Northrop Grumman B-21 Raider (LRS-B)

[flateric]

Simple logic - if B-21 should carry 30,000 lbs MOB-57, then how much? Say two. Anyone with Raymer's RDS or more advanced software like CREATE-AV or MDAO can rapidly make more or less correct models and conclusions.

 

[In_A_Dream]

If you havent read the Rand study on the projected PLA Pacific dominance numbers of targets and there incresing difficulty to neutralize we are wasting our time here. BTW .. not doing ur homework for u.

Quick side note: In this thread and others, you are coming off a little arrogant and it's off-putting for simple conversation. Friendliness and an open mind will get you further.

 

[Foo Fighter]

This whole thread is going a bit pear shaped.

 

[sferrin]

This whole thread is going a bit pear shaped.

Yep. I don't understand why it's so difficult for some people to admit that the B-21 will be less capable than the B-2. *shrugs*

 

[shin_getter]

You will not deliver sufficient payload as a deterent in the Pacfic.

How much of the challenge is payload limited as opposed to ISR limited?

If you are striking something like a carrier task force, a lot of payload is great for overwhelming defenses.

If you are striking hidden, fleeting land targets, one might rarely be able to find enough targets to use up a big bomb load before running out of fuel. A lot of bombers that can cover more of space and time can result in more targets destroyed than one big bomber.

Then there is the question of survivability: there are types of losses that is largely independent of marginal changes in vehicle performance (eg. CAP gets penetrated, refueling chain shot down, etc). If those tends to dominate than spending additional money on defensive performance is not worth while.

If one looks at developments in civil aviation, twin engined aircraft have proven to be more economical than larger 3 or 4 engined aircraft. From a pure payload perspective a smaller air frame is fine, the extra cost is in sensors and defensive systems.

 

[bobbymike]

This whole thread is going a bit pear shaped.

Yep. I don't understand why it's so difficult for some people to admit that the B-21 will be less capable than the B-2. *shrugs*

Someone smarter than me should list all the areas of capability for a heavy bomber with a more capable/less capable checklist such as;

Stealth
Range
Electronics
Software
Payload
Self Defense?
Targeting
Upgrade potential
Etc.

 

[aim9xray]

Nice list. How adding about some of the "ilities" upon which all of the above mentioned capabilities rely:

Reliability
Maintainability
Affordability
Operability
Availability
Repairability
MTTR
MTBF (and so on for all the "M" figures of merit)

Without improvements in these qualities and many more, you have a flying LCS. If and when it is able to get off the ground.

These are qualities that are often ignored by observers and are at the core of How Things Work In Real Life.

 

[Mark S.]

If you have a dispersed target set a greater number of bombers make sense. I can see where in either a conventional or nuclear conflict a role of a bomber would be hunting and killing road mobile missile launchers. Additionally you could find in a lot of texts that the probability of kill, (PK) for a bomber delivered gravity weapon was on average 67%. Sure a stealthy airframe would be more survivable but as you drop the weapons your PK goes down. So will the aircraft survive long enough to drop all 16 weapons in its bays as in the B-2? Another interesting point is it's often noted that the go-to-war load out of the B-1 was a fuel tank in the forward bay, 8 gravity weapons in the mid bay and 8 SRAM's in the aft one. In actually you have only 8 weapons for targets while using the SRAM's for SEAD to get to your targets. Before the advent of cruise missiles B-52's had the capability at most to carry internally 8 gravity weapons. It might just be that there isn't a requirement for a larger number of weapon stations in a bomber than about 8 or so. My only concern is that the B-21 would be able to carry 8 LRSO's or an equivalent hypersonic weapon in the future. The real question is how many bombers on alert will be able to launch and reach their targets to inflict the level of damage needed to cause the opponent to surrender in a nuclear exchange? If you can get 50 bombers launched with 8 weapons each for a total of 400 weapons with a suggested PK of 80% then you can destroy 320 targets.

 

[Desertfox]

Lets not forget that weapons have gotten both smaller and more accurate/effective. A single B-2 has far less payload capability than a wing of B-52Ds, but it would be far more effective. The same way, the B-21 might carry less but if each bomb is more effective on its own, it does not need to carry as many to achieve the same effect.

 

[NeilChapman]

This whole thread is going a bit pear shaped.

Yep. I don't understand why it's so difficult for some people to admit that the B-21 will be less capable than the B-2. *shrugs*

Someone smarter than me should list all the areas of capability for a heavy bomber with a more capable/less capable checklist such as;

...
...

And how would you define each category and how would each be weighted?

