Northrop Grumman B-21 Raider (LRS-B)

Orbital ATK - Antennas and other good stuff!

"Orbital ​ATK's industry leadership in high-strength, lightweight composite materials makes it the partner of choice to develop and fabricate technically complex components for military aircraft. Key products include:

Stabilators, pivot shafts and inlet bypass screens for the Lockheed Martin F-22 Raptor.
Upper and lower wing skins, straps, engines nacelles, covers and inlet ducts for the Lockheed Martin F-35 Joint Strike Fighter
Low-observable antennas for the Lockheed Martin F-117 Nighthawk stealth fighter, the Northrop Grumman B-2 Spirit stealth bomber and other tactical aircraft
Solid-state radar and communications radomes for the Northrop Grumman Global Hawk unmanned aerial vehicle and the MESA radar system on the Boeing 737 Airborne Early Warning and Control aircraft.
Counterbalance assemblies for the Boeing C-17 Globemaster II aircraft.
Precision optical benches for Northrop Grumman's high-energy laser used in the Airborne Laser (ABL) missile defense system on board a modified Boeing 747 aircraft."

Love that last one...
 
Rockwell - Nav, comms cockpit display, new VLF one-way comms?

www.airforce-technology.com

B-2 Spirit Stealth Bomber, United States of America

Northrop Grumman is the prime contractor for the US Air Force B-2 Spirit stealth bomber. The B2 stealth bomber can penetrate air-defence shields.
www.airforce-technology.com www.airforce-technology.com

"The B-2's navigation suite includes a Rockwell Collins TCN-250 tactical air navigation system (TACAN) and a VIR-130A instrument landing system.

"The B-2 Spirit stealth bomber has the capacity to carry up to 40,000lb of weapons, including conventional and nuclear weapons."
The communications equipment is supplied by Rockwell Collins. A Milstar military strategic and tactical relay satellite communications system is installed in block 30 aircraft.

The aircraft have been upgraded with Link 16 communications link."

www.dailyairforce.com

Dailyairforce.com is for sale | HugeDomains

Get full access to this domain. Easy, seamless transactions. Zero percent financing available.
www.dailyairforce.com

"Communications experts at Rockwell Collins Inc. in Richardson, Texas, are starting full-scale development of a very low frequency (VLF) aviation radio for the U.S. Air Force B-2 Spirit strategic bomber to enable the aircraft crew to communicate with national command authorities while on long-range missions."
 
Spirit AeroSystems - The Wichita aircraft parts maker created when Boeing Co. spun off its Wichita commercial airplane business. Largest first-tier aerostructures manufacturer. (wiki)

Spirit Aerosystems is a major supplier of fuselages and other components for planes built by Boeing and Airbus.

"Spirit AeroSystems hopes to use the defense programs it has participated in so far to build a larger portfolio of defense work

▪ P-8A Poseidon: Spirit builds the fuselage of the Navy surveillance and anti-submarine jet, which is based off the Boeing 737-800. Boeing is under contract to deliver 62 of the airplanes to the Navy, with 31 deliveries completed.

▪ KC-46A Pegasus air refueling tanker: Spirit builds the forward fuselage and other parts of the next-generation tanker that is based off the Boeing 767. Boeing plans to manufacture 179 tankers for the Air Force.

▪ CH-53K King Stallion helicopter: Spirit builds the composite fuselage of the next-generation heavy lift helicopter destined for the Marine Corps. Spirit has delivered 11 of the fuselages to Sikorsky, which is expected to deliver up to 200 of the helicopters to the Marines.

▪ V-280 Valor tilt-rotor: Spirit delivered the first fuselage of the Bell Helicopter-Lockheed Martin prototype aimed to compete in the Army’s Future Vertical Lift program, which aims to replace the Army’s fleet of 2,000 medium-class utility and attack helicopters. The Army program has not been funded nor has a contract been awarded.

Read more here: http://www.kansas.com/news/business/aviation/article47621165.html#storylink=cpy

If I'm not mistaken NG partnered with Boeing to build the big autoclave for the B-2 wings. Perhaps this is better than working with Boeing? It's interesting to partner with Spirit when NG is building the center fuselage for the F-35. On the other hand, this is pretty low production. Farming this out makes sense. NG also get's access to all Spirits expertise.

I wonder if they'll ask Spirit to build at 42? That would be convenient.
 
