US Next Generation Bomber Studies

[Jeb]

"A loadout of AMRAAMs in an otherwise less-than-usable space is a relatively small investment in the overall design and if they never get fired, that's OK, but they'd be a damn useful secondary."

I understand where you are coming from, but there is no such thing as "less-than-usable space" in modern aircraft design, especially one that fits a "box" more than 12 feet long and probably a third as wide and tall.
Take any cutaway of modern combat aircraft from 1950 onwards and there is no "empty space" anywhere. If you have a cubic foot available, someone will cram in avionics or systems.
Having to cater for an additional weapons bay, door actuators, extender trapeze, power, heavier empty weight (weapons bays are giant holes in your structures, which structural designers abhor) , plus making sure you have enough cg range, to live with and without the weapons aboard in every corner of the flight envelope and combination of remaining fuel/bombs, is a major PITA. If you get to the point where you have empty space, it's because you could have made the vehicle smaller/lighter/cheaper in the first place.

Yeah, poor choice of words on my part. What I was getting at was more that if they want to have the secondary role, this forward space is ideal for the missile loadout. It could even possibly be used for an alternative load...SDBs or something.

 

[kagemusha]

It has only two engines, with serpentine ducts for both the inlets and nozzles. No afterburner?

 

[sublight_]

RFP has been issued

http://aviationweek.com/awin-only/rfps-issued-usaf-bomber-competition

This is behind a paywall.

 

[sublight_]

It seems to me this would have a rather attention getting acoustic and thermal signature at mach2. Is the plan to dash close to target at Mach2 and then go subsonic over contested territory?

 

[bobbymike]

As mentioned it makes one opine about CONOPS. Does the Air Force envision some off board cueing systems (AWACS, networked F-35s, F-22s, stealthy UAVs) allowing the NGB to sneak close to the enemies CAP and 'surprise' launch a bunch of AMRAAMs?

I think the best answer to that is the one Donnage gave up thread. The vehicle cruises at Mach 2.5 for 4000nm. (2000n.m. radius). There isn't anything available that can escort it over the entire mission so it needs to have a self defense capability. It could also double as an excellent long range interceptor.

Thank you, one other question;

1) If the NGB will be alone or maybe in a pair, is it or could it be technologically feasible to pass targeting information from a space based radar to an aircraft so it could remain 'electronically silent' and then to target other aircraft?

 

[quellish]

Thank you, one other question;

1) If the NGB will be alone or maybe in a pair, is it or could it be technologically feasible to pass targeting information from a space based radar to an aircraft so it could remain 'electronically silent' and then to target other aircraft?

Yes. And the space based radar could act as a bistatic illuminator

 

[marauder2048]

Consider the rate of closure between this aircraft and a supersonic, low RCS interceptor.
Combine this with the much reduced detection and tracking range the bomber would have
against a low RCS interceptor and you have precious little time to devise an alternate route and
countermeasure combination that would take you out of the engagement zone of the interceptor threat
without putting you in the engagement zone of another threat. Hence, a kinetic (AAM) solution.

At least you'll get the MLD/IRST on the interceptor to fixate on your missile launch and not you.

 

[Avimimus]

Bombers clearly won't be trolling for Migs, with out going into too much detail, still those AMRAAMS can be quite useful. Knew several B-1 aircrew who discussed at length how carrying a couple on the external pylons would really increase the Bone's survival in the face of certain threats. You don't have to shoot the defender down for the AMRAAM to be useful...

I.E. If you force your attacker to go defensive, then that puts you in a much better position to survive and escape their attack.

 

[bobbymike]

Bomber RFP News to Stay Hidden

Although Air Force acquisition chief William LaPlante recently told Air Force Magazine that the service would release the request for proposals for the Long-Range Strike Bomber as early as the end of June—now only days away—expect no public announcements, said Air Force spokesman Ed Gulick on Thursday. “The Air Force is committed to a fair acquisition process” on LRS-B, said Gulick. “To ensure this occurs, we are prohibited from releasing information” on the current acquisition phase, he said. Certain parts of the LRS-B program are deemed too vulnerable to discuss publicly, to prevent “sensitive information” from reaching “potential adversaries,” said Gulick. Future release of acquisition milestones, he said, “will be considered and released as appropriate.” LaPlante told the magazine the final RFP would be out about now—after months of back-and-forth discussions with potential contractors—and that a downselect to a single contractor would come in the late spring 2015 timeframe. Contractors have been especially tight-lipped about the program, and word is the Defense Department has even forbidden them to run any advertising promoting their capabilities to accomplish this project. Boeing and Lockheed Martin have teamed to bid, and Northrop Grumman has indicated it’s interested, too.​
—John A. Tirpak
6/27/2014

 

[marauder2048]

Thank you, one other question;

1) If the NGB will be alone or maybe in a pair, is it or could it be technologically feasible to pass targeting information from a space based radar to an aircraft so it could remain 'electronically silent' and then to target other aircraft?

