Northrop Grumman B-21 Raider (LRS-B)

[Josh_TN]

There’s no way anyone gets any until the USAF has at least replaced the B-1 force. Likely B-2 as well, given their strong desire to discontinue entire types of aircraft to end training/maintenance cycles for cost savings. Then maybe a couple of the most trusted allies would be offered such, if they they had any interest, which I doubt most would for cost reasons. About the only country I think which might actually have enough of a need despite the high cost is Australia. It looks like this is going to be a very long ranged platform that potentially wouldn’t need an escort, which *might* justify costs. Their basing of US bombers will likely mean they already have access to host infrastructure. But I think we’d be talking about the late 2030s by then and the entire geopolitical situation maybe completely different anyway.

 

[Mark Nankivil]

There’s no way anyone gets any until the USAF has at least replaced the B-1 force. Likely B-2 as well, given their strong desire to discontinue entire types of aircraft to end training/maintenance cycles for them for cost savings. Then maybe a couple of the most trusted allies would be offered such, if they they had any interest, which I doubt most would for cost reasons. About the only country I think which might actually have enough of a need despite the high cost is Australia. It looks like this is going to be a very long ranged platform that potentially wouldn’t need an escort, which *might* justify costs. Their basing of US bombers will likely mean they already have access to host infrastructure. But I think we’d be talking about the late 2030s by then and the entire geopolitical situation maybe completely different anyway.

I don't know about that. If the the Chinese threat is such, then AUS having them as well makes sense, more so than simply basing US B-21s in AUS.

Would make for an interesting maritime patrol aircraft too

Enjoy the Day! Mark

 

[sferrin]

I don't think it will. It will have a replacement for MOP which is smaller but not necessarily less destructive. MOP was a quick development and not very optimised. There were statements in 2011/2012 timeframe about a smaller replacement for next-generation bombers.

Does mop have earth penetration ability. Then its useless agaisnt say Iranian targets under mountains. I'm not sure why mop is even needed. Distributed smaller explosions are more destructive than 1 large one.

MOP is a 30,000lb penetrating bomb. As in 200 feet of earth and then boom.

 

[Deino]

Interesting ...

https://twitter.com/x/status/1599717448734822400

View: https://twitter.com/i/web/status/1599717448734822400

 

[Josh_TN]

I don't think it will. It will have a replacement for MOP which is smaller but not necessarily less destructive. MOP was a quick development and not very optimised. There were statements in 2011/2012 timeframe about a smaller replacement for next-generation bombers.

Does mop have earth penetration ability. Then its useless agaisnt say Iranian targets under mountains. I'm not sure why mop is even needed. Distributed smaller explosions are more destructive than 1 large one.

MOP is a 30,000lb penetrating bomb. As in 200 feet of earth and then boom. View attachment 688529

It seems like a worst case scenario for payload is ~30,000lbs / one B-2 bomb bay, in which case a single GBU-57 could be integrated. Though whether it actually will depends on whether the USAF replaces it or not; the B-2s probably will handle that weapon for the next decade until they are replaced by B-21, so if the handful of MOPs are retired in favor of something smaller or more effective I could easily see it never being integrated with B-21 even though the payload and bomb bay could accommodate it.

Given the large central fuselage section that seems to be (visually from one angle) as large as the B-2's, it seems to me the B-21 either has more payload than the 30,000+ lbs (is that figure an official USAF release or was it some official's off the cuff statement?) or else it carries that payload significantly further than a B-2. The new bomber is definitely more than half the volume of its predecessor by very large margin. Presumably if less ordnance is carried, then a significant amount of additional fuel is. The statement that it doesn't have to operate from "the same theater" to me implies a range closer to the B-52's than the B-2's. If you could push the combat radius out to 5000 miles/8000km then unrefueled strikes against the PRC coast from Alaska/Hawaii would be possible which would have huge value in an anti access environment. I don't know if that is what "out of theater" or "won't need logistical support" means in that quote, but it *might* be a vague way of stating a combat radius sufficient to hold targets at risk from the US sans tanker support. It would be quite game changing were that the case and it seems like it would be an achievable goal if you were willing to sacrifice payload. Though the combat radius is probably something we won't know for years, possibly even decades, given how close to the chest the USAF is playing its cards now. We still know next to nothing about NGAD and we don't know what an AIM-260 even looks like despite the fact it is scheduled to enter service next year (AFAIK).