Stealth = RCS? 25%?
Range = Min 5000nm? 25%?
Electronics = ? ?
Software = open arch? 10%
Payload = Some min? ?
Self Defense? = How defined?
Targeting = How defined?
Upgrade potential : Is this part of open arch?
Etc.

And if I increase payload, does that reduce the stealth score which decreases my survivability score?
And if I increase loiter time what happens to my stealth score?
And if I increase range what happens to my stealth score?
Can I mitigate my stealth score through electronic warfare capability?
Do I decrease strategic strike capability for self defense payload?
etc

[/QUOTE]

 

[jsport]

Lets not forget that weapons have gotten both smaller and more accurate/effective. A single B-2 has far less payload capability than a wing of B-52Ds, but it would be far more effective. The same way, the B-21 might carry less but if each bomb is more effective on its own, it does not need to carry as many to achieve the same effect.

...went through this argument already including slides describing new wpns ..Still need the payload volumn. Why must we go on this bomb size subject yet gain? Many of thes tgts are uite hardenerd and proliferating.. More folks who refuse to do their homework.

 

[jsport]

This whole thread is going a bit pear shaped.

Yep. I don't understand why it's so difficult for some people to admit that the B-21 will be less capable than the B-2. *shrugs*

Someone smarter than me should list all the areas of capability for a heavy bomber with a more capable/less capable checklist such as;

...
...

And how would you define each category and how would each be weighted?

Stealth = RCS? 25%?
Range = Min 5000nm? 25%?
Electronics = ? ?
Software = open arch? 10%
Payload = Some min? ?
Self Defense? = How defined?
Targeting = How defined?
Upgrade potential : Is this part of open arch?
Etc.

And if I increase payload, does that reduce the stealth score which decreases my survivability score?
And if I increase loiter time what happens to my stealth score?
And if I increase range what happens to my stealth score?
Can I mitigate my stealth score through electronic warfare capability?
Do I decrease strategic strike capability for self defense payload?
etc

[/QUOTE]
A deep magazine defense DEW alone likely requires a larger craft. DEW not stealth is the likely key to future survivability. Repeating.. DMS-M problems and associated counter-stealth will likely render stealth less and less a real factor. (maybe no factor in a few yrs), BWB still makes most sense so inherently some stealth... However, a smaller stealth target will not likely equate to survivablity very soon.

 

[bobbymike]

New USAF Materials Hint At High-Altitude Role For B-21 | Aviation Week Network

The design of the Northrop Grumman B-21’s trailing edge has led to speculation about a high-altitude role for the secretive stealth bomber, and new U.S. Air Force statements appear to confirm that analysis.

aviationweek.com

 

[sferrin]

New USAF Materials Hint At High-Altitude Role For B-21 | Aviation Week Network

The design of the Northrop Grumman B-21’s trailing edge has led to speculation about a high-altitude role for the secretive stealth bomber, and new U.S. Air Force statements appear to confirm that analysis.

aviationweek.com

ISTR that originally they wanted the B-2 to cruise at 80,000ft. Both it and the U-2 use the same engine. The -100 for the B-2 and the -101 for the U-2. Don't know the extent of the differences.

 

[rooster]

New USAF Materials Hint At High-Altitude Role For B-21 | Aviation Week Network

The design of the Northrop Grumman B-21’s trailing edge has led to speculation about a high-altitude role for the secretive stealth bomber, and new U.S. Air Force statements appear to confirm that analysis.

aviationweek.com

ISTR that originally they wanted the B-2 to cruise at 80,000ft. Both it and the U-2 use the same engine. The -100 for the B-2 and the -101 for the U-2. Don't know the extent of the differences.

Wonder if that would have been for more range or being further away from the ground transmitters.

 

[sferrin]

Maybe for increasing the distance the upper surface features are masked by the lower part of the aircraft? At that time the B-2 was more of a true flying wing, rather than having a protruding upper fuselage.

 

[Zoo Tycoon]

Interesting the diablo main landing gear. This means the max take off weight is limited to no more than 100Tons by runway strength and tyre technology. That’s quite a bit lower than B2 which has an MTOW of 170 Tons and B52 at 220Tons.

Using a simple prorata to the B2 that would put the payload at 12Tons for comparable range.

 

[TomcatViP]

The B21 is a CFRP airplane. You probably can time that by a factor of two. Add then the flying wing factor which raise lift available at landing.

 

[Zoo Tycoon]

The B2 is also CFRP. The basic LG configuration is sized by take off taxi conditions at speeds well below the wing is developing any lift so no extra factors.

 

[TomcatViP]

I don't dispute the Max T. O weight

My point was on the table conversion b/w max T. O weight and payload. Composite will alter favorably the empty weight fraction (well, at least with serious guys like they are at Northrop) , hence impact directly the Max payload. Also the lift available for T. O and landing will dictate what ratio of payload you can have.