Yes. And the space based radar could act as a bistatic illuminator

For a bi-static receiver traveling at Mach 2.5?! Very brave, sir

 

[Black Dog]

I think the best answer to that is the one Donnage gave up thread. The vehicle cruises at Mach 2.5 for 4000nm. (2000n.m. radius). There isn't anything available that can escort it over the entire mission so it needs to have a self defense capability. It could also double as an excellent long range interceptor.

Any idea on max speed... and how stealthy can it be at that cruise speed? Especially given that it won't be exactly small either.

 

[donnage99]

Any idea on max speed... and how stealthy can it be at that cruise speed? Especially given that it won't be exactly small either.

Stealth is effected very little by the size of the aircraft. It's more about shape.

 

[Black Dog]

Any idea on max speed... and how stealthy can it be at that cruise speed? Especially given that it won't be exactly small either.

Stealth is effected very little by the size of the aircraft. It's more about shape.

But wouldn't a larger aircraft (LRS-B) generate a larger thermal signature at Mach 2.5 than say a smaller one like a F-22? (if the F-22 can even go that fast..) Forgive my ignorance please

 

[sublight_]

But wouldn't a larger aircraft (LRS-B) generate a larger thermal signature at Mach 2.5 than say a smaller one like a F-22? (if the F-22 can even go that fast..) Forgive my ignorance please

It would have a VERY noticeable acoustic and thermal signature at Mach 2+.

(nobody has said what the cruise altitude is, but at 70k feet your going to have between 1 to 1.5 lbs of overpressure.)

 

[quellish]

(nobody has said what the cruise altitude is, but at 70k feet your going to have between 1 to 1.5 lbs of overpressure.)

It's too bad nobody spent a ton of money developing technology for over pressure reduction. Oh wait....

 

[Sundog]

It would have a VERY noticeable acoustic and thermal signature at Mach 2+.

(nobody has said what the cruise altitude is, but at 70k feet your going to have between 1 to 1.5 lbs of overpressure.)

Already addressed

 

[Mat Parry]

Thermal signatures might be a tougher nut to crack?

I seem to remember reading in Richelson's 'space sentinels' about US missile launch warning satellites tracking (or at least detecting) either TU-22 blinders or TU-160 blackjacks in flight.

Possibly this was only when the target was operating in afterburner but still, a precedent exists

 

[sublight_]

(nobody has said what the cruise altitude is, but at 70k feet your going to have between 1 to 1.5 lbs of overpressure.)

It's too bad nobody spent a ton of money developing technology for over pressure reduction. Oh wait....

And not a single QSST to show for it....

 

[sferrin]

(nobody has said what the cruise altitude is, but at 70k feet your going to have between 1 to 1.5 lbs of overpressure.)

It's too bad nobody spent a ton of money developing technology for over pressure reduction. Oh wait....

And not a single QSST to show for it....

There isn't even a regular one. Why would you expect a quiet one?

 

[quellish]

And not a single QSST to show for it....

The Quiet Supersonic Platform program was not risk reduction for a transport. Nor were the other related DARPA or contractor programs.

 

[sublight_]

Given that phrases like "low risk" and "existing technology" are constantly used in reference to next gen bomber, I'm not optimistic that high temperature RAM, overpressure reduction, and a bright IR signature are the best way to go on a high profile, cost conscious program.

 

[mz]

If the heat was concentrated in a narrow area like a long nose spike, you could conceivably use an active heat transfer circuit to transfer it elsewhere... Though thats not off the shelf tech. Especially if you use less conventional fuels as heat sink.

Otherwise it is a bit hard to see how the issue can be solved...

 

[sferrin]

Given that phrases like "low risk" and "existing technology" are constantly used in reference to next gen bomber, I'm not optimistic that high temperature RAM, overpressure reduction, and a bright IR signature are the best way to go on a high profile, cost conscious program.

We're not talking about Mach 3+ speeds here. There is already high temperature RAM sufficient for Mach 2 cruise. Overpressure reduction has to do with shape and there's no particular reason one shape should arbitrarily be more expensive than another.

 

[marauder2048]

Thermal signatures might be a tougher nut to crack?

ESAV is pretty much predicated on the use of variable cycle engines. There, the third air stream is used to cool the
fuel intended for recirculation which was initially used to cool the airframe (note the close proximity of the fuel tanks to the skin).
The third airstream is also used to cool downstream engine components.

My understanding is that JP-8+100 in combination with coatings and on-board de-oxygenation can get very close to the heat sink properties of JP-7.

