Northrop Grumman B-21 Raider (LRS-B)

[NeilChapman]

Is it the Nuc/Bio protection, skin, size? What components are making this bomber cost ~$400M more than F35?

It's larger and has much more aggressive signature requirements.

Is there any available information about updates to RAM tech? Perhaps systems that allow more "hardy" surfaces that require less protection from the elements?

 

[NeilChapman]

With a subsonic speed you still fly hours and hours and hours to go on the theater and to destroy the mobile launcher it's not an advantage, the time you will be here it will be gone. And to escape a danger zone a dash speed is an assurance to survive the fighters.

Perhaps not hours and hours and hours if you can forward deploy. New START allows deployments, no? If the RAM is more hardy can they rotate B-21's in the Pacific through less traditional bases outside continental US and Guam?

 

[quellish]

I'm trying to isolate component costs to work through the $400M.

That will not work. A pound of a stealth aircraft will cost X times as much as a non stealth aircraft. The more aggressive the signature goal the greater the value of X.

This does not mean it uses more expensive RAM or raw materials. It means that every step of the process to manufacture the aircraft is more expensive. More testing is done, etc.

How has RAM as implemented on B-2 and later F22 changed in the last 20 years? Will this be as expensive as built on B-2?

RAM itself has not changed significantly in 20 years. How it is employed and how it is part of the aircraft design process has changed dramatically.

 

[Airplane]

With what you say about it it will become a big target for S-400, if it have just the stealth capacity for survive.

That doesn't make much sense, considering that the stealth features are the main features needed in avoiding and suppressing S-400 type systems.

Yeah, I think many Mach 3 aircraft look cool as well, but that doesn't make it the right platform for the mission. You'll find what many aviation fanboys don't understand is the mission defines the aircraft, not the other way around. I'm not knocking them for that, I was the same way until I became an Aero Engineer. It's obvious the NGB mission was based on a supersonic profile, but that also proved too costly, as noted by AeroFranz earlier. To reduce cost, they came up with a subsonic mission profile for the LRSB and found it met cost goals. The B-21 is the result of all of their (Both LM/Boeing and Northrop) design studies to best meet that mission profile.

This is factual. I'm also not convinced in that the bomber will be a subsonic wing at all w/o supersonic cruise/dash. It's the height of stupidity for the DoD to telegraph so extremely far by years in advance of what the new bomber's flight profile is going to be. The DoD is dumb, but *that* dumb, IDK.
30 years ago it may have been not possible to engineer a supersonic "B-2" class stealth airplane. But advances in stealth (not chemistry of coatings) and black box/skin technology have become possible to turn on and off stealth and be supersonically and maneuverably aerodynamic....

Likewise, for the B-21 to make use of hypersonic weapons against mobile targets, something else has to be flying out ahead of the -21 and locating. Supersonic cruise helps the bomber get to weapons release area sooner to react (not to evade Migs unless it is Mach 3+ which it aint!)..... not convinced the -21 is subsonic at all.

 

[AeroFranz]

"30 years ago it may have been not possible to engineer a supersonic "B-2" class stealth airplane. But advances in stealth (not chemistry of coatings) and black box/skin technology have become possible to turn on and off stealth and be supersonically and maneuverably aerodynamic...."

The (daunting) physics are pretty much the same. There have been no fundamental breakthroughs, just things getting incrementally better.
Not sure what you mean by "turn on and off stealth and be supersonically and maneuverably aerodynamic".

Questions of relevance of maneuverability influence on survivability for a stealth bomber aside, maneuver limits are set by what the airframe is stressed for. You can't have a lightweight airframe and pull, say, 6gs. You also need a healthy T/W. All these things have an effect on payload/range, which is the most important attribute in a bomber.

 

[Mr London 24/7]

...It's obvious the NGB mission was based on a supersonic profile...

...This is factual...

Nope.

Air Force Next-Generation Bomber: Background and Issues for Congress [2009] (https://www.fas.org/sgp/crs/weapons/RL34406.pdf)

General Characteristics of Envisioned Aircraft:

Testimony and press reports suggest that Air Force officials prior to the FY2010 budget
submission envisaged the next-generation bomber as a new-design aircraft that uses existing
aircraft technologies, because the 2018 target in-service date would not allow enough time to
develop new technologies.