But wouldn't it possible that we have here some new technologies in tyre design? Max admissible runway load is sized in function of generic tyre geometries. What would constitute a true limit is the strain that the concrete layers can sustain. With a tyre that flatten more for example, the load is evened on a larger surface, reducing the true stress. Hence a higher load on pavement.

Conjunctural of course...

 

[totoro]

The biggest reason why B-21 is somewhat smaller than other US bombers is going to be runway requirements. Mark my words. It'll probably end up requiring 20-30% shorter runways than either B2 or B1B. Coupled with the expected low maintenance stealth skins, USAF is likely desiring to base B-21s on a much, much bigger number of bases than possible with older bombers. Basically, it's going to be using it for tactical strikes, primarily. Hence the often cited desire to purchase many of them, possibly as many as 150.

 

[flateric]

good point

 

[Zoo Tycoon]

I don't dispute the Max T. O weight

My point was on the table conversion b/w max T. O weight and payload. Composite will alter favorably the empty weight fraction (well, at least with serious guys like they are at Northrop) , hence impact directly the Max payload. Also the lift available for T. O and landing will dictate what ratio of payload you can have.

But wouldn't it possible that we have here some new technologies in tyre design? Max admissible runway load is sized in function of generic tyre geometries. What would constitute a true limit is the strain that the concrete layers can sustain. With a tyre that flatten more for example, the load is evened on a larger surface, reducing the true stress. Hence a higher load on pavement.

Conjunctural of course...

Of course NG might have some secret stuff which could improve mass fraction, or tires or brakes but I have my doubts. Over the last decade or more there’s certainly not been any published significant improvements in carbon fibre modulus or tyre ply ratings or brake thermal capacity (Not for the want of RT expenditure either) and none of these are in NG sphere of expertise, I.e they don’t manufacture them. More likely they’ll be able cash a relatively small evolution in the structural optimisation from B2 experience which will take the payload from 12Tons to 12.5Tons.

Airport pavement loading standards for both military/civil are set by international agreements and conventions. I guess if they’re only ever going to operate from USAF owned runways they can do what they want, but it would be a big operational flexibility limitation that’s deeply built in.

In order to achieve a greater payload it makes much more sense to trade it against a lower range, especially with air2air refuelling.

 

[Josh_TN]

If nothing else, the ‘new’ design sheds weight by adopting the original diamond tail of the ATB instead of the low altitude saw tooth tail. That and I would imagine modern materials and design would shave some weigh compared to the B-2. We all agree it will lighter with less payload; we just seem to disagree on the importance. I agree with above post that B-21s will probably serve as almost more a fighter bomber role in a conflict when it is in service in numbers. I somewhat doubt it will be more forward based than current bombers, however.

 

[jsport]

If nothing else, the ‘new’ design sheds weight by adopting the original diamond tail of the ATB instead of the low altitude saw tooth tail. That and I would imagine modern materials and design would shave some weigh compared to the B-2. We all agree it will lighter with less payload; we just seem to disagree on the importance. I agree with above post that B-21s will probably serve as almost more a fighter bomber role in a conflict when it is in service in numbers. I somewhat doubt it will be more forward based than current bombers, however.

Any fighter bomber needs a low altitude option and high dynamic maneuver. NGs purposed 6th Gen fighter might fit that bill. NG 6th G is a BWB but should consider varible geometry of some type morphing or mechanical for low slow. F-22 can fly at 86mph but it cant at just above treetops. USAF has abandoned low altit infil at its own detriment.

 

[NeilChapman]

... I somewhat doubt it will be more forward based than current bombers, however.

Are any forward-based? The bombers are continually forward-deployed. I wouldn't be surprised to see more forward-deployments with additional upgrades to logistic support facilities maintained for US bombers.

The Marine's have proposed to reduce their air component. They'll be looking for the AF to be close.

 

[Josh_TN]

There’s generally a six plane detachment at Al Udied and another at Guam. Sometimes more are surged or sent to other locations such as Fairford or Diego. My point about forward basing was in regards to proximity to opponents. For instance, I can’t see B-21s being based at Kadena because that puts them in easy SRBM range. So while there may be more B-21s and they may take on missions more akin to strike/interdiction aircraft (F-15E), I don’t see them being based any closer than legacy heavy bombers.

 

[totoro]

There’s generally a six plane detachment at Al Udied and another at Guam. Sometimes more are surged or sent to other locations such as Fairford or Diego. My point about forward basing was in regards to proximity to opponents. For instance, I can’t see B-21s being based at Kadena because that puts them in easy SRBM range. So while there may be more B-21s and they may take on missions more akin to strike/interdiction aircraft (F-15E), I don’t see them being based any closer than legacy heavy bombers.