 

[sublight_]

....Overpressure reduction has to do with shape and there's no particular reason one shape should arbitrarily be more expensive than another.

But who has merged a Quiet supersonic shape with an RCS optimized shape? Attainable? Yes, but wow, that is going to take some hard work. And that is going to cost a lot.

 

[sferrin]

....Overpressure reduction has to do with shape and there's no particular reason one shape should arbitrarily be more expensive than another.

But who has merged a Quiet supersonic shape with an RCS optimized shape? Attainable? Yes, but wow, that is going to take some hard work. And that is going to cost a lot.

True. The two would seem (at first glance) to be pulling in opposite directions.

 

[Sundog]

But who has merged a Quiet supersonic shape with an RCS optimized shape? Attainable? Yes, but wow, that is going to take some hard work. And that is going to cost a lot.

Every one of these designs by Northrop Grumman has been a low boom design. When you look at the ESAV design, you're looking at a stealthy low boom design. As with any aircraft design, there's trade offs no matter what the design spec's are that it has to meet. In fact, IIRC, when these designs were first shown by Northrop Grumman, they were advertised as low boom designs.

My guess as to why they went to the swept forward trailing edge from the arrow wing was probably so they didn't have to deal with the pitch up characteristics of the arrow wing. Of course, the new design probably has a lower radar signature as well. Or maybe it's just the way the modified delta handles the tailless flight controls that was the driver for the new wing shape. Whatever the case, all of them in this series have been low boom designs.

 

[quellish]

But who has merged a Quiet supersonic shape with an RCS optimized shape? Attainable? Yes, but wow, that is going to take some hard work. And that is going to cost a lot.

Look through the previous 70+ pages in this thread.

 

[ouroboros]

From Stephen Trimble's Twitter feed. LRS-B concept?

Source:
https://twitter.com/FG_STrim/status/480433706268491776
http://mdolab.engin.umich.edu/MDO_Workshop_2011/Agenda_files/Kolonay_MDO_2011_SORCER.pdf

Interesting use of the space behind the cockpit and below the DSI cone as the main/rear bomb bay. But, considering how far back the pilots lean and overall shape, this bay seems shallows-ish and wide, so no volumetrically large weapons, only long and slim perhaps? With the push for standoff weapons (hypersonics) and smaller guided weapons (SDB-2) I guess this is acceptable, but no MOAB.

The cockpit windows seem close to useless though. Periscopes and virtual windscreens, maybe via helmet projection perhaps?

I seem to have a vague recollection of previous work on this shape being a 4 engine setup though...

 

[marauder2048]

so no volumetrically large weapons, only long and slim perhaps? With the push for standoff weapons (hypersonics) and smaller guided weapons (SDB-2) I guess this is acceptable, but no MOAB.

That's consistent with remarks made by Global Strike Command's leadership; the desire for less massive, more volumetrically efficient and potentially higher velocity payloads. There was a recent (April 2014) Industry day for the High Velocity Penetrating Weapon (HVPW) which is definitely in accord with that philosophy.

 

[bobbymike]

so no volumetrically large weapons, only long and slim perhaps? With the push for standoff weapons (hypersonics) and smaller guided weapons (SDB-2) I guess this is acceptable, but no MOAB.

That's consistent with remarks made by Global Strike Command's leadership; the desire for less massive, more volumetrically efficient and potentially higher velocity payloads. There was a recent (April 2014) Industry day for the High Velocity Penetrating Weapon (HVPW) which is definitely in accord with that philosophy.

Do you have the link?

 

[bobbymike]

http://www.nextgov.com/defense/2014/07/surprise-air-force-may-have-already-developed-its-long-range-strike-bomber/88285/?oref=ng-dropdown

CRS Insights

Budget Highlight: Air Force Long Range Strike Bomber

Jeremiah Gertler, Specialist in Military Aviation (jgertler@crs.loc.gov, 7-5107)
July 2, 2014 (IN10095)

In early July, the U.S. Air Force is expected to issue a Request for Proposals to design, develop, and build a fleet of 80-100 new long-range strike systems to be fielded in the mid-2020s. Although long-range strike systems are typically thought of as bomber aircraft, the more general description is used because it is not yet clear whether the proposed Long Range Strike Bomber (LRS-B) is to be a single platform or a group of smaller systems working in concert.

Most of the current U.S. bomber fleet is composed of 76 B-52 Stratofortresses, which average 50 years in age, and whose ability to penetrate modern air-defense systems is increasingly challenged. The 80-100 LRS-Bs would replace the B-52s and likely some of the 63 B-1s still in service (with an average age of 28 years.) The B-52s and B-1s are currently projected to remain in service through 2040, which would be consistent with a mid-2020s introduction of the first LRS-Bs.

