Northrop Grumman B-21 Raider Production And Delivery Thread

keesje · Wed Nov 29, 2017 4:34 pm

This could become a lenghty thread :veryhappy:

http://uk.businessinsider.com/area-51-b-21-stealth-bomber-tested-2017-11?international=true&r=UK&IR=T

Who will have the first photo?

JetBuddy · Wed Nov 29, 2017 6:09 pm

I think it will be a while before we see the first one roll out.

Tugger · Wed Nov 29, 2017 6:38 pm

keesje wrote:
Who will have the first photo?

Probably Google (Maps) but they also probably have a requirement to remove any "secret" items from such images prior to posting online in their Earth Maps.

Tugg

PaddyOMaddy · Thu Nov 30, 2017 8:38 am

This may be a stupid question, but why is it not called the B-3?

Ozair · Thu Nov 30, 2017 10:35 am

PaddyOMaddy wrote:
This may be a stupid question, but why is it not called the B-3?

Just guessing but perhaps because the B-2 was an NG aircraft and the B-21 is also an NG aircraft. Also everything we know to date appears to suggest the B-21 will essentially be a new B-2, given it is subsonic, likely two bomb bays, likely four engines, reasonably similar flying wing profile.

I've also seen some comments suggesting the "21" stands for 21st century so perhaps the USAF PR folks had a hand in it.

TWA772LR · Thu Nov 30, 2017 5:47 pm

I remember when Northrup Grumman had the floor open to the public for name suggestions. One of the top results was Nukey McMeltface.

Ozair wrote:

I've also seen some comments suggesting the "21" stands for 21st century so perhaps the USAF PR folks had a hand in it.

*puts on tinfoil hat* Similar to the Irkut MS-21... :scratchchin:

QuarkFly · Thu Nov 30, 2017 6:50 pm

Ozair wrote:
...Also everything we know to date appears to suggest the B-21 will essentially be a new B-2, given it is subsonic, likely two bomb bays, likely four engines, reasonably similar flying wing profile...

I believe that although the B21 looks like the B2...it is smaller, so could be a single bomb-bay? And I thought it was already indicated that the B21 would be a twin engine aircraft. Pratt won the B21 engine contract and will likely use a version of the F135 from the F35 -- a 30-klb thrust engine -- four of them would be way too much power and weight for a subsonic aircraft smaller than the B2.

Ozair · Thu Nov 30, 2017 8:54 pm

QuarkFly wrote:
I believe that although the B21 looks like the B2...it is smaller, so could be a single bomb-bay?

Not sure about one larger bomb bay against two smaller but is certainly possible. To me there is some redundancy in two smaller bays equipped with rotary launchers and we have seen even with smaller cranked kite aircraft such as the X-47B there are two smaller bays.

I indicated in the previous thread that I expect the B-21 to have some form of self defensive A2A missile so perhaps one large bomb bay and two smaller A2A bays that may also handle small A2G ordnance?

QuarkFly wrote:
And I thought it was already indicated that the B21 would be a twin engine aircraft. Pratt won the B21 engine contract and will likely use a version of the F135 from the F35 -- a 30-klb thrust engine -- four of them would be way too much power and weight for a subsonic aircraft smaller than the B2.

You’re right, found this reference indicating as such,

James said the twin-engine B-21 will allow the Air Force to operate in a "high-end threat environment" and give the Air Force the flexibility to launch airstrikes from the continental United States, attacking anywhere in the world.

http://www.courant.com/hc-pratt-b-21-en ... story.html
Agree on using the F135 or a minimal modified derivative of. There is great growth potential in the engine and, in that size range, the AETP being funding by the US requires compatibility with the F-35 so an enduring support chain and upgrade program will be available. The GE AETP is looking to provide the following,

GE's adaptive cycle, three-stream engine extends aircraft operating range by more than 30%, improves fuel consumption by 25% and increases thrust by more than 10%. With the AETP and follow-on development programs, GE's engine could be ready to power the US military's most advanced combat jets.

https://www.geaviation.com/press-releas ... ontract-us

I do expect them to maximise the electrical generation potential as I see the B-21 with a directed energy weapon from IOC with the capacity for further upgrade so additional excess thrust is highly probable.
Whatever eventuates though, I'm expecting to have a lot of interesting conversations over the next 7-10 years as more details are released.

Mods, not sure if it is possible with the current software but would be a great feature of the forum to have a couple of posts fixed at the top of the thread with all the facts and their references on configuration, capability and intent. Would probably stop a lot of unnecessary back and forth we have seen in some of the other enduring threads.

