Northrop Grumman B-21 Raider (LRS-B)

[martinbayer]

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?

Presumably it depends on the combination of flight altitude, airspeed, and duration, in conjunction with structural as well as thermal protection materials and concepts, but your point is very well taken. The alternating black, white and pink X-15 paint schemes, as well as the black Oxcart/Blackbird family vs. the white XB-70, which were both pretty much intended for the same operating environment, come readily to mind.

 

[Rhinocrates]

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?

I think it depends on a combination of altitude, airspeed and flight duration in conjunction with structural as well as thermal protection materials and concepts, but your point is very well taken regardless. The alternating black, white and pink X-15 paint schemes come readily to mind.

Just to further complicate things, maybe it's anti-flash (that is, nuclear flash). The British V-bombers were painted white in their early years and the Tu-160 still is.

Anecdote or pisstake, I'm not sure, but I remember watching a documentary on the Vulcan and a former pilot said that they were issued with eye patches. They'd wear it over one eye, and when they were blinded by a nuclear explosion, they'd switch the patch over to the blind eye. I'm guessing extraction of urine, but maybe...

Anyway, with lasers being seriously planned, a reflective or ablative coating might be used (and maybe the 'chrome' finish seen on some planes) is as much an anti-laser as anti-IR detection technology.

However, we shouldn't jump to conclusions too soon - this is the first reveal of the first aircraft and they aren't willing to show off everything right away - after all, we still don't know how many engines it has. Matt white or light grey gives away little detail.

The geometry of the windows is more certain. My guess that it is a compromise between the absolute maximum the designers would allow and the absolute minimum the pilots would tolerate. The windshield is just enough for takeoff and landing and approach for midair refuelling while the side slits give a reassuring view of the leading edge and inlets. Synthetic vision takes care of the rest. A transparent material is probably less likely to be optimally stealthy, so the smaller the area the better, and the less likely the pilots are to be dazzled or blinded by lasers.

This Boeing NGAD concept from a few years back has a surprisingly small transparency for a fighter and I suspect that it's only there for landing if many of the synthetic visions systems are knocked out while the BAE Systems P.125 concept has no direct outside vision for the pilot at all. It's the logical continuation of a trend - the flat centre panes and circular-section canopies designed to minimise distortion were seen in for the last time in the MiG-25, Tornado, and F-14, then the centre panes went in the F-15, Su-25 and Eurofighter, and then we saw the blended blisters of the F-22, F-35, and Su-57. Smaller transparencies look inevitable.

 

[VTOLicious]

Judging from taxiway plate size thiz cat iz rly smal with ~120 ft/36 m wingspan

I agree
52.4 m * (34.3 : 49.5) = 36.3 m (119 ft)
wing area 226 m2
maximum take-off 226 m2 * 368 kg/m2 = 83200 kg
engines: 83200 kg * 0.2 = 16640 kgf : 2 = 8320 kg - two F118-GE-100

 

[Sundog]

If you know it's not the same hanger then it would be helpful if you would provide information on the two hangers.

All I know is the hanger it was rolled out of was purpose built for the B-21 program.

 

[flateric]

Judging from taxiway plate size thiz cat iz rly smal with ~120 ft/36 m wingspan

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:

I didn't saw the second pic has so good plate lines reference. With taxiway plate sizing of 150 inches it has almost 40 m wingspan (that quite match @zaphd numbers and 16 m lenght with 268m2 area.

 

[totoro]

Isnt the hangar from which the plane came out known? Hundreds od people were there. Can anyone point out the hangar building in a shot from google maps/google earth?

 

[CiTrus90]

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.

The egress panels are most probably those that can be seen in Overscan's close up picture. I've outlined the one on the right side of the craft:

I do not think those are for the ejection seats. I've made a quick drawing to get a (very) rough estimate of where the glazings are, and they clearly do not line up with where I'd expect the pilots to seat:

So, unless the seats slide to the sides during the ejection procedure, this is why I think those are emergency egress panels and (possibly) explosive ones. I think the crew is meant to enter and exit the B-21 in the same way as on the B-2, via a ladder on the bottom of the craft, but after the B-2's crashes in 2008 and 2021 it might have been noticed that in case the landing gear collapses while on the runway, the pilots only option to leave the aircraft would be to eject. Which is not great for the human body, unless necessary to avoid worse injuries or death.

