Future USAF Transport Projects (MACK, ATT, NGT, AMC-X, AJACS, HAWSTOL, Speed Agile)

[Machdiamond]

You seem to have have skipped the "at this scale" part in your quote.
It is large enough so that FJ44 data can be scaled up realiably to the real deal, unlike the X-48 for example.
--Luc

 

[Aeroengineer1]

The engines installed in this are the FJ-44-4 engines rated at 3600lbs of thrust.

Adam

 

[Matej]

Some of the technologies developed for the JSF program would also help drive down the costs.

Some of the technologies developed for the Senior Citizen made it into JSF and some of the technologies developed for the JSF will (probably) make it to the Speed Agile. What an irony.

 

[AeroFranz]

I appreciate the explanations, but it's still not clear what characteristics are being modeled. Engine operability and engine performance are engine specific; you can't tell me that an FJ44 at 3,600lb thrust and completely different BPR scales adequately to something like a V2500 or CFM56. A theoretical engine thermodynamic cycle model would probably come closer than using empirical relationships to scale your WT data.
As I suggested, you're possibly better off with an external gas generator that can provide exactly the flow conditions that you want to replicate. But I have never worked in a wind tunnel and would like to understand.


I know there are other aspect to consider. There is talk of re-fanning a commercial engine in deference to LO requirements (smaller diameter fan, maybe that gets you closer to the FJ44?). The Boeing guys in Huntington Beach are still laughing at my student design team, when in 2004 we told them that we wanted to make a stealthy COTS CF6 installation for a STOL transport we were designing for a competition. Ain't gonna happen. Can't have huge gaping inlets, and large fans don't like distortions provided by blockers and other trcks that kinda work on small BPR engines.


There is also the issue of providing bleed air to whatever hybrid powered lift system is being used. Once again, it seems like you would be better served by piping massflow from outside the vehicle; this is commonly done in subscale VTOL testing.

 

[Machdiamond]

An external gas generator and huge ducting capable of pumping something like 200 lbs per second of air at high temperature? That sounds incredibly complicated. How about simply using an FJ44 instead?
I don't see why hybrid powered lift and fan blockers would be involved in this project, I wouldn't worry too much about those.
--Luc

 

[Aeroengineer1]

Just getting enough cooling air up to this model was a challenge, let alone enough to power the blown slots. This model was also to help get the TRL's higher for components. To do this you needed more than just a small scale model.

Adam

 

[AeroFranz]

An external gas generator and huge ducting capable of pumping something like 200 lbs per second of air at high temperature? That sounds incredibly complicated. How about simply using an FJ44 instead?
I don't see why hybrid powered lift and fan blockers would be involved in this project, I wouldn't worry too much about those.
--Luc

As I mentioned in a previous post, it is not uncommon in VTOL subscale testing to duct massflow from the outside to test hot gas reingestion or suckdown. The test models are generally smaller, and would not fit a gas generator internally. I admit I do not know the upper limit of where it makes sense to use an external device or install small engines. I think that compared to the full-scale deal, the outer moldlines of this model had to be changed a lot in order to fit the -44s. What happens to your stability and control data once you change your moldline?


I do not know what the scope of these specific test was, however, engine performance and operability are not, IMHO, something you can test by similarity using a completely different engine and installation.
The "real" thing is supposed to be stealthy, STOL, and fly at M0.8. That means the engine installation is facing severe compromises in that it must have treatments or shaping for LO (and attendant pressure losses), possibly a re-fanned engine of ten times the thrust of the -44, and nice smooth airflow at low speed AND high speed. I mentioned powered lift because that's always been the mandate of AJACS/Speed Agile, so add bleed air requirements to that. All things that affect engine operation.
How is a pitot, non-representative engine installation going to help you model "operability and performance"? Without knowing more about the specific goals of the test, I would say "It doesn't".


Far from me to criticize the work being done, on the contrary. I think it's a very interesting project and I am sure that the choices made were backed by sound engineering thought. However, the scant information contained in the picture caption and the quote do not provide any clue as to this. They were probably not meant for the consumption of other aerospace engineers involved in conceptual design, which may be a little be more inquisitive than the public at large. If Aeroengineer can provide more details - (which i would understand if he could not! ) I would be very interested in learning them. Congratulations on working on such an interesting project - I wish I were doing large scale wind tunnel testing instead of being a cubicle monkey!