SCAT15F · Thu Nov 30, 2017 11:20 pm

Given that the F135 has 28,000 lbs dry and will certainly get a larger fan for a better subsonic efficiency, I can see the derivative for the B-21 having 36-40,000 lbs thrust.

Ozair · Fri Dec 01, 2017 12:08 am

SCAT15F wrote:
Given that the F135 has 28,000 lbs dry and will certainly get a larger fan for a better subsonic efficiency, I can see the derivative for the B-21 having 36-40,000 lbs thrust.

Indeed, PW is already promising an initial improvement.

Pratt & Whitney can now offer a Growth Option 1.0 upgrade configuration for the F135 engine, which powers the fifth generation F-35 Lightning II fighter aircraft. The engine testing, conducted at Pratt & Whitney's West Palm Beach, FL, facility, verified this upgrade can provide a 5 to 6 percent fuel burn improvement and a 6 to10 percent thrust increase across the F-35 flight envelope.

https://www.prnewswire.com/news-release ... 66212.html

iamlucky13 · Fri Dec 01, 2017 10:28 pm

Ozair wrote:
PaddyOMaddy wrote:
This may be a stupid question, but why is it not called the B-3?

Just guessing but perhaps because the B-2 was an NG aircraft and the B-21 is also an NG aircraft. Also everything we know to date appears to suggest the B-21 will essentially be a new B-2, given it is subsonic, likely two bomb bays, likely four engines, reasonably similar flying wing profile.

I've also seen some comments suggesting the "21" stands for 21st century so perhaps the USAF PR folks had a hand in it.

That is correct. Here's the USAF press release on the designation:
http://www.af.mil/News/Article-Display/ ... ke-bomber/

I'd have preferred they stick with some sort of semi-coherent numbering scheme, but I don't suppose a 21 will show up on radar any more easily than a 3.

Ozair · Thu Apr 19, 2018 10:51 pm

First significant news for the program.

B-21 bomber finishes preliminary design review, and Air Force official is 'comfortable' with progress

A U.S. Air Force official told a Senate subcommittee Wednesday that the new B-21 bomber has completed its preliminary design review and that he was "comfortable" with the progress made by builder Northrop Grumman Corp. The bomber is now on its way to critical design review, said Lt. Gen. Arnold Bunch Jr., the military deputy of the office of the assistant secretary of the Air Force for acquisition. Citing the "nature of the work," Bunch declined to go into further detail about how the Air Force planned to spend the $2.3 billion it requested for the bomber program for fiscal year 2019 when asked by Sen. Ted Cruz (R-Texas). However, he said the program was "continuing engineering manufacturing development" and "some of those risk reduction areas."

The first set of software for the platform has been delivered, and the program is getting "set up" for the next set of software to come in, Bunch told the Senate Armed Forces Subcommittee on Airland during a hearing about Air Force modernization efforts.

"We're making everything ready to begin our test program in the future," he said. "We're making good progress. I'm comfortable today with where we're at, and the progress that Northrop Grumman is making on the program."

Northrop Grumman, which won the bomber contract in 2015, is building the aircraft at its plant in Palmdale. The plant also churns out the Global Hawk high-altitude surveillance drone for the Air Force, the closely related Triton drone for the Navy and the center fuselage for the F-35 Joint Strike Fighter.

http://www.latimes.com/business/la-fi-b ... story.html

The article states US$2.3 billion for the program in 2019 which is a decent slice of funding. I also wonder when we will see the first prototype given there is no indication as yet to a delay to IOC which was supposed to be ten years after contract sign.

mmo · Fri Apr 20, 2018 5:39 am

Just a bit more on the B-21.

Looks as if the USAF will try to purchase more than the 100 talked about. Currently there are 9 Bomb Squadrons and the 100 had been planned to cover replacements for the B-1 and B-2 with the balance used for training. The USAF would like to increase the numbers in each squadron and then increase the number of squadrons from 9 to 14-16.

https://www.flightglobal.com/news/artic ... -d-447860/

Chaostheory · Fri Apr 20, 2018 12:15 pm

mmo wrote:
Just a bit more on the B-21.

Looks as if the USAF will try to purchase more than the 100 talked about. Currently there are 9 Bomb Squadrons and the 100 had been planned to cover replacements for the B-1 and B-2 with the balance used for training. The USAF would like to increase the numbers in each squadron and then increase the number of squadrons from 9 to 14-16.

https://www.flightglobal.com/news/artic ... -d-447860/

The USAF already has a huge issue with pilot shortages. How do they plan on pumping out even more crews? Are we going to see attrition in the transport or fighter squadrons?