I believe the ejection panels can't be seen in the available pictures due to a mix of the angles at which these have been taken, the lights used in the hangar and the kind of surface coating on the aircraft.

Edit: I also believe the side windows' shape and size are dictated by the structural requirements for these egress panels, rather than any laser/stealthiness theory.

 

[martinbayer]

If you know it's not the same hanger then it would be helpful if you would provide information on the two hangers.

All I know is the hanger it was rolled out of was purpose built for the B-21 program.

Any online or offline documentation to back that assertion up?

 

[flateric]

Any online or offline documentation to back that assertion up?

What for? It's a well known fact that Northrop has started an intense build-up at Site 4 after they have won LRS-B.

 

[martinbayer]

Any online or offline documentation to back that assertion up?

What for? It's a well known fact that Northrop has started an intense build-up at Site 4 after they have won LRS-B.

Call me agnostic, but I'd still like to see concrete references for that "well known fact".

 

[Orionblamblam]

Any online or offline documentation to back that assertion up?

What for? It's a well known fact that Northrop has started an intense build-up at Site 4 after they have won LRS-B.

Call me agnostic, but I'd still like to see concrete references for that "well known fact".

https://y.yarn.co/981893f4-1fc1-43be-a0c9-49c44dfb01b1.mp4

 

[overscan (PaulMM)]

I don't think the intake lip is curved in planform - I think its a "tick' with one longer edge and a shorter edge.

 

[flateric]

exactly it is

 

[martinbayer]

Any online or offline documentation to back that assertion up?

What for? It's a well known fact that Northrop has started an intense build-up at Site 4 after they have won LRS-B.

Call me agnostic, but I'd still like to see concrete references for that "well known fact".

https://y.yarn.co/981893f4-1fc1-43be-a0c9-49c44dfb01b1.mp4

Not helping.

 

[CiTrus90]

I don't think the intake lip is curved in planform - I think its a "tick' with one longer edge and a shorter edge.

I know, but mine was a quick drawing, and as said privately as well, I'm not going to post any accurate drawing (if I were to make them) in the open just to have them stolen/reposted without my permission

 

[overscan (PaulMM)]

Also, the bottom part of the intake is hard to discern, but perhaps if you mashed together the B-2 intake with a Tacit Blue flush type intake... the effective intake area would be greater than it looks from the front. Might also explain the shyness in showing the intake area in artist's impressions.

 

[Hanz2k]

F118 is 85kN engine while F135 is 125kN engine. B2 has 340kN thrust vs. B21 250kN thrust - basically only 35% less, but with at least 45% lower fuel consumption. If they use some technologies from Adaptive Engine then they could have even more thrust. And of course lower fuel consumption mean less weight. Basically it could be B2 resized - benefiting from lower fuel consumption plus smaller airframe mean lower drag. B2 has 75 tons of fuel on board, B21 with lower fuel consumption could require around 40 tons for same range. Last thought - maybe resize around fuel doesn’t require to cut weapons capacity?

 

[totoro]

B-21 also has 3-4 m narrower MLG, (using 39.5 m wingspan estimate) so there might be less physical space to place two MOP sized bomb bays one parallel to the other between them.

 

[zaphd]

Thanks for pointing out that it's a different hangar. I used this screenshot from a part of the release video where two people were standing in the doorway to estimate the door height of the hangar. Result: 8.55-9.12m depending on what kind of assumptions you make about the height of the people. If we assume the door height is the center of the range 8.84m (coincidentally this is exactly 29 feet), the corresponding wingspan would be 41.5m.

Additionally I would like to point out that in pictures taken from close by where the plane is covering the whole view, there is a considerable fish eye type perspective effect. This is especially apparent in some of the indoor photos that were released. In this effect the distances at the edge of the photo appear shorter than those at the center, which can lead to a smaller size estimate if unaccounted for.

 

[steelpillow]

I understand all of that.

Yep. Not every reader of this thread might, though.

 

[steelpillow]

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.

Structurally simpler and lighter as well to keep all the volume and mass (including engines) nearer centerline.

