Northrop Grumman B-21 Raider (LRS-B)

[NMaude]

Could. Depends on how high you need to get for the bombs to reach terminal velocity.

You could definitely reach higher terminal speed if it included an SRM to accelerate it during its terminal dive.

 

[TomS]

You could definitely reach higher terminal speed if it included an SRM to accelerate it during its terminal dive.

Sure, and some penetrators do this. But they don't need extra altitude for that. Indeed, the optimum solution is to fire the rocket at the end of the weapon's flight, just a few thousand feet above the target, to ensure that it is all burnt just before impact.

 

[NMaude]

the optimum solution is to fire the rocket at the end of the weapon's flight, just a few thousand feet above the target, to ensure that it is all burnt just before impact.

I don't recall if it was in this thread or another but @Scott Kenny suggested something based on a BLU-109 with a Mk-72 booster attached in tandem with it.

 

[TomS]

I don't recalled if it was in this thread or another but @Scott Kenny suggested something based on a BLU-109 with a Mk-72 booster attached in tandem with it.

That's a rather crude solution. And you still have the issue of hanging the weapon on a pylon when the booster is several inches wider than the penetrator. There are more elegant ones. This Lockheed Martin patent describes a couple of options. A rocket motor literally wrapped around the penetrator is a really clever idea.

https://patents.google.com/patent/US6276277B1/en

 

[NMaude]

That's a rather crude solution.

Yes it is but it's available if you need a quick-and-dirty interim solution.

And you still have the issue of hanging the weapon on a pylon when the booster is several inches wider than the penetrator.

I've thought about it last year after Scott made his Mk-72 booster suggestion and it occurred to me that the SM-3 Block-II airframe could be used with the Mk-72 booster but the rest of airframe frame using only the casing (No pressure domes, blast-tubes, solid-propellant and liners) with the BLU-109 inside (It is 95" long and 14.5" wide) supported by internal bulkheads, wing-strakes and using a repackaged JDAM GCU to guide and control it with maybe an off-the-shelf terminal-homing seeker (AIM-9X seeker for example) for either aim-point selection or for hitting a moving target.​

 

[Scott Kenny]

That's a rather crude solution. And you still have the issue of hanging the weapon on a pylon when the booster is several inches wider than the penetrator.

It was strictly a military-off-the-shelf solution, for events like the original GBU-28 5000lb design.

Thinking about it now, the ESSM rocket would probably be best for a quick design.

There are more elegant ones. This Lockheed Martin patent describes a couple of options. A rocket motor literally wrapped around the penetrator is a really clever idea.

https://patents.google.com/patent/US6276277B1/en

That is going to be really bulky, unless you assume the weapon to be the diameter of a Mk84 and have a much narrower penetrator.

 

[Scott Kenny]

Oops, missed this.

You could definitely reach higher terminal speed if it included an SRM to accelerate it during its terminal dive.

Sorry, I meant "terminal velocity" in the aerodynamic sense, not in the sense of "velocity in terminal phase right before impact." The drag-limited speed of the bomb.

 

[NMaude]

Oops, missed this.

Sorry, I meant "terminal velocity" in the aerodynamic sense, not in the sense of "velocity in terminal phase right before impact." The drag-limited speed of the bomb.

Well if you fire the rocket-motor near the end so that it's still thrusting when the missile impacts the ground.

 

[Scott Kenny]

Well if you fire the rocket-motor near the end so that it's still thrusting when the missile impacts the ground.

Yes, that's what you'd want. Firing the rocket in the last ~5-10 seconds of flight. Firing the booster before then would mean the bomb would slow down before impact.

 

[TomS]

Yes, that's what you'd want. Firing the rocket in the last ~5-10 seconds of flight. Firing the booster before then would mean the bomb would slow down before impact.

That patent actually goes into this. It says the bomb would typically be free-falling at a hair over 1000 fps. The rocket would roughly double that, adding 1000 fps in just 1.2 seconds.