ZaphodHarkonnen · Fri Apr 20, 2018 12:47 pm

Chaostheory wrote:
mmo wrote:
Just a bit more on the B-21.

Looks as if the USAF will try to purchase more than the 100 talked about. Currently there are 9 Bomb Squadrons and the 100 had been planned to cover replacements for the B-1 and B-2 with the balance used for training. The USAF would like to increase the numbers in each squadron and then increase the number of squadrons from 9 to 14-16.

https://www.flightglobal.com/news/artic ... -d-447860/

The USAF already has a huge issue with pilot shortages. How do they plan on pumping out even more crews? Are we going to see attrition in the transport or fighter squadrons?

Well if the crew is going from 4+ down to 2 maybe they're thinking of retraining other bomber crew members into pilots?

Slug71 · Fri Apr 20, 2018 2:29 pm

mmo wrote:
Just a bit more on the B-21.

Looks as if the USAF will try to purchase more than the 100 talked about. Currently there are 9 Bomb Squadrons and the 100 had been planned to cover replacements for the B-1 and B-2 with the balance used for training. The USAF would like to increase the numbers in each squadron and then increase the number of squadrons from 9 to 14-16.

https://www.flightglobal.com/news/artic ... -d-447860/

Interesting. With the advancements in ICBMs and cruise missiles, I'd have thought the future is moving in that direction and therefore less demand of bombers.

ZaphodHarkonnen · Fri Apr 20, 2018 2:56 pm

Slug71 wrote:
mmo wrote:
Just a bit more on the B-21.

Looks as if the USAF will try to purchase more than the 100 talked about. Currently there are 9 Bomb Squadrons and the 100 had been planned to cover replacements for the B-1 and B-2 with the balance used for training. The USAF would like to increase the numbers in each squadron and then increase the number of squadrons from 9 to 14-16.

https://www.flightglobal.com/news/artic ... -d-447860/

Interesting. With the advancements in ICBMs and cruise missiles, I'd have thought the future is moving in that direction and therefore less demand of bombers.

Remember that the B21 is going to be quite a bit smaller in raw payload compared to the B-1 and B-52. And with the increase of precision weapons and the loitering of CAS missions the bombers are doing they may end up being used more compared to the BUFF and Bone.

Tugger · Fri Apr 20, 2018 3:29 pm

Chaostheory wrote:
mmo wrote:
Just a bit more on the B-21.

Looks as if the USAF will try to purchase more than the 100 talked about. Currently there are 9 Bomb Squadrons and the 100 had been planned to cover replacements for the B-1 and B-2 with the balance used for training. The USAF would like to increase the numbers in each squadron and then increase the number of squadrons from 9 to 14-16.

https://www.flightglobal.com/news/artic ... -d-447860/

The USAF already has a huge issue with pilot shortages. How do they plan on pumping out even more crews? Are we going to see attrition in the transport or fighter squadrons?

Well my thoughts on it are: I would bet money that the B-21, while intended to be crewed, will be designed to integrate pilotless features or full systems. While I don't think it means full autonomous capability, I would not be surprised if slaved flight was not possible (two or three on a run with one lead bomber in control etc.). This will increase capability while decreasing crew needed.

Tugg

mmo · Fri Apr 20, 2018 5:47 pm

ZaphodHarkonnen wrote:
Slug71 wrote:
mmo wrote:
Just a bit more on the B-21.

Looks as if the USAF will try to purchase more than the 100 talked about. Currently there are 9 Bomb Squadrons and the 100 had been planned to cover replacements for the B-1 and B-2 with the balance used for training. The USAF would like to increase the numbers in each squadron and then increase the number of squadrons from 9 to 14-16.

https://www.flightglobal.com/news/artic ... -d-447860/

Interesting. With the advancements in ICBMs and cruise missiles, I'd have thought the future is moving in that direction and therefore less demand of bombers.

Remember that the B21 is going to be quite a bit smaller in raw payload compared to the B-1 and B-52. And with the increase of precision weapons and the loitering of CAS missions the bombers are doing they may end up being used more compared to the BUFF and Bone.

Of course, you do realize the BUFF is planned on flying until sometime into the 2050s. So, new engine and upper wing reskin will need to be accomplished.

45272455674 · Mon Apr 23, 2018 8:04 am

keesje wrote:
This could become a lenghty thread

Who will have the first photo?

Won't be too far away:

http://uk.businessinsider.com/b-21-raid ... ?r=AU&IR=T

I think there was a sighting of a test aircraft last year but it wasn't photographed. Either it was a test aircraft or something fairly similar.

