Northrop Grumman B-21 Raider (LRS-B)

With this new pictures the B-21 look bigger than we think at first , 2 or 4 engines ?
 
I cannot see the B-21 having four engines dark sidius, it is too late to even redesign the Raider with four engines without having cost consequences.
 
I see your point dark sidius, but I suppose that we will just have to wait and see what happens when the B-21 enters production and service then we get the official factsheet with all the data from the USAF.
 

B-21 Needs Faster Fuel Transfer From Air Refuelers | Aviation Week Network

The disclosure offers a rare glimpse into the secretive operational plans for the Air Force’s next-generation bomber.
aviationweek.com aviationweek.com

……
The stealthy Raider needs to top off its gas tanks faster than the fuel transfer rates of the Air Force’s current aerial refuelers allow, Gen. Randall Reed, Transportation Command chief, told the Senate Armed Services Committee during a hearing.

Reed said he learned of the B-21’s extra refueling requirement during a meeting in the past month with Gen. Anthony Cotton, the head of Strategic Command.
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It was not immediately clear why the B-21 needs a faster fuel transfer rate than other aircraft, including the Northrop B-2A stealth bomber that the Raider eventually replaces.

But a boom that pumps fuel faster would reduce the amount of time that the bomber operates in the presence of a more observable air refueling aircraft.

It was also not clear if the solution would be a modification to the existing refueling booms on the Boeing KC-46 and KC-135, or if a new refueling boom would be required.

Asked to elaborate on Reed’s comments, a Transportation Command spokesman walked back his statement.

“The U.S. Air Force’s KC-135 and KC-46 are suited to conduct refueling of the B-21 Raider,” the spokesman said.
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raptor82 said:

B-21 Needs Faster Fuel Transfer From Air Refuelers | Aviation Week Network

The disclosure offers a rare glimpse into the secretive operational plans for the Air Force’s next-generation bomber.
aviationweek.com aviationweek.com
Click to expand...
I cannot imagine why refueling rate matters... Assuming a B-21 fuel capacity between 50-100% of the B-2, that would be between 8.5 to 17 minutes of refueling, which is a tiny fraction of the subsequent mission time (11.25 hours assuming a unrefueled range of 5000 nmi, can reach up to 20 hours with more efficient civilian-derived engines) and will happen from 2500 nmi to more than 4000 nmi away from the intended target. Even if the B-21 is designed to be a shorter-ranged aircraft (very unlikely) that has to refuel within the second island chain, the ingress and egress of the tanker would take much longer and be much more dangerous...

Another possibility is maybe to avoid revealing the raiders' actions by space-based reconnaissance of the tankers...? I don't know...
 
kmrumble said:
Av Week has amended this story to say the USAF will need more tankers, not faster flow rates.
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OK that makes much more sense... But 100 B-21s is not going to increase the size of the bomber fleet by that much...? The fighter fleet will use many more tanker sorties anyway...
 
TomcatViP said:
Have anyone though at RAM being exposed to the jets exhausts from the Tanker?
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I'm sure that the B-21's designers have considered that issue, the RAM treatments for the B-21A will no doubt be a massive improvement over the RAM treatments for the B-2A (No doubt they will be a great deal easier to maintain).
 
JoshuaH said:
I cannot imagine why refueling rate matters... Assuming a B-21 fuel capacity between 50-100% of the B-2, that would be between 8.5 to 17 minutes of refueling, which is a tiny fraction of the subsequent mission time (11.25 hours assuming a unrefueled range of 5000 nmi, can reach up to 20 hours with more efficient civilian-derived engines) and will happen from 2500 nmi to more than 4000 nmi away from the intended target. Even if the B-21 is designed to be a shorter-ranged aircraft (very unlikely) that has to refuel within the second island chain, the ingress and egress of the tanker would take much longer and be much more dangerous...

Another possibility is maybe to avoid revealing the raiders' actions by space-based reconnaissance of the tankers...? I don't know...
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I believe one goal for the Raider was improving mission capable rates. If you have 100 raiders on high mission capable rates, you might need a lot of tankers. Especially if they are flying from Whiteman or somewhere in CONUS to the Pacific. That is one explanation.

Maybe 17 minutes is too long if you're worried about hordes of 3-engine Chinese interceptors dogpiling your tanker tracks. I don't know. I know a stealth tanking capability would be useful though.
 
NMaude said:
I'm sure that the B-21's designers have considered that issue, the RAM treatments for the B-21A will no doubt be a massive improvement over the RAM treatments for the B-2A (No doubt they will be a great deal easier to maintain).
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IIRC, one of the primary requirements for B-21 was less maintenance on the RAM. Possibly to the point of a larger RCS than the B-2, but the emphasis was on maintainability, not on getting the tiniest possible RCS.