The aircraft would likely be subsonic and stealthy;

it might have an unrefueled range of 2,000 to 3,000 miles;

and it might carry 28,000 to 40,000 pounds of
armaments.

Whether the aircraft would be manned or unmanned was not determined, but Air Force officials suggested that, in light of the 2018 target in-service date, the initial version of the aircraft, at least, would likely need to be manned.

It was also stated that the aircraft’s basic design might also serve as the basis of the design for a new Air Force long-range reconnaissance aircraft

The 2018 Bomber [NGB]: THE CASE FOR ACCELERATING THE NEXT GENERATION LONG-RANGE STRIKE SYSTEM [2008] (http://www.northropgrumman.com/Abou...ments/pdfs/The_2018_Bomber_the_case_for_a.pdf)

The 2037 bomber sought by the Air Force was to
provide long-range, supersonic cruise, a large pay-
load and very low observability to survive in all
environments—day and night. An examination of
the “art of the possible” applied to an aircraft
fielded twenty years sooner led to a shift in these
requirements. The Air Force conducted an
NGLRS Analysis of Alternatives (AoA) following
the 2006 QDR directive, and in May 2007
declared the following properties for the 2018 [NGB]
bomber:
• Be a manned aircraft
• Carry 14,000 to 28,000 pounds of weapons
• Be subsonic
• Have a combat radius of 2,000 miles or greater
• Be highly survivable

 

[Sundog]

So it was the bomber before the NGB that was supersonic (I knew one of the previous design studies was...). So given that, what made the NGB so damned expensive that they had to go to the LRSB?

 

[flateric]

So it was the bomber before the NGB that was supersonic (I knew one of the previous design studies was...). So given that, what made the NGB so damned expensive that they had to go to the LRSB?

Because it has started to become "everything for everyone" (citation)

“We put only mature capabilities on LRS-B as opposed to every good idea technology,” Walden promised the House committee, referring to the Long Range Strike-Bomber. “In short, it does not have to be everything for everyone.”

This is the team guiding the U.S. Air Force’s next stealth bomber

When the Air Force needed a new long range bomber, it turned to its secretive product development team.

fortune.com

Guys, you really need to read one of those NGB/LRS-B CRS papers before entering discussion then (no offense here). Even Wiki articles on NGB + LRS-B would be good starting point.

 

[quellish]

So given that, what made the NGB so damned expensive that they had to go to the LRSB?

Mission and feature creep. Ambitious goals that required solutions that were not yet mature.

LRS-B reduced risk and cost vs. previous efforts by setting realistic goals and using solutions that were more technically mature. Some of these things were already very mature. Some of them (very few) were rapidly brought to a higher TRL.

 

[GeorgeA]

P&W statement on the B-21 program:

http://www.pw.utc.com/News/Story/20160314-1800

Pratt & Whitney is proud to have been selected as the propulsion provider by Northrop Grumman for the U.S. Air Force B-21 Bomber Program. The company has made significant investment in research and development to mature critical technologies applicable to the B-21 platform. Combining this investment with our fielded fifth generation experience with F119 and F135 engines, Pratt & Whitney is technology-ready for the B-21 development program. We are prepared to work with Northrop Grumman to develop and field a B-21 weapon system that fulfills Air Force mission requirements.

 

[Airplane]

So given that, what made the NGB so damned expensive that they had to go to the LRSB?

Mission and feature creep. Ambitious goals that required solutions that were not yet mature.

LRS-B reduced risk and cost vs. previous efforts by setting realistic goals and using solutions that were more technically mature. Some of these things were already very mature. Some of them (very few) were rapidly brought to a higher TRL.

I don't believe there are no classified supersonic stealth vehicles flying with which to use as technically mature technology.