 

[lancer21]

For what it's worth, recent cgi of this thing

Northrop Grumman B-21 Raider 3D Model by NETRUNNER_pl

Northrop Grumman B-21 RaiderLowpoly model of american stealth strategic bomberThe Northrop Grumman B-21 Raider is an American 6th-generation strategic bomber under development for the United States Air Force (USAF) by Northrop Grumman. As part of the Long Range Strike Bomber (LRS-B) program, it...

www.renderhub.com

 

[DrRansom]

I could see push to sell the B-21 to other countries - geography dictates that UK and Australia need bombers of some sort for the military requirements. Australia's light fighter fleet basically relegates the country to coastline defense missions.

What is clear from the design is that the B-21 can only serve as half the bomber force. A B-52 or B-52 replacement is required for extra-large munitions and one could argue a LO F-15E/F-111 replacement could have value as a cheaper (200-300mm/copy) stand-off munition delivery truck, once Pacific Basing issues questions have been sorted.

But, even if it is half the payload of the B-2, having 100 B-21s versus 20 B-2s seems very much worthwhile. More aircraft, better resilience to attrition, more geographically dispersed targets at a time.

 

[flateric]

For what it's worth, recent cgi of this thing

Northrop Grumman B-21 Raider 3D Model by NETRUNNER_pl

Northrop Grumman B-21 RaiderLowpoly model of american stealth strategic bomberThe Northrop Grumman B-21 Raider is an American 6th-generation strategic bomber under development for the United States Air Force (USAF) by Northrop Grumman. As part of the Long Range Strike Bomber (LRS-B) program, it...

www.renderhub.com

This one is certainly for Aussies

 

[F-2]

Electrofluidsystems on Instagram: "Flying wings need twisted wings with washout. The new B-21 Raider from @northropgrumman might even have a perfect bell-shaped lift distribution with a non-linear geometric twist distribution. All flying wings of our

Electrofluidsystems shared a post on Instagram: "Flying wings need twisted wings with washout. The new B-21 Raider from @northropgrumman might even have a perfect bell-shaped lift distribution with a non-linear geometric twist distribution. All flying wings of our PlasmaFalcon and PlasmaRay...

www.instagram.com

 

[Desertfox]

The B-21 is designed for ALCMs just not the ALCM. My money is on it having space for two rotary launchers.

 

[Josh_TN]

The B-21 is designed for ALCMs just not the ALCM. My money is on it having space for two rotary launchers.

Are any of the LRSO requirements public? I think the goal is equal or greater range, which implies a weapons of similar size/length to AGM-86. I think at least one bay of 20' length is a given.

 

[rooster]

The B-21 is designed for ALCMs just not the ALCM. My money is on it having space for two rotary launchers.

The B-21 is designed for ALCMs just not the ALCM. My money is on it having space for two rotary launchers.

Are any of the LRSO requirements public? I think the goal is equal or greater range, which implies a weapons of similar size/length to AGM-86. I think at least one bay of 20' length is a given.

There isn't much more heat to tap out of the williams jets used so fuel load is the primary weight and size driver. Warhead design is what is now. It will be the same size as the 86.

The 21 doesn't have a central weapons bay. It has 2 side bays like b2. Therefore it has 2 weapons bays sized for alcms. It may only cary 6 instead of 8 per bay is reasonable to assume.

 

[CiTrus90]

Just in passing and OT, but for the people still wondering if smaller/bigger size necessarily translates into smaller/bigger RCS, here's the ADM-20 Quail which was used as a decoy for B-52s in the 60s.

