Northrop Grumman B-21 Raider (LRS-B)

[stealthflanker]

I guess it's gonna put some hefty premium for highspeed directional datalinking.

 

[marauder2048]

I guess it's gonna put some hefty premium for highspeed directional datalinking.

As opposed to the current hefty premium for highspeed directional datalinking?

 

[stealthflanker]

As opposed to the current hefty premium for highspeed directional datalinking?

Your point being ?

I might need to elaborate. What i mean with that is the Raider will have to carry its own phased array datalink antenna or relegate the job to its Attack radar. If it wish to control the drones 360, means there has to be multiple antenna. Each with its own boxes and they need cooling too. The longer it desires to control the drone (also with requirement for it to be high bandwidth which means high frequency or big antenna or both with power) This puts premium on space.

 

[marauder2048]

As opposed to the current hefty premium for highspeed directional datalinking?

Your point being ?

I might need to elaborate. What i mean with that is the Raider will have to carry its own phased array datalink antenna or relegate the job to its Attack radar. If it wish to control the drones 360, means there has to be multiple antenna. Each with its own boxes and they need cooling too. The longer it desires to control the drone (also with requirement for it to be high bandwidth which means high frequency or big antenna or both with power) This puts premium on space.

Yeah..that's IFDL or MADL or Super MADL (see the recent contract) or MIDAS.
Absolutely *nothing* of what you claimed above is true wrt to size, weight, power and cooling.

 

[stealthflanker]

Yeah..that's IFDL or MADL or Super MADL (see the recent contract) or MIDAS.
Absolutely *nothing* of what you claimed above is true wrt to size, weight, power and cooling.

Yeah, that was my bad. claiming hefty was my undoing. Apologize.

 

[marauder2048]

Yeah..that's IFDL or MADL or Super MADL (see the recent contract) or MIDAS.
Absolutely *nothing* of what you claimed above is true wrt to size, weight, power and cooling.

Yeah, that was my bad. claiming hefty was my undoing. Apologize.

No problem. IIRC, Harris stated that their revenue (I presume gross) for an
entire F-35 shipset including the 6 x MADL antenna/receiver units is $2.2 million.

 

[Josh_TN]

I’d think the harder part would be making a disposable drone with a directional datalink, since as pointed out there are fighter sized examples already. But I suppose the drone can be omnidirectional at a certain price point.

 

[Grey Havoc]

"B-21s With Air-To-Air Capabilities," Drones, Not 6th Gen Fighters To Dominate Future Air Combat

The Air Force's vision of the future of aerial combat has evolved greatly as of late and has moved away from plans for new, costly manned fighters.

www.thedrive.com

Trainwrecks everywhere.

 

[Sundog]

I never had any doubt the B-21 was going to have A2A capability. One, for self defense. Two, for the long ranges of the pacific. Given it's size, it should have an amazing radar system that can see farther out than fighters. The B-21 will be a super stealthy missileer, as just one of it's missions. So it will be able to patrol the Pacific. We're still going to have fighters, contrary to any piece at the Drive. It's really just a matter of what the mix is going to be and what size the fighters need to be. My guess is the fighters will be sized for basing in Australia, with regard to the Pacific. Australia is far enough away to give a decent warning time regarding an attack and big enough that forces can be repositioned.

 

[sublight_]

B-21 And Fighters Prepare For Disruptive Software-led Change | Aviation Week Network

U.S. Air Force thinks a software development shift will drive combat aircraft advances and change the defense industry business model.

aviationweek.com

A recipe for yet more disaster?

What do you view as problematic?

Open Source software / architecture has been more than a bit of a disappointment, not to mention that it is a security nightmare at the best of times. And these are far from the best of times.

Oh really? 2.5 billion Android phones would like a word with you. More than half the web servers on the planet would also like a word with you. A bazillion Linux users would like a word with you... Shall I go on?

 

[Grey Havoc]

Oh really? 2.5 billion Android phones would like a word with you. More than half the web servers on the planet would also like a word with you. A bazillion Linux users would like a word with you... Shall I go on?

Been a long time since Linux was considered to be automatically secure. Not to mention that recent distributions & developments have been mostly disappointing. Android was never secure, nor particularly robust for that matter.

 

[jsport]

A fighter all right

 

[Arjen]

Oh really? 2.5 billion Android phones would like a word with you. More than half the web servers on the planet would also like a word with you. A bazillion Linux users would like a word with you... Shall I go on?

Been a long time since Linux was considered to be automatically secure. Not to mention that recent distributions & developments have been mostly disappointing. Android was never secure, nor particularly robust for that matter.