Since Kadena was mentioned, the unmentioned enemy in question in the post above is likely China. And if so, war against China would be a war where Japan would be made, one way or the other, to participate. So suddenly there's not just Kadena but dozens of other sites across Japan that might house B-21.

And if there's going to be war against China, many new airbases would be constructed. The Guam area alone has several islands with existing runways that could be expanded into airbases. And it's certainly easier and quicker to establish a base for tactical planes or even B-21 than for B-2 planes.

 

[Josh_TN]

I suspect any war between the US and China would be brief and largely a ‘come as you are’ affair. Both sides can bring a lot of PGMs to bear on each other, even assuming fighting remained conventional. I doubt there would be remotely even time to construct anything, though existing civilian airports could adopted relatively easily if they had sufficient facilities. But it would make more sense to keep extremely long ranged types farther afield and it seems likely B-21 will have range similar to B-2 given the more aerodynamic design and modern engines/materials.

 

[rooster]

If nothing else, the ‘new’ design sheds weight by adopting the original diamond tail of the ATB instead of the low altitude saw tooth tail. That and I would imagine modern materials and design would shave some weigh compared to the B-2. We all agree it will lighter with less payload; we just seem to disagree on the importance. I agree with above post that B-21s will probably serve as almost more a fighter bomber role in a conflict when it is in service in numbers. I somewhat doubt it will be more forward based than current bombers, however.

Fighter bomber? Never. If the usaf develops a very long ranged aam that can get targeting info from tbd satellites or f35s, then perhaps. But the usaf won't waste NBC hardened 100+ airframes on anti air. Maybe if they buy enough then it can take over for the mudhen in some scenarios.

 

[Josh_TN]

Poor choice of words on my part; by fighter bomber I meant the interdiction/strike role. F-111 or F15E. I agree it won’t be used for air to air, though it wouldn’t shock me if it had a couple bays for short range AAMs/ARMs for self defense.

 

[Foo Fighter]

Perhaps the problem is in the terms used for aircraft being rather old hat and dated. Strike aircraft would perhaps be a better term than the more common bomber descriptive.

 

[rooster]

It seems a little smallish for those extra bays holding anti missile missiles or amraams. Then again the avenger had 2 small missiles bays for harm... So maybe.

I think the problem with using the raider as a strike aircraft is that its the typical set of pearls too expensive to wear. We need a true long range dedicated strike aircraft.

 

[Sundog]

Re: Capability

The B-21 can hit targets the B-2 can't, because the B-2 would be at risk. It doesn't matter how much more you think a B-2 can carry or how much farther you think it can fly if it can't get to the target. Otherwise, if this is just about what we can carry and how far, we should just be buying more B-52s.

 

[TomcatViP]

Or some Roc ?

 

[shin_getter]

A deep magazine defense DEW alone likely requires a larger craft. DEW not stealth is the likely key to future survivability. Repeating.. DMS-M problems and associated counter-stealth will likely render stealth less and less a real factor.

It is obvious that the B-21 isn't designed for a heavy DEW paradigm and the concept is like likely premature for developing aircraft for near future service at this point. The key technologies is still evolving fast and the countermeasures (which will determine whether the system is general purpose or one time bump) not even started being developed.

DEW have relatively poor synergy with aircraft anyways. We'd be expecting pitches for invulnerable laser/microwave battleships before DEW dependent aircraft. Aircraft is about mobility and the ability to disengage. I'd expect to see DEW softkill as "enhanced jamming" far before hard kill, and such DEW platforms as separate from other aircraft as it is itself high emissions but can help in the survivability of other lower observability aircraft..

 

[rooster]

Was not Tacit Blue an experiment in some kind of early DEW tech (plus of course battlefield surveillance) ?

 

[bobbymike]

Air Force Increases Need for More LongRange Bombers

Air Force Increases Need for More LongRange Bombers

www.nationaldefensemagazine.org

 

[sferrin]

Re: Capability

The B-21 can hit targets the B-2 can't, because the B-2 would be at risk. It doesn't matter how much more you think a B-2 can carry or how much farther you think it can fly if it can't get to the target. Otherwise, if this is just about what we can carry and how far, we should just be buying more B-52s.

Nobody is debating that. What has been going on for pages and pages is that somebody claimed NO capability was lost between the B-2 and B-21. Payload IS a capability. So unless the B-21 has the payload of a B-2 then capability IS being lost.

 

[TomcatViP]

I think some of you are seeing a balanced equation when us see an Heaviside curve: before, there is nothing to score untill there is a threshold of capability.