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Author Topic: Northrop Grumman B-21 Long Range Strike Bomber  (Read 298837 times)

Offline Sundog

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Re: Northrop Grumman B-21 Long Range Strike Bomber
« Reply #1530 on: April 09, 2019, 05:41:45 pm »
I found this on Steve Trimble's DEW Line. As he notes, the B-2 went from CDR to first flight in about three and a half years and the B-21's CDR was in Novemeber of 2018. Just saying. I expect the B-21 to be a little faster since it is using advanced manufacturing and it is smaller than the B-2.

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Bunch says next critical milestone for B-21 is....first flight.

He didn't disclose when, but keep an eye to the skies... sometime...

1:00 PM - 9 Apr 2019
« Last Edit: April 09, 2019, 05:46:18 pm by Sundog »

Offline Grey Havoc

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Offline totoro

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Re: Northrop Grumman B-21 Long Range Strike Bomber
« Reply #1532 on: April 10, 2019, 03:44:44 am »
We don't really know how much smaller, if any, B-21 is going to be. It does seem the requirements and size grew over time, over the last 10 or so years.
Also, size is not really very relevant. Complexity is. Of which we know little, if any.

F-35 was using much more advanced manufacturing than older planes yet that didn't help. So requirements and complexity trump all those.

That being said, I don't see why B-21 could not indeed make the first flight sometime in summer of 2022. Still on track for entry into service in late 2020s.
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Offline sferrin

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Re: Northrop Grumman B-21 Long Range Strike Bomber
« Reply #1533 on: April 10, 2019, 05:31:14 am »
We don't really know how much smaller, if any, B-21 is going to be. It does seem the requirements and size grew over time, over the last 10 or so years.
Also, size is not really very relevant.

Size will have a huge effect on payload and range.  (Being dependent on a flock of tankers so you can perform your mission is not a positive.)
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Offline TomS

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Re: Northrop Grumman B-21 Long Range Strike Bomber
« Reply #1534 on: April 10, 2019, 06:42:02 am »
We don't really know how much smaller, if any, B-21 is going to be. It does seem the requirements and size grew over time, over the last 10 or so years.
Also, size is not really very relevant.

Size will have a huge effect on payload and range.  (Being dependent on a flock of tankers so you can perform your mission is not a positive.)

Size isn't very relevant for the time between CDR and first flight, which was the question at hand here. 

Offline sferrin

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Re: Northrop Grumman B-21 Long Range Strike Bomber
« Reply #1535 on: April 10, 2019, 06:51:05 am »
We don't really know how much smaller, if any, B-21 is going to be. It does seem the requirements and size grew over time, over the last 10 or so years.
Also, size is not really very relevant.

Size will have a huge effect on payload and range.  (Being dependent on a flock of tankers so you can perform your mission is not a positive.)

Size isn't very relevant for the time between CDR and first flight, which was the question at hand here.

Good point.  :-X
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Offline NeilChapman

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Re: Northrop Grumman B-21 Long Range Strike Bomber
« Reply #1536 on: April 10, 2019, 02:01:36 pm »
We don't really know how much smaller, if any, B-21 is going to be. It does seem the requirements and size grew over time, over the last 10 or so years.
Also, size is not really very relevant.

Size will have a huge effect on payload and range.  (Being dependent on a flock of tankers so you can perform your mission is not a positive.)

Size isn't very relevant for the time between CDR and first flight, which was the question at hand here.

Good point.  :-X


And the mission is different.  B-2 is designed to accommodate low level flight.  B-21 looks to be designed for 50k+ missions.  The efficiency of flight at this level would determine fuel load and engine selection, hence size, no? 

Also seems likely that B-21 will be strategically smaller if only to open up a significant number of alternative runways.  There just aren't that many available to aircraft the size of B-2.

Plus, given the small production run, weren't all B-2's were basically hand built?  I don't see that even being feasible given where we are with materials and manufacturing today.



« Last Edit: April 10, 2019, 02:05:08 pm by NeilChapman »

Offline NeilChapman

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Re: Northrop Grumman B-21 Long Range Strike Bomber
« Reply #1537 on: April 10, 2019, 03:41:03 pm »
We don't really know how much smaller, if any, B-21 is going to be. It does seem the requirements and size grew over time, over the last 10 or so years.
Also, size is not really very relevant. Complexity is. Of which we know little, if any.

F-35 was using much more advanced manufacturing than older planes yet that didn't help. So requirements and complexity trump all those.

That being said, I don't see why B-21 could not indeed make the first flight sometime in summer of 2022. Still on track for entry into service in late 2020s.

Complexity is relative. 

All the 'tech' in B-21 is supposedly the 'latest' but not "new" for the program.  Airframe and integration were to be the 'only' new endeavors.  How difficult is building a new airframe? Even though it's a clean-sheet design, it looks a lot like B-2 to me and they've been working on B-2 and it's maintenance upgrades for 30 years.  I wouldn't be surprised if there is very little risk here except for manufacturing techniques. And if there is, the risk was mitigated with RQ-180. How successful is the integration?  We'll see in testing.  Yet modeling flight dynamics was pretty good even back with YF-23 and that was 30 years ago. 