FrmrKSEngr · Thu Apr 26, 2018 12:32 am

Slug71 wrote:
mmo wrote:
Just a bit more on the B-21.

Looks as if the USAF will try to purchase more than the 100 talked about. Currently there are 9 Bomb Squadrons and the 100 had been planned to cover replacements for the B-1 and B-2 with the balance used for training. The USAF would like to increase the numbers in each squadron and then increase the number of squadrons from 9 to 14-16.

https://www.flightglobal.com/news/artic ... -d-447860/

Interesting. With the advancements in ICBMs and cruise missiles, I'd have thought the future is moving in that direction and therefore less demand of bombers.

Wow, where have I heard that before. Care to comment Mr McNamara?

FrmrKSEngr · Thu Apr 26, 2018 12:46 am

cpd wrote:
keesje wrote:
This could become a lenghty thread

Who will have the first photo?

Won't be too far away:

http://uk.businessinsider.com/b-21-raid ... ?r=AU&IR=T

I think there was a sighting of a test aircraft last year but it wasn't photographed. Either it was a test aircraft or something fairly similar.

Given that PDR occurred about 6 months ago, I would expect CDR to be at least 1 year from PDR. CDR is usually at least 80% drawing release. I don't see a prototype before that point. Maybe another year after CDR, but even that would be sporty.

What may be undergoing testing or soon to be tested are proof of concept vehicles for systems and other particular aspects of the aircraft. Things like the F-22 757 avionics test bed, or the Stealth range models for the F-117 program. Possibly a sub-scale flying demonstrator.

Of course, it is possible the USAF is blowing smoke about PDR and is actually further along than stated. We will see when they release pictures.

Ozair · Thu Apr 26, 2018 12:53 am

FrmrKSEngr wrote:
Of course, it is possible the USAF is blowing smoke about PDR and is actually further along than stated. We will see when they release pictures.

I think they’re a little further along than they are indicating, especially as there has been no indication of a slip of IOC past 2025. To meet that IOC date you would expect they have a full scale prototype flying today and are looking for low rate initial production to begin very soon. Factor in a 5-7 year test and evaluation phase and enough aircraft to meet an IOC target (likely 8-10 aircraft in a squadron with the required aircrew and ground personnel trained to proficiency) and they have to have been moving along already.

Alternatively, that IOC date could slide two plus years…

45272455674 · Thu Apr 26, 2018 1:00 am

Ozair wrote:
FrmrKSEngr wrote:
Of course, it is possible the USAF is blowing smoke about PDR and is actually further along than stated. We will see when they release pictures.

I think they’re a little further along than they are indicating, especially as there has been no indication of a slip of IOC past 2025. To meet that IOC date you would expect they have a full scale prototype flying today and are looking for low rate initial production to begin very soon. Factor in a 5-7 year test and evaluation phase and enough aircraft to meet an IOC target (likely 8-10 aircraft in a squadron with the required aircrew and ground personnel trained to proficiency) and they have to have been moving along already.

Alternatively, that IOC date could slide two plus years…

I think you are right, I suspect they are well along the way and we'll probably see it photographed sooner rather than later. What was sighted a while back reflected the look of the B21 very closely.

FrmrKSEngr · Thu Apr 26, 2018 1:45 am

Mind Games - Potential schedule
6 Aircraft test program with the following 9 supporting stand-up for IOC (8 operational, 1 dedicated trainer)
PDR - Nov 2017
CDR - Nov 2018
Permanent DTE aircraft
A/C 1 Prototype roll-out - Nov 2019
AC 2 - Apr 2020
AC3 - Sept 2020
LRIP 3 planes per year
Pre-Flight 1 configuration (DTE for upgrade to flight 1 Operational config)
AC4 - Jan 2021
AC5 - May 2021
AC6 - Sept 2021
Flight 1/IOC Configuration
AC 7, 8, 9 - 2022 - Start Initial Operational training.
AC 10, 11, 12, -2023
AC 13, 14, 15 - 2024
IOC 2025
After IOC increase rate to 12 per year.

Slug71 · Thu Apr 26, 2018 2:39 am

FrmrKSEngr wrote:
Slug71 wrote:
mmo wrote:
Just a bit more on the B-21.

Looks as if the USAF will try to purchase more than the 100 talked about. Currently there are 9 Bomb Squadrons and the 100 had been planned to cover replacements for the B-1 and B-2 with the balance used for training. The USAF would like to increase the numbers in each squadron and then increase the number of squadrons from 9 to 14-16.

https://www.flightglobal.com/news/artic ... -d-447860/

Interesting. With the advancements in ICBMs and cruise missiles, I'd have thought the future is moving in that direction and therefore less demand of bombers.