 
NeilChapman said:
"very low frequency (VLF) aviation radio for the U.S. Air Force B-2 Spirit strategic bomber to enable the aircraft crew to communicate with national command authorities while on long-range missions."
Click to expand...

To enable the crew to still receive commands when everything else has been obliterated or jammed.
 
Tidbits about engines.

"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"

www.flightglobal.com

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 www.flightglobal.com

Other interesting details on the P&W Geared Turbofan engine suggested to be part of B-21 program. Looks like P&W can easily scale this design way up (100,000 lbs thrust).

www.bloomberg.com

The Little Gear That Could Reshape the Jet Engine

A simple idea’s almost 30-year, $10 billion journey to the aircraft mainstream.
www.bloomberg.com www.bloomberg.com


rpdefense.over-blog.com

P&W gears up for next-generation military engine - RP Defense

31/05/11 By Stephen Trimble Flight International Not too long ago - October 2007, to be precise - engine maker Pratt & Whitney seemed painted into a strategically perilous corner. New requirements were emerging for next-generation bombers, sixth-generation...
rpdefense.over-blog.com rpdefense.over-blog.com

books.google.com

Breakthrough: The Geared Turbofan from Pratt & Whitney

Pratt & Whitney was at one time the dominant player in commercial aircraft engines, only to lose market leadership to GE and CFM International over the past two decades. After an extended 20 year period of research and development on a new architecture that proved fruitful, P&W is poised for a...
books.google.com

 
sublight is back said:
NeilChapman said:
"very low frequency (VLF) aviation radio for the U.S. Air Force B-2 Spirit strategic bomber to enable the aircraft crew to communicate with national command authorities while on long-range missions."
Click to expand...

To enable the crew to still receive commands when everything else has been obliterated or jammed.
Click to expand...

I understand it's the same system used on the Ohio-class boomers.
 
bobbymike said:
http://nationalinterest.org/blog/the-buzz/revealed-behind-the-shadowy-b-21-stealth-bombers-veil-15450
Click to expand...

I'm not sure I understand what we don't know about the pricing. There was a "not to exceed" cost for production. AF projected EMD at ~$21B and NG projected costs came in significantly lower than that. AF has already lowered EMD expectations in budget and the funds reallocated.

What else is necessary at this point? There's nothing to know until EMD is finished.
 
Grey Havoc said:
www.flightglobal.com

F-35 chief expects P&W's bomber work to reduce F135 cost

The head of the multinational F-35 Joint Strike Fighter programme expects Pratt & Whitney to significantly reduce the cost of the F135 now that it has been named as the propulsion system supplier for the Northrop Grumman B-21 bomber.
www.flightglobal.com www.flightglobal.com
Click to expand...

That would seem to answer both which engine and how many. I can't imagine it being large enough to require 4 non-afterburning F135s.
 
Last edited by a moderator:
breakingdefense.com

B-21 And F-35 Engines May Share Tech; Pratt Won't Talk - Breaking Defense

WASHINGTON: The B-21 bomber probably uses some common technologies and equipment to that used for the Joint Strike Fighter’s F135 engine. We can’t be certain because no one will confirm it. But Lt. Gen. Chris Bogdan, head of the F-35 program, did tell the annual McAleese/Credit Suisse conference...
breakingdefense.com breakingdefense.com

While nothing has been said publicly about the B-21’s speed or range capabilities, I’ve heard from one source that the B-21 will be extremely fast (no, no numbers) and that would be consistent with the use of the fighter-jet core. Also, there’s the research that’s been going for more than five years into advanced engines known as the Adaptive Engine Transition Program.
 
bobbymike said:
http://breakingdefense.com/2016/03/b-21-and-f-35-engines-may-share-tech-pratt-wont-talk/

While nothing has been said publicly about the B-21’s speed or range capabilities, I’ve heard from one source that the B-21 will be extremely fast (no, no numbers) and that would be consistent with the use of the fighter-jet core. Also, there’s the research that’s been going for more than five years into advanced engines known as the Adaptive Engine Transition Program.
Click to expand...

Pretty sure the "one source" is talking smack. The B-2 also use a "fighter-jet core" (F118 uses the core of the F110). Come to think of it so did all the B-52s.
 
sferrin said:
bobbymike said:
http://breakingdefense.com/2016/03/b-21-and-f-35-engines-may-share-tech-pratt-wont-talk/

While nothing has been said publicly about the B-21’s speed or range capabilities, I’ve heard from one source that the B-21 will be extremely fast (no, no numbers) and that would be consistent with the use of the fighter-jet core. Also, there’s the research that’s been going for more than five years into advanced engines known as the Adaptive Engine Transition Program.
Click to expand...

Pretty sure the "one source" is talking smack. The B-2 also use a "fighter-jet core" (F118 uses the core of the F110). Come to think of it so did all the B-52s.
Click to expand...
Wouldn't it be neat, IMO, if they rolled our a Mach 3+ strike bomber and said "Ya that first picture was disinformation"

I know won't happen but still......
 
sferrin said:
Grey Havoc said:
Grey Havoc said:
https://www.flightglobal.com/news/articles/f-35-chief-expects-pws-bomber-work-to-reduce-f135-423013/
Click to expand...
Click to expand...

That would seem to answer both which engine and how many. I can't imagine it being large enough to require 4 non-afterburning F135s.
Click to expand...

I guess the question is -

  • Off-the-shelf F135 complete engine (minus afterburner) @ 28,000lb
  • Off the shelf F135 fan with a smaller PW1000G derived core for a higher bypass ratio @ 20,000lb
  • Off the shelf F135 core with a larger fan @ >30,000lb

SFC of the F135 is generally quoted at 0.866, which seems ridiculously high.

A bypass ratio of 0.57:1 and overall pressure ratio of 28 compares nicely to the Russian Lyulka AL-31F. Made with much older technology, it has bypass ratio of 0.59:1 and OPR 23 and has mil SFC of 0.67 - 0.7 depending on version. I can't really see how the F135 can be less fuel efficient.
 
F135-PW-600 derived?
Use the drive shafts to turn electrical power generators instead of lift fans?
DEW, AESA... "other things" may be electrically thirsty.
 
PaulMM (Overscan) said:
sferrin said:
Grey Havoc said:
Grey Havoc said:
https://www.flightglobal.com/news/articles/f-35-chief-expects-pws-bomber-work-to-reduce-f135-423013/
Click to expand...
Click to expand...

That would seem to answer both which engine and how many. I can't imagine it being large enough to require 4 non-afterburning F135s.
Click to expand...

I guess the question is -

  • Off-the-shelf F135 complete engine (minus afterburner) @ 28,000lb
  • Off the shelf F135 fan with a smaller PW1000G derived core for a higher bypass ratio @ 20,000lb
  • Off the shelf F135 core with a larger fan @ >30,000lb
Click to expand...

Is a F135-style low spool with a PW1000G core not possible for 30-40k lb thrust class?
 
NeilChapman said:
PaulMM (Overscan) said:
sferrin said:
Grey Havoc said:
Grey Havoc said:
https://www.flightglobal.com/news/articles/f-35-chief-expects-pws-bomber-work-to-reduce-f135-423013/
Click to expand...
Click to expand...

That would seem to answer both which engine and how many. I can't imagine it being large enough to require 4 non-afterburning F135s.
Click to expand...

I guess the question is -

  • Off-the-shelf F135 complete engine (minus afterburner) @ 28,000lb
  • Off the shelf F135 fan with a smaller PW1000G derived core for a higher bypass ratio @ 20,000lb
  • Off the shelf F135 core with a larger fan @ >30,000lb
Click to expand...

Is a F135-style low spool with a PW1000G core not possible for 30-40k lb thrust class?
Click to expand...

Yes, given a larger core which keeps the overall design to a low bypass ratio. Not sure it would need any more than 30,000lb thrust though.
 
bobbymike said:
http://breakingdefense.com/2016/03/b-21-and-f-35-engines-may-share-tech-pratt-wont-talk/

While nothing has been said publicly about the B-21’s speed or range capabilities, I’ve heard from one source that the B-21 will be extremely fast (no, no numbers) and that would be consistent with the use of the fighter-jet core. Also, there’s the research that’s been going for more than five years into advanced engines known as the Adaptive Engine Transition Program.
Click to expand...

What is extremely fast? Will it supercruise? I'm sure there are a host of bomber pilots that would welcome relief from 30+ hour bombing runs.
Or by fast do you mean "accelerates quickly through high subsonic speeds?"

I'd like to understand if it's possible to have a flying wing supercruise. Will one of the AE's help me out?

On the engines from what I've been reading looks like three options - with risk based on development timeframe, depends if this info correct and what level of risk/performance NG was willing to assume.

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) 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.

My thoughts are on #1 and #2. Since PW hinted at the work several years ago I'm leaning toward #2 with the likelihood that PW has gotten more than 25k lb thrust from the engine in the last few years.

We shall see!
 
Here's some scientific wild-ass guesses:

Empty Weight: 110,000lb
Fuel: 110,000lb
Max Takeoff Weight: 250,000lb
Max Payload: 28,000lb (14 x 2000lb JDAM)*
Engines: 2 x P&W F135, 28,000lb st each
Range: 5,000nm (B-1B class)

(14 JDAMs load given by Northrop in 2018 Bomber paper (1120 JDAMs delivered by NGLRS fleet = 80 available aircraft x 14)
 
One thing to think about is that the ADVENT engine is probably going to be sized similar to the F-135. The USAF may have gone with the F-135 as a short term solution, pending ADVENT development next decade. This would also strongly suggest that any F-X program would use ADVENT as well.

For speed, there was some talk of supersonic dash, but that seems to be unlikely. NeilChapman - I would be the problem is aero-elastics on the bomber wings. Going high transonic / low supersonic will require stiffer wings, which decreases their aerodynamic efficiency.
 
Can a flying wing design go supersonic even if for only short periods of time?

I am really starting to wonder just how accurate that initial design sketch was at all.
 
Flyaway said:
Can a flying wing design go supersonic even if for only short periods of time?
Click to expand...

Yes. With the right wing. (It ain't gonna look like a B-2 or any of the others we're use to seeing. More of a delta I'd think.)
 
For example, Taranis is supersonic and it's vaguely the same shape as the B-21 (a single sawtooth flying wing). But the sweep angle is very telling -- Taranis is much more swept than a classic flying wing like the B-2, and that has to do with Mach numbers. If the B-21 is as much like the B-2 as that initial render suggests, it's solidly subsonic.
 
TomS said:
For example, Taranis is supersonic and it's vaguely the same shape as the B-21 (a single sawtooth flying wing). But the sweep angle is very telling -- Taranis is much more swept than a classic flying wing like the B-2, and that has to do with Mach numbers. If the B-21 is as much like the B-2 as that initial render suggests, it's solidly subsonic.
Click to expand...

I think there's a chance B-21 is more highly swept (say, 45 degrees) and the angle chosen for the render was intended to disguise this, like with the first F-117 image.
 
Thanks all! I didn't think the B-21 would deviate much from the B-2 mission/performance requirements. Too much program risk. But I do perceive a need for it to accelerate quickly while remaining stealthy.

I haven't seen anything about upgrades to the Nuclear/Biological protection systems in B-2 or B-52. If there hasn't been I'd perceive this as a high risk issue for EMD. Last time it was done was 25 years ago. Does anyone know if these systems have been incrementally upgraded like we've seen with avionics/comms/EWS etc that would reduce risk in EMD for construction time and costs?

Understand the Passive Thermal Protection Panels in B-2 take a while to install which is a factor for mission prep times. Are there new solutions for this tech?

PaulMM - "I think there's a chance B-21 is more highly swept (say, 45 degrees) and the angle chosen for the render was intended to disguise this, like with the first F-117 image."

Would that look more like the aircraft in the commercial?

All - Has anyone critically analyzed the difference in what we perceived on the commercial and the AF released picture? We just seemed to brush over it. Any photographers or engineers that can explain the difference (lighting? Angles?) - or was it just a different design?
 
PaulMM (Overscan) said:
Here's some scientific wild-ass guesses:

Empty Weight: 110,000lb
Fuel: 110,000lb
Max Takeoff Weight: 250,000lb
Max Payload: 28,000lb (14 x 2000lb JDAM)*
Engines: 2 x P&W F135, 28,000lb st each
Range: 5,000nm (B-1B class)

(14 JDAMs load given by Northrop in 2018 Bomber paper (1120 JDAMs delivered by NGLRS fleet = 80 available aircraft x 14)
Click to expand...

I read "somewhere??" that according to the New START treaty heavy bombers were limited to "some" range. Now I can't find that anywhere. Does anyone know if this is true or not? New START ends in 2021 so for B-21 it's moot.
 