4decaa said:
Maybe 17 minutes is too long if you're worried about hordes of 3-engine Chinese interceptors dogpiling your tanker tracks. I don't know.
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I'm sure that's part of it.


4decaa said:
I know a stealth tanking capability would be useful though.
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I dunno, as close as planes need to fly together to refuel you get weird reflections and radar spikes. Which may defeat the stealth entirely.

I'd rather have stealth C130-equivalents, tactical airlifters.
 
Scott Kenny said:
IIRC, one of the primary requirements for B-21 was less maintenance on the RAM. Possibly to the point of a larger RCS than the B-2, but the emphasis was on maintainability, not on getting the tiniest possible RCS.




I'm sure that's part of it.



I dunno, as close as planes need to fly together to refuel you get weird reflections and radar spikes. Which may defeat the stealth entirely.

I'd rather have stealth C130-equivalents, tactical airlifters.
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I think the B-21 will have a smaller RCS than the B-2. Take a look at the surface finish of the B-21 (from the first and previous hi-def images) vs. the B-2, very different and you can tell the surfacing techniques have changed and evolved, including easier to maintain but with excellent RCS performance. I think part of B-2 long-term upgrade effort will be to implement B-21 treatments onto the B-2 fleet. NG has been evolving and improving RCS materials and application techniques for a very long time, you have too in order to stay ahead. I am pretty sure that externally, internally and systems wise to the B-21, there is a little NG magic going on, we just won't have an idea for a very, very long time. You can see how tight they are regarding the flight testing effort and this is at EAFB, only very few images to date.
 
Hydroman said:
I think the B-21 will have a smaller RCS than the B-2. Take a look at the surface finish of the B-21 (from the first and previous hi-def images) vs. the B-2, very different and you can tell the surfacing techniques have changed and evolved, including easier to maintain but with excellent RCS performance. I think part of B-2 long-term upgrade effort will be to implement B-21 treatments onto the B-2 fleet. NG has been evolving and improving RCS materials and application techniques for a very long time, you have too in order to stay ahead. I am pretty sure that externally, internally and systems wise to the B-21, there is a little NG magic going on, we just won't have an idea for a very, very long time. You can see how tight they are regarding the flight testing effort and this is at EAFB, only very few images to date.
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I mean, yes, I'm sure they've figured out some tricks that are now affordable to do that weren't when building the B-2s. But IIRC the primary driver for B-21s was always less maintenance, not needing climate-controlled hangars, greater availability.

So if RCS wasn't as tiny as it could possibly be but the aircraft had twice the uptime, that was preferred over tiny RCS at the cost of low availability.
 
4decaa said:
I believe one goal for the Raider was improving mission capable rates. If you have 100 raiders on high mission capable rates, you might need a lot of tankers. Especially if they are flying from Whiteman or somewhere in CONUS to the Pacific. That is one explanation.

Maybe 17 minutes is too long if you're worried about hordes of 3-engine Chinese interceptors dogpiling your tanker tracks. I don't know. I know a stealth tanking capability would be useful though.
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The tanker tracks for Raiders are probably going to be over Hawaii or Alaska though… I would imagine stealth tanking capability more useful for the short-ranged fighters.
 
I wonder about ensuring crew readiness once the B-21 reaches combat. B-2 crews, I heard, took lawn chairs along to rest in - but would something be designed in now if a B-21 is expected to be in the air a long time? Bunks, a head, MREs, a jacuzzi, perhaps a miniature golf course, a charming café? OK, maybe the first three?
 
Rhinocrates said:
I wonder about ensuring crew readiness once the B-21 reaches combat. B-2 crews, I heard, took lawn chairs along to rest in - but would something be designed in now if a B-21 is expected to be in the air a long time? Bunks, a head, MREs, a jacuzzi, perhaps a miniature golf course, a charming café? OK, maybe the first three?
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They should include 2 sandbags. The orders to the aircrew will be to carry the sandbags from one side of the plane to the other, and then back again, 25 times per hour.
 
Reading the actual quote regarding tanking, it seems pretty clear to me that the concern was the total capacity of the tanker fleet, not the transfer rate between aircraft. I do not see any possibility of B-21 requiring more fuel than a B-2 so I cannot imagine transfer rates matter significantly. What probably will change dramatically is the sortie rate: B-21 likely will have a much higher availability rate than either B-2 or B-1, and eventually it will exist in greater numbers as well.
 
Though seriously, I do wonder what facilities there would be to ensure crew readiness during a long mission.
 

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