Wow, where have I heard that before. Care to comment Mr McNamara?

Point?

Ozair · Thu Apr 26, 2018 2:42 am

FrmrKSEngr wrote:
Mind Games - Potential schedule
6 Aircraft test program with the following 9 supporting stand-up for IOC (8 operational, 1 dedicated trainer)
PDR - Nov 2017
CDR - Nov 2018
Permanent DTE aircraft
A/C 1 Prototype roll-out - Nov 2019
AC 2 - Apr 2020
AC3 - Sept 2020
LRIP 3 planes per year
Pre-Flight 1 configuration (DTE for upgrade to flight 1 Operational config)
AC4 - Jan 2021
AC5 - May 2021
AC6 - Sept 2021
Flight 1/IOC Configuration
AC 7, 8, 9 - 2022 - Start Initial Operational training.
AC 10, 11, 12, -2023
AC 13, 14, 15 - 2024
IOC 2025
After IOC increase rate to 12 per year.

Given B-21 was supposed to be low risk and extensive re-use the above schedule works for me if a little tight in the early years. Obviously hinges on NG being able to deliver the aircraft in the timeframe required and get the supplier base functioning to support that production rate.

FrmrKSEngr · Thu Apr 26, 2018 9:52 am

Slug71 wrote:
FrmrKSEngr wrote:
Slug71 wrote:

Interesting. With the advancements in ICBMs and cruise missiles, I'd have thought the future is moving in that direction and therefore less demand of bombers.

Wow, where have I heard that before. Care to comment Mr McNamara?

Point?

The point was that it sounded like McNamara and the ICBM crowd of the late 50s early 60s. The missiles will save us. The similar thinking that got us the F-4 without cannons. It is just history repeating itself.

mxaxai · Thu Apr 26, 2018 12:41 pm

Ozair wrote:
FrmrKSEngr wrote:
Of course, it is possible the USAF is blowing smoke about PDR and is actually further along than stated. We will see when they release pictures.

I think they’re a little further along than they are indicating, especially as there has been no indication of a slip of IOC past 2025. To meet that IOC date you would expect they have a full scale prototype flying today and are looking for low rate initial production to begin very soon. Factor in a 5-7 year test and evaluation phase and enough aircraft to meet an IOC target (likely 8-10 aircraft in a squadron with the required aircrew and ground personnel trained to proficiency) and they have to have been moving along already.

Alternatively, that IOC date could slide two plus years…

It does seem like an ambitious schedule. But I guess it is something to aim for and nobody will be sad if it achieves IOC in 2027 or 2030 or perhaps even 2032, as delays will inevitably happen and it's not like the USAF urgently need it anyways.

It took the F-35 6 years from prototype to first flight of the serial version and another 10 years to achieve IOC. Not sure if you can cut that by more than 50 % for the next all-new stealth aircraft.

Ozair · Thu Apr 26, 2018 9:26 pm

mxaxai wrote:
It does seem like an ambitious schedule. But I guess it is something to aim for and nobody will be sad if it achieves IOC in 2027 or 2030 or perhaps even 2032, as delays will inevitably happen and it's not like the USAF urgently need it anyways.

Given the angst that occurred over the F-22 and F-35 delays I can see much internet furore if the IOC was delayed that long. The good thing for the B-21 is the program is essentially in the dark and, unlike the F-35, there is a lot less public scrutiny.

mxaxai wrote:
It took the F-35 6 years from prototype to first flight of the serial version and another 10 years to achieve IOC. Not sure if you can cut that by more than 50 % for the next all-new stealth aircraft.

It helps that the B-21 isn’t comparatively developing much additional technology, the program will be using the stealth coatings from the F-35, likely a variation of the F-35 sensor engine, probably a variant of the F135 etc. Hence the challenges are less about technological innovation, which was seen with the F-35 and F-22, and more about integration and production. Still hard but more predictable in their issues and typically easier to deal with.

Ozair · Thu May 03, 2018 9:31 pm

A list of the likely first three US bases for the B-21 has bene announced and it should probably be no surprise that Ellsworth is likely to be first on the list. Given the USAF operates the B-1there, which will all be replaced by B-21s, it makes sense to start replacing that airframe with B-21s as they arrive.