 

[NeilChapman]

P&W statement on the B-21 program:

http://www.pw.utc.com/News/Story/20160314-1800

Pratt & Whitney is proud to have been selected as the propulsion provider by Northrop Grumman for the U.S. Air Force B-21 Bomber Program. The company has made significant investment in research and development to mature critical technologies applicable to the B-21 platform. Combining this investment with our fielded fifth generation experience with F119 and F135 engines, Pratt & Whitney is technology-ready for the B-21 development program. We are prepared to work with Northrop Grumman to develop and field a B-21 weapon system that fulfills Air Force mission requirements.

I posted some ideas about engines a few pages back. Does this sound like Option #2?

1. Straight up F135 - probably with latest improvements.
Low Risk, already certified engine.

2. F135-style low spool w/GTF (PW1000G) core - Certifications on commercial P1000G starting this year. PW working on these (self-funded while GE & RR working ADVENT) since before 2010 so probably ready to certify? Different 1000G cores will be certified over next couple of years beginning in spring of 2016. No 3rd air stream.
Higher Risk - 1000G Not yet certified. PW built 10k lb thrust demonstrator engine (PW9000) six years ago in 2010. Hinted at NGB engine (25k lb thrust was mentioned) in 2011. Could be ready to go?

3. AETP Program - Build full-up engine based on AETD program - Starts in 2016. PW was not involved in ADAPTIVE program. That was GE and RR. GE & PW will work with Boeing, NG and LM on studies for fit and integration into new aircraft designs.
Highest Risk - Engines not built.

 

[TomS]

I'd be surprised if it isn't a PW9000 (F135 low-pressure spool plus PW1000G high-pressure spool). It clearly has F135 components, hence to price reduction on the F135. PW9000 seems to be very scaleable (they've talked about engines between 10k and 25k using the same absic architecture), so they could probably design it at whatever power point they need (within reason). Two 25k engines would definitely imply a smaller aircraft, though.

 

[quellish]

https://www.flightglobal.com/news/articles/f-35-chief-expects-pws-bomber-work-to-reduce-f135-423013/

So adding 100 aircraft (200 engines + spares, etc) to the existing buy of 3100 (3100 + spares, etc.) is going to impact the unit cost of the engine in some significant way? A 6% increase in production volume? That seems incredibly optimistic.

Perhaps Bogdan knows something we do not, like the B-21 uses 8 engines.

 

[_Del_]

So adding 100 aircraft (200 engines + spares, etc) to the existing buy of 3100 (3100 + spares, etc.) is going to impact the unit cost of the engine in some significant way? A 6% increase in production volume? That seems incredibly optimistic.

Perhaps Bogdan knows something we do not, like the B-21 uses 8 engines.

Well, it might reduce/simplify parts of the supply train. I don't know that it will drive down the price of a F135, but it seems likely a derived engine is going to be cheaper than a brand new engine development process.

 

[quellish]

Well, it might reduce/simplify parts of the supply train. I don't know that it will drive down the price of a F135, but it seems likely a derived engine is going to be cheaper than a brand new engine development process.

Cheaper for the LRS-B program? Definitely.
Cheaper for the F-35 program? Uhhh...

Wether there are 8 F135s or 2 on the B-21 it would still require modification for the mission - non after burning, higher altitude, etc. I would expect the B-21 engine to be similar to the F135 like the F118 is similar to the F110.

 

[_Del_]

I agree. I was just pointing out that there ARE advantages in using an existing engine or derivative. Even the modest 5% might add up over the two programs lifetimes. I don't think you're going to see F-35 prices plummet because of this sort of commonality, if that's what is being proposed.

 

[NeilChapman]

I'd be surprised if it isn't a PW9000 (F135 low-pressure spool plus PW1000G high-pressure spool). It clearly has F135 components, hence to price reduction on the F135. PW9000 seems to be very scaleable (they've talked about engines between 10k and 25k using the same absic architecture), so they could probably design it at whatever power point they need (within reason). Two 25k engines would definitely imply a smaller aircraft, though.

Perhaps that depends on the efficiencies of the design? Wasn't there an objective for LRS-B for persistence or loiter time to respond to TSTs? NG has been known in the past to nail their design criteria (YF-23).