 

[flateric]

more NG Speed Agile

 

[flateric]

NASA Ames Research Center Aviation Systems Division Highlights

05.25.11
Speed Agile Concept Demonstrator (SACD) Simulation on the Vertical Motion Simulator
The first of a two-part simulation of the Boeing SACD concept aircraft was completed in April 2011. Boeing engineers with help from SimLabs simulation engineers integrated a flight dynamics model of the SACD aircraft in the Vertical Motion Simulator (VMS) and conducted an experiment to understand the aircraft's handling qualities, evaluate the baseline flight control system, assess the landing/take-off field length performance, and to gather data to set flying qualities requirements for future vehicles of this class. Several Boeing test pilots participated in the experiment, testing three different control systems over different flying tasks in approximately 1000 data runs. The Boeing engineers and pilots described the VMS support and capabilities as “exceptional.” In the second part of the simulation, NASA's Aeronautics Research Mission Directorate (ARMD) will evaluate an innovative control system, Control Allocation for Pilot-Induced Oscillation (CAPIO), using the Boeing SACD model. (POC: Steven Beard)
http://www.aviationsystemsdivision.arc.nasa.gov/news/highlights/af_highlights_20110525.shtml
07.21.11
Control Allocation for Pilot-Induced Oscillation (CAPIO) Simulation on the Vertical Motion Simulator (VMS)
This pilot-in-the-loop simulation evaluated CAPIO's effectiveness in alleviating pilot-induced oscillations that occur when control surface actuators hit rate limits typically during aggressive maneuvering. The Cruise-Efficient Short Take-Off and Landing (CESTOL) mobility concept aircraft developed by Boeing Research and Technology (BR&T) for the Air Force Research Lab's Speed-Agile Concept Demonstrator (SACD) Program was used and the NASA-developed CAPIO controller was integrated with the SACD baseline flight control system. The system was evaluated using aggressive and precision maneuvers that were specifically designed to expose any Pilot Induced Oscillation (PIO) tendencies in the system in a controlled and repeatable manner. Seven experienced test pilots evaluated the system in a total of 647 data runs. The Principal Investigator for the study stated that, “The VMS staff support was excellent. Their dedication made this an outstanding experiment.”
http://www.aviationsystemsdivision.arc.nasa.gov/news/highlights/af_highlights_20110721.shtml

 

[Stargazer]

Not a very good picture, but the first top view I've seen of the Lockheed's AMC-X (Speed Agile) project:

 

[flateric]

Speed Agile Concept Demonstration (SACD) powered model in Arnold Engineering Development Center (AEDC) National Full Scale Aerodynamics Complex (NFAC) WT and model of production configuration in Langley National Transonic Facility (NTF) WT
For better quality first photo see last AWST issue

 

[flateric]

http://www.google.com/patents?id=hWr9AQAAEBAJ

 

[Mat Parry]

I enjoyed reading the patent, Thank you Flateric
As is often the case, function defines form and I have to admit Boeing's configuration is quite elegant.... I doubt I'll ever see one of these flying however for the reasons stated earlier in this discussion.

 

[flateric]

http://www.aurora.aero/Common/Downloads/Media/PDF/APR-241.pdf

 

[RanulfC]

Speed Agile Concept Demonstration (SACD) powered model in Arnold Engineering Development Center (AEDC) National Full Scale Aerodynamics Complex (NFAC) WT and model of production configuration in Langley National Transonic Facility (NTF) WT
For better quality first photo see last AWST issue

So... The second picture is what is left after Congress finishes "adjusting" the program budget then correct?

::::grin::::

Randy

 

[flateric]

from http://www.advancedtechnologiesinc.com

 

[Triton]

AFRL researchers are testing this 23 percent scale model of the Speed Agile vehicle at the Arnold Engineering and Development Center’s National Full Scale Aerodynamics Complex, the world’s largest wind tunnel. (AEDC/NFAC Photo)

Source:
http://www.wpafb.af.mil/news/story.asp?id=123281015

 

[Triton]

A 23%-scale turbofan-powered model of Lockheed Martin's Speed Agile powered-lift STOL airlifter concept for AFRL was tested in the National Full-Scale Aerodynamics Complex (NFAC) at NASA Ames Research Center in California. This consolidation effort brings together experts in scramjets engines, alternative fuels, unmanned vehicles, hypersonic vehicles, collision avoidance, and aircraft energy optimization.

