Northrop Grumman B-21 Raider (LRS-B)

insidersource said:
2,000lb JDAM is just under 13 feet long. So two of these bombs would fit perfectly in tandem on a rotary launder.
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You need clearances around the launcher. If the doors are actually 26 feet long, I doubt you can fit two 2000-lb JDAMs nose-to-tail. If they are 27 feet, it gets a lot more feasible.
 
Scott Kenny said:
Pretty sure that won't fit into a B-21. We're looking at something closer to a stretched ASALM for the hypersonic cruise missile.
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It seems that four of them can be carried around the rotating launcher, similar to the 5000 lbs JDAMs…
 
Josh_TN said:
I sincerely doubt a $700 million aircraft would be used to fire medium range AAMs.
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I see the $700M number in most of the articles about the B-21, but I have no idea where it comes from. The only official number has always been the original $550M APUC in 2010 dollars. That number will inflate to a LOT more than $700M by the time production aircraft roll off the line. I asked Grok to do the inflation arithmetic and come up with a unit price list assuming 100 production aircraft are delivered from 2028 to 2039 using a learning curve of 80%. Here's the result:

Example unit costs (then-year dollars)
  • Unit 1 (2028): $1,374.2M
  • Unit 8 (2028): $1,219.8M (learning already reduces cost within the year)
  • Unit 50 (2034): $1,198.4M
  • Unit 96 (2039): $1,392.7M
  • Unit 100 (2040): $1,418.0M
Anyone interested in how that calculation was made is welcome to review the underlying assumptions and arithmetic here:
https://x.com/i/grok/share/e942d959b1a2469f86a375c519f8aab1
The above estimates include no allowance for the write-offs Northrop has already taken on the first 21 LRIP units, which would add about $150M per copy to the first 21 aircraft. If that cost increase goes into the estimating base for units 22 to 100, it would add about $250M per copy for those aircraft. So, with the APUC translated to then-year dollars, accounting for financial disclosures to date, I wind up here:
Unit 1: $1.524B
Unit 100: $1.668B
 
kmrumble said:
I see the $700M number in most of the articles about the B-21, but I have no idea where it comes from.
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I believe that is total program cost (dev, production, lifetime sustainment) divided by number of aircraft. Which in the 90s was a popular way to do it, but it’s very problematic . You cut product ion and the apparent unit cost goes up a lot
 
JoshuaH said:
I find it really hard to imagine swapping in a new rotary launcher or two new racks with all the bombs on them is more time consuming than putting in the bombs one by one...
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I think you misunderstood the discussion. No one suggested installing the racks while they are loaded with bombs. The discussion is swapping out the empty rotary launcher with empty bomb racks between missions. The bombs would still be loaded one by one into the aircraft. Swapping out the empty rotary launcher for the empty bomb racks would take significant time. Just to carry extra Mk82 bombs or use the space more efficiently is a bit ridiculous.

Seragina said:
The rotary launchers use adapters and other racks that offer both 14" and 30" as well as other optional locations. You mount your specific rack to these if needed.
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I have already mentioned using racks on the rotary launcher to allow four 6 foot long weapons in the place of a single 2000lb bomb. Even with custom racks the 500lb bombs will never fit nicely or efficiently on the rotary launcher.

Seragina said:
Amusingly, the USAF kept complaining in their report to congress about the B1 needing 24 hours to reload compared to 4-5 or so hours for the B52 as one of the reason they needed the more numerous LRS-B/B21.
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This is why it is critical to allow the B-21 to be loaded with bomb lifts used by fighter jets. This can only be achieved by loading bombs one by one with a rotary launcher. With a conventional bomb rack to get the bombs up to the top of the weapon bay would require different lifts.

The US wants the B-21 to be rearmed at locations where it doesn't need any inflight refueling to perform the mission. No specialist equipment required. The history of the B-21 comes from the Next-Generation Bomber program. NGB was a stealthy, subsonic, medium-range and medium payload bomber. NGB mentioned all the advantages of having the bombers located closer to the theatre with rapid loading. These advantages still apply to the B-21.
 
Forest Green said:
Unknown at this stage, we don't know the IWB length accurately, or ARRW dimensions for that matter.
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We have solid ARRW dimensions, have known them for years.

But you're correct that the B-21 IWB dimensions aren't precisely known. I've been assuming B-2 to B-52 sized, leaning more towards B-52 size. 6ft wide, 6ft deep and 28ft long.


JoshuaH said:
It seems that four of them can be carried around the rotating launcher, similar to the 5000 lbs JDAMs…
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Where was that discussed? I don't remember reading it. IIRC you can't quite fit 24" diameter cylinders around a rotary launcher.
 
Scott Kenny said:
Where was that discussed? I don't remember reading it. IIRC you can't quite fit 24" diameter cylinders around a rotary launcher.
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Sorry about the confusion, but I said it because the number checks out, not because it was discussed before… Just using your estimation, the width of the bomb bay being six feet or 72 inches, and each of the missiles taking 24 inches, that leaves 24 inches for the rotary spindle and release mechanisms, and the missiles won’t collide with each other.
 