Bill Sweetman wrote "some early-2000s Northrop Grumman designs were described by one engineer as having “sailplane-like” efficiency. While the RQ-180 will almost certainly be shown to be a much lighter aircraft than the LRS-B, its wingspan is likely quite close to that of the bomber, and its development will have validated the CFD and CEM codes used in the design, along with radar-absorbent materials and coatings. The UAV will also be providing operational experience with new stealth technologies, underpinning Northrop Grumman estimates of the LRS-B’s operating cost."

Maybe the lessons learned will provide efficiencies that we have not seen in the past.

 

[DrRansom]

So adding 100 aircraft (200 engines + spares, etc) to the existing buy of 3100 (3100 + spares, etc.) is going to impact the unit cost of the engine in some significant way? A 6% increase in production volume? That seems incredibly optimistic.

Perhaps Bogdan knows something we do not, like the B-21 uses 8 engines.

I viewed this more as wishful thinking, the price of the F-135 has been a point of contention for the F-35 program for some time.

 

[NeilChapman]

https://www.flightglobal.com/news/articles/f-35-chief-expects-pws-bomber-work-to-reduce-f135-423013/

So adding 100 aircraft (200 engines + spares, etc) to the existing buy of 3100 (3100 + spares, etc.) is going to impact the unit cost of the engine in some significant way? A 6% increase in production volume? That seems incredibly optimistic.

Perhaps Bogdan knows something we do not, like the B-21 uses 8 engines.

Sounded like politics to me. Pressure on P&W as they're negotiating the next "lot" of F-35's - LRIP 9, 55 planes - big bucks. According to LM as reported by Bill Carey in AINOnline "LRIP 8 cost of an F-35A for the U.S. Air Force without its F135-PW-100 engine was $94.7 million. The price of an F-35A with its engine was $108 million, which was $4 million lower than Lot 7 prices, according to the Pentagon’s F-35 Joint Program Office (JPO)."

That's just over 13M per engine for A's. If they could drop that to 10M it's an extra $165M bucks saved. That's good "walking around" money.

 

[overscan (PaulMM)]

in 2010

Last February, company officials first disclosed the PW9000 as a "limited development activity" to adapt the core of the PW1000G geared turbofan for the military aircraft market.

P&W now reveals the GTF core - or high-pressure spool - is combined with the low-pressure spool of the F135 fighter engine for the PW9000, and that a finished product could be closer to reality than previously indicated.

"The PW9000 is very real," P&W Military Engines president William Boley told reporters during a media roundtable at the Air Force Association convention on 15 September.

Asked to clarify if he means a PW9000 design concept or a functioning engine is real, Boley started to answer, but stopped himself.

P&W vice president of business development and aftermarket services William Begert noted that the company has both open and closed discussions about the PW9000, and it is sometimes "awkward" to explain details in an open forum.

Whenever the engine is available, P&W plans to offer the engine for a wide range of potential applications. A 25,000lb-thrust (110kN) version of the engine could power the US Air Force's revived penetrating bomber programme, Boley says.

P&W hints at availability of all-new engine for military aircraft

Pratt & Whitney has confirmed the existence of an advanced new engine tailored for the next-generation of military aircraft.

www.flightglobal.com

 

[overscan (PaulMM)]

Posted earlier before in NGB topic by Bobbymike:

P&W Pitches Engine For Long-Range Strike
By JOHN REED (DefenseNews.com)
Published: 15 Sep 2010 17:50

Pratt & Whitney officials today said the company may offer its PW9000 engine for whatever aircraft emerges from the Air Force's talks with the Pentagon over the future of long-range strike.

The engine features the stealth technology of Pratt's F135 engine, built for the F-35 Lightning II Joint Strike Fighter, wrapped around the core of the company's super fuel-efficient geared turbofan engine, which was designed for commercial jets, said Warren Boley chief of Pratt's military aircraft engines division on Sept. 15 during an Air Force Association-sponsored conference in Maryland.