But the Quail was built specifically to mimic the radar reflection of a B-52 or similar - McDonnell went out of their way in the design to do that. Nothing with its shape that can be construed as an effort at stealth, it was essentially a flying radar reflector.

Enjoy the Day! Mark

That is what I'm getting at, since there are people stating that the B-21, being a % smaller than the B-2, is going to have an RCS that is going to be that % smaller as well.
It doesn't work that way, with the example being that of the Quail which, as you correctly point out, was built to mimic the signature of a B-52. The Quail is significantly smaller in its physical dimensions than a B-52, yet it did not have a smaller RCS, it had the same RCS as a B-52.
That's because size doesn't matter that much.
...
At least here in this context...

 

[kaiserd]

The B-21 is designed for ALCMs just not the ALCM. My money is on it having space for two rotary launchers.

The B-21 is designed for ALCMs just not the ALCM. My money is on it having space for two rotary launchers.

Are any of the LRSO requirements public? I think the goal is equal or greater range, which implies a weapons of similar size/length to AGM-86. I think at least one bay of 20' length is a given.

There isn't much more heat to tap out of the williams jets used so fuel load is the primary weight and size driver. Warhead design is what is now. It will be the same size as the 86.

The 21 doesn't have a central weapons bay. It has 2 side bays like b2. Therefore it has 2 weapons bays sized for alcms. It may only cary 6 instead of 8 per bay is reasonable to assume.

With respect right now we just don’t know how many weapon bays the B-21 has or its/ their dimensions and capacity.
Speculation of varying quality is all that we do currently have in this regard.

A thought that occurred to me was that the B-21 could have one deeper central bay approx. equivalent to one of the B-2s bays and this could be flanked by an additional shallower bay each side approx equivalent in size to a one of the F-35s bays (but potentially longer), with these side bays being relatively tightly package with the engines and inlets.
However I have zero evidence for any of that speculation and it’s best not to (even just inadvertently) present assumptions as fact.

 

[Josh_TN]

There isn't much more heat to tap out of the williams jets used so fuel load is the primary weight and size driver. Warhead design is what is now. It will be the same size as the 86.

The 21 doesn't have a central weapons bay. It has 2 side bays like b2. Therefore it has 2 weapons bays sized for alcms. It may only cary 6 instead of 8 per bay is reasonable to assume.

Do we definitively know that B-21 has two weapons bays??? I haven't seen anything but guess work indicating such.

 

[Josh_TN]

With respect right now we just don’t know how many weapon bays the B-21 has or its/ their dimensions and capacity.
Speculation of varying quality is all that we do currently have in this regard.

A thought that occurred to me was that the B-21 could have one deeper central bay equivalent to one of the B-2s bays and this could be flanked by an additional shallower bay each side approx equivalent in size to a one of the F-35s bays (but potentially longer).
However I have zero evidence for that speculation and it’s best not to (even just inadvertently) present assumptions as fact.

I was thinking along the same lines - I wouldn't think that the USAF would want to get away from the strategic rotary launcher model for a bomb bay (if nothing else just to have comonality with the B-52 fleet for the next 2-3 decades). But since it seems likely the B-21 will have some self defense capability (to me anyway) I could easily see smaller F-35 sized bays that leverage anything developed for that platform as a quick response weapon separate from the main warload. If there were defensive weapons, you wouldn't want them inside the main payload space and have to cycle the main doors to release them. I assume that is a slower process that presents a much larger radar return than a smaller bay. Also more wind resistance; the B-2 bay I believe has air spoilers to help weapon separation of part of its opening cycle. An F-35 sized bay wouldn't even necessarily have to be inside the MGLs I'd think; that is rather insignificant amount of weight for a bomber that could be moved outward (though the more centrally located the better I'd imagine).

Total speculation, unlikely to be proven right or wrong for years...

 

[overscan (PaulMM)]

Just in passing and OT, but for the people still wondering if smaller/bigger size necessarily translates into smaller/bigger RCS, here's the ADM-20 Quail which was used as a decoy for B-52s in the 60s.