JoshuaH said:
Sorry about the confusion, but I said it because the number checks out, not because it was discussed before… Just using your estimation, the width of the bomb bay being six feet or 72 inches, and each of the missiles taking 24 inches, that leaves 24 inches for the rotary spindle and release mechanisms, and the missiles won’t collide with each other.
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You need a bit of clearance around the ordnance to drop safely (and to load the rotary into the aircraft). If you look at all the cruise missiles designed around the rotary launcher, they're only about 18" tall.
 
insidersource said:
The history of the B-21 comes from the Next-Generation Bomber program. NGB was a stealthy, subsonic, medium-range and medium payload bomber.
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“It won’t need to be based in theatre. It won’t need logistical support to hold any target at risk.” —Lloyd J. Austin, at the B-21 rollout ceremony Dec. 2022

The medium range aspect of the NGB is probably already thrown out somewhere down the line…
 
TomS said:
You need clearances around the launcher. If the doors are actually 26 feet long, I doubt you can fit two 2000-lb JDAMs nose-to-tail. If they are 27 feet, it gets a lot more feasible.
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Two JDAM nose-to-tail are under 26 feet. A perfect fit.


JoshuaH said:
“It won’t need to be based in theatre. It won’t need logistical support to hold any target at risk.” —Lloyd J. Austin, at the B-21 rollout ceremony Dec. 2022

The medium range aspect of the NGB is probably already thrown out somewhere down the line…
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Please read more carefully.

insidersource said:
NGB mentioned all the advantages of having the bombers located closer to the theatre with rapid loading. These advantages still apply to the B-21.
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I am always extremely specific with my wording. I never said the B-21 will be based in theatre.

Flying 40 hour bombing missions from continental USA with multiple refueling tankers per bomber is stupid. This is only done if the bomber requires extreme levels of support that is not found at closer bases. The B-21 will be located closer to theatre. The perfect bomber location requires no inflight refueling but is still located safely outside of the theatre.

Bases located 3,000 miles from the target would be an ideal distance if we assume the B-21 has similar range to the B-2. If we draw a 3,000 mile ring around bases in Australia, the UK and Diego Garcia it covers nearly all of the potential targets.
 
quellish said:
I believe that is total program cost (dev, production, lifetime sustainment) divided by number of aircraft. Which in the 90s was a popular way to do it, but it’s very problematic . You cut product ion and the apparent unit cost goes up a lot
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My dearest, beloved, oh so close to my very own heart, freely sharing fountain of knowledge of relevant US military related information Quellish, please pray tell, what is a "product ion", how can you tell it apart from naturally born/occurring ions in the wild, but most importantly, what is the exact relevance of them in this discussion??? Thank you for your attention to this matter! MJB
 
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insidersource said:
If we draw a 3,000 mile ring around bases in Australia, the UK and Diego Garcia it covers nearly all of the potential targets.
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Sure, B-2 currently operates out of at least two of these three locations (UK and Diego Garcia), and frequently visit the other (Australia). So the SBRA currently on the B-2 fleet is probably not a problem…
 
Forest Green said:
So we do. I'd say they probably will fit then, definitely on length, diameter could be a squeeze for RLA.
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I need to amend my comment on loading the RLA into the bird, you're almost certainly doing that with the ARRWs in an X setup to maximize ordnance-to-wall clearance as you're stuffing things into the bay.

But you still need enough space for the RLA to physically rotate to ARRWs in the + setup to drop and I'm questioning how exactly a 26"/66cm cylinder fits onto the RLA when all the weapons designed for the RLA are 18" tall.
 
Scott Kenny said:
I need to amend my comment on loading the RLA into the bird, you're almost certainly doing that with the ARRWs in an X setup to maximize ordnance-to-wall clearance as you're stuffing things into the bay.

But you still need enough space for the RLA to physically rotate to ARRWs in the + setup to drop and I'm questioning how exactly a 26"/66cm cylinder fits onto the RLA when all the weapons designed for the RLA are 18" tall.
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Even the AGM-129?
 
I mean, it's certainly possible that the B-21's weapons bay is bigger than I'm guessing, wide enough to hold 4x GBU-72s on an RLA. Proportionally it doesn't look like the L:W ratio is 4.67:1 like it would be for a 28x6 bay.

However, it may be better for a B-21 to carry those in clips like the B-52 carries the bigger nukes. Like this:

(USAF image from wiki)
 

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FighterJock said:
That would be the B-83 nuclear bombs then Scott Kenny as they are currently the only large nuclear bombs left in the US inventory if I am right.
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Sadly, true. (For now. There is talk of getting rid of those too. There is no shortage of idiots in Congress.)
 
FighterJock said:
That would be the B-83 nuclear bombs then Scott Kenny as they are currently the only large nuclear bombs left in the US inventory if I am right.
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I'm saying that it would be better to hang GBU-72s on a clip like the one in the picture (which happens to be for B28s).
 
insidersource said:
The whole point of creating all of these 6 foot long glide bombs and small cruise missiles is that four of them can fit where a single 2,000lb JDAM is located. The added benefit is everything fits the F-35 and probably the F-47.