Boley also said that work on the PW9000 is partly funded by a portion of the $1.7 billion set aside by the Pentagon to keep development work humming on technologies such as engines, radars and datalinks that will be key to any future long-range strike weapons. This hybrid engine technology can deliver between 10,000 and 30,000 pounds of thrust, meaning that it could also be used for a variety of other new aircraft, according to Boley. "In a future of small quantity [aircraft buys] and tight budgets" a scalable engine like the PW9000 "provides a tremendous opportunity for customers as well as Pratt," said Boley.

 

[overscan (PaulMM)]

Rereading the articles from 2010, the PW9000 using the fan from the F135 can produce thrusts from 15,000 to 30,000lbs, and the bomber engine was 25,000lb. Given the fan size is fixed, the thrust variation is only achieved by scaling the core up and down, the bigger thrusts meaning lower bypass ratio.

Assuming 30,000lbs is achieved with a low bypass ratio (e.g 0.5) we could presumably guestimate the bypass ratio which would produce 25,000lb using an engine simulator...

 

[overscan (PaulMM)]

US7448578B2 - Aircraft with forward opening inlay spoilers for yaw control - Google Patents

An aircraft comprises first and second wings positioned on opposite sides of a longitudinal axis with each of the first and second wings including an upper surface and a lower surface, wherein no control surfaces are attached to the lower surface of the wings. A first forward opening control...

www.google.com

This Northrop patent seems interesting - it describes a method of using control surfaces only on the top side of an aircraft, and inboard, not at the edges - this would be interesting for extreme stealth (providing you are above your adversary).

 

[sferrin]

The engine features the stealth technology of Pratt's F135 engine, built for the F-35 Lightning II Joint Strike Fighter,

Now that's interesting. AFAIK the only engine-specific "stealth technology" on the F-35 is the radar blocker / afterburner spray bars aft of the turbine section. ???

 

[Mr London 24/7]

US7448578B2 - Aircraft with forward opening inlay spoilers for yaw control - Google Patents

An aircraft comprises first and second wings positioned on opposite sides of a longitudinal axis with each of the first and second wings including an upper surface and a lower surface, wherein no control surfaces are attached to the lower surface of the wings. A first forward opening control...

www.google.com

This Northrop patent seems interesting - it describes a method of using control surfaces only on the top side of an aircraft, and inboard, not at the edges - this would be interesting for extreme stealth (providing you are above your adversary).

Indeed, this relates to ICE/FATE work: http://www.secretprojects.co.uk/forum/index.php/topic,3547.msg60775.html#msg60775

 

[Sundog]

The engine features the stealth technology of Pratt's F135 engine, built for the F-35 Lightning II Joint Strike Fighter,

Now that's interesting. AFAIK the only engine-specific "stealth technology" on the F-35 is the radar blocker / afterburner spray bars aft of the turbine section. ???

Which would be a relatively inexpensive way to keep the engines stealthy, without serpentine ducts, and keep the costs down as a result? Especially since we know the inlets and nozzles are on the upper surface, so the wing shields them from below rather well. It almost makes me wonder of the exhaust/nozzles will be axisymmetric like they were on the FB-23 for lower costs?

 

[overscan (PaulMM)]

I would doubt a straight port from F -35 as I am sure rear aspect RCS target for B-21 is much tougher.

 

[Sundog]

I would doubt a straight port from F -35 as I am sure rear aspect RCS target for B-21 is much tougher.

Yeah, true. But I was thinking, sort of how you could kind of see the YF-23's engine face from certain forward aspects, maybe this is the same way, to the serpentine inlets and exhaust aren't as curved as super stealthy designs? Maybe from a slightly high forward or rearward angle you would be able to see the engine faces, so the blockers will help in that regard, simplifying the propulsion system. Just an idea.

 

[Ian33]

Anyone here remember the Patent that appeared for a stealthy inlet design that twisted as and when a radar threat appeared, but relaxed and let air straight in when it wasn't viewed by a radar?

Was designed for a bomber application IIRC.

 

[Sundog]

Anyone here remember the Patent that appeared for a stealthy inlet design that twisted as and when a radar threat appeared, but relaxed and let air straight in when it wasn't viewed by a radar?

Was designed for a bomber application IIRC.