No operating system is automatically secure, although OpenBSD users might argue it comes close. There is no reason why open source software should be any less secure than proprietary software - on the one hand you get 'many eyes watching' (open source) on the other hand you get 'security by obscurity' (proprietary software). The risk of 'security by obscurity' is that bugs found by malevolent parties stay obscure too, which means proprietary software's bugs can be exploited for longer periods. Which, frankly, scares the willies out of me.
B-21 systems adopting open source OS and/or software?
My employer handles very large amounts of confidential information, linux has been chosen as one of several operating systems to be used on servers in the future - with ever increasing use of linux. Performance and security were big considerations in the adoption of linux.

 

[marauder2048]

Oh really? 2.5 billion Android phones would like a word with you. More than half the web servers on the planet would also like a word with you. A bazillion Linux users would like a word with you... Shall I go on?

Been a long time since Linux was considered to be automatically secure. Not to mention that recent distributions & developments have been mostly disappointing. Android was never secure, nor particularly robust for that matter.

Android has gone the SELinux route and I think on DoD applications, Android is going to be a hypervisor'ed OS so
its ultimate security is less of an issue.

B-21 systems adopting open source OS and/or software?

There's nothing in the article about open source OS or software beyond containers. They are mainly talking about the government owning
the IP (source code, toolchain, system integration labs) for any {hard, firm, soft}ware that's under contract.

 

[Arjen]

I couldn't immediately reach the AW-piece, but now I have. The government striving for ownership of source code etc seems eminently sensible to me from the government's point of view. But. Agile development can be a blessing, a curse or anything in between. With the government involved? Hmmm.

 

[marauder2048]

But. Agile development can be a blessing, a curse or anything in between. With the government involved? Hmmm.

If you are striving to get early feedback from the operational community I'm not sure there's a better way.
Yes, they can come and sit in your high fidelity simulator but it's not really the same.

But it does shift the burden to the test ranges and flying test assets which have availability constraints.

 

[Josh_TN]

There seems to be a wider move inside the USAF to own their designs and software and not be reliant on single venders for open ended maintenance contracts. I'm not sure that is an achievable goal, but I can't blame them for trying. Procurement as it stands is horrible mess.

 

[marauder2048]

There seems to be a wider move inside the USAF to own their designs and software and not be reliant on single venders for open ended maintenance contracts. I'm not sure that is an achievable goal, but I can't blame them for trying. Procurement as it stands is horrible mess.

In an alternate universe where maskless lithography were cheap and high throughput, DOD might be in a very different
position vis-a-vis software.

It used to be the case that DOD was a major player in custom semiconductors but as the
mask and foundry costs have skyrocketed (for everyone) it made progressively less sense to expend huge sums
for like 200 ASICs.

 

[Arjen]

Agile development can be a blessing, a curse or anything in between. With the government involved? Hmmm.

If you are striving to get early feedback from the operational community I'm not sure there's a better way.

Best case, yes. FUBAR if you get it wrong.

 

[marauder2048]

Agile development can be a blessing, a curse or anything in between. With the government involved? Hmmm.

If you are striving to get early feedback from the operational community I'm not sure there's a better way.

Best case, yes. FUBAR if you get it wrong.

Why is that the case since this mainly about mission systems? Those don't typically have safety of flight implications.

 

[Arjen]

Any military aircraft is pretty much useless without functioning mission systems. Still, not quite as bad as having it fall from the sky because of failing avionics.

 

[marauder2048]

Any military aircraft is pretty much useless without functioning mission systems. Still, not quite as bad as having it fall from the sky because of failing avionics.

How is any of this relevant for operational test of mission systems?

If it's truly control laws or other FCS mods that's a different story but I don't see any indication they are proposing agile
methods for those.

 

[Arjen]

I do not / did not claim development of B-21's FCS will use agile methods. Mess up agile, and you simply do not get the return on investments you would like. We are straying off-topic.

 

[marauder2048]

Mess up agile, and you simply do not get the return on investments you would like. We are straying off-topic.

vs.

FUBAR if you get it wrong.

Hence my confusion.

 

[Arjen]

Messing up beyond recognition happens in the office too. Organisational hell ensues.

 

[Sundog]

B-21 Main Base 1 Beddown. It has some interesting information about noise and flight levels.

 

[Sundog]

My analysis of the B-21 is based off of the first two images shown below; the third is what I generated.

