Published in 2015, the latest National Military Strategy of the United States acknowledged that, in addition to the early 21st century threats faced by the US like terrorism and insurgency, the possibility of a major war with great powers such as Russia and China was growing. Moreover, these potential foes are currently fielding increasingly advanced technologies on par with – or capable of negating – western tech advantages.
Western Air forces in particular, which enjoyed near undisputed air superiority since World War II, will encounter anti-access and area-denial strategies backed up by sophisticated air defense systems. In the Mitchell Institute for Aerospace Studies’ “Survivability in the Digital Age: The Imperative for Stealth” report published last northern hemisphere summer, Maj. Gen. Mark Barrett and Col. Mace Carpenter wrote “Over the long run, the U.S. will engage opponents who field increasing numbers of powerful digital multiband radars. And that is particularly troubling when ground-based systems alert surface-to-air missile (SAM) batteries about approaching aircraft.”
Russia and China are now developing and fielding air defenses that take sensing information sharing to the next level in an attempt to counter U.S. stealth capabilities. Even the improvement of US stealth technology such as RAM coatings, designs and heat signatures won’t entirely counterbalance these new defenses.
Former Air Force pilot Mark Gunzinger and Bryan Clark of the Center of Strategic and Budgetary Assessment wrote in a 2015 report, “96% of all American Precision Guided Munitions (PGM) are direct attack weapons with ranges under 50 nm.” If long range standoff cruise missiles exist, such as the 540mn AGM-158 JASSM (Joint Air-to-Surface Standoff Missile) they are more expensive and can have difficulty engaging hardened or mobile targets. Even if next-gen F-35 could “use their stealth to penetrate the air defense bubble, they would probably not have the range to engage high value targets inland,” and “due to payload limitations and their inability to loiter because of fuel constraints and the air defense threat, they would also struggle to engage highly mobile targets.” An Air Force official contacted by Aviation Week’s Pentagon correspondent Lara Seligman states that pilots tank typically two or three times on a 6hr mission.
As such to provide intruding aircraft with the most favourable circumstances, Col. Carpenter wrote “you got to have tankers to get you in and get you out. The closer a tanker can get you to the fight, the better it is for the strike packages.” But these tankers are themselves highly vulnerable. Like AWACS and C4ISTAR aircraft they are mostly converted airliners and transport aircraft lacking advanced defense systems. The Soviet Union and its successor state Russia already recognized these vulnerabilities and developed so-called “AWACS killers” like the Novator K-100 and R-37M air-to-air missiles with ranges up to 400km. Tankers are also increasing vulnerable to stealth aircraft, as highlighted by US Air Mobility Command head Gen. Carlton Everhart, who declared to Bloomberg in April “I’ve got first-generation tankers refueling fifth-gen fighters. The enemy doesn’t have to look for the fighter — he just has to look for me.”
To provide tankers with increased survivability, researches are currently focusing on stealth and defensive lasers. In 2016 the US Air Force Air Mobility Command (AMC) announced the KC-Z next-generation tanker aircraft program. Lockheed Martin’s proposal, a hybrid wing-body aircraft with engines embedded within the airframe, would not have a high level of stealth but its low profile would naturally reduce radar reflections. On October this year the Command unveiled a study, called the High Value Airborne Asset Study, which identified survivability gaps on existing tankers, plus Boeing E-3 airborne warning and control system and Northrop Grumman E-8C joint surveillance target attack radar system aircraft and could set the stage for a “cloaking technology”.
A year before the study completion, Gen. Everhart called for a stealth tanker but he declared to Inside the Air Force he “backed off of it because I just didn’t have the ‘bucks’ to get there. Now I’m starting to change my philosophy again and say, ‘Maybe I need to take another look at that.'” The “cloaking” would involve taking radiant energy from a radar and diffusing it to disguise a tanker or airlifter’s outline to make it “look like it is not a tanker or an airlifter, so you don’t want to take a shot,” he said, adding “you are changing the calculus of the adversary.”
Speaking at the Air Force Association’s 2017 annual convention, he indicated “it’s not as simple as I think it is. If you get one electron out, you just identified yourself to the adversary.” In collaboration with the US Air Force Research Laboratory, AMC will undertake the first demonstration within 6 months on a KