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Northrop Grumman B-21 Long Range Strike Bomber

marauder2048

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Would not that be active flutter mitigation?
From Britt et al.

The Twist Adaptive Wing System (TAWS) and Continuous Aerodynamic Control Surface concepts strive for aerodynamic
controls which are seamless for both improved aerodynamic performance and survivability. TAWS is geared towards
medium to high aspect ratio wings. It incorporates an internal mechanism to twist the wing to provide incremental lift for
maneuvering, load alleviation and performance optimization. The TAWS concept has also showed significant
potential in reduced manufacturing costs by reduced part count and sealing the structure from environmental damage.
Continuous aerodynamic control surfaces technologies can be generally describes as advanced seals
which maintain structural continuity for relatively conventional aerodynamic control mechanisms.

Concepts in this class will be of continued interest for military bombers and transports due to multiple benefits
provided, particularly survivability. In fact, deformable surfaces were considered in the early B-2 design stages,
but were abandoned due to lack of technical readiness and inadequate control authority at low speed.
 

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shedofdread

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The aerolastic component could well be the wing twisting as it bends - as the wing flexes up, washout is introduced that it unloads and bends back down. How that plays into lift distribution (and therefore the stability of a tailless platform) and RCS, well that would be 'parcel of work' alright....

Getting rid of traditional control surfaces (or at least not having to use them in certain scenarios) would be useful too but I'd be surprised if wing warping per se could be used on such a platform. SB4 style wing tips? The joint would provide a challenge or two.

Edit - just seen post by marauder2048
 

GeorgeA

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There's no hint of it anywhere in the GAO protest; you would fully expect Boeing and Lockheed to invoke it as evidence of their goodness, righteousness and probity.
Wouldn’t a discussion of a classified vehicle be limited to the classified annex to the protest?
 

overscan (PaulMM)

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No flying demonstrator in 2015 at least.



This week, the service briefed no fewer than 12 Washington defence analysts about the bomber, and the main message was that the technologies being baked into the bomber are more mature and ready than previously disclosed.

There is no flying demonstrator, it has been confirmed, but plenty of prototyping activities and wind tunnel tests have been done, as well as parallel efforts to ready critical subsystems.

Sources who attended the briefing say the optionally-manned, penetrating bomber will be a collection of very mature technologies powered by an advanced derivative of an existing engine.
 

overscan (PaulMM)

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There's no hint of it anywhere in the GAO protest; you would fully expect Boeing and Lockheed to invoke it as evidence of their goodness, righteousness and probity.
Wouldn’t a discussion of a classified vehicle be limited to the classified annex to the protest?
I am sure Lockheed and Boeing planned to build a demonstrator for NGB. Doubt it got to flying stage though.

That has no bearing on whether Northrop built a demonstrator for B-21.
 

marauder2048

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There's no hint of it anywhere in the GAO protest; you would fully expect Boeing and Lockheed to invoke it as evidence of their goodness, righteousness and probity.
Wouldn’t a discussion of a classified vehicle be limited to the classified annex to the protest?
The specific reference would be blacked out. But it would look like: "Boeing leveraged work on <blank> to justify
its cost estimate of <blank>." GAO and the AF are explicit in the record in the protest as regarding Boeing's previous work
cited as a basis for estimating cost/risk as having little bearing on LRS-B.
 

FighterJock

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It will be interesting to see what sort of design Boeing and Lockheed came up with during the course of the LRS-B programme, I would be highly surprised if they came up with another flying wing design.
 

marauder2048

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There's no hint of it anywhere in the GAO protest; you would fully expect Boeing and Lockheed to invoke it as evidence of their goodness, righteousness and probity.
Wouldn’t a discussion of a classified vehicle be limited to the classified annex to the protest?
I am sure Lockheed and Boeing planned to build a demonstrator for NGB. Doubt it got to flying stage though.

That has no bearing on whether Northrop built a demonstrator for B-21.
Actually, a demonstrator for NGB would have made complete sense: it was supposed to be a VLO bomber
with supersonic dash and (according to former CSAF Norton Schwartz) air-to-air missiles.