The Air Force has picked 3 bases for its new next-generation bomber — here's where the B-21 Raider is headed

The Air Force said Wednesday that the new B-21 Raider bombers would go to three bases in the US when they start arriving in the mid-2020s.

The service picked Dyess Air Force Base in Texas, Ellsworth Air Force Base in South Dakota, and Whiteman Air Force Base in Missouri as "reasonable alternatives" for the new bomber.

The Air Force said that using existing bomber bases would reduce operational impact, lower overhead, and minimize costs.

"Our current bomber bases are best suited for the B-21," Heather Wilson, the secretary of the Air Force, said in a release.

Sen. Mike Rounds of South Dakota has said Ellsworth is a candidate to be the first to get the next-generation bomber.

The B-21 will eventually replace the B-1 Lancer and the B-2 Spirit at those bases as well — though the Air Force doesn't plan to start retiring those bombers until it has enough B-21s to do so.

Barksdale Air Force Base in Louisiana and Minot Air Force Base in North Dakota will continue to host the B-52 Stratofortress, the workhorse bomber that was first introduced in 1952 and is expected to remain in service until the 2050s.

A final basing decision is expected next year after ensuring compliance with the National Environmental Policy Act and other regulations.

"We are designing the B-21 Raider to replace our aging bombers as a long-range, highly survivable aircraft capable of carrying mixed conventional and nuclear payloads, to strike any target worldwide," Gen. David Goldfein, the Air Force chief of staff, said in the release.

Air Force Brig. Gen. Carl Schaefer, commander of the 412th Test Wing, said in March that the B-21 would head to Edwards Air Force Base in California for testing "in the near future." His announcement appeared to confirm that the Raider would undergo operational testing sooner than expected.

http://www.businessinsider.com/air-forc ... &IR=T&IR=T

Interesting point in the last sentence of the article, that the B-21 will start testing at Edwards AFB in the near future. That lends credibility to the thoughts of some of us that the USAF is further along than first thought.

ZaphodHarkonnen · Thu May 03, 2018 10:03 pm

Maybe they really have gone hard on the idea of taking the F-35 guts and putting them in a bigger airframe. Would seem reasonable.

Ozair · Thu May 03, 2018 11:22 pm

ZaphodHarkonnen wrote:
Maybe they really have gone hard on the idea of taking the F-35 guts and putting them in a bigger airframe. Would seem reasonable.

No doubt. The tech is available and fully paid for by the US Government. Now just scale larger and in the form of a flying wing. The B-21 would benefit from just about everything created for the F-35 bar the STOVL such as engine, stealth skin material, sensor fusion engine, EODAS, avionics, radar, HMD and even down to electrohydroactuators.

Slcpilot · Fri May 04, 2018 12:44 am

There is one aspect of the B-21 Raider that still leaves me perplexed. Has anyone seen definitive evidence of the aircraft having 2 or 4 engines?

While 2 engines certainly seem reasonable in terms of what’s available for a practical thrust/weight ratio, any displacement from the centerline will most likely result in significant yawing with an engine out.

This is obviously countered in traditional aircraft with a vertical stab and rudder. In a B-2, losing an engine can be obviously countered by increasing thrust on the remaining engine on the failed side, decreasing thrust on the opposite side, using drag rudders on the opposite side, or a combination of all three through the fly by wire system.

A 2 engine B-21 would likely only have the option of using drag rudders on the opposite side of the failed engine. While I’m not so naive to think this hasn’t been adequately addressed, the possibility of the B-21 having 4 smaller engines is intriguing to me.

Thoughts/comments?

SLCPilot

EDIT : I read from a link above Deborah Lee James calls it a twin engine aircraft. The question remains. How does it control yaw with an inoperable engine?

mxaxai · Fri May 04, 2018 2:54 am

If the engines are close to each other, near the centreline, the resulting moment arm is very short. The yaw could probably be countered by rudders if they are close enough. Other solution: Don't expect the plane to fly on one engine. Operate it like a single-engine aircraft and glide or eject if an engine fails. Nobody seems to have a problem with flying the F-35 transoceanic.

LightningZ71 · Fri May 04, 2018 3:37 pm

From what little has been revealed in the graphic models that have been released, it appears that both the whole aircraft and the distance between the engines is smaller on the B-21 as compared to the B-2. While there will absolutely be asymetric thrust, it won't be as far from centerline as it would be on a B-2 layout. Couple that with a fully automated flight control system that can rapidly compensate for the imbalance, and it shouldn't be too big of a problem.

ZaphodHarkonnen · Fri May 04, 2018 8:23 pm

There’s also an assumption it will have a classic large central bomb bay. We know it is intended more for modern precision weapons so it may have a narrower bomb bay and possibly one centreline and another two outboard of the engines. But we’ll have to wait for pics.