This means the rotary launcher will be built for two 2,000lb JDAM in tandem with 30inch spacing between the mounting provisions. The BRU-61 rack has the same 30inch spacing allowing four 6 foot weapons. The rotary launcher would only be removed when the big bunker buster weapon is carried.
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This makes great logical sense as an organic improvement/advancement of the rotary system. 16 x 2000lb JDAM seems very excessive (balancing range/payload), but 16 x 1000lb JDAM makes things very interesting.
 
Scott Kenny said:
I mean, it's certainly possible that the B-21's weapons bay is bigger than I'm guessing, wide enough to hold 4x GBU-72s on an RLA.
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On that note, the B-2 can hold GBU-37 5klbs GAMs onto its RLA. GBU-37s are probably about the same size as GBU-72s (But probably still much thinner than ARRWs! Steel has a much higher density than carbon fiber shell and HTPB rocket fuel)
 

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JoshuaH said:
On that note, the B-2 can hold GBU-37 5klbs GAMs onto its RLA. GBU-37s are probably about the same size as GBU-72s (But probably still much thinner than ARRWs! Steel has a much higher density than carbon fiber shell and HTPB rocket fuel) View attachment 805689
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I think this image was taken at the CTF around my time there. The B-2s bays are large, don't know if the ARRW would fit?
 
Josh_TN said:
I was thinking 4x4x3 =48, or 27,600
Is the 5000 the weight of three SBRA?
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SBRA accomodates 20x 500lb and 3x SBRA empty weight almost 5050 lb max.

All stations on the rotaries for the B52, B1, B2 are rated for 5000 lb stores.
The AGM-183 is too heavy and bulky even if the load of 4x for the rotary wouldn't be a problem. It would require a new adapter and rack that occupies more connection points on the rotary.
Comparing loading capacity it's 8x5000 lb + 2200= 42.2kllb on the rotary; and GBU-57 30+klb on ceiling/deck afaik.
So just loadwise either could work. We are back to square one about size.

I'm assuming the B21's bay to be 7.6x1.56+m.
As posted previously the deck load looks to be at least maxed at 30+klb (same requirement for GBU-57) and up to 40 klb.
It seems to me it would be able to accomodate all in all possible configurations.
 

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Seragina said:
Also let's not forget the Next Generation Penetrator for which the request was for it to remain within 22klb.
I've alway assumed it was meant to increase magazine load to two. So the actual deck load rating is likely 45klb.
https://www.thedefensenews.com/news...-to-Succeed-30000-Pound-GBU-57-Bunker-Buster/
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From the link, "The size and weight limits are aligned with integration requirements for the B-21 Raider stealth bomber, which is expected to carry one NGP per mission under current planning assumptions."

From two 30,000lb bombs down to one 22,000lb bomb. How depressing. Even the B-29 did better.
 
The B-2 was tested with 2 30k lb bombs, and did two MOP per bomber strikes, but in reality it was designed around, ideally, a total load of 40k lb for long range missions in high threat areas. Like real world missions against Russia or China. Even that likely doesn't allow for a full fuel load. 60 k lb of bombs would eat into its fuel allowance even further. As per USAF, B2 empty weight is 160 000 lb, meaning a 60k lb bomb load would lead to 220 k lb without fuel. Given that the MTOW, per USAF is 336 k lb, that means 116 k lb of fuel, instead of 167 k lb. A 30% reduction. Sure, that can be rectified to an extent with in air refueling, but you'd still need more tanker top ups, as max weight in air would still be less than if such a heavy load wasn't carried around.

Basically, i think USAF never really indented to regularly use B2 with two MOPs anyway, operationally. That's why officially it's max loadout is 40 000 lb. Sure, in 2025, when they hit iran, 7 bombers dropped 14 MOPs. But Iran is a much, much more permissible target area than either Russia or China would be and B2s had to fly just 300 miles inside hostile territory. In Russia/China, B2s would often have to fly several times as much inside enemy territory, so fuel loads carried would be much more critical.
 
sesame2002 said:
Idk man, i dont think it's so sad megaton weapons are falling out of fashion, i would rather have my post apocalypse with some of humanity left rather than non...
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Problem is, they're only "falling out of fashion" in the US. Russia and China are still balls to the wall.
 
https://www.thedefensenews.com/news...-to-Succeed-30000-Pound-GBU-57-Bunker-Buster/

Weight Reduction and Platform Integration​

Procurement documentation specifies that the NGP warhead must weigh 22,000 pounds or less, representing a reduction of roughly one-third compared to the GBU-57. The size and weight limits are aligned with integration requirements for the B-21 Raider stealth bomber, which is expected to carry one NGP per mission under current planning assumptions.

The reduced form factor is also intended to allow potential integration with additional platforms as future force structure evolves. While the GBU-57 is exclusive to the B-2 fleet, the NGP is being designed with broader compatibility considerations, subject to certification and testing.
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Rapid Dragon NGPs. Well, maybe not, but regardless the broad compatibility approach presents more targeting dilemmas for the adversary.
 

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