Source:
http://www.wpafb.af.mil/news/story.asp?id=123307634

 

[flateric]

thanks to Stephen Trimble, a new Boeing's Speed Agile patent
http://www.freepatentsonline.com/8302908.pdf

 

[Triton]

"Boeing team wins Aviation Week award for concept military aircraft technologies"
by
Nate Hulings

Source:
http://www.boeing.com/Features/2013/03/corp_avweek_award_03_25_13.html

An Air Force mobility aircraft is on a mission to deliver soldiers and their supplies to a remote region of the world, but its target airstrip is rudimentary and shorter than ideal.

It’s a challenge becoming ever-more present in today’s battlefields, and the reason why Boeing took part in the Air Force Research Laboratory’s Speed Agile Concept Demonstrator Program along with other aerospace leaders. The goal was to design future concept “speed agility” aircraft that could take off and land on shorter runways and fly at a wide range of speeds, while carrying the necessary payloads.

And though it may be years before any of the team’s developments make it onto an aircraft, their innovative achievements are not going unnoticed. Earlier this month, the program was awarded Aviation Week magazine’s Laureate Awards in Aeronautics and Propulsion at an event in Washington, D.C.

“It is a great honor for our team to have been selected to receive such a coveted award intended to recognize extraordinary and innovative achievements in aerospace, aviation, and defense,” said Mark Anderson, BR&T Flight Sciences Technology director. “This recognition speaks volumes as to the technical excellence of our Boeing engineering team.”

Graham Warwick, Aviation Week’s managing editor for technology, said the program impressed by “using a modest, but sustained investment in ground testing, at increasing scale, to mature technology to a higher readiness level.” He also noted that “too often such valuable and successful engineering efforts go unrecognized because they do not culminate in a highly visible flying testbed.”

Over the course of five years, the team from BR&T, the company’s central research and development organization, built and wind-tunnel tested several small-scale aircraft models for aerodynamics, developed an advanced hybrid powered lift system, and designed a robust flight control system that was validated through a piloted simulation test with Boeing and Air Force pilots utilizing NASA’s Ames Vertical Motion simulator.

“In the past, you made an airplane that could use a short field or one that could efficiently travel at high-speed cruise,” said John Vassberg, Boeing Technical Fellow and the company’s chief aerodynamicist for the research program. “Our research and testing proves that we can develop an airplane that can do both effectively.”

According to Kamal Shweyk, manager of the Flight Dynamics and Control team responsible for the Vehicle Management System, by developing components and technologies to a point where they are proven feasible and effective to meet multiple and traditionally conflicting mission requirements, Boeing is positioning itself well for when the Air Force goes to market for its next-generation transport aircraft.

One major milestone was developing a safe and robust flight control system for an aircraft that can fly at low enough speeds to land on a short runway, while also cruising at speeds faster than 0.8 Mach, which is much faster than the C-130 and other current mobility aircraft.

“The benefit from these years of research and testing is that Boeing was able to develop and mature technologies that are key to realizing a fully integrated speed agile concept,” Shweyk said. “While this technology isn’t being implemented right away, successful testing and validation of these systems will better position us when our customer is ready to develop its next generation of transport aircraft.”

Another major challenge for the team was finding a way to slow down the aircraft to a point where it could land on less than 2,000 feet of runway -- about half of the normal distance.

Their answer was a hybrid-lift system that rotates the thrust during landings, slowing the aircraft down enough to use half as much runway space.

Vassberg said the airframe’s design met the Air Force’s strict requirements, noting that the inboard section of the wing incorporated vectored thrust to provide powered lift, while the active flow control (AFC) was utilized over the outboard wing to increase the aircraft’s maximum lifting capabilities.

“We had a lot of challenges along the way, but it was very gratifying to see all the pieces come together,” he said. “This was a huge success for Boeing.”

According to Vassberg, active flow control technology is drawing the attention of Boeing Commercial Airplanes because it allows for shorter and steeper descents, making for a smaller acoustic footprint.

 

[Triton]

"Boeing awarded patent for Speed Agile stealth transport concept"
By
Dave Majumdar on April 2, 2013

Source:
http://www.flightglobal.com/blogs/the-dewline/2013/04/boeing-awarded-patent-speed-ag.html

Boeing was granted a patent for a swept-wing powered lift aircraft on 26 March, which looks like it is based on the company's submission to the US Air Force Research Laboratory's Speed Agile program--which is a "collaborative effort" between NASA, Lockheed Martin and Boeing.

The AFRL program aims to study what it would take to develop a stealthy short take-off replacement for the C-130 Hercules series that could take-off and land in less than 1500ft and cruise at around Mach 0.8.

In any case, if the nation were ever to actually build something like this, it's not inconceivable that there could eventually be gunship and tanker variants. Of course, developing something like this would take money--something America is currently a little short on.

Per the USAF:

The SACD's high-efficiency STOL design incorporates a hybrid powered lift system. This lift system features a simplified mechanical design and low-drag integration. This lift system minimizes the engine size requirement so that both propulsion integration drag and power differential between takeoff and cruise are as small as possible, eliminating a major source of fuel efficiency problems and speed limitations in legacy systems.

Through a series of developments and demonstrations, the Speed Agile team concluded their effort in 2012 with large-scale validation tests and transonic validation tests, followed by a flight control simulation in which pilots rated the system highly.

Efficient point-to-point travel enabled by the SACD has the potential to eliminate dependence on major airports and extensive surface infrastructure to save time, fuel and environment. The resulting impact of this ability is a dramatic reduction in logistics footprint, fuel burn and time required to move people and supplies anywhere in the world via direct delivery to a forward base.

Boeing patent:
http://www.scribd.com/doc/133613080/US8403256B1-pdf

 

[flateric]

http://www.wpafb.af.mil/news/story.asp?id=123341698


AFRL Speed Agile team recognized as best in the industry

by Holly Jordan AFRL/RQOB3/26/2013 - WRIGHT-PATTERSON AIR FORCE BASE, Ohio -- Air Force Research Laboratory's Speed Agile Powered Lift System Concept Demonstration team was honored with the Aviation Week Laureate Award for Aeronautics/Propulsion at a ceremony at the National Building Museum in Washington, D.C., on March 7. The Speed Agile team is led by Barth Shenk and Cale Zeune from the AFRL Aerospace Systems Directorate. In a collaborative effort with NASA, Lockheed Martin and Boeing, the team began research efforts in 2002 to explore innovative approaches in the development of next-generation tactical mobility aircraft. Key objectives of such a vehicle were transoceanic range at transonic speed, and Short Takeoff and Landing (STOL) performance with loads heavier than a C-130. In response to these needs, the AFRL team developed the Speed Agile Concept Demonstrator (SACD), a four-engine, multi-mission aircraft that offers speed agility; operates routinely from short, improvised airfields; carries larger and heavier payloads; and employs precise and simple flight controls. The Speed Agile team benefitted from the contributions of Arnold Engineering Development Center in Tennessee and the Large Amplitude Multi-mode Aerospace Research Simulator (LAMARS) at Wright-Patterson AFB. "Through the combined efforts of such a great team, dedicated partners and tremendous facilities, the Speed Agile concept is poised to make tremendous contributions to the warfighter," Mr. Shenk said. "This award is a wonderful honor at the culmination of this long, collaborative effort." The SACD's high-efficiency STOL design incorporates a hybrid powered lift system. This lift system features a simplified mechanical design and low-drag integration. This lift system minimizes the engine size requirement so that both propulsion integration drag and power differential between takeoff and cruise are as small as possible, eliminating a major source of fuel efficiency problems and speed limitations in legacy systems. Through a series of developments and demonstrations, the Speed Agile team concluded their effort in 2012 with large-scale validation tests and transonic validation tests, followed by a flight control simulation in which pilots rated the system highly. Efficient point-to-point travel enabled by the SACD has the potential to eliminate dependence on major airports and extensive surface infrastructure to save time, fuel and environment. The resulting impact of this ability is a dramatic reduction in logistics footprint, fuel burn and time required to move people and supplies anywhere in the world via direct delivery to a forward base. Aviation Week's Laureate Awards are awarded annually for extraordinary achievements in aerospace, aviation and defense. Nominees are considered from throughout the aerospace industry. In receiving the award, the AFRL Speed Agile team joins a prestigious group of pioneering scientists and leaders from around the world.

 

[donnage99]

http://www.mydaytondailynews.com/news/news/local-military/afrl-team-wins-major-aviation-honor/nXGQT/

 

[fightingirish]

The Speed Agile Concept Demonstrator, or SACD, is a US Air Force Research Laboratory program to mature specific technologies needed for developing an advanced airlift solution that meets the needs of the services in the future. This image shows the model in a NASA wind tunnel.

Source: http://www.codeonemagazine.com/

 

[Ian33]

Would it be possible to make a stealthy refueller? I' ve always seen that as a real weak link in the military aviation chain. AWACs too. Looks good though.

 

[yasotay]

The Speed Agile Concept Demonstrator, or SACD, is a US Air Force Research Laboratory program to mature specific technologies needed for developing an advanced airlift solution that meets the needs of the services in the future. This image shows the model in a NASA wind tunnel.

Source: http://www.codeonemagazine.com/

The comment that it is an "airlift solution that meets the needs of the services in the future" should be followed by "through the lens of a C-17 mafia at AMC". I understand that LockMart has to play to the audience, but the stealthy airlifter is not close to what their primary customer (the US Army) is interested in. It will be interesting to see if the USAF Inc. is able to push this through a cash strapped Congress with the US Army shrugging and saying it does not meet their needs.

 

[AeroFranz]

Would it be possible to make a stealthy refueller? I' ve always seen that as a real weak link in the military aviation chain. AWACs too. Looks good though.

Two stealthy airplanes flying in formation have a much greater signature than the sum of the two separately. That doesn't even take into account the boom itself, and having to expose a receptacle (normally retracted in LO aircraft). My guess is that it would be very hard. But then harder things have been accomplished, so...

 

[Mr London 24/7]

'Stealthy Mobility and Support Aircraft for United States SOF' (presentation, brief B-MACK mention):

http://www.csbaonline.org/4Publications/PubLibrary/S.20070222.Stealthy_Mobility_/S.20070222.Stealthy_Mobility_.pdf

The author has creds:

http://www.defense.gov/bios/biographydetail.aspx?biographyid=198


And other history including 2009 testimony to HASC inc call for an 'M-X' type SOF aircraft:


http://www.csbaonline.org/4Publications/PubLibrary/T.20090303.Special_Operations/T.20090303.Special_Operations.pdf

 

[yasotay]

Great stuff actually. While I have not read the full testimony I did note that nowhere in the slides did it talk about an inconsequential issue, namely landing. You can be as stealthy as you want, but having to land on a runway makes it rather redundant. With all of the talk about anti-access going around the pundits and most everyone knowing airports are kind of important to getting into a country, landing at an airfield is pretty predictable and dumb. Okay so they come up with stealth material that can take the rigors of debris impacts while landing off of a runway. Just hope it does not rain before taking your stealth lifter in to land in the dirt. Little issue of a thing called a California Bearing Ratio ( at least in the US). And I sure hope you are not planning on landing more than one or two stealthy lifters on that dirt, because with all that weight and braking you get these nasty things called ruts, that do bad things to landing gear. Finding a lot of contiguous >5000 foot, straight, plots of dirt is a bit challenging in many places outside the desert regions.
But all of that is irrelevant as the Air Force Inc. will get its stealthy high subsonic lifter regardless of what the rest of their customer base needs them to have. You don't really think they are going to get the funds to build just for the SOF community do you?

 

[quellish]

But all of that is irrelevant as the Air Force Inc. will get its stealthy high subsonic lifter regardless of what the rest of their customer base needs them to have. You don't really think they are going to get the funds to build just for the SOF community do you?

Actually it's more complicated than that. SOCOM would own these aircraft and would pay for some parts of their life cycles, while USAF would pay for other parts. This has changed several times over the years, but if you look at recent procurement, operations, and training for the AC/MC-130J you'll see that more and more it's SOCOM's money being spent. In the past the balance was different.

 

[Mr London 24/7]

'Theatre Airlift 2010' (Col Alexander P. Shine (from 1988) for refs ATT/ATTMA):


http://www.airpower.maxwell.af.mil/airchronicles/apj/apj88/win88/shine.html

Most significant has been the combined work of the Military Airlift Command (MAC), Air Force Aeronautical Systems Division (ASD), and contractors from Boeing, McDonnell Douglas, Lockheed, and the General Research Corporation, under the heading of Advanced Transport Technology Mission Analysis (ATTMA). The ATTMA study attempts both to define requirements and suggest technological possibilities for an advanced theater transport (ATT)

There is much difference of opinion on the issue of low-observable (LO) design. Everyone involved in ATTMA agrees that a large LO aircraft can be built. But there is considerable debate on the extent to which the radar cross section can be reduced and the significance of radar-directed threats to airlifters

And finally... 'California Bearing Ratio' (from an Army Aviator! - for Yasotay ):

Designing a theater transport that can land with a substantial payload on 1,500-foot strips with a California Bearing Ratio of 6 will not be difficult or costly. However VSTOL capability will come only at great cost and technological risk

 

[yasotay]