Northrop is known for releasing the silhouettes of their designs before we even know the aircraft's size, so I assumed the one shown in the logo is accurate, in much the same way they made that star image from B-2 planforms before the B-2 rolled out. Also, the image of the shadow in what I assume to be the production plant is what I used to scale the wingspan of 108 feet. I then used the reference wing area from my drawing, 2011 square feet compared to the B-2's 5140 square feet, to scale the fuel fraction with regard to the B-2. I also used the same scale factor to scale the empty weight. I assumed the crew weight and gear, etc., to be the same for the B-21 as with the B-2, which came out to be approximately 1000lbs. I assumed the payload was half that of a B-2, which is 40,000 lbs. normal and 50,000 lbs. overload for the B-2. So for the B-21, I used 20,000 lbs. for the standard payload and 25,000 lbs. for the overload condition. Which works out well, as another Aero Engineer who attended school with me and reviewed my work said he figured it should be able to carry one MOAB which weighs around 21,000 lbs.

I then used the aspect ratio and the wetted area aspect ratio from Raymer's book in the first chapter to estimate the max L/D. I also assumed the T/W ratio would be similar to that of the B-2. As a result, I determined the engine the B-2 would use would most likely be a version of the passport engine, the same one P&W is proposing to re-engine the B-52. That would greatly help the supply chain/maintenance depots to have that much commonality across the bomber fleet. Also, given the thrust needed for the B-21 and the thrust range available for the passport range, these engines can generate plenty of excess energy to power the onboard systems. The P&W data card also notes that the passport engine has ten percent better tsfc than comparable engines. So I just used the F-118's tsfc as reference, which is .67, which yields a tsfc for the B-21s engines of .603 . As a result, I get that B-21 will have approximately 1000 miles greater range than the B-2. The specifications are listed below. This is just my best guess based off of the currently available information. Take it with a grain of salt. I just thought it would be an interesting analysis.

	B-2		B-21
We (lbs):	158000		61817​
Wg (lbs):	376000		148155​
Wf(lbs):	167000		65338​
Wcrew (lbs):	1000		1000​
Wpayload (lbs):	50000		20000​
Engine Thrust (lbs/each):	17000		13397​
No. of Engines:	4		2​
Wingspan, b (ft.):	172		108​
Wing Area, S (sq. ft.)	5140		2011​
Wetted Area Ratio:	2.4		2.4​
Wetted Aspect Ratio:	2.4		2.4​
L/D (max):	22		22​
Wing Area Scale Factor:			0.39​
(used to scale fuel load)
Total Thrust (lbs):	68000		26794​
T/W Ratio (Take-off):	0.18		0.18​
Wing Loading (Take-off):	73.15		73.67​
Fuel Fraction:	0.44		0.44​
Payload Fraction:	0.13		0.13​
Aspect Ratio:	5.76​		5.80​
Loiter L/D:	22​		22​
Cruise L/D:	19.1​		19.1​
Cruise Speed (mph):	560​		560​
Max. Speed (mph):	630​		630​
Powerplant:	F118-GE-100		P&W PW800
Max Thrust (lbs):	19000​		18000​
sfc (lbf/(lbs*hr):	0.67​		0.603​
W1(lbs):			141621​
W2 (lbs):			89351​
Range (SM):	6900​		8149​
Range (NM):	6000​		7082​

 

[Bhurki]

50,000 lbs. overload for the B-2

B-2 carries 2xMOP in overload, thats 60,000 lbs
B21 shall carry 1 MOP, so 30k lbs.

I determined the engine the B-2 would use would most likely be a version of the passport engine, the same one P&W is proposing to re-engine the B-52.

Mr. Wittman said the B21 will have a variant of F135 engine(no reheat)

 

[Sundog]

50,000 lbs. overload for the B-2

B-2 carries 2xMOP in overload, thats 60,000 lbs
B21 shall carry 1 MOP, so 30k lbs.

I determined the engine the B-2 would use would most likely be a version of the passport engine, the same one P&W is proposing to re-engine the B-52.

Mr. Wittman said the B21 will have a variant of F135 engine(no reheat)

Who is Mr. Wittman? I would just like to see all of the info he has to offer. Also, thanks for the update on the MOP. I'll have to adjust the loadout accordingly. Although, there is talk of the next gen MOP being smaller with a rocket motor to achieve the same kinetic effect.

 

[Bhurki]

Who is Mr. Wittman?

HASC member. He stated back in 2018 that B21 would feature modified F135 engines.

Congressman Details Integration Issues With The B-21's Exotic Air Inlet Design

The representative provided more information than ever before on a number of "hiccups" the next generation stealth bomber project is facing.

www.thedrive.com

Lt.Gen Chris Bogdan, F35 program chief had hinted but not directly confirmed the same back in 2016.

 

[Bhurki]

Wingspan, b (ft.):172 108

Wingspan at 108 ft is too small.