Flyaway said:
Penalty for breaking Northrop's B-21 contract is '$300 million'

www.flightglobal.com

Penalty for breaking Northrop's B-21 contract is '$300 million'

The US Air Force says it would cost the US government upward of $300 million to breaks its cost-plus contract with Northrop Grumman to develop the B-21 strategic bomber.
www.flightglobal.com www.flightglobal.com
Click to expand...

I get why Sen. McCain doesn't want cost plus contracts - duh. But he's known about this for how long? And now he's squawking about it? And if he claims he didn't know then he's seriously been not paying attention - ahhhh... his oversight job. LRS-B has been one if the largest new aircraft programs for the AF in the last few years.

I hope someone calls him on it. Bad form Senator.
 
NeilChapman said:
PaulMM (Overscan) said:
Here's some scientific wild-ass guesses:

Empty Weight: 110,000lb
Fuel: 110,000lb
Max Takeoff Weight: 250,000lb
Max Payload: 28,000lb (14 x 2000lb JDAM)*
Engines: 2 x P&W F135, 28,000lb st each
Range: 5,000nm (B-1B class)

(14 JDAMs load given by Northrop in 2018 Bomber paper (1120 JDAMs delivered by NGLRS fleet = 80 available aircraft x 14)
Click to expand...

I read "somewhere??" that according to the New START treaty heavy bombers were limited to "some" range. Now I can't find that anywhere. Does anyone know if this is true or not? New START ends in 2021 so for B-21 it's moot.
Click to expand...

The treaty doesn't define maximums but the minimum range to be considered a "heavy bomber" (greater than 8,000 km unrefueled).

I would think the Air Force would have to assume that the option to extend the treaty to 2026 is in fact exercised.
 
NeilChapman said:
I read "somewhere??" that according to the New START treaty heavy bombers were limited to "some" range. Now I can't find that anywhere. Does anyone know if this is true or not? New START ends in 2021 so for B-21 it's moot.
Click to expand...

The definition of a heavy bomber is in the treaty's Protocol:

23. (80.) The term "heavy bomber" means a bomber of a type,
any one of which satisfies either of the following criteria:
(a) Its range is greater than 8000 kilometers; or
(b) It is equipped for long-range nuclear ALCMs.

A bomber shall not be considered to be a heavy bomber if
it meets neither criterion (a) nor criterion (b) or if
otherwise agreed by the Parties.

24. (81.) The term "heavy bomber equipped for non-nuclear
armaments" means a heavy bomber that is not equipped for long-range
nuclear ALCMs, nuclear air-to-surface missiles, or
nuclear bombs.

25. (82.) The term "heavy bomber equipped for nuclear
armaments" means a heavy bomber equipped for long-range
nuclear ALCMs, nuclear air-to-surface missiles, or nuclear
bombs.
Click to expand...

So basically, if your bomber has a range of more than 8-000 km (~4300 nm), it is a heavy bomber. If it has a range of less than that and can carry long-range nuclear cruise missile, it also counts.
 
NeilChapman said:
Flyaway said:
Penalty for breaking Northrop's B-21 contract is '$300 million'

https://www.flightglobal.com/news/articles/penalty-for-breaking-northrops-b-21-contract-is-3-422960/
Click to expand...

I get why Sen. McCain doesn't want cost plus contracts - duh. But he's known about this for how long? And now he's squawking about it? And if he claims he didn't know then he's seriously been not paying attention - ahhhh... his oversight job. LRS-B has been one if the largest new aircraft programs for the AF in the last few years.

I hope someone calls him on it. Bad form Senator.
Click to expand...

It's an election year for McCain that looks like it's going to be particularly bruising (primary and general).
One of the unacknowledged losers in Boeing's bomber bid is surely Raytheon which has a huge presence in his state.
 
marauder2048 said:
NeilChapman said:
Flyaway said:
Penalty for breaking Northrop's B-21 contract is '$300 million'

https://www.flightglobal.com/news/articles/penalty-for-breaking-northrops-b-21-contract-is-3-422960/
Click to expand...

I get why Sen. McCain doesn't want cost plus contracts - duh. But he's known about this for how long? And now he's squawking about it? And if he claims he didn't know then he's seriously been not paying attention - ahhhh... his oversight job. LRS-B has been one if the largest new aircraft programs for the AF in the last few years.

I hope someone calls him on it. Bad form Senator.
Click to expand...

It's an election year for McCain that looks like it's going to be particularly bruising (primary and general).
One of the unacknowledged losers in Boeing's bomber bid is surely Raytheon which has a huge presence in his state.
Click to expand...