The apparent radical descoping for LRS-B would have made flying the NGB demonstrator for it the
crude equivalent of McAir flying the YF-23 for the Super Bug.
 

rooster

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You don't need a demonstrator if there were/ are other things flying close in mold line to the bomber... In automotive we use surrogate data all the time. Cheaper and faster. So yes, there was no demonstrator and they had surrogate data in hand. $0.02.
 

FighterJock

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US Air Force delays first B-21 flight (to 2022)

Wonder why the delay? The last news I heard things were going well in the building of the first prototype.
 

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Bhurki

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General Weatherington says, " The onset of ramp may be a bit late, but the ramp will certainly be steeper than initially thought".

Combined with the reduced requirement of combat coded B-1B to 24 (total 45) from 36 (total 62), the B21 certainly has the impetus to not lose a day in being operationalized.
IOC is set for 2030.
 
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haavarla

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It doesn't really matter if you are Biased towards this or that.
The reality is, there will always be Delays on these programs. Change of design, change of requirements perhaps while they are developing it..
The list goes on.
 

marauder2048

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General Weatherington says, " The onset of ramp may be a bit late, but the ramp will certainly be steeper than initially thought".

Combined with the reduced requirement of combat coded B-1B to 24 (total 45) from 36 (total 62), the B21 certainly has the impetus to not lose a day in being operationalized.
IOC is set for 2030.
Where do you get a 2030 date for IOC? Do you mean nuclear certified?
 

Bhurki

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General Weatherington says, " The onset of ramp may be a bit late, but the ramp will certainly be steeper than initially thought".

Combined with the reduced requirement of combat coded B-1B to 24 (total 45) from 36 (total 62), the B21 certainly has the impetus to not lose a day in being operationalized.
IOC is set for 2030.
Where do you get a 2030 date for IOC? Do you mean nuclear certified?
General's answer to a question asked in the mitchell inst interview.
 

marauder2048

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General Weatherington says, " The onset of ramp may be a bit late, but the ramp will certainly be steeper than initially thought".

Combined with the reduced requirement of combat coded B-1B to 24 (total 45) from 36 (total 62), the B21 certainly has the impetus to not lose a day in being operationalized.
IOC is set for 2030.
Where do you get a 2030 date for IOC? Do you mean nuclear certified?
General's answer to a question asked in the mitchell inst interview.
Weatherington's answer was super vague. Oscillating between IOC and FOC dates.
 

Josh_TN

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If first flight in is scheduled inside the next couple years, it seems to be IOC would occur well before 2030. The December 2021 first flight date was always optimistic, but I assume it won't take more than an extra year or two given the comments on the program. It looks like the B-21 is being built rather pragmatically with tech off the shelf, much like FFG(X).
 

rooster

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If first flight in is scheduled inside the next couple years, it seems to be IOC would occur well before 2030. The December 2021 first flight date was always optimistic, but I assume it won't take more than an extra year or two given the comments on the program. It looks like the B-21 is being built rather pragmatically with tech off the shelf, much like FFG(X).
I think we have lots of big shelves.
 

Josh_TN

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If first flight in is scheduled inside the next couple years, it seems to be IOC would occur well before 2030. The December 2021 first flight date was always optimistic, but I assume it won't take more than an extra year or two given the comments on the program. It looks like the B-21 is being built rather pragmatically with tech off the shelf, much like FFG(X).
I think we have lots of big shelves.
Honestly, when it comes to stealth bombers, isn't it a pretty deep shelf for the US? The US is about three generations deep into low RCS designs.
 

rooster

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Stand by for visual stealth!
Spirit is already visually stealthy. I've seen at airshow events as is flies off and becomes a narrow sliver that melts into the sky. If you're talking about luminescent panels I hope its not a future hangar queen that can't survive a half dozen rain storms
 

marauder2048

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Oscillating between IOC and FOC dates.
If its oscillating between IOC and FOC, then its certainly IOC at the very least.
He wasn't even clear when his dates were rooted. I looked through the transcripts and it's incredibly unclear.
If you have timestamps of interest let me know.
Going back to the earlier documents, the consistent line has been (conventional) IOC one decade from contract award.
If you want to count from the lifting of the stop-work order for the protest, that's still mid-2020s.
 

sublight is back

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If you're talking about luminescent panels I hope its not a future hangar queen that can't survive a half dozen rain storms
If your thinking very short range then you would use panels. I'm thinking small powerful emitters embedded in the skin or popups to obscure it from EO sensors.
 

