USAF Tanker Competition saga

@TomcatViP you're pretty much spot on. Not to be a broken record, but before the final down select I did get my hands on both B767-200/300 and A330 POH's and did do the fuel numbers, which came out just as you speculated. Those results were posted on Key, but appear to be lost to the ether.

Requirements, mission profile, when the KC-135 routinely isn't using all of it's full offload potential it's a pretty tough sell to go bigger and burn more gas for something that already isn't used. Yes, I used to fly -135's, that's based of off talk amongst the crew dogs. The only existing medium sized jet in production is the 767, it's the closest thing in size and capability to what the USAF has built it's operations around. It isn't so much that the A330 is bad, it's a pretty good choice if you only have to pick one airframe that does it all as witnessed by Oz, UK, NATO and all the others. It's just not a good fit when it's pitched as a KC-135 replacement, and it's not a very good KC-10 replacement which puts it in a bad spot for USAF.

Again,

KC-135 136' x 131' 322,500 lbs. 200,000 lbs. of fuel
KC-46 159' x 156' 415,000 lbs. 212,300 lbs. of fuel
A330 MRTT 193' x 198' 514,000 lbs. 245,000 lbs. of fuel
A330 LMXT 193' x 198' 533,500 lbs. 271,700 lbs. of fuel
KC-10 181' x 165' 590,000 lbs. 356,000 lbs. of fuel
777F 209' x 212' 768,800 lbs. 320,863 lbs. of fuel (OEW: 318,300 lbs. , 129,637 lbs. of capacity left to use.)

The numbers illustrate things pretty well.

Here's the sad thing,10 days ago was my 20th anniversary of my first day of active duty. Before that, when I was a cadet, I had a conversation with a Lt Col in the Pentagon who told us about how Boeing came to them after 9/11 and offered a great deal on all of the green 767's airlines had backed out of, paid deposits and cancelation fees, and that they would use all of the NRE Japan spent to develop their tankers and sell those converted green jets to us for less than the list price... Of course we know what happened from history, but what could have been if it weren't for...

Edit:

Left out the B-52 dimensions, why? Well a whole lot of places that have -135's shared the ramp at some point with B-52's so things like refueling pits are sized for the BUFF which isn't an issue for the smaller -135, but would cost a lot of money for something bigger than a BUFF.

B-52 159' x 185'
 
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...Darleen? ...McCain?

What I'd really like to know is who had the hots for, er, who wanted the remote viewing system and why. I would not be surprised if the NRE for the current system(s) probably has exceeded that of breaking the OML and doing at least something like the KC-10 system "pod" and direct/mirror viewing system. And who is responsible for NOT prototyping the RVS camera as a separate effort? Did someone mis-state/misrepresent the TRL? It's a little known fact that the Advanced Refueling Boom for the KC-10 was flight tested on a KC-135A. Why not RVS?
 
@aim9xray yeah those might be the beginnings of a list. I got my acquisitions badge in 2005 when all that was blowing up and suffered through lots of ethics training as a result the next 7 years. Embarrassed the hell out of me, I never ever wore that badge on any of my uniforms ever except the one day that I graduated from that training. Wings and a maintenance badge were far more respectable.

I don't remember much about the RVS and if I did I couldn't say anything. Helped write cards for the test with the Italian bird since they wanted to connect with a BUFF first. That said, the test boomer did mention the expresso machine...
 
@TomcatViP you're pretty much spot on. Not to be a broken record, but before the final down select I did get my hands on both B767-200/300 and A330 POH's and did do the fuel numbers, which came out just as you speculated. Those results were posted on Key, but appear to be lost to the ether.

Requirements, mission profile, when the KC-135 routinely isn't using all of it's full offload potential it's a pretty tough sell to go bigger and burn more gas for something that already isn't used. Yes, I used to fly -135's, that's based of off talk amongst the crew dogs. The only existing medium sized jet in production is the 767, it's the closest thing in size and capability to what the USAF has built it's operations around. It isn't so much that the A330 is bad, it's a pretty good choice if you only have to pick one airframe that does it all as witnessed by Oz, UK, NATO and all the others. It's just not a good fit when it's pitched as a KC-135 replacement, and it's not a very good KC-10 replacement which puts it in a bad spot for USAF.