But the Quail was built specifically to mimic the radar reflection of a B-52 or similar - McDonnell went out of their way in the design to do that. Nothing with its shape that can be construed as an effort at stealth, it was essentially a flying radar reflector.

Enjoy the Day! Mark

That is what I'm getting at, since there are people stating that the B-21, being a % smaller than the B-2, is going to have an RCS that is going to be that % smaller as well.
It doesn't work that way, with the example being that of the Quail which, as you correctly point out, was built to mimic the signature of a B-52. The Quail is significantly smaller in its physical dimensions than a B-52, yet it did not have a smaller RCS, it had the same RCS as a B-52.
That's because size doesn't matter that much.
...
At least here in this context...

Its RCS *will* be smaller,. primarily because of the shaping.

 

[steelpillow]

That's because size doesn't matter that much.

Size does matter. It's just that things get complicated - very abstrusely complicated - and everything else matters as well. I should know, I had to sign the Official Secrets Act. Lots of it is now public knowledge, but I am not going to second-guess which bits.

But to any budding test bench experimenters I recommend the standard EMI/EMC precautions: duct tape - lots and lots of duct tape, oodles and squoodles and container loads of duct tape. And nasty-minded duct tape police 24/7. And watch those error bounds like your job depends on it. Just don't look out the windows (in joke).

 

[aim9xray]

And don't ever forget the combo to to your container. Ever.
Ever.

Just say'n.

 

[Josh_TN]

View: https://www.youtube.com/watch?v=58alk3OnoGY&t=9s

 

[Fluff]

With respect right now we just don’t know how many weapon bays the B-21 has or its/ their dimensions and capacity.
Speculation of varying quality is all that we do currently have in this regard.

A thought that occurred to me was that the B-21 could have one deeper central bay equivalent to one of the B-2s bays and this could be flanked by an additional shallower bay each side approx equivalent in size to a one of the F-35s bays (but potentially longer).
However I have zero evidence for that speculation and it’s best not to (even just inadvertently) present assumptions as fact.

I was thinking along the same lines - I wouldn't think that the USAF would want to get away from the strategic rotary launcher model for a bomb bay (if nothing else just to have comonality with the B-52 fleet for the next 2-3 decades). But since it seems likely the B-21 will have some self defense capability (to me anyway) I could easily see smaller F-35 sized bays that leverage anything developed for that platform as a quick response weapon separate from the main warload. If there were defensive weapons, you wouldn't want them inside the main payload space and have to cycle the main doors to release them. I assume that is a slower process that presents a much larger radar return than a smaller bay. Also more wind resistance; the B-2 bay I believe has air spoilers to help weapon separation of part of its opening cycle. An F-35 sized bay wouldn't even necessarily have to be inside the MGLs I'd think; that is rather insignificant amount of weight for a bomber that could be moved outward (though the more centrally located the better I'd imagine).

Total speculation, unlikely to be proven right or wrong for years...

For 200BN, I'd like to think they have come up with a denser packing system than the rotary launcher. Triangles come to mind, 2 per rectangle. Very thin racking system that drops out with the missile.

USAF wants 100 aircraft, so one tactic has to be saturation of the enemies AD. More aircraft, with more missiles would help.

 

[Rolead]

Regarding the engines, if you have a desirable 'asset' would you risk it having two engines ? If one was to fail where would that leave you. For the current engines what is the MTBF ?

Robert

 

[Fluff]

Regarding the engines, if you have a desirable 'asset' would you risk it having two engines ? If one was to fail where would that leave you. For the current engines what is the MTBF ?

Robert

Well we put 300 people on planes with 2 engines, and thousands of F16 and now F35 flying around with 1 engine. 4 engines doubles the likelihood of a failure........(and steps back....)

 

[overscan (PaulMM)]

Regarding the engines, if you have a desirable 'asset' would you risk it having two engines ? If one was to fail where would that leave you. For the current engines what is the MTBF ?