F-35 was different, ostensibly one but really three new airframes and net new tech throughout.  That's what B-21 program was seeking to avoid from what I understood.  Also, F-35 has 1500 domestic and nine partner countries of international suppliers.  B-21 has 7 top-tier suppliers and NG supplies significant portions of F-35 tech, some portion of which will be in B-21.  It's likely that Palmdale is not only being used for final assembly but that a large amount of process and part work is also being done there. Vertical integration also adds a certain level of efficiency. 

DoD was beat up pretty good for B-2 with $20B in R&D cost.  It was further beat up by F-35 but those 1500 suppliers in almost every state guaranteed some base level of congressional support.  It's likely why B-21 is being handled by the Air Force Rapid Capabilities Office to limit the possibility of bureaucratic changes to the program.  Also, the DoD is not allowing cost information to be used politically.  Strategically and fiscally the US can't afford another program debacle like F-35.

NG seems risk averse to me. They ate the F-20.  YF-23 didn't win, probably in part because of the late USAF changes to B-2 and the difficulties those changes saddled on the program.  We've seen them remove themselves from TX and then the X-47B change in priorities.  Looking at how they've written the contracts for B-21, they have chosen to protect themselves financially from the changing priorities of DoD.  That being said, they are a relatively nimble (compared to Boeing and LM) company focused on engineered solutions. NG's outreach to automobile manufacture assembly line suppliers allowed them to develop the Integrated Assembly Line (IAL) for F-35.  The IAL has achieved a 450% increase in throughput cutting the assembly time of all three of the F-35 center fuselage by half compared to previous fighters. This history suggests to me they may have their ducks in a row for the B-21 build.

So now we have the unique situation of DoD recognizing their procurement shortcomings and taking steps to mitigate political and bureaucratic influences and the manufacturer a bit gun shy. We've seen NG partner with KUKA Systems North America early in the B-21 program, the same group that help create the IAL. We seen NG already hire some 5000 employees working B-21 at the Palmdale plant

If I were NG, I'd suspect that the perceived success or difficulty with B-21 and F-35 will play some part in what company is trusted with the next prize, PCA and F/A-XX.  For these reasons I expect NG will surprise us with B-21.



Offline sferrin

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Re: Northrop Grumman B-21 Long Range Strike Bomber
« Reply #1538 on: April 10, 2019, 04:42:58 pm »
And the mission is different.  B-2 is designed to accommodate low level flight.  B-21 looks to be designed for 50k+ missions.

As was the B-2. That they added low-level flight didn't change the size of the bomber or it's payload. 

The efficiency of flight at this level would determine fuel load and engine selection, hence size, no?

Which is why the B-2 uses basically the same engine as the U-2.

https://www.geaviation.com/sites/default/files/datasheet-F118.pdf

Also seems likely that B-21 will be strategically smaller if only to open up a significant number of alternative runways.  There just aren't that many available to aircraft the size of B-2.

How do you figure? 

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Offline Flyaway

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Re: Northrop Grumman B-21 Long Range Strike Bomber
« Reply #1539 on: April 10, 2019, 11:49:26 pm »
Full article.

Next Milestone for Future B-21 Bomber? First Flight

Quote
The Air Force's stealthy new bomber is getting ready to take its first flight.

"Our next major milestone is first flight," Lt. Gen. Arnold Bunch, the Air Force's military deputy to the Office of the Assistant Secretary for Acquisition at the Pentagon, said of the B-21 Long Range Strategic Bomber program.

During a Senate Armed Services subcommittee on airland hearing Tuesday, Bunch told lawmakers the program has met all developmental checkpoints and is on schedule.

While he didn't reveal when the flight will take place, officials have said the first B-21 is expected to reach initial operating capability in the mid-2020s.

Offline coanda

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Re: Northrop Grumman B-21 Long Range Strike Bomber
« Reply #1540 on: April 12, 2019, 06:21:28 am »

Additive manufacturing and generative design is not helping reduce time to flight of any full-size aircraft rght now.  Mainly due to materials and processes qualifications.  In the future, maybe...

Industrial improvements in terms of tooling, CF processing and robotics are far more likely to be driving any reductions in industrial schedules.

« Last Edit: April 12, 2019, 08:15:24 am by flateric »

Offline TomcatViP

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Re: Northrop Grumman B-21 Long Range Strike Bomber
« Reply #1541 on: April 12, 2019, 03:14:59 pm »
Don't forget the complex ducting associated with a distributed propulsion system. Additive manufacturing and generative design will certainly lead to some time gain, hence money.

Offline coanda

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Re: Northrop Grumman B-21 Long Range Strike Bomber
« Reply #1542 on: April 16, 2019, 08:28:04 am »
Yes, disposable inner moulds for ducting is a good use for AM as tooling.