Again,

KC-135 136' x 131' 322,500 lbs. 200,000 lbs. of fuel
KC-46 159' x 156' 415,000 lbs. 212,300 lbs. of fuel
A330 MRTT 193' x 198' 514,000 lbs. 245,000 lbs. of fuel
A330 LMXT 193' x 198' 533,500 lbs. 271,700 lbs. of fuel
KC-10 181' x 165' 590,000 lbs. 356,000 lbs. of fuel
777F 209' x 212' 768,800 lbs. 320,863 lbs. of fuel (OEW: 318,300 lbs. , 129,637 lbs. of capacity left to use.)

The numbers illustrate things pretty well.

Here's the sad thing,10 days ago was my 20th anniversary of first day of active duty. Before that, when I was a cadet, I had a conversation with a Lt Col in the Pentagon who told us about how Boeing came to them after 9/11 and offered a great deal on all of the green 767's airlines had backed out of, paid deposits and cancelation fees, and that they would use all of the NRE Japan spent to develop their tankers and sell those converted green jets to us for less than the list price... Of course we know what happened from history, but what could have been if it weren't for...

More fuel is never a bad thing, especially if you can get it to the fight from shorter runways - and especially given expanded enemy A2AD capabilities and the USAF's tilt to the Pacific.

And we're comparing a combat proven tanker that works, with a functioning RVS, with proven auto AAR capability, with a KC-46 that doesn't.

If the answer in 2022 is "as close a match as possible" to the KC-135, then you've asked the wrong question.
 
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@Jackonicko : At mission range, both can offload the same amount of fuel. The A330 airframe is slower at cruise, heavier and probably a bit more draggy.

Hence more of its carried fuel is for its own consumption. This is why LM want to increase the mass fraction of fuel to give a positive delta regarding the KC-46. However, Boeing maintains that it can match this increase in a lighter weight package (because, again, having less mass, less drag, and being faster at cruise...).

At the end, if the mission profile stays the same,
it's even more advantageous for the USAF to keep their KC-46 and move toward a block upgrade since fleet cost will be impacted favorably.
LM & Airbus have to disrupt the end objectives one way or another if they want to win. The extended range was one way of doing it but sadly not enough. They need to push the envelope (not the one under the table, obviously) even further, that it'd be with range, embedded systems, basing facilities, cost or whatever I don't know.
"Both can offload the same amount of fuel?"

That's simply not the case, as the RAF, RAAF, RSAF, RSAF, France, UAE et al will all confirm.

You are spreading myth, propaganda and outright falsehood.

The difference in fuel burn between the two aircraft is negligible, whereas the difference in fuel available for offload is about 16%.

Moreover, one of the two can operate from a typical tanker runway of 12,000 ft with a full load of fuel, and one can't. That adds time for the tanker requiring a greater balanced fuel length to go and hit the tanker itself.

As to cruise speed - the KC-46 figure is 530 mph - 460 kts. The cruise speed of the A330 MRTT is 464 kts.

The UK and Australia did extensive evaluation of the 767 and A330, and would snort with derisive laughter at the completely unsupported "probably more draggy". As indeed do I!
 
You'd have to look back in the thread (scroll up) at the mission requirements: both satisfy offload qty at the specified range!
There is no myths. It's called reading an RFP and adhering to it.
A330 is also significantly heavier and bigger. There is no miracle in the world of Sciences to make it fly more economically, spending less fuel, but only while cruising at a lower speed or cutting down embarked fuel qty to match only mission requirements.

Please try to open your eyes before qualifying other posters with insulting vile intentions.
 
You'd have to look back in the thread (scroll up) at the mission requirements: both satisfy offload qty at the specified range!
There is no myths. It's called reading an RFP and adhering to it.
A330 is also significantly heavier and bigger. There is no miracle in the world of Sciences to make it fly more economically, spending less fuel, but only while cruising at a lower speed or cutting down embarked fuel qty to match only mission requirements.

Please try to open your eyes before qualifying other posters with insulting vile intentions.
@TomcatViP We shouldn't feed the trolls. Doubtful that they will accept the challenge to go to Google, find the relevant performance manuals for KC-135, B767 and A330 and run the numbers and post their results. Discussions of lifecycle costs, PBD's, Mil Con, etc. might just overload the brain set to spew talking points from nice glossy brochures targeted at congress critters and staff. Never mind explaining actual experience with hardware and crews (some who even evaluated things, others who signed stuff and can't talk details).

