29 septembre 2020 |
International,
Aérospatial
Steve Trimble
Proposals for a next-generation tanker that would come after the last Boeing KC-46 delivery in fiscal 2029 have popped up every few years since 2006, only to get sidetracked by yet another acquisition process misstep or technical problem afflicting the program's frustrating development phase.
As a fresh sense of optimism gathers among senior U.S. Air Force leaders about the direction of the KC-46 program, a new discussion has started between Defense Department officials and the Air Mobility Command (AMC) about the future of the air-refueling mission. Some proposals in the discussions include revived versions of various older concepts for weaponized larger tankers and smaller stealth tankers. But this time, discussions involve
taking a wider view of the overall need to defend and deliver fuel to aircraft in combat, with implications for base defenses, the size and range of future fighters and next-generation tanker designs.
A perceived turnaround in the fortunes of the KC-46 program allows the Air Force to reopen the next-generation discussion. Since at least 2016, a heated dispute over Boeing's original design—and, later, proposed fixes—for the KC-46's remote vision system (RVS) sidetracked planning for a next-generation tanker. Air Force officials complained that Boeing's original RVS design fell short of operator requirements, especially when the receiver aircraft was backlit by the Sun. In addition, the canted layout of the belly-mounted, panoramic cameras created subtle distortions in the displayed video that proved bothersome to some RVS operators, Air Force officials say.
The Air Force and Boeing finally agreed to a redesign plan in January 2019. The Air Force is finalizing a test report on an enhanced RVS, which was formerly known as RVS 1.5. AMC officials have committed to review the test data but offered no promises on whether they would approve the enhanced
RVS to be installed in the KC-46. The installation would require parking a fleet of more than 36 delivered KC-46s to complete the retrofit, and the AMC remains unsure whether the improvement is worth the delay.
The enhanced RVS offers only software updates to the current system, but the AMC clearly wants more. Boeing has committed to a more dramatic upgrade called RVS 2.0. Including hardware and software changes, this Boeing-funded, second-generation RVS system is expected to meet the image-resolution standards demanded by the Air Force and create a path to inserting the software algorithms necessary to give the KC-46 an optional autonomous-refueling mode.
Boeing is scheduled to deliver the first 12 RVS 2.0 shipsets by the end of 2023 and begin the retrofit process on delivered KC-46s, says Gen. Jacqueline Van Ovost, the AMC commander. The AMC expects a production cutin for RVS 2.0 starting in 2024, although Boeing's KC-46 global sales and marketing director, Mike Hafer, says the first RVS 2.0-equipped aircraft could start rolling off the assembly line in late 2023.
Will Roper, the Air Force's assistant secretary for acquisition, technology and logistics, says the progress toward fielding the RVS 2.0 makes him feel “excited” about the KC-46 program. “I think we've turned a new page,” he says.
In mid-September, Roper and Van Ovost met to discuss what will follow the KC-46. The next-generation tanker discussion comes after a series of dramatic acquisition decisions surrounding Air Force aircraft. Most visibly, Roper led a push in 2018 to cancel the Joint Stars recapitalization program, which was replaced with the Advanced Battle Management System (ABMS). More quietly, Roper also drove the Air Force to rethink the acquisition strategy for the Next-Generation Air Dominance (NGAD) program. The ABMS and NGAD are now characterized by an architecture of multiple systems, with no single-aircraft
silver bullet solution.
Roper acknowledges that the nature of tanker operations does not immediately lend itself to a distributed multiplatform solution.
“We can break up a J-Stars [replacement into multiple systems],” Roper says. “We may be able to break up an [E-3 Airborne Warning and Control System] in the future, but we can't break up fuel easily.”
Still, Roper prefers to address the future air-refueling problem in an era of great power competition with a similar architectural approach as ABMS and NGAD.
“When there's a solvable problem and you need to turn multiple knobs, the Pentagon likes to turn one and only one,” Roper says. “And [aerial refueling] sounds like a really good architectural question that you'd want to have an architected solution for—[rather than] design a one-solution candidate in the form of a platform.”
Roper's turnable knobs for a future air-refueling system cover a wide range of options, including two with only indirect impacts on a tanker aircraft design. To Roper, the problem of air refueling includes defending the bases closest to an adversary where aircraft can be refueled on the ground. Likewise, another part of the solution is to move away from relatively small fighter aircraft that lack sufficient range for a Pacific theater scenario.
“Maybe having small, currently sized fighters is not the way to go in the future,” Roper says. “Thinking about bigger fighters is a natural question to lay alongside the question, ‘How does your future tanker force look?'”
Air-refueling capacity also is partly a function of the vulnerability of the tanker aircraft. Fewer and perhaps smaller tankers may be possible if existing tanker aircraft could operate closer to the battlefield. The Air Force now uses fighters on combat air patrols to defend high-value assets, such as tankers, surveillance and command-and-control aircraft. Those fighters conducting the patrols also add to the refueling burden. A possible solution is to weaponize tankers such as the KC-46 and KC-135. The Air Force is developing podded defensive lasers and miniature self-defense munitions.
“We don't put weapons and sensors on tankers to shoot down aircraft, but the current KC-46 is a big airplane with the ability to mount sensors and weapons on the wings,” Roper says. “We're going to look at all those [options].”
The Air Force also believes a new tanker aircraft is necessary. As far back as 2002, research began on stealthy mobility aircraft under the Air Force Research Laboratory's Speed Agile program. As the KC-X acquisition program kicked off, the Air Force released a tanker road map in 2006 that called for launching a KC-Y acquisition program in 2022 and a KC-Z program by 2035. By 2016, AMC leaders openly discussed proposals for leapfrogging the KC-Y requirement, which sought to buy a larger version of a commercial derivative. Instead, AMC officials began investigating concepts for an autonomous stealthy aircraft. By 2018, Lockheed Martin's Skunk Works had defined a concept for such an aircraft, which featured an undisclosed refueling technology that could dock with a receiver aircraft without compromising radar stealth.
As discussions have reopened in September, the Air Force is again considering the acquisition of a mix of larger and smaller aircraft to fulfill the demand for in-flight refueling in the 2030s and 2040s.
“One trade we can do is having bigger tankers that stand off a lot farther,” Roper says, “[and] having smaller, microtankers that do that last mile, the dangerous mile—and we expect to lose some of them.”
The Air Force's budget justification documents suggest research on a next-generation tanker will continue at a low level: Nearly $8 million was requested in fiscal 2021 to “assess promising configurations in high- and low-speed wind tunnels.” The Air Force also is designing a small, pod-mounted tactical air-refueling boom, according to budget documents. The latter suggests that one option for increasing refueling capacity for aircraft equipped with boom receivers is to integrate a podded fuel-delivery system on tactical aircraft, such as a Lockheed Martin C-130.
“I expect that as we really look at airpower in the truly contested environment, we'll be looking at fuel very strategically,” Roper says. “We may have a different solution for outside [a threat area] versus inside. And I think we will value, increasingly, aircraft that have range for the last mile.”
https://aviationweek.com/defense-space/aircraft-propulsion/kc-46-progress-revives-next-generation-tanker-talks