Robert

Well we put 300 people on planes with 2 engines, and thousands of F16 and now F35 flying around with 1 engine. 4 engines doubles the likelihood of a failure........(and steps back....)

Yep, modern engines are reliable enough this isn't really a worthwhile argument. Advantages to the Air Force of using F135 outweigh minor benefits of using say 4 x F414.

F-35 reached 100,000 flight hours without loss, and the expected loss rate (from all causes) was on average one (F-35) aircraft loss every 30,000 hours. Twin-engined F-15 averaged 2.36 losses per 100,000 hours.

 

[paralay]

,

 

[paralay]

,

 

[Desertfox]

The B-21 is designed for ALCMs just not the ALCM. My money is on it having space for two rotary launchers.

Are any of the LRSO requirements public? I think the goal is equal or greater range, which implies a weapons of similar size/length to AGM-86. I think at least one bay of 20' length is a given.

LRSO is a straight replacement of the ALCM, similar warhead, same pylons and launchers as ALCM, so assuming same size as the AGM-86 would be a good estimate.

 

[Josh_TN]

For 200BN, I'd like to think they have come up with a denser packing system than the rotary launcher. Triangles come to mind, 2 per rectangle. Very thin racking system that drops out with the missile.

USAF wants 100 aircraft, so one tactic has to be saturation of the enemies AD. More aircraft, with more missiles would help.

I suspect there will be multiple rack systems like the B-2, which has the rotary system for most weapons in the 1000kg/2000lb range, a large vertical rack system for Mk 82s, and a suspension system for the MOP. So some kind of rack, rotary or otherwise, that accommodates large weapons like AGM-58, HACM, LRSO, and Mk84's with various add on kits. But I think it highly likely that the B-21 will have some kind of specialized system for dispensing SDB-I/II: that weapon type maximizes bomb load and PGM inventory while minimizing price and providing stand off. Given the fact it will most likely spend most of its time at very high altitude, the stand-off range of glide bombs would be extended compared to tactical aircraft usage. I would guess that the USAF would want to retain the capability of carrying 80+ weapons like the B-2; at 250lbs/200lbs for GBU-39/53 it seems to me you could easily carry 20-25,000lbs of bombs + rack system and have a warload of ~100 weapons.

 

[sferrin]

I'd hope the weapons bay (bays?) is at least long enough to carry AGM-86C. Sure, it's an unlikely combo but we don't want to run into the "too long for the elevator" problem of CVNs.

 

[datafuser]

Radar signature is a function of the reflectivity

Yes, mostly.

and size of a given feature.

No.
Small feature can have a big return. Big feature can have a small return. RCS is not dependent on volume or physical size. The electrical size of something in relation to the frequency can affect the RCS. As a general rule though the size of an object does not have a direct affect on the RCS. Saying a given shape, made smaller, will produce a smaller RCS is not correct at all, and this has been known since the 1960s. It was this knowledge that allowed Boeing to create the SRAM (and other things) with a very small RCS even though it was "common knowledge" at the time that size and RCS were directly related (again, they are not).

Please don't offer me naive BS, I am a time-served EM engineer. I look forward to your citation for what "has been known since the 1960s".

If size (a) does affect radar signature (σ), is it in Optical Region where the following relationships hold?

λ << a
σ = π a2

https://www.ll.mit.edu/sites/default/files/outreach/doc/2018-07/lecture%204.pdf

 

[Josh_TN]

I'd hope the weapons bay (bays?) is at least long enough to carry AGM-86C. Sure, it's an unlikely combo but we don't want to run into the "too long for the elevator" problem of CVNs.

It is to receive LRSO, which is likely of similar length, and in any case will replace AGM-86 anyway.

 

[Woody]

From Time Magazine.