 

[TomS]

That is going to be really bulky, unless you assume the weapon to be the diameter of a Mk84 and have a much narrower penetrator.

That's exactly what they were talking about. Or at least the preferred embodiment is something like Figure 4 or 5.

As an example, a
bomb having rocket motor with an outer diameter of 17 inches and with a penetrator having a length of 94.5 inches can be made to emulate the shape, weight, and inertial
characteristics of the GBU-27.

The purpose of this design was to avoid an overly long weapon, which is what happens when you bolt the rocket on the back of the warhead.

 

[Josh_TN]

Durrandel had such an arrangement. It was a small anti runway munition.

 

[NMaude]

Durrandel had such an arrangement. It was a small anti runway munition.

Is it still in service?

 

[Josh_TN]

Is it still in service?

No, long gone. It was unguided. It was a French weapon that the US bought small quantities of.

https://en.wikipedia.org/wiki/Matra_Durandal

 

[4decaa]

https://insidedefense.com/daily-news/air-force-northrop-nearing-agreement-speed-b-21-productionAnyone have full access to this?

Be interested to see if Warden put out any new information here.

Warden said at Citi’s Global Industrial Tech and Mobility Conference today. The program is now transitioning to production, she added, with the company discussing a growth framework with the Air Force. “I am still optimistic... [paywall]

 

[FighterJock]

This will be good news for the B-21.

 

[JoshuaH]

https://insidedefense.com/daily-news/air-force-northrop-nearing-agreement-speed-b-21-productionAnyone have full access to this?

Be interested to see if Warden put out any new information here.

I think the full transcript is here: https://m.investing.com/news/transc...egic-growth-in-defense-93CH-4511635?ampMode=1

 

[CastleBravo]

Oops, missed this.

Sorry, I meant "terminal velocity" in the aerodynamic sense, not in the sense of "velocity in terminal phase right before impact." The drag-limited speed of the bomb.

If I pull up a terminal velocity calculator and plug in a rough estimate of a GBU-57 with a drag coefficient of 0.15, a mass of 30klbs, and a frontal cross-section of .7m^2, I get a terminal velocity of over 1,400m/s.

With no drag, an object accelerating at 1g for 45,000ft will reach ~520m/s. From 65,000ft, it would be 620m/s. If the guided bomb can generate some decent lift/drag, it can also convert some of its Mach .85 forward velocity to vertical.

 

[Not James Stockdale]

Would a bomb with that shape have an issue with transonic drag? Do they normally impact at supersonic velocities?

 

[OliverSedlacek]

I don't know how subsonic drag coefficients relate to transonic and supersonic drag but I'd concur that it's going to be supersonic when it reaches the ground.

 

[CastleBravo]

Would a bomb with that shape have an issue with transonic drag? Do they normally impact at supersonic velocities?

Tallboy didn't have a problem with transonic drag; it hit at Mach 1.2 when dropped from 30,000ft. Dropping from higher up would allow the bomb to pass the transonic region at a higher altitude where there is less air/drag as well.

 

[Flyaway]

https://aviationweek.com/defense/ai...-links-acceleration-b-21-proposed-order-boost

 

[FighterJock]

It will be interesting to see what happens to the B-21 order boost, I have always wanted to see more Raiders ordered than the current USAF allocated order.

 

[Josh_TN]

An increase in production rate always made sense to me. The B-21 is one of the few capabilities the U.S. still has a clear lead in and bombers in particular are going to be essential to delivering large numbers of munitions over extended ranges. All the development work is largely paid for; increasing production to maximize that investment (and retire those worn out B-1s) always seemed like an obvious choice to me.

 

[SlothmanAllen]

I wonder if the Republicans will be able to pass the proposed additional $450 billion reconciliation bill for the DoD? Bringing defense spending to 5% of GDP would likely significantly alter force sizes across the entire Air Force. B-21 production could potentially be accelerated beyond what is proposed above.