The reverse is actually true. One of the great benefits of the all-wing design is span loading; put the weight where the lift is, don't put the lift metres from the weight.

Also, it is worth noting that the majority of thrust from a subsonic turbofan acts on the fan, compressor and combustion chamber. The exhaust only does much if you are using a very un-stealthy afterburner. Moving it inboard does help a bit, but even with a central nozzle the single surviving engine is still pushing hard on one side.

 

[seruriermarshal]

Thanks for pointing out that it's a different hangar. I used this screenshot from a part of the release video where two people were standing in the doorway to estimate the door height of the hangar. Result: 8.55-9.12m depending on what kind of assumptions you make about the height of the people. If we assume the door height is the center of the range 8.84m (coincidentally this is exactly 29 feet), the corresponding wingspan would be 41.5m.

Additionally I would like to point out that in pictures taken from close by where the plane is covering the whole view, there is a considerable fish eye type perspective effect. This is especially apparent in some of the indoor photos that were released. In this effect the distances at the edge of the photo appear shorter than those at the center, which can lead to a smaller size estimate if unaccounted for.

Yes , fish eye

 

[VTOLicious]

Also, it is worth noting that the majority of thrust from a subsonic turbofan acts on the fan, compressor and combustion chamber. The exhaust only does much if you are using a very un-stealthy afterburner. Moving it inboard does help a bit, but even with a central nozzle the single surviving engine is still pushing hard on one side.

I disagree on "majority of thrust". If that would be the case a Harrier wouldn't be able to hover.

 

[rooster]

Judging from taxiway plate size thiz cat iz rly smal with ~120 ft/36 m wingspan

I agree
52.4 m * (34.3 : 49.5) = 36.3 m (119 ft)
wing area 226 m2
maximum take-off 226 m2 * 368 kg/m2 = 83200 kg
engines: 83200 kg * 0.2 = 16640 kgf : 2 = 8320 kg - two F118-GE-100

I think your people are overly tall.
It's probably closer to 132 ft just doing crude approx with educated guesses.
Not sure why wingspan matters in the discussion on the capability. No one says the f104 wingspan is small therefore the f104 is smaller than a Viper. People there said it didn't look much smaller than a b2.
Its lighter, therefore needs less wing.
One thing is for sure is that if it's a twin, it's got a higher thrust to weight ratio than b2 in case of stuff happens and it finds itself with 50% less power.
There's more unknowns than knowns. It may have burners for takeoff with a full load for all we know. Gives better short field performance after all. So why not? It will be a long time before we see the rest of the airframe.
Was not senior peg a smallish airplane being smaller than a b2? If so then if the 21 is significantly smaller than b2 then the usaf went back to that concept to keep cost down to buy more aiframes. Force_capability per airframe ratio is smaller which keeps losing an airframe has less impact on overall fleet capability. Lose 1 b2 and you lost 5% of the fleet capability by comparison.

 

[steelpillow]

Also, it is worth noting that the majority of thrust from a subsonic turbofan acts on the fan, compressor and combustion chamber. The exhaust only does much if you are using a very un-stealthy afterburner. Moving it inboard does help a bit, but even with a central nozzle the single surviving engine is still pushing hard on one side.

I disagree on "majority of thrust". If that would be the case a Harrier wouldn't be able to hover.

Another misconception.
The vertical jet lift on the Harrier is generated on the sides of the duct/nozzle where it bends to deflect the air down.
But on your B-21 the duct would need to be an S shape to create the offset. The first bend would create reverse thrust as the air was turned sideways, and the second bend an equal amount of forward thrust as it was turned back again; net exhaust thrust, zero. It does create a small yawing moment to help the drag rudder, but its short moment arm (half the offset) is too small to be of much help.