Andre3K · Fri May 04, 2018 9:07 pm

ZaphodHarkonnen wrote:
There’s also an assumption it will have a classic large central bomb bay. We know it is intended more for modern precision weapons so it may have a narrower bomb bay and possibly one centreline and another two outboard of the engines. But we’ll have to wait for pics.

Moving the weapons stations away from the centerline will always create balance issues if all the ordinance isn't dropped at once. I think it would be safer to leave it all near the centerline.

meecrob · Sat May 05, 2018 2:21 am

Andre3K wrote:
ZaphodHarkonnen wrote:
There’s also an assumption it will have a classic large central bomb bay. We know it is intended more for modern precision weapons so it may have a narrower bomb bay and possibly one centreline and another two outboard of the engines. But we’ll have to wait for pics.

Moving the weapons stations away from the centerline will always create balance issues if all the ordinance isn't dropped at once. I think it would be safer to leave it all near the centerline.

I agree that its safer to keep it centreline, but something in the back of my mind thinks that there is some pretty sophisticated FBW planned that may be able to compensate for the weight imbalance. Probably a FBW update for after EIS.

mxaxai · Sat May 05, 2018 7:14 am

meecrob wrote:
Andre3K wrote:
ZaphodHarkonnen wrote:
There’s also an assumption it will have a classic large central bomb bay. We know it is intended more for modern precision weapons so it may have a narrower bomb bay and possibly one centreline and another two outboard of the engines. But we’ll have to wait for pics.

Moving the weapons stations away from the centerline will always create balance issues if all the ordinance isn't dropped at once. I think it would be safer to leave it all near the centerline.

I agree that its safer to keep it centreline, but something in the back of my mind thinks that there is some pretty sophisticated FBW planned that may be able to compensate for the weight imbalance. Probably a FBW update for after EIS.

Don't most fighter-bombers store heavy ordnance under their wings, relatively far from the centreline? Surely they don't drop it all at the same time.

DigitalSea · Sat May 05, 2018 10:09 am

I wouldn't worry about the B-21. The Air Force has a next gen replacement ahead of it in the works that will really blow your mind (mainly due to the competition with China).

As a general statement, you're going to see a dramatic shift in the defense industry soon. We haven't had a "strategic competitor" quite like China in a long time. They are a very "universally driven" nation in the sense that their short term and long term goals politically/militarily aligned (which will help facilitate whatever goals they need to achieve). In essence, Cold War 2.0 has begun.

flyingclrs727 · Sat May 05, 2018 7:33 pm

PaddyOMaddy wrote:
This may be a stupid question, but why is it not called the B-3?

21st century

Andre3K · Sat May 05, 2018 7:36 pm

mxaxai wrote:
meecrob wrote:
Andre3K wrote:

Moving the weapons stations away from the centerline will always create balance issues if all the ordinance isn't dropped at once. I think it would be safer to leave it all near the centerline.

I agree that its safer to keep it centreline, but something in the back of my mind thinks that there is some pretty sophisticated FBW planned that may be able to compensate for the weight imbalance. Probably a FBW update for after EIS.

Don't most fighter-bombers store heavy ordnance under their wings, relatively far from the centreline? Surely they don't drop it all at the same time.

Typically when the ordinance is very heavy, they try to drop from both sides. Missiles don't weigh much so they aren't a big deal

Spacepope · Sun May 06, 2018 11:06 pm

Andre3K wrote:
mxaxai wrote:
meecrob wrote:

I agree that its safer to keep it centreline, but something in the back of my mind thinks that there is some pretty sophisticated FBW planned that may be able to compensate for the weight imbalance. Probably a FBW update for after EIS.

Don't most fighter-bombers store heavy ordnance under their wings, relatively far from the centreline? Surely they don't drop it all at the same time.

Typically when the ordinance is very heavy, they try to drop from both sides. Missiles don't weigh much so they aren't a big deal

I can't think of a current US bomber that doesn't have its ordinance on the centerline. B-52s have pylons on the very inboard wings but that's so close to center that it really doesn't matter.