Rhinocrates

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If your thinking very short range then you would use panels. I'm thinking small powerful emitters embedded in the skin or popups to obscure it from EO sensors.
Thinking left field here, cephalopods use their abilities not only to hide, but to confuse. Towards the end of this TED talk, marine biologist Roger Hanlon looks at biomimetic design applying cephalopod techniques to clothing - but a smart skin could be applied to an aircraft to hide from or confuse EO, as well as old-fashioned eyeballs.


Moreover, synthetic 'papillae' could alter the aerodynamic properties of the skin.

Most of this article is paywalled, but you can get the gist - visual patterns can be used to confuse recognition software.


By the way, the principle goes back to the First World War and 'dazzle painting' that was used to confuse optical rangefinders. Animated dazzle would be a logical next step, and BAE has trialled 'Adaptiv' camouflage for tanks. It's apparently robust enough to consider for tanks, but tanks can't fly...



I have no idea if anything like this would be applied to the B-21 of course, but I imagine someone's exploring the possibilities.
 

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IMOHO working on photon's trajectory (similarly to stealth) and capture would more be the trick. What you see is what ping back to you.
For a sensor that is frequency walled, harvesting those photons or mitigating with their frequency could be a path to go.

Don't forget also that the size of holes in a panel with traps to capture photons is irrelevant aerodynamically and RCS wise. It might then be that those problems are decorelated, easing their solutions...
 
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mkellytx

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Stand by for visual stealth!
Spirit is already visually stealthy. I've seen at airshow events as is flies off and becomes a narrow sliver that melts into the sky. If you're talking about luminescent panels I hope its not a future hangar queen that can't survive a half dozen rain storms
It isn't necessarily visual stealth as much as a very small profile head on. Back in the day I was on a 135 serving as a radar target and it was amazing how it would just appear out of nowhere, and we were using TCAS to know where to look. The only chance you'll get for visually spotting it is to get some parallax to see it from above or below.
 

Josh_TN

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There were experiments all the way back in WWII using incandescent lights to wash out the shadow of aircraft. They were successful at making aircraft much harder to spot at longer distances, but I think the the arrangement wasn't very aerodynamically friendly and probably not cheap. However now adays it wouldn't be difficult to give off light to blend it with the ambient background using much lower powered (and conformal) LEDs that can cycle through any color combination. I doubt it's worth the effort on a military aircraft though. It seems to me unless you can cover up your IR signature, there isn't a lot of point in obscuring your visual. Most peer a/c will have an IRST and even AAMs are imaging infrared.
 

Mark S.

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The first F-4C, 63-7407 was used as a testbed for the "Yehudi" lights. They were on the sides of the intakes about where the unit insignia goes and under the nose just forward of the nose gear. The aircraft was initially painted white but when the lights were added the top and sides were repainted light ghost grey. The fairings were rectangular with both fore and aft ends tapering to a point in a pyramidal fashion at the fuselage surface. The forward pyramid was clear glass with the light inside. Don't have any info on how successful the project was. Believe it was named Compass Ghost.
 

rooster

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Daylight stealth and luminescent panels or thousands of LED emitters is best left to a few dozen or so drones forfollowing and taking out terrorists. The wiring harnesses for thousands of emitters is Complex and heavy. Why do you need to complicate a heavy bomber with standoff weapons that will operate presumably mostly at night? Something relatively small like a spirit or raider at 50k and without contrails is hard to spot visually already.
 

Jeb

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Stand by for visual stealth!
Spirit is already visually stealthy. I've seen at airshow events as is flies off and becomes a narrow sliver that melts into the sky. If you're talking about luminescent panels I hope its not a future hangar queen that can't survive a half dozen rain storms
It isn't necessarily visual stealth as much as a very small profile head on. Back in the day I was on a 135 serving as a radar target and it was amazing how it would just appear out of nowhere, and we were using TCAS to know where to look. The only chance you'll get for visually spotting it is to get some parallax to see it from above or below.
But the net effect is still the same. And then just imagine if there was some edge treatment that made the planform outline seem to have even less contrast, like a light gloss grey wavy paint effect along the leading and trailing edge.
 

NUSNA_Moebius

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220? I honestly didn't expect that high and am doubtful it ever will.
 
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