The fact sheet for the -135 lists a 150,000 lb. offload at 1,500 mi (1303 nm), which sounds very much like the SIOP profile. It would be useful to compare the numbers for all three against this and a more fighter centric mission profile of fly 500 nm, offload 80,000 lb. over 4 hours with reserves. Points of comparison, balanced field length (by mission type, not just for Max Gross), fuel burn by leg (transit to/from, refuel, loiter, hold, divert), best speed/Mach by leg (this ties in with the last one, don't use a 40kft cruise values for an 18kft refuel orbit), excess capacity (if any), extrapolate operating costs (state $/gal of JP-8, bonus points High/Med/Low cases).

Won't bother asking questions about bearing weights, concrete thickness, taxiways, hangers, ramp spacing (especially important if there's built in refuel equipment). Anyhow I digress...
 
KC-Z probably moving forward in 2024... But who's ready?!!

“Development of the leap-ahead KC-Z tanker was originally slated to occur in the 2030s, but as a competition for a KC-Y tanker looks increasingly unlikely, the service is now planning on moving up KC-Z development, Paul Waugh, the Air Force’s program executive officer for mobility and training aircraft, told reporters last week,” according to Breaking Defense. “Instead of waiting until the next decade to start work on KC-Z, the Air Force now plans to start ‘pre-analysis of alternatives work’ next year, with a formal analysis of alternatives (AOA) to kick off in 2024, Waugh said.”


IMOHO, we are about to see radical designs popping out from nowhere. Hold down to your keyboard guys.
 
KC-Z probably moving forward in 2024... But who's ready?!!

“Development of the leap-ahead KC-Z tanker was originally slated to occur in the 2030s, but as a competition for a KC-Y tanker looks increasingly unlikely, the service is now planning on moving up KC-Z development, Paul Waugh, the Air Force’s program executive officer for mobility and training aircraft, told reporters last week,” according to Breaking Defense. “Instead of waiting until the next decade to start work on KC-Z, the Air Force now plans to start ‘pre-analysis of alternatives work’ next year, with a formal analysis of alternatives (AOA) to kick off in 2024, Waugh said.”


IMOHO, we are about to see radical designs popping out from nowhere. Hold down to your keyboard guys.

Looking forward to the UAC bid this time...


(And yes, Key Aero really is the best summary of the 2010 fiasco I can find...)
 
It's interesting that the KC-46 adherents stick their fingers in their ears and chant "la, la, la, I'm not listening" while waving an ancient requirements document that describes a direct KC-135 replacement, operating from improbably long stateside runways, jammed closely together on vulnerable ramps, and that takes no account of what China's A2AD capabilities do to required fuel offload figures.

o_ODo not mistake experience and knowledge with advocacy. Just because I knew people involved with that source selection, flew in the squadron that did DT for said aircraft, flew tankers half of my time in uniform, worked on/flew heavy's eight of my ten years in uniform (12 if you count ROTC) does not an adherent make. Here's a bit of a resume of sorts from my old flight suits.
Patches.jpg
Enough said.

It does help provide insight into how after over half a century operating over 800 airframes, half still in service today (~500 at the time of the source selection) why the AOA turned out the way it did and the JROC approved the requirements they did. I understand the data set and where it comes from. I've also walked more than a few USAF flight lines both as a maintainer and aircrew. Do take a look at the ramps of Fairchild, Grissom, McConnell, MacDill, McGuire and Pease to see if you notice anything that would adversely drive lifecycle costs one way or the other. I'm aware of China's A2AD, I've tested large aircraft defensive systems, can't really comment more than that.

And yes, I lived through these events as an officer in USAF Acquisitions, there might have been just a few ethics clue sticks swung at my career field over those years.

In today's world, more fuel from a shorter runway is a powerful advantage.
A bit of a broken record here, as if repetition of the same tired bullet point will somehow make it more persuasive. Okay, hint here, unlike fighters, general aviation or the car in your garage; heavy aircraft don't typically fly missions with full tanks unless they absolutely must. I can count on my two hands the number of times I've flown with full tanks or launched jets with them. But rather than encourage another ignorant response, please do take a look at the three charts below and say which one or combination of them you would use to confirm or refute that assertion. Feel free to augment them with one or more for the A330, the airliner is fine since neither the KC-46 or MRTT Dash One's are exactly public domain.

TO Chart C.JPG TO Chart B.JPG TO Chart C.JPG

Please do adjust for reasonable mission profile(s), over a decade ago I did so on Key and posted the screenshots. The data tells its own story that may differ from the narrative marketing types propagate, not they'd ever compare apples to oranges to sell something.
 