TranscendZac · Mon May 07, 2018 1:05 am

Astonishingly the B-2 is still totally ahead of its time and way ahead of anything the Chinese or anyone else has. And yet, you can be sure the B-21 will be yet again, significantly ahead of anything else now or projected for decades to come. I’m convinced that we are at a point technologically where weapons systems are so lethal globally, there simply will NOT be an all out war between the US and any other global power. Far too many political and economical interests now that weren’t so much a factor in prior global wars. These huge military expenditures are simply not necessary. Too bad we can’t find common ground as human beings and dump the trillions we all collectively spend on military tech and instead spend that on space exploration and medical/environmental technology.

mxaxai · Mon May 07, 2018 2:43 am

Spacepope wrote:
Andre3K wrote:
mxaxai wrote:
Don't most fighter-bombers store heavy ordnance under their wings, relatively far from the centreline? Surely they don't drop it all at the same time.

Typically when the ordinance is very heavy, they try to drop from both sides. Missiles don't weigh much so they aren't a big deal

I can't think of a current US bomber that doesn't have its ordinance on the centerline. B-52s have pylons on the very inboard wings but that's so close to center that it really doesn't matter.

The Eurofighter, for example, carries two cruise missiles on its two heavy wing pylons and carries all bombs on the smaller wing pylons, both inboard and outboard. I believe this is similar for all Eurocanards.

Ozair · Mon May 07, 2018 4:16 am

Spacepope wrote:
I can't think of a current US bomber that doesn't have its ordinance on the centerline. B-52s have pylons on the very inboard wings but that's so close to center that it really doesn't matter.

Correct they all have central weapons bays. The B-52 has the external racks but don't forget the B-1 also had external racks...

Never used in anger I believe but the capability was there.

mxaxai wrote:
The Eurofighter, for example, carries two cruise missiles on its two heavy wing pylons and carries all bombs on the smaller wing pylons, both inboard and outboard. I believe this is similar for all Eurocanards.

A fighter bomber carrying external ordnance is a different prospect to a dedicated large bomber with internal weapons bays. For most large bombers, the internal bays are more than enough for the weapons required, especially in the precision age.

In the context of your statement though, the recent US/French/British attack on Syria saw the French launch SCALP missiles from Rafales. One of the ten missiles failed to launch and the missile was jettisoned. The Rafale could almost certainly fly and may well have been able to land with that asymmetric load but obviously landing with malfunctioning unexploded ordnance is never a great idea. The F-15E can carry two GBU-28 5000lb weapons (perhaps three if they carry a centreline but I haven’t seen that loadout) on the hip stations and can drop one and not the other and still fly and fight.

Most fighter aircraft have G limitations when carrying A2G loads, such as the Rafale at 5.5G and the F-16 a similar restriction, which are built into the FCS. Obviously large bombers don’t typically manoeuvre at those limits and the weapons carriage is primarily centreline anyway.

mxaxai · Mon May 07, 2018 4:49 am

Ozair wrote:
Most fighter aircraft have G limitations when carrying A2G loads, such as the Rafale at 5.5G and the F-16 a similar restriction, which are built into the FCS. Obviously large bombers don’t typically manoeuvre at those limits and the weapons carriage is primarily centreline anyway.

My point had been that placing ordnance outboard of the engines, relatively far from the centreline, can be done. In bomb bays or on external hardpoints, that doesn't change the mass distribution. If it works for fighter bombers it should work for bombers like the B-21 as well.

Ozair · Mon May 07, 2018 5:19 am

mxaxai wrote:
My point had been that placing ordnance outboard of the engines, relatively far from the centreline, can be done. In bomb bays or on external hardpoints, that doesn't change the mass distribution. If it works for fighter bombers it should work for bombers like the B-21 as well.

No one is saying it can't and there is no reason a B-21 couldn’t have a couple of internal bays out wide on the wing that house A2A missiles or small A2G weapons. It could certainly have external pylons but there is little value in that and given no current US bomber flies with external pylons outside the engines there clearly isn’t a need to do so. Putting weapons on an outboard pylon or bay obviously necessitates structural changes that add weight and complexity.

The likely smaller size of the B-21 also means any internal or external pylons you place outside of the engines take the place of fuel carriage and I expect the B-21 will attempt to maximise fuel carriage, especially as already indicated in the age of precision munitions where larger weapons loads are not necessary.

Spacepope · Mon May 07, 2018 12:39 pm

Ozair wrote:
Spacepope wrote:
I can't think of a current US bomber that doesn't have its ordinance on the centerline. B-52s have pylons on the very inboard wings but that's so close to center that it really doesn't matter.

Correct they all have central weapons bays. The B-52 has the external racks but don't forget the B-1 also had external racks...

Never used in anger I believe but the capability was there.

The pylon mounting points were sealed due to one of the START treaties i believe. In the past few years, one of the forward pylons was allowed to be reactivated and carries the laser designator pod.

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