As long as it's all bark I guess I could care less. It does open him up to questions about his oversight performance.

TomS - You da' Man! I knew I read it somewhere. Just couldn't find it. Thanks!
 
PaulMM (Overscan) said:
TomS said:
For example, Taranis is supersonic and it's vaguely the same shape as the B-21 (a single sawtooth flying wing). But the sweep angle is very telling -- Taranis is much more swept than a classic flying wing like the B-2, and that has to do with Mach numbers. If the B-21 is as much like the B-2 as that initial render suggests, it's solidly subsonic.
Click to expand...

I think there's a chance B-21 is more highly swept (say, 45 degrees) and the angle chosen for the render was intended to disguise this, like with the first F-117 image.
Click to expand...

I am thinking you're right here judging by the careful wording used when the image was released. I can see something like this being hidden.
 
PaulMM (Overscan) said:
TomS said:
For example, Taranis is supersonic and it's vaguely the same shape as the B-21 (a single sawtooth flying wing). But the sweep angle is very telling -- Taranis is much more swept than a classic flying wing like the B-2, and that has to do with Mach numbers. If the B-21 is as much like the B-2 as that initial render suggests, it's solidly subsonic.
Click to expand...

I think there's a chance B-21 is more highly swept (say, 45 degrees) and the angle chosen for the render was intended to disguise this, like with the first F-117 image.
Click to expand...

What would be the most logical advantage of a more highly swept wing, speed, range or stealth? a combination? Something completely different - EWS performance?
 
I don't think higher sweep necessarily means higher cruise speed requirement.
Airliners cruise around M0.8, just below drag rise, with very limited sweep- way less than the B-2. Having even more sweep would theoretically allow you to have really thick airfoils and still stay below drag rise, but i don't see it. The reason airliners try to unsweep the wing is because it gives better L/D.
Because of the way transsonic drag rises, you get diminishing returns for trying to fly faster. The B-21 needs a lot of range and cruise efficiency is at a premium. No, if NG incorporated more sweep, it's because of signature, IMHO.
 
AeroFranz said:
I don't think higher sweep necessarily means higher cruise speed requirement.
Airliners cruise around M0.8, just below drag rise, with very limited sweep- way less than the B-2. Having even more sweep would theoretically allow you to have really thick airfoils and still stay below drag rise, but i don't see it. The reason airliners try to unsweep the wing is because it gives better L/D.
Because of the way transsonic drag rises, you get diminishing returns for trying to fly faster. The B-21 needs a lot of range and cruise efficiency is at a premium. No, if NG incorporated more sweep, it's because of signature, IMHO.
Click to expand...

Indeed, just look at the F-117.
 
Sundog said:
AeroFranz said:
I don't think higher sweep necessarily means higher cruise speed requirement.
Airliners cruise around M0.8, just below drag rise, with very limited sweep- way less than the B-2. Having even more sweep would theoretically allow you to have really thick airfoils and still stay below drag rise, but i don't see it. The reason airliners try to unsweep the wing is because it gives better L/D.
Because of the way transsonic drag rises, you get diminishing returns for trying to fly faster. The B-21 needs a lot of range and cruise efficiency is at a premium. No, if NG incorporated more sweep, it's because of signature, IMHO.
Click to expand...

Indeed, just look at the F-117.
Click to expand...

Yep. If someone had flashed this around in 1984 and said it was a TAV. . .
 

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AeroFranz said:
I don't think higher sweep necessarily means higher cruise speed requirement.
Airliners cruise around M0.8, just below drag rise, with very limited sweep- way less than the B-2. Having even more sweep would theoretically allow you to have really thick airfoils and still stay below drag rise, but i don't see it. The reason airliners try to unsweep the wing is because it gives better L/D.
Because of the way transsonic drag rises, you get diminishing returns for trying to fly faster. The B-21 needs a lot of range and cruise efficiency is at a premium. No, if NG incorporated more sweep, it's because of signature, IMHO.
Click to expand...

It depends if you think it's the same kind of thing as a B-2 & I am not convinced it is. The B-21 maybe more like a heavy attack aircraft rather than just pure global bomber and therefore things like air to air capability and high dash speed may come into play for its design.
 
Flyaway said:
The B-21 maybe more like a heavy attack aircraft rather than just pure global bomber and therefore things like air to air capability and high dash speed may come into play for its design.
Click to expand...
BS
 

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