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More Aero Sciences stuffs (brief) for you & all those that might need a refresh or an update:

1: every takeoff must be planned with the possibility that you'd have to abort. It's called a rejected takeoff procedure and calculations includes the necessary extra runway length for a full stop. Many runways do include Stopway, a paved section that is not fully maintained for that possibility (beyond the full width line baring one of its extremities).

2: tires have maximum sustainable speed beyond which the tires will start to deteriorate. During normal operations, you won't accelerate beyond that extrema. Hence, once you've reached that point in your takeoff planning, where you are computing at which speed you will rotate and lift off, normal operations are not possible and you would have to reduce your takeoff weight in order to safely operate from that airfield.

3: Brakes are converting kinetic energy into heat. For your braking pads to not deteriorate, a balance b/w heat dissipation and the heat generated through the pad's friction must be reached. Once beyond that point, your brake action is null, pads material is degrading rapidly and even melting aways. Hence you can't stop your aircraft during a rejected takeoff and risk crashing beyond the runway length.

All those parameters are expressed in those curves in function of the departing airport altitude. The chart shows clearly how maximum takeoff weight departure is a seldom occurrence. What is exactly what @mkellytx patiently tried to explain to you.

Last but not least, I posted in the KC-Z thread recent report from real operations (training) showing how MRTT had to be based away from the operating area because of airport available space and (not explicitly mentioned but easily guessed) runway available length at the secondary airfield.

An A330 is perfect if you have only few tanker in your Airforce. You probably have enough base and dispersion airfield to manage the handfull of them you own. But then, during combined operations, difficulties start to show up: parking space for them is becoming rapidly a scarce commodity when the volume offered as transferable fuel doesn't increase much if not at all.
As I have written, Airbus needs to pack more juice in them: more transferable fuel, more missions or more anything that could justify their rational usefulness.
 
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@TomcatViP you're pretty much spot on. Not to be a broken record, but before the final down select I did get my hands on both B767-200/300 and A330 POH's and did do the fuel numbers, which came out just as you speculated. Those results were posted on Key, but appear to be lost to the ether.

Requirements, mission profile, when the KC-135 routinely isn't using all of it's full offload potential it's a pretty tough sell to go bigger and burn more gas for something that already isn't used. Yes, I used to fly -135's, that's based of off talk amongst the crew dogs. The only existing medium sized jet in production is the 767, it's the closest thing in size and capability to what the USAF has built it's operations around. It isn't so much that the A330 is bad, it's a pretty good choice if you only have to pick one airframe that does it all as witnessed by Oz, UK, NATO and all the others. It's just not a good fit when it's pitched as a KC-135 replacement, and it's not a very good KC-10 replacement which puts it in a bad spot for USAF.

Again,

KC-135 136' x 131' 322,500 lbs. 200,000 lbs. of fuel
KC-46 159' x 156' 415,000 lbs. 212,300 lbs. of fuel
A330 MRTT 193' x 198' 514,000 lbs. 245,000 lbs. of fuel
A330 LMXT 193' x 198' 533,500 lbs. 271,700 lbs. of fuel
KC-10 181' x 165' 590,000 lbs. 356,000 lbs. of fuel
777F 209' x 212' 768,800 lbs. 320,863 lbs. of fuel (OEW: 318,300 lbs. , 129,637 lbs. of capacity left to use.)

The numbers illustrate things pretty well.

Here's the sad thing,10 days ago was my 20th anniversary of my first day of active duty. Before that, when I was a cadet, I had a conversation with a Lt Col in the Pentagon who told us about how Boeing came to them after 9/11 and offered a great deal on all of the green 767's airlines had backed out of, paid deposits and cancelation fees, and that they would use all of the NRE Japan spent to develop their tankers and sell those converted green jets to us for less than the list price... Of course we know what happened from history, but what could have been if it weren't for...

Edit:

Left out the B-52 dimensions, why? Well a whole lot of places that have -135's shared the ramp at some point with B-52's so things like refueling pits are sized for the BUFF which isn't an issue for the smaller -135, but would cost a lot of money for something bigger than a BUFF.

B-52 159' x 185'
The USAF seems to like the KC-10. Any idea why they didn't buy any later, based on the MD-11?
 
@sferrin you have a point, always baffled me, the small number procured. Admittedly, putting CFM56s (and spare TF33s) on KC-135s was an enormous bargain - and perhaps took money off the tanker mafia for years or decades. But still, some more KC-10s beyond the paltry procured... a hundred, for example... why not ?
 
The USAF seems to like the KC-10. Any idea why they didn't buy any later, based on the MD-11?
@sferrin I said the same thing 15-16 years ago on rec.aviation.military, it felt like a huge missed opportunity. That said, the timing was all wrong. The KC-10's had plenty of life left in them at the time the line shut down in 2001 (we all know who acquired them/shut it down). The tanker in need of replacement at the time was the KC-135E, which lands us squarely back into this topic. If you paid attention lately the KC-10's will be retired before KC-Z comes out, first ones left for DM in 2020.
 
@sferrin you have a point, always baffled me, the small number procured. Admittedly, putting CFM56s (and spare TF33s) on KC-135s was an enormous bargain - and perhaps took money off the tanker mafia for years or decades. But still, some more KC-10s beyond the paltry procured... a hundred, for example... why not ?
@Archibald the answer to, "Why 60?" sounds like something that could be found from a DTIC search under Advanced Tanker Cargo Aircraft Program, there has to be something there that explains that rationale.

The decision to re-engine the -135's with CFM56 was one of the greatest decisions made by a blue suiter, for the benefit of USAF. The worst thing about it was that it created an airframe without a one for one replacement and the airframes will be older than the pilot's grandparents when they finally retire.
 
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The decision to re-engine the -135's with CFM56 was one of the greatest decisions made by a blue suiter, for the benefit of USAF. The worst thing about it was that it created an airframe without a one for one replacement and the airframes will be older than the pilot's grandparents when they finally retire.
No question about that ! There was also a parallel move where they scavenged a crapton of TF33s from old airliners and put them on the KC-135s that could not get CFM56 for some reason. Another smart move. The KC-135 enormous fleet (800 !) really repaid the initial investment many, many times (a dozen ?).
Those old birds are rock solid. I can tell that France is perfectly happy with its own fleet - vintage 1964, still there although the Airbus are coming at least.
 
IIRC, this was based on which command had what money.
- SAC (active duty) bought the CFM-56 retrofit.
- AFRES and ANG (reserves) bought the used civil JT3D (TF33) engines.
The airline JT3Ds did have some operational advantages (thrust reversers) and were a lot cheaper to buy [used]. In addition, they did not have to wait at the end of the line until SAC had bought all their CFM-56s.

A goodly number of the reserve KC-135Es (JT3D conversions) were later converted to CFM-56s and fly today as KC-135Rs (having flown with three vastly different sets of engines).
 

USAF Accelerates Plans For Next-Generation Airlifter And Tanker​


The U.S. Air Force is speeding up plans to look beyond its Boeing C-17 and Lockheed Martin C-5M airlift fleets, announcing that next year it will begin work on new airlift capability, paralleling a similar move for its aerial refueling fleet.
“This coming year, the Department of the Air Force will be working to define the next generation of airlift and tanker capabilities,” Air Force Secretary Frank Kendall said during the Airlift/Tanker Association Annual Convention in Aurora, Colorado, on Oct. 28.
Earlier this year, the service said it wanted to accelerate its future KC-Z tanker by moving up pre-analysis of alternatives research to 2023 from a previous projected timeline of 2030. Kendall says the future airlifter will also need to be moved up as the service studies how it could deliver people and materiel to a war in the Pacific as its bases and logistics hubs come under attack.
In June, the service released a solicitation for an Advanced Aerial-Refueling Family of Systems for the KC-Z, looking at capabilities including stealth, improved situational awareness, self-protection and autonomy, among others.
 
No ****, of course the air force will (have to) move beyond non survivable tubular fuselage designs. He desperately makes it sound like it's a certain realization that suddenly sprung into their minds when stealth/BWB tanker and cargo plane concepts have been gestating for 20 years (X-48, MACKS, , Speed Agile, AFRL Distributed Propulsion Concept, etc)
China’s growing reach with precision missiles means the Air Force must shift away from traditional tankers and cargo aircraft towards stealthy ones, Secretary Frank Kendall said Dec. 11.
“The threat’s taking that freedom away from us,” he said. Adversaries like China are able to track and shoot U.S. aircraft from increasingly long ranges, so mobility aircraft must be designed with survivability in mind
The Air Force is taking an early look at blended wing body aircraft concepts for cargo and transport roles, but “that doesn’t exist in the commercial world yet,” so there’re no civil aircraft the Air Force can adapt to future mobility needs, Kendall noted.
“It may [exist] at some point,” he said, “but it doesn’t yet, so we are doing some early design work on that, possibly moving towards a prototype as a DOD program. But there’s more to come on that; that’s a work in progress.”
Although the Air Force will continue to recapitalize its aging tankers by continuing “core tanker modernization,” Kendall said the service will “have to move beyond that to the next generation.
 