 

[bring_it_on]

Despite persistent rumors—and some defense official comments—that the B-21 would be substantially smaller than the B-2, that was not apparent at the rollout. A rough approximation of the wingspan, made possible by the presence of a B-2 at a Northrop Grumman aircraft a few feet away, suggests the wingspan of the B-21 is perhaps only 22 feet or so shorter than that of the B-2, which would indicate a span of about 150 feet. However, this estimation is fraught because the angle of wing sweepback on the B-21 may be deeper than that of the B-2. A close encounter with the draped B-21 minutes before the unveiling indicated it may have a deeper sweep angle than the B-21, but whether it has a “cranked” or bent shape was unclear.

Eight Features That Show the New Raider is Not the B-2.1 | Air & Space Forces Magazine

More than 34 years of technological advances since the B-2’s 1988 rollout were clearly in evidence at the rollout of the B-21.

www.airandspaceforces.com

 

[BDF]

I suspect there will be multiple rack systems like the B-2, which has the rotary system for most weapons in the 1000kg/2000lb range, a large vertical rack system for Mk 82s, and a suspension system for the MOP. So some kind of rack, rotary or otherwise, that accommodates large weapons like AGM-58, HACM, LRSO, and Mk84's with various add on kits. But I think it highly likely that the B-21 will have some kind of specialized system for dispensing SDB-I/II: that weapon type maximizes bomb load and PGM inventory while minimizing price and providing stand off. Given the fact it will most likely spend most of its time at very high altitude, the stand-off range of glide bombs would be extended compared to tactical aircraft usage. I would guess that the USAF would want to retain the capability of carrying 80+ weapons like the B-2; at 250lbs/200lbs for GBU-39/53 it seems to me you could easily carry 20-25,000lbs of bombs + rack system and have a warload of ~100 weapons.

My money is on two, somewhat shallower bays. Enough probably carry two 6 round rotary launchers and my WAG is a total max payload of 28Klbs. I know some of suspected a single B-2 bay but that seems way too restrictive in my view. Much more flexibility with two albeit smaller bays. Mark Gunzinger on the Aerospace Advantage podcast indicated that it will also be able to carry external ordnance as well. It will be interesting to see how and where if that's accurate.

 

[Josh_TN]

External ordnance sounds crazy, to be honest. I guess we’ll find out eventually…if we live long enough…

 

[flateric]

Interesting ...

https://twitter.com/x/status/1599717448734822400

View: https://twitter.com/i/web/status/1599717448734822400

I

Mark Gunzinger on the Aerospace Advantage podcast indicated that it will also be able to carry external ordnance as well. It will be interesting to see how and where if that's accurate.

It was known for ages.

 

[overscan (PaulMM)]

which would indicate a span of about 150 feet

 

[overscan (PaulMM)]

Added the Twitter images.

I think this is broadly correct except for the trailing edge not aligning.

 

[BLACK_MAMBA]

Looks to be a photo from ever so slightly to port this time. Doesn't show much different, but still interesting.

https://twitter.com/x/status/1599907968568463362

View: https://twitter.com/clemente3000/status/1599907968568463362?t=Gfu9Od6jvC-TWqRq7_xcWA&s=19

 

[quellish]

Nope. The relationship between radar wavelength and size of physical features means a smaller B-2 could be more detectable to long wavelength radars for example.

Bahret put this well:

The result of all this experimentation was a gradually increasing understanding of flare spots-what they were for different vehicles, how they behaved at different radar frequencies, and how they should be modeled. The picture emerged that the influence of a flare spot was related to its’ geometry first of all, but also to its’ dimensions measured in the wavelengths with which it was illuminated.
What this means in simple terms is that at what are called “microwave frequencies”-those above 2000 megahertz (mhz) or so -a normal aircrafts’ echo derives from a set of individual sources, while at much lower frequencies, the increasing tendency is for the entire aircraft to act like one big source-with only the general shape being a factor. At extremely low frequencies, even the shape loses influence and only the volume matters.

A fighter sized aircraft is difficult to shape to reduce RCS at low frequencies. A large aircraft like the B-2 presents opportunities to using shaping to reduce RCS across a much wider range of frequencies. If you took a B-2 and shrank it though the shaping would become less effective as it got smaller - the RCS would change, and not likely for the better.