If payload fraction is assumed to be the identical(due to largely similar shape) and total payload is reduced to 50% of B2, then every dimension of the jet will reduce about 20% (1/2^0.33, since mass∝volume and volume∝dimension³)
As such the wingspan should be about 130-140ft.

In terms of payload carriage, I think it'll feature a single bay the same size as the two on B-2 to make use of existing configurations (using the AF rotary launcher and so on).

 

[TomcatViP]

@apparition13 : if she has distributed propulsion (exhausts), the wings won't probably fold!

 

[Sundog]

Wingspan, b (ft.):172 108

Wingspan at 108 ft is too small.

If payload fraction is assumed to be the identical(due to largely similar shape) and total payload is reduced to 50% of B2, then every dimension of the jet will reduce about 20% (1/2^0.33, since mass∝volume and volume∝dimension³)
As such the wingspan should be about 130-140ft.

In terms of payload carriage, I think it'll feature a single bay the same size as the two on B-2 to make use of existing configurations (using the AF rotary launcher and so on).

OK, I read the article at the drive. The congressman didn't speculate about the engines, the Drive did. Two F-135s would generate too much thrust which would cut into range. I also assumed the design I have shown above would have the same size weapons bay as the B-2, hence half the load. Also, given that it has longer range than the standard B-2, I assume it wouldn't carry as much fuel to carry the MOP, so I'll stick with my original analysis.

 

[sublight_]

My analysis of the B-21 is based off of the first two images shown below; the third is what I generated...... (snip)

Where are your altitude figures? Does the B-21 not have a ceiling significantly higher that B-2? Remember that flutter from much longer wings was part of the risk reduction program. It think that changes your proposed dimensions significantly.

 

[sferrin]

Which works out well, as another Aero Engineer who attended school with me and reviewed my work said he figured it should be able to carry one MOAB which weighs around 21,000 lbs.

MOAB is shoved out the back of a C-130, and is not carried by any bomber. MOP (GBU-57), which is carried by the B-52 and B-2, weighs 30,000lbs.

MOAB


MOP (GBU-57)

 

[rooster]

My analysis of the B-21 is based off of the first two images shown below; the third is what I generated.

Dude. Your 20,000 pound payload is not even 8 agm86.

 

[rooster]

Wingspan, b (ft.):172 108

Wingspan at 108 ft is too small.

If payload fraction is assumed to be the identical(due to largely similar shape) and total payload is reduced to 50% of B2, then every dimension of the jet will reduce about 20% (1/2^0.33, since mass∝volume and volume∝dimension³)
As such the wingspan should be about 130-140ft.

In terms of payload carriage, I think it'll feature a single bay the same size as the two on B-2 to make use of existing configurations (using the AF rotary launcher and so on).

OK, I read the article at the drive. The congressman didn't speculate about the engines, the Drive did. Two F-135s would generate too much thrust which would cut into range. I also assumed the design I have shown above would have the same size weapons bay as the B-2, hence half the load. Also, given that it has longer range than the standard B-2, I assume it wouldn't carry as much fuel to carry the MOP, so I'll stick with my original analysis.

Too much thrust????? Yeah ok, considering that we can safely assume the 21 will need EXCESS thrust for flight control as deflecting surfaces increases RCS. I guess we may as well build a half scale b2 and call it a night.

 

[Sundog]

Which works out well, as another Aero Engineer who attended school with me and reviewed my work said he figured it should be able to carry one MOAB which weighs around 21,000 lbs.

MOAB is shoved out the back of a C-130, and is not carried by any bomber. MOP (GBU-57), which is carried by the B-52 and B-2, weighs 30,000lbs.

MOAB
View attachment 642335

MOP (GBU-57)
View attachment 642336

Yeah, meant MOP. Such is life.

 

[Sundog]

My analysis of the B-21 is based off of the first two images shown below; the third is what I generated...... (snip)

Where are your altitude figures? Does the B-21 not have a ceiling significantly higher that B-2? Remember that flutter from much longer wings was part of the risk reduction program. It think that changes your proposed dimensions significantly.

My understanding is that was Lockheed-Martin, not Northrop-Grumman. But that has to do with structural efficiency by lowering the structural weight of the wing. Also, you don't need high aspect ratio wings for high altitude. You need a large wing area. See the Avro Vulcan. The design I showed above is based off the information released by N-G in the images above, so far. If you have other information actual from them, please provide it. BTW, I assumed it would operate at 50,000 to 55,000 ft.

 

[Josh_TN]

Most observers agree the B-21 would have a higher ceiling given its superior shape (diamondback Tail vs sawtooth). I would also assume composite structures have advanced greatly since the b-2 was designed. 50-55k feet seems reasonable. Pretty sure even B-2 can hit that ceiling depending on load.