Defense News Article from March 8:


Forbes Article from Yesterday:


Also, a petition to rename this thread or create a new thread with the recent replies entitled "Next Generation Aerial-refueling System (NGAS) Discussion" in the near future
 
Uh-uhh.. Fast-forwarding the whole program by 5-10 years is a really daunting objective! Wonder how they are going to achieve that? KB-21?
USAF secretary Frank Kendall disclosed the 2030s goal to lawmakers on 2 May, saying the approach aligns with a broader shake up of USAF procurement plans.
In January, the USAF had unveiled a project to develop its Next Generation Air-refuelling System (NGAS) – a clean-sheet tanker aircraft with low-observability. A related request for information (RFI) put the new tanker’s initial operational capability milestone at 2040.
“It won’t be 2040 – it’s going to be much sooner than that,” Kendall said during a 2 May congressional budget hearing. “We want to get to that design as quickly as we can.”
 
Uh-uhh.. Fast-forwarding the whole program by 5-10 years is a really daunting objective! Wonder how they are going to achieve that? KB-21?
USAF secretary Frank Kendall disclosed the 2030s goal to lawmakers on 2 May, saying the approach aligns with a broader shake up of USAF procurement plans.
In January, the USAF had unveiled a project to develop its Next Generation Air-refuelling System (NGAS) – a clean-sheet tanker aircraft with low-observability. A related request for information (RFI) put the new tanker’s initial operational capability milestone at 2040.
“It won’t be 2040 – it’s going to be much sooner than that,” Kendall said during a 2 May congressional budget hearing. “We want to get to that design as quickly as we can.”
Yeah, that would be far too fast. At least more than 10 years would be needed

However, there may also be the possibility that they might use some already-developed technologies from the B-21 Raider (Specifically the stealth technologies and the airframe design) and incorporate it in the NGAS program. That could somewhat shorten the program duration by a bit, but it seems like everything else would have to be innovated.
 
I wonder if perhaps they are thinking of building directly off the B-21 platform and power plant? It likely already has a large amount of fuel, and you could add an extra 20-30,000lbs sans bomb bay and with boom. It probably won’t have anything like a KC-46 offload but you could skip a lot of basic development.
 
A B-21 tanker derivative would work because there would not need to have all the extra development time needed to produce a brand new design from scratch.
 
A B-21 based tanker would carry way too little fuel and have much too high a burn rate to be useful with the distances required in the Pacific. And I'm not really how much money it would really save given the massive changes needed from the base B-21.
 
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A B-21 based tanker would carry way too little fuel and have much too high a burn rate to be useful of the distances required in the Pacific. And I'm not really how much money it would really save given the massive changes needed from the base B-21.

If the solution is a much larger blended wing aircraft, it seems to me it will be hugely expensive for a tanker.
 
I think some are confusing the role of a tanker with that of a bomber: nobody needs to refuel above the target.

A penetrative tanker is something that can penetrate the long range defenses of an opponent, not overfly its capital city!

Here we have something that is far less stealthy than a B-2, 21 or F-35. But still, far more survivable in contested airspace than a tube&wing design. Then the cost equation will drive what level of low observability can be achieved while remaining affordable for the Services.
 
A B-21 based tanker would carry way too little fuel and have much too high a burn rate to be useful of the distances required in the Pacific. And I'm not really how much money it would really save given the massive changes needed from the base B-21.

If the solution is a much larger blended wing aircraft, it seems to me it will be hugely expensive for a tanker.
Possibly, but there have been some BWB/semi-BWB concepts that could be a very nice C-5/KC-10 replacement. It may be expensive, but total buy would only be on the order of 100 or so airframes that would fill the very large transport/deployment tanker role (namely thinking about the semi-BWB concept LM showed a few years ago). That said, it appears the advanced tanker will be a more survivable KC-135/KC-46 sized aircraft.
 

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