Yeah, it was similar to the variable vanes in a powerplant. I think Boeing was planning on using one in the X-32.

 

[flateric]

Business as Usual Building a New Bomber

An Air Force official used contradictory statements to justify the risky contract to build the B-21, while others revealed that some of the same old tricks are being used to ensure the program’s political support.

www.pogo.org

 

[sferrin]

You mean they build stuff we're the companies are? I. Am. Shocked. Obviously they should be building this in Alaska, where nobody has a production facility, to avoid these horrific injustices. :

 

[marauder2048]

There are 45 total senators on the SASC and Defense Appropriations Subcommittee (it's mostly fixed size for the Senate) so even if you just randomly threw darts on a map of the US
to pick industry partners you would end up with a large number of elected officials from partner home states on defense related committees.

 

[sferrin]

There are 45 total senators on the SASC and Defense Appropriations Subcommittee (it's mostly fixed size for the Senate) so even if you just randomly threw darts on a map of the US
to pick industry partners you would end up with a large number of elected officials from partner home states on defense related committees.

I think it would be amusing for POGO to come up with a plan for how the thing could be built without any of the work being done in states with members on the SASC or DAS. Sadly, their target audience would never dare question their motives.

 

[NeilChapman]

There are 45 total senators on the SASC and Defense Appropriations Subcommittee (it's mostly fixed size for the Senate) so even if you just randomly threw darts on a map of the US
to pick industry partners you would end up with a large number of elected officials from partner home states on defense related committees.

I think it would be amusing for POGO to come up with a plan for how the thing could be built without any of the work being done in states with members on the SASC or DAS. Sadly, their target audience would never dare question their motives.

Compared to the 9 countries, 45 states and 3 final assembly and check out facilities for F-35, B-21 is being built in a one-stall garage.

 

[NeilChapman]

Maybe we could start by using the proper terminology. There are significant barriers to making a flying wing supersonic (actually it's pretty much impossible for stability and control purposes primarily, and other reasons after that). I can only guess some posts were actually referring to supersonic tailless deltas. Very different thing. Otherwise, no, a flying wing doesn't have the surfaces in the right places to cope with the aerodynamic shift.

But is B-21 a flying wing? The NG commercial doesn't look much like the "rendering" the AF provided. As the AF stated that the drawing is based of a design concept from the beginning of the process and there may have been some changes. Granted, I'm only an interested 3rd party and don't have the expertise that you and many others here possess.

Can anyone point me to some reading material to understand the differences between a cranked-kite and a delta cranked-arrow? Or perhaps you or one of the other AE's can explain in brief?

 

[AeroFranz]

Hmmm...i think that there may be differing opinions, but i'll try to give mine and others can chime in.
I think it's mostly a matter of sweep and aspect ratio.
Examples of delta cranked arrow include the F-16XL and some SST designs. It's got high sweep (the inboard being 50-60 degrees) and low AR, and is a supersonic planform. The short span keeps the wingtips within the nose shock wave at the design Mach number.

The only examples i know of cranked-kite originated with Northrop (are there others?), and in particular the X-47B. As a concession to subsonic efficiency, they have longer, unswept outer panels. They are strictly subsonic.

 

[LowObservable]

Cranked-arrow is a wing shape that's associated with supersonic aero rather than stealth. The idea is to have a blunt-edge inner wing inside the shock cone and a thin, sharp-edged outer wing that intersects the shock. Basically a Draken with a trapezoidal outer panel instead of a delta.

Cranked-kite is really a variation on the early-B-2 "manta", that allows the configurator to adjust the center section chord, volume and depth (to accommodate propulsion and weapons) independent of span. It's mostly an NG thing but note that the recent Anglo-French shapes use it.

 

[overscan (PaulMM)]

There's no chance B-21 is a cranked-delta or supersonic, you are clutching at straws here.

If you want to imagine a supersonic 'flying wing' bomber, aerodynamics makes it hard to do much different to Sukhoi's 1969 T-4MS design:

https://www.secretprojects.co.uk/threads/1665

Northrop's STAV project, 40 years later:

https://www.secretprojects.co.uk/threads/2681