The Long Range Strike Bomber program began in FY2012, replacing the Air Force Next Generation Bomber program, an earlier effort to develop a manned bomber. While it will initially be deployed as a manned aircraft, LRS-B could eventually become optionally manned, with the aircraft operated remotely for some operations. Air Force officials have stated that LRS-B would be manned for nuclear missions.

Development Profile

The RFP may be less than it seems, however. As Figure 1 shows, the projected LRS-B budget increases more than 10-fold in the current Future Years Defense Program, from $258.7 million in FY2013 to $3,451.2 million in FY2019. Aviation analysts and industry officials confirm CRS's assessment that this funding stream resembles a production program more than a typical development profile. This may indicate that significant LRS-B development has already been completed, presumably in classified budgets. Such prior development would also help explain how the Air Force intends to get the system from a Request for Proposals to initial operational capability in about 10 years, when equally or less-complicated systems like the F-22 and F-35 have taken more than 20.


Figure 1. Long Range Strike Bomber Funding

media/image1.emf [not included here]

Source: DOD budget submissions for FY2014 and FY2015.


If there has in fact been considerable prior development, the Air Force will be challenged to construct a truly competitive RFP. Two competitors have declared an interest in the program: a team of Boeing and Lockheed Martin, and Northrop Grumman. Although Northrop is reportedly building a large, classified UAV, whichever competitor may have done the bulk of any such preliminary LRS-B development is likely to have an advantage in the production contract.

Cost

The Air Force has pegged the new bomber's price tag at $550 million each, excluding development (i.e., the cost of building each at full-rate production, known as "unit recurring flyaway" cost). While standing by that cost, Air Force officials have observed that capping the cost now or in the future is likely to result in limiting some of the LRS-B's capabilities or restricting the quantity produced. These tradeoffs are typical of a budget-constrained development program. Some analysts indicate that including development, each LRS-B could cost $810 million. These figures appear not to include any prior classified funding.

Even at the lower estimate, development and funding of LRS-B will take up a substantial portion of the bomber budget, which also includes modernization and update programs for the existing fleet of B-52s, B-1s, and B-2s in the coming years. This could pose a particular challenge if LRS-B development proves more expensive than projected, as is not uncommon in aircraft programs. Given a constrained budget topline, growth in LRS-B could put pressure on maintaining and improving legacy bomber fleets. This maintenance is required to ensure today's bombers remain effective and to avoid a capability gap until LRS-B comes along.

CRS will continue to follow this program, and expects to issue an "In Focus" paper and eventually a full report following publication of the RFP.

 

[sublight_]

It sounds as if the program could be a mix of really stealthy platforms and really fast platforms.

 

[TomS]

I don't see much that suggests a high-speed component to LRS-B. I think it's more likely that there could be a persistent overflying ISR element (a large, highly stealthy UAV) and an optionally manned "bomb truck."

 

[sublight_]

I don't see much that suggests a high-speed component to LRS-B. I think it's more likely that there could be a persistent overflying ISR element (a large, highly stealthy UAV) and an optionally manned "bomb truck."

Then what about this Air Force quote and the last 4 pages of supersonic talk?

I have only talked with one Air Force official who has said anything in any detail about the bomber. And it wasn’t much — just that it will be much faster than anything that currently flies such missions.

http://breakingdefense.com/2014/06/air-force-keeps-mum-on-new-bomber-rfp/

 

[TomS]

I had not seen that -- I thought you were referring to something in the CRS report.

 

[sublight_]

Yes, the CRS report says: the more general description is used because it is not yet clear whether the proposed Long Range Strike Bomber (LRS-B) is to be a single platform or a group of smaller systems working in concert.

And since the talk has been about both the subsonic and supersonic platforms, maybe the plan is to have both.

 

[Sundog]

Yes, the CRS report says: the more general description is used because it is not yet clear whether the proposed Long Range Strike Bomber (LRS-B) is to be a single platform or a group of smaller systems working in concert.

And since the talk has been about both the subsonic and supersonic platforms, maybe the plan is to have both.

It could be that the RQ-180 is a subsonic component of the system?

 

[phrenzy]

I find the hough speed thing quite curious, is it not the case that even where they have had to option of high speed bombers like the B-1 thru are often not flown supersonic during most of the missions they fly Nowdays?

Perhaps they have developed new mission profiles that require high speed ingress/egress and some clever new technology to minimise the signature of high speed aircraft. It does fly in the face of what everyone was expecting though, a big high subsonic flying wing or blended body design... maybe they are picking up a super sized fb-22/23 as part of the program.

Does anyone know roughly what payload capacity they will be aiming for? I would have thought they would be big on retaining the capability to carry MOP style weapons given that everyone is going underground which would indicate at least one very large bomb Bay.

 

[sublight_]

The congressional research service thinks the Air Force has LRS prototypes flying already...