'Theatre Airlift 2010' (Col Alexander P. Shine (from 1988) for refs ATT/ATTMA):


http://www.airpower.maxwell.af.mil/airchronicles/apj/apj88/win88/shine.html

Most significant has been the combined work of the Military Airlift Command (MAC), Air Force Aeronautical Systems Division (ASD), and contractors from Boeing, McDonnell Douglas, Lockheed, and the General Research Corporation, under the heading of Advanced Transport Technology Mission Analysis (ATTMA). The ATTMA study attempts both to define requirements and suggest technological possibilities for an advanced theater transport (ATT)

There is much difference of opinion on the issue of low-observable (LO) design. Everyone involved in ATTMA agrees that a large LO aircraft can be built. But there is considerable debate on the extent to which the radar cross section can be reduced and the significance of radar-directed threats to airlifters

And finally... 'California Bearing Ratio' (from an Army Aviator! - for Yasotay ):

Designing a theater transport that can land with a substantial payload on 1,500-foot strips with a California Bearing Ratio of 6 will not be difficult or costly. However VSTOL capability will come only at great cost and technological risk

The statement is almost correct. Landing a theater transport ... with a CBR of 6 will not be difficult. The trick is landing more than one there. Witness the initial airlift into Afghanistan where days were spent fixing a dirt runway after a couple of heavy theater transport landed. Instead of bringing in tropps and supplies they had to bring in engineering equipment. Good thing the Taliban did not argue the point. Same happened in northern Iraq when the US flew the 173rd Airborne into a regular runway. Then there is the lost point that what is CBR 6 when it is dry, is NOT when it is wet. "Sorry fella's your mission to seize the rouge nuke is cancelled because it rained last night."
With a VTOL a 1500 foot strip is large enough to land 3 aircraft, regardless of the CBR rating (ever seen a CH-47 landed in a lake? ... CBR 0). A VSTOL capability will come at greater cost ...compared to a stealth transport? Sorry I would have to see the numbers, but I will put money down that is not true. Technology wise I'll say maybe. B)

 

[antigravite]

Boeing was issued a BWB Aircraft Patent # US8256706.
It has some interesting illustrations.

A.

 

[sferrin]

Boeing was issued a BWB Aircraft Patent # US8256706.
It has some interesting illustrations.

A.

Reminds me of this one:

 

[antigravite]

WOW! almost perfect match. Your version seem to be the civilian chapter.

A.

 

[sferrin]

WOW! almost perfect match. Your version seem to be the civilian chapter.

A.

There's a thread here somewhere with that design in it but for the life of me I couldn't find it. IIRC it's a Lockheed design.

edit: Here it is http://www.secretprojects.co.uk/forum/index.php/topic,215.195.html (Post #196. You'll also like posts #201 & 202.)

 

[Sundog]

It's the advanced cargo design being looked at by the USAF. Isn't the program called FAST or something like that?

 

[Stargazer]

It's the advanced cargo design being looked at by the USAF. Isn't the program called FAST or something like that?

It's the Boeing AJACS.

 

[Aeroengineer1]

Indeed those two projects are related, both the Boeing and the Lockheed model were part of the Speed Agile Concept Demonstrator program. I know the Lockheed model very well as I was one of the primary engineers for the physical design of the wind tunnel model.

 

[bobbymike]

Requirements Mulled for Next-Generation Airlifter

Air Mobility Command is in the early stages of defining requirements for the Air Force's next-generation airlifter, the C-X, and it could replace the C-17 and C-130 alike, said command boss Gen. Paul Selva. He told the Daily Report that AMC is "beginning to define what the airlift fleet looks like, not in 2020, but into the early '30s and on into the '40s." If requirements demand an aircraft able to operate in contested or denied airspace, that suggests curtailing C-130 buys late in this decade, he said, so that the Air Force isn't "buying ourselves into a legacy airplane" that can't do the job. Much depends on how the Army shapes itself for "tactical and operational maneuver" and "the contribution that [air]lifter will make to that maneuver," said Selva. AMC has been working with Air Force Materiel Command and the Air Force Research Lab to explore what's possible, he said. After this "conceptual" work, AMC may still need one cargo airplane for strategic work and one for tactical tasks, but Selva said he wants a plan in hand well before the C-17 starts to retire "so we don't collide with a sort of 'double recap' requirement." The Air Force might still replace all its C-130Hs with C-130Js, but "it's not clear" at this point "that that's the only option," he said during the mid December interview.