 

[Sferrin]

That's a rather crude solution. And you still have the issue of hanging the weapon on a pylon when the booster is several inches wider than the penetrator. There are more elegant ones. This Lockheed Martin patent describes a couple of options. A rocket motor literally wrapped around the penetrator is a really clever idea.

https://patents.google.com/patent/US6276277B1/en

There have been several antitank missile concepts like that as well.

https://patents.google.com/patent/US8119956B2/en

 

[Josh_TN]

I wonder if the Republicans will be able to pass the proposed additional $450 billion reconciliation bill for the DoD? Bringing defense spending to 5% of GDP would likely significantly alter force sizes across the entire Air Force. B-21 production could potentially be accelerated beyond what is proposed above.

They will not, at least not before November, and it seems unlikely they control the House post November. Increasing the defense budget would run up against the affordability issue in an election year. The 1 trillion figure was just a made up number with no basis in reality.

That said, the last budget already increased money for B-21 with the intention of increasing production rate.

 

[flateric]

https://news.northropgrumman.com/b-21/northrop-grumman-accelerating-b-21-raider-production

 

[NMaude]

I wonder how many airframes NG has rolled out so far?

 

[JoshuaH]

The accompanying DAF announcement:
https://www.af.mil/News/Article-Dis...n-capacity-to-deliver-combat-capability-fast/
25% acceleration in production rate, estimated first delivery to Ellsworth in 2027.

 

[Sferrin]

https://media.defense.gov/2026/Feb/23/2003879259/-1/-1/0/250911-F-AF000-1100.JPG

 

[SlothmanAllen]

They will not, at least not before November, and it seems unlikely they control the House post November. Increasing the defense budget would run up against the affordability issue in an election year. The 1 trillion figure was just a made up number with no basis in reality.

That said, the last budget already increased money for B-21 with the intention of increasing production rate.

I thought with reconciliation they can pass the bill without Democrat support? I guess you are saying that they have no chance of doing so before the November deadline?

 

[Training_Dummy]

The supply chain doomers in a tailspain. Love to see it. You know who you are.

 

[Josh_TN]

I thought with reconciliation they can pass the bill without Democrat support? I guess you are saying that they have no chance of doing so before the November deadline?

The Freedom Caucus would vote against it, along with every Republican in a vulnerable seat. Senate would shoot it down too. But several extra billion was already allocated explicitly to speed B-21 production rate.

 

[NMaude]

The Freedom Caucus would vote against it,

I want to see the Free-Dumb caucus go down in flames. Interfering with B-21 funding would definitely cost them.

 

[joshjosh]

A 25% increase is actually rather disappointing. This will have a marginal impact.

 

[bring_it_on]

It adds 20+ aircraft to the production program keeping timelines basically the same. If they want to increase it further, they would probably want to wait for this particular bump and additional learning curve efficiencies to be realized. And obviously find additonal funding to take beyond 125 or so aircraft. And also, since this is a rate increase, future DAF budgets have to support those higher annual quantities. I think there was some reporting that plans were to buy 7 B-21's a year at planned peak rates.This would take it to nearly 9 aircraft or an additional $2 Bn or so per year.

 

[FighterJock]

Quite bring_it_on, additional funding will come given time.

 

[Grey Havoc]

I strongly do not believe that the US would be willing to have unmanned nuclear bombers.

Originally, the LRS-B / B-21 was planned as an optionally manned platform, ostensibly as a means for extended range operations.

 

[Josh_TN]

A 25% increase is actually rather disappointing. This will have a marginal impact.

25% is rather impressive for a platform of that size and complexity. Look at how hard expanding the production of missiles has been. You cannot just double a complicated systems output overnight when its program was already built around a lower level. Think of all of the subcontractors and long lead items involved in something as complex as an intercontinental stealth bomber.