NeilChapman
Interested 3rd party
- Joined
- 14 December 2015
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So...
When is taxi testing to start?
When is taxi testing to start?
Nope. The relationship between radar wavelength and size of physical features means a smaller B-2 could be more detectable to long wavelength radars for example.Small feature can have a big return. Big feature can have a small return. RCS is not dependent on volume or physical size. The electrical size of something in relation to the frequency can affect the RCS. As a general rule though the size of an object does not have a direct affect on the RCS. Saying a given shape, made smaller, will produce a smaller RCS is not correct at all, and this has been known since the 1960s. It was this knowledge that allowed Boeing to create the SRAM (and other things) with a very small RCS even though it was "common knowledge" at the time that size and RCS were directly related (again, they are not).
Quellish, but if we compare B2 with let say 50% sized B2 - the second should have smaller RCS. Is that correct?
So basically it comes to the point, if some element of the airframe resonate with radar wavelength?Nope. The relationship between radar wavelength and size of physical features means a smaller B-2 could be more detectable to long wavelength radars for example.Small feature can have a big return. Big feature can have a small return. RCS is not dependent on volume or physical size. The electrical size of something in relation to the frequency can affect the RCS. As a general rule though the size of an object does not have a direct affect on the RCS. Saying a given shape, made smaller, will produce a smaller RCS is not correct at all, and this has been known since the 1960s. It was this knowledge that allowed Boeing to create the SRAM (and other things) with a very small RCS even though it was "common knowledge" at the time that size and RCS were directly related (again, they are not).
Quellish, but if we compare B2 with let say 50% sized B2 - the second should have smaller RCS. Is that correct?
What are those, Adours?
Some here at SPF may laugh at my naivety but would the DOD/USAF proceed to build a bomber with “dramatically” less payload than its other bombers?
If yes is this the reason we’ll see B-52s forever with talk of “bomb trucks” like B-17s loaded with JASSMs?
Weopon have became more compact: more energetic material (~100%), more precision, better engineering (flight vehicles design)... Hence a bigger bomb might not be required to get a greater boom.Probably the biggest contributor IMHO. But one can't rule out a smaller payload [to B-2] as well. There are some things we just won't know for a little while longer.Well, my bet that biggest savings and at the end requirement for smaller airframe came from switching from 4 engine into 2 engine config.
I think they did use people with various heights in the reveal. For a purpose.They should have hired NBA basketball stars or midgets to throw off size analysis.
Does mop have earth penetration ability. Then its useless agaisnt say Iranian targets under mountains. I'm not sure why mop is even needed. Distributed smaller explosions are more destructive than 1 large one. Its not the 21 will be clearing forests for helicopter landing areas. They make for nice TV clips but....I don't think it will. It will have a replacement for MOP which is smaller but not necessarily less destructive. MOP was a quick development and not very optimised. There were statements in 2011/2012 timeframe about a smaller replacement for next-generation bombers.
I think all we need to take out Iranian mountain targets are four Super Hornets with two GBU-24s each. They would operate in pairs of one E and one F...Does mop have earth penetration ability. Then its useless agaisnt say Iranian targets under mountains. I'm not sure why mop is even needed. Distributed smaller explosions are more destructive than 1 large one. Its not the 21 will be clearing forests for helicopter landing areas. They make for nice TV clips but....I don't think it will. It will have a replacement for MOP which is smaller but not necessarily less destructive. MOP was a quick development and not very optimised. There were statements in 2011/2012 timeframe about a smaller replacement for next-generation bombers.
Though the B-21 is supposed to be smaller than the B-2, its wingspan seemed nearly as wide, though with a possibly different angle of sweep than that of the B-2. The “fuselage” seemed to have a deeper keel than that of the B-2. No dimensions of the aircraft were offered.
Not the reveal, but a day prior.I think they did use people with various heights in the reveal. For a purpose.They should have hired NBA basketball stars or midgets to throw off size analysis.
Width to height is near 8:1
Albion (Al) Bowers, not Jonathan Bowers. BTW, the first paper was "A Retrospective: Historical Flying Wing Examples" by Albion Bowers and David Lednicer.The aerodynamics of this thing fascinate me; some comment is given in the article. The hundreds if not thousands of iterative computer designs have converged on several classic historical features that are generally ignored or forgotten by the mainstream.Northrop, U.S. Air Force Roll Out the B-21 Raider | Aviation Week Network
The B-21 Raider was displayed at the company’s secretive Plant 42 complex about 34 years after a similar ceremony for its predecessor the B-2.aviationweek.com
The tailored airflow over the centre section echoes Reimar Horten's deep concern for the subtleties of the mitteneffekt (middle effect), which he never entirely resolved. He also wanted to improve the engine installation to a more conformal design.
Those intakes remind me somewhat of the NACA duct used for many small auxiliary intakes in the cold war era and trialled as an engine intake on the North American YF-93. No doubt the B-21 version is far more advanced, but the principle appears to be the same, and is I suspect the secret to decelerating the leading-edge flow at transonic speeds.
The wing outer sections have pronounced washout and, as far as I can tell, leading-edge droop. These features may be traced historically back through the majority of tailless swept wings, including the production Convair deltas, Avro Vulcan and Horten types, to the Dunne machines of the pioneer era and his 1909 patent. The first such design to fly, the D.5 biplane of 1910, received the first ever official certificate of performance for a stable aeroplane. Twenty or so years after that Ludwig Prandtl developed the theory of the bell-shaped lift distribution which offers the lightest structure and lowest drag for any given wing size, and for which these two features are necessary. Lippisch published a simplified calculation, which Horten adopted (though for some reason Lippisch seldom did). NASA only publicly caught up in this millennium, with Jonathan Bowers' PRANDTL-D flying wing project. Clearly, the key benefit for the digitally-controlled B-21 is not the inherent stability but Prandtl's minimal weight and drag. Once you sweep the wing, the stability comes with that package. Also of interest is that, right up to his rediscovery by Bowers, Prandtl was ignored by the mainstream and it was believed that these design features increased drag; this was voiced as a major criticism of the Dunne, and Northrop never incorporated them, not even in the B-2. Now, we see that they actually enhance the B-21's low drag characteristics.
The question I ask myself now is, did Northrop Grumman secretly take forward all these long-known but also long-obscure aerodynamic features, or did their computers arrive at something they knew nothing of beforehand? Either way, the B-21 looks like becoming a major vindication of all those maverick forebears.
U.K. or aus having some, leads to ‘strategic ambiguity’ for an enemy. Am I about to go to war with USA, or aus.Questions...
1. Do we think that is the final color?
2. Anybody else find it interesting that the chiefs of both the Australian and U.K. Royal Air Forces were present?
3. NG states B-21 designed to fly "every day" as a "high cycle" aircraft. What would one consider as an acceptable number of expected lifetime flight cycles or flight hours for an airframe designed today?
Lastly...
When walking through the woods don't forget to look up.
Is it possible those are standard 2' drop ceiling tiles above this bomber? It looks like the lights are every 8 tiles apart. Looks bigger than 120' to me. And if I'm right, I'd appreciate the credit. ;-)
View attachment 688452
View attachment 688452
Nice drawing. However you need to make a fundamental decision to start with - four spike or six spike, mmkay?
You don't say...
Note that correlation is not necessarily causation though...
What for? It's a well known fact that Northrop has started an intense build-up at Site 4 after they have won LRS-B.
Call me agnostic, but I'd still like to see concrete references for that "well known fact".
They put colored tape on the floor to make measuring things easyIs it possible those are standard 2' drop ceiling tiles above this bomber? It looks like the lights are every 8 tiles apart. Looks bigger than 120' to me. And if I'm right, I'd appreciate the credit. ;-)
I just don't think you understandI think all we need to take out Iranian mountain targets are four Super Hornets with two GBU-24s each. They would operate in pairs of one E and one F...Does mop have earth penetration ability. Then its useless agaisnt say Iranian targets under mountains. I'm not sure why mop is even needed. Distributed smaller explosions are more destructive than 1 large one. Its not the 21 will be clearing forests for helicopter landing areas. They make for nice TV clips but....I don't think it will. It will have a replacement for MOP which is smaller but not necessarily less destructive. MOP was a quick development and not very optimised. There were statements in 2011/2012 timeframe about a smaller replacement for next-generation bombers.
Anyway, fairly in depth article from Air Force Magazine about the B-21 program and how we still know very little about the aircraft.
https://www.airandspaceforces.com/m...-21-bomber-remains-a-secret-following-reveal/
Also going to highlight this quote about the B-21's size from the reporter who was at the reveal:
Though the B-21 is supposed to be smaller than the B-2, its wingspan seemed nearly as wide, though with a possibly different angle of sweep than that of the B-2. The “fuselage” seemed to have a deeper keel than that of the B-2. No dimensions of the aircraft were offered.
PLEASE some of us are reading this with a mouthful of Tannat. Give us a View attachment 688453RCS B-2 ~ 0.38 m2, B-21 ~ 0.156 m2Quellish, but if we compare B2 with let say 50% sized B2 - the second should have smaller RCS. Is that correct?
based on a comparison of the frontal view
There has been some talk about the RAAF acquiring B-21s. Haven't heard much about it for the UK. With the most basic of calculations, an order of 24 aircraft would be approx ~24.5 bil in AUD, say another 6B for spare parts and other items/support. That's around 1/3rd of the projected cost for the Attack class submarines, so I don't think it's out of the question.Questions...
2. Anybody else find it interesting that the chiefs of both the Australian and U.K. Royal Air Forces were present?
Somehow Bill's a friend of a friend on Facebook - for what it's worth he watched the whole thing at home like the rest of us!Given Bill works for Northrop Grumman now, its not likely any time soon.
I wondered what had happened to Bill Sweetman. He had gone quiet lately. A Northrop sponsored book on the B-21 would be good though.
Questions...
1. Do we think that is the final color?
2. Anybody else find it interesting that the chiefs of both the Australian and U.K. Royal Air Forces were present?
3. NG states B-21 designed to fly "every day" as a "high cycle" aircraft. What would one consider as an acceptable number of expected lifetime flight cycles or flight hours for an airframe designed today?
Lastly...
When walking through the woods don't forget to look up.
Is it possible those are standard 2' drop ceiling tiles above this bomber? It looks like the lights are every 8 tiles apart. Looks bigger than 120' to me. And if I'm right, I'd appreciate the credit. ;-)
View attachment 688452
B-21 evolved surface treatments, alien ship looking but I would expect this over many years of refinement. Even the B-2 has evolved treatments over the years since I was on the program up to 1996.The egress panels are most probably those that can be seen in Overscan's close up picture. I've outlined the one on the right side of the craft:What I haven't been able to determine, is where are the egress panels? Does the flight crew sit more under those side windows? Are those the panels that get blown off for ejection? Because I don't see anything on the top between them for egress.
View attachment 688379
I do not think those are for the ejection seats. I've made a quick drawing to get a (very) rough estimate of where the glazings are, and they clearly do not line up with where I'd expect the pilots to seat:
View attachment 688380
So, unless the seats slide to the sides during the ejection procedure, this is why I think those are emergency egress panels and (possibly) explosive ones. I think the crew is meant to enter and exit the B-21 in the same way as on the B-2, via a ladder on the bottom of the craft, but after the B-2's crashes in 2008 and 2021 it might have been noticed that in case the landing gear collapses while on the runway, the pilots only option to leave the aircraft would be to eject. Which is not great for the human body, unless necessary to avoid worse injuries or death.
I believe the ejection panels can't be seen in the available pictures due to a mix of the angles at which these have been taken, the lights used in the hangar and the kind of surface coating on the aircraft.
Edit: I also believe the side windows' shape and size are dictated by the structural requirements for these egress panels, rather than any laser/stealthiness theory.
Monty Pythons and the holy grail intensifies... KABOOM !!!Lets call him "Tim".
Both countries already operate unique US military technology. Weirdly I think the B-21 would be more exportable in limited circumstances than the NGAD technology wise. Unlike the B-2 it’s designed to be a multipurpose lower cost high cycle platform. I could imagine the B-21 slotting into the UK, Japan & Italian multi platform sixth generation combat aircraft. By the way Japan might be worth a sale after all they are in theatre so to speak.U.K. or aus having some, leads to ‘strategic ambiguity’ for an enemy. Am I about to go to war with USA, or aus.Questions...
1. Do we think that is the final color?
2. Anybody else find it interesting that the chiefs of both the Australian and U.K. Royal Air Forces were present?
3. NG states B-21 designed to fly "every day" as a "high cycle" aircraft. What would one consider as an acceptable number of expected lifetime flight cycles or flight hours for an airframe designed today?
Lastly...
When walking through the woods don't forget to look up.
Is it possible those are standard 2' drop ceiling tiles above this bomber? It looks like the lights are every 8 tiles apart. Looks bigger than 120' to me. And if I'm right, I'd appreciate the credit. ;-)
View attachment 688452
View attachment 688452
I
Questions...
1. Do we think that is the final color?
2. Anybody else find it interesting that the chiefs of both the Australian and U.K. Royal Air Forces were present?
3. NG states B-21 designed to fly "every day" as a "high cycle" aircraft. What would one consider as an acceptable number of expected lifetime flight cycles or flight hours for an airframe designed today?
Lastly...
When walking through the woods don't forget to look up.
Is it possible those are standard 2' drop ceiling tiles above this bomber? It looks like the lights are every 8 tiles apart. Looks bigger than 120' to me. And if I'm right, I'd appreciate the credit. ;-)
View attachment 688452
If we go by the person to the right wingtip, he is approx. 75 pixels tall. Lets call him "Tim". I assume that he is standing below the front wingtip, which means he is in the right plane for maximum span, wingtip to wingtip.
The wingspan of the B-21 is 1947 pixels, which is 25.96 Tims.
If Tim is 5ft tall, then that makes the B-21 129 ft span. If Tim is 6ft, then its 155ft span.
My money's on 150ft+.
Albion (Al) Bowers, not Jonathan Bowers. BTW, the first paper was "A Retrospective: Historical Flying Wing Examples" by Albion Bowers and David Lednicer.
I was going the other way, B2 172 feet, each engine about 6 feet, so take 2 off, = 160 feet.I
Questions...
1. Do we think that is the final color?
2. Anybody else find it interesting that the chiefs of both the Australian and U.K. Royal Air Forces were present?
3. NG states B-21 designed to fly "every day" as a "high cycle" aircraft. What would one consider as an acceptable number of expected lifetime flight cycles or flight hours for an airframe designed today?
Lastly...
When walking through the woods don't forget to look up.
Is it possible those are standard 2' drop ceiling tiles above this bomber? It looks like the lights are every 8 tiles apart. Looks bigger than 120' to me. And if I'm right, I'd appreciate the credit. ;-)
View attachment 688452
If we go by the person to the right wingtip, he is approx. 75 pixels tall. Lets call him "Tim". I assume that he is standing below the front wingtip, which means he is in the right plane for maximum span, wingtip to wingtip.
The wingspan of the B-21 is 1947 pixels, which is 25.96 Tims.
If Tim is 5ft tall, then that makes the B-21 129 ft span. If Tim is 6ft, then its 155ft span.
My money's on 150ft+.
Following up on this analysis.
The thrust from two F-135s is likely 56,000lb compared to 72,000lb for the B-2's 4 engines , which is roughly 75% of the thrust. I expect the weight of the B-21 to be roughly in the area of 75% the weight of the B-2.
Assuming density is the same, you would expect the B-21 to be 75% of the volume of the B-2.
Dimensions would be reduced by the third root of 0.75 which is 0.90.
So if B-21 was exactly the same shape as the B-2 but scaled to 75% weight, you would expect the wingspan to be 0.9 * 172 ft = 154.8ft.
A B-2 scaled to 130 ft would be 75% of the B-2 span, but the volume would be reduced to less than half (43%) of the B-2. This would seem to leave it too small, and overpowered.
Obviously tremendously oversimplified, as it isn't the exact same shape, but still interesting I think?
I
Questions...
1. Do we think that is the final color?
2. Anybody else find it interesting that the chiefs of both the Australian and U.K. Royal Air Forces were present?
3. NG states B-21 designed to fly "every day" as a "high cycle" aircraft. What would one consider as an acceptable number of expected lifetime flight cycles or flight hours for an airframe designed today?
Lastly...
When walking through the woods don't forget to look up.
Is it possible those are standard 2' drop ceiling tiles above this bomber? It looks like the lights are every 8 tiles apart. Looks bigger than 120' to me. And if I'm right, I'd appreciate the credit. ;-)
View attachment 688452
If we go by the person to the right wingtip, he is approx. 75 pixels tall. Lets call him "Tim". I assume that he is standing below the front wingtip, which means he is in the right plane for maximum span, wingtip to wingtip.
The wingspan of the B-21 is 1947 pixels, which is 25.96 Tims.
If Tim is 5ft tall, then that makes the B-21 129 ft span. If Tim is 6ft, then its 155ft span.
My money's on 150ft+.
Following up on this analysis.
The thrust from two F-135s is likely 56,000lb compared to 72,000lb for the B-2's 4 engines , which is roughly 75% of the thrust. I expect the weight of the B-21 to be roughly in the area of 75% the weight of the B-2.
But the Quail was built specifically to mimic the radar reflection of a B-52 or similar - McDonnell went out of their way in the design to do that. Nothing with its shape that can be construed as an effort at stealth, it was essentially a flying radar reflector.Just in passing and OT, but for the people still wondering if smaller/bigger size necessarily translates into smaller/bigger RCS, here's the ADM-20 Quail which was used as a decoy for B-52s in the 60s.