt hangars are the same looking at taxiway markings.
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They weren’t the same hangar
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If you know it's not the same hanger then it would be helpful if you would provide information on the two hangers.
 

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