 

[NeilChapman]

Judging from taxiway plate size thiz cat iz rly smal with ~120 ft/36 m wingspan

I agree
52.4 m * (34.3 : 49.5) = 36.3 m (119 ft)
wing area 226 m2
maximum take-off 226 m2 * 368 kg/m2 = 83200 kg
engines: 83200 kg * 0.2 = 16640 kgf : 2 = 8320 kg - two F118-GE-100

I think your people are overly tall.
It's probably closer to 132 ft just doing crude approx with educated guesses.
Not sure why wingspan matters in the discussion on the capability. No one says the f104 wingspan is small therefore the f104 is smaller than a Viper. People there said it didn't look much smaller than a b2.
Its lighter, therefore needs less wing.
One thing is for sure is that if it's a twin, it's got a higher thrust to weight ratio than b2 in case of stuff happens and it finds itself with 50% less power.
There's more unknowns than knowns. It may have burners for takeoff with a full load for all we know. Gives better short field performance after all. So why not? It will be a long time before we see the rest of the airframe.
Was not senior peg a smallish airplane being smaller than a b2? If so then if the 21 is significantly smaller than b2 then the usaf went back to that concept to keep cost down to buy more aiframes. Force_capability per airframe ratio is smaller which keeps losing an airframe has less impact on overall fleet capability. Lose 1 b2 and you lost 5% of the fleet capability by comparison.

Would we say that the weapons load is more capable today? Perhaps that adds 'weight' to the distributed performance of the system.

 

[bring_it_on]

While the payload is definitely TBD, I think the SecDef's comments on its efficiency and range should probably lay to rest any doubts on its ability to match or exceed the unrefueled range of the B-2 or B-1. If it has shorter legs, I seriously doubt he would have stuck his neck out and claimed an exact opposite in prepared remarks.

The range of the B-21, Austin said, is unmatched by any other bomber.

"It won't need to be based in-theater, it won't need logistical support to hold any target at risk," the secretary said.

World Gets First Look at B-21 Raider

As the first strategic bomber in more than three decades, the Air Force's B-21 will serve as the backbone of America's bomber force, Secretary of Defense Lloyd J. Austin III said.

www.defense.gov

 

[paralay]

,

 

[NeilChapman]

One thing is for sure is that if it's a twin, it's got a higher thrust to weight ratio than b2 in case of stuff happens and it finds itself with 50% less power.

Would this also be necessary if there were higher expected operating altitudes?

 

[totoro]

How are b-2 engines accessed and replaced? Through the panels on the belly, between weapon bays and landing gear?

Is it more plausible that b21 retains a similar system ? Or is it more plausible engines are accessed from the top or via some other way? (Sliding backward after a large top panel is removed?)

 

[SOC]

Regarding the side windows - might they be positioned in part to help view the intakes and outer leading edges, to determine if de-icing is needed? Might higher operating altitudes make icing a bigger issue to be aware of?

 

[VTOLicious]

Also, it is worth noting that the majority of thrust from a subsonic turbofan acts on the fan, compressor and combustion chamber. The exhaust only does much if you are using a very un-stealthy afterburner. Moving it inboard does help a bit, but even with a central nozzle the single surviving engine is still pushing hard on one side.

I disagree on "majority of thrust". If that would be the case a Harrier wouldn't be able to hover.

Another misconception.
The vertical jet lift on the Harrier is generated on the sides of the duct/nozzle where it bends to deflect the air down.
But on your B-21 the duct would need to be an S shape to create the offset. The first bend would create reverse thrust as the air was turned sideways, and the second bend an equal amount of forward thrust as it was turned back again; net exhaust thrust, zero. It does create a small yawing moment to help the drag rudder, but its short moment arm (half the offset) is too small to be of much help.

The B-2 actually has an s-duct on the exhaust side.

What I propose is an s-duct that shifts the thrust vector closer to the centerline (see sketch, top and side view).

Consequently, if one engine fails, the yaw-moment created by the remaining engine would be smaller.

 

[TomcatViP]

it probably has distributed exhaust. So no proper S-duct on the exhaust side.

Angled windows and exacerbated washout.... Would that be for a high AoA cruise attitude?

 

[flateric]

Regarding the side windows - might they be positioned in part to help view the intakes and outer leading edges, to determine if de-icing is needed? Might higher operating altitudes make icing a bigger issue to be aware of?

They apparently are like on B-2.
Icing happens at quite a limited envelope and never was associated with high altitudes yet you have issues with cold fuel but this is other story.
B-2 just don't have LE de-icing/anti-icing stuff for example.

 

[zaphd]

Would we say that the weapons load is more capable today? Perhaps that adds 'weight' to the distributed performance of the system.

Combat load:
1 multi-position launcher - 1000 kg
8 AGM-158 - 8168 kg
2 AIM-120 - 322 kg
2 AIM-9 - 182 km
total: 9672 kg

What makes you think it'll have only 1 rotary launcher ?
I think the primary reason it has such a fat belly is to incorporate 2 of those.

I think the most popular view before the unveiling has been that the internal configuration is a tall B-2 style central bay with the engines and engine ducting on the side (example of this is in the concept art from a CSBA study from 2010). However, I'm starting to question whether this is necessarily the case based on what we've seen.

One thing, as you and Tuna have mentioned, is the thick lower fuselage, which is considerably fatter than the B-2 on the lower sides. The wide stance of the main landing gear is also related to this. Another thing is that the intakes seem to curve inward according to speculation on the brightened pictures that were posted a few pages back.

Perhaps, based on this, the engines are on the top side of the central fuselage, with wide, medium depth payload bays on the bottom. Somewhat reminiscent of an F-22, except bigger. That would mean no MOPs, but wide and relatively shallow bays without rotaries would probably allow easier integration and mixing of different kinds of weapons, including AAMs. Another possible explanation for the bloated lower fuselage is small bays for AAMs flanking a deeper central bay with a rotary launcher.

 

[TinWing]

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.

Twins always need a higher power to weight ratio because of the engine out scenario

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.

How does asymmetric thrust work when you are a flying wing? Sounds like flat spin to hell if you just do the default.

While the payload is definitely TBD, I think the SecDef's comments on its efficiency and range should probably lay to rest any doubts on its ability to match or exceed the unrefueled range of the B-2 or B-1. If it has shorter legs, I seriously doubt he would have stuck his neck out and claimed an exact opposite in prepared remarks.

The range of the B-21, Austin said, is unmatched by any other bomber.

"It won't need to be based in-theater, it won't need logistical support to hold any target at risk," the secretary said.

World Gets First Look at B-21 Raider

As the first strategic bomber in more than three decades, the Air Force's B-21 will serve as the backbone of America's bomber force, Secretary of Defense Lloyd J. Austin III said.

www.defense.gov

I’m really glad that the B-21 “won’t need logistical support to hold any target at risk.” No logistical support, ever! Hopefully with the help of N-G, Lockmart can make sure that later production variants of the F-35 “won’t need logistical support,” either. This is game changer for sure. As a proud American, my heart is bursting with patriotic pride. We finally eliminated all logistical support costs from a military aircraft. Just think of the impact on commercial aviation if the technology that eliminated logistical support costs from the B-21 is ever declassified.

Putting sarcasm aside, the fact that an unprovable claim about the highly classified attribute of range was followed by a wildly implausible claim about the elimination of logistical support should tell you that both matters are areas of concern.

Honestly, I’m sure the B-21 will fly and probably will meet its range requirements, which no doubt are adequate, whatever they are. However, the B-21 is definitely much smaller than the B-2 and is a medium bomber compliment to the re-engined B-52J. Pretty much the same relationship the B-47 had with the B-36

Maybe if the original B-2 had been scaled down by a third and the low level requirement eliminated, it would have come into service earlier, at a lower cost and the fleet would have been built out to a more useful number than 21.

 

[archipeppe]

I wonder if US will keep such new aircraft for itself (as B-1, B-2, etc.) or did will share it with the most reliable allies (UK, Australia, others...)?
F-35 become a big deal in the end....

 

[flateric]

How are b-2 engines accessed and replaced? Through the panels on the belly, between weapon bays and landing gear?

Is it more plausible that b21 retains a similar system ? Or is it more plausible engines are accessed from the top or via some other way? (Sliding backward after a large top panel is removed?)

yes/yes/no

 

[paralay]

,

 

[flateric]

Perhaps, based on this, the engines are on the top side of the central fuselage, with wide, medium depth payload bays on the bottom. Somewhat reminiscent of an F-22, except bigger. That would mean no MOPs, but wide and relatively shallow bays without rotaries would probably allow easier integration and mixing of different kinds of weapons, including AAMs. Another possible explanation for the bloated lower fuselage is small bays for AAMs flanking a deeper central bay with a rotary launcher.

This is actually how Boeing/Lockheed NGB was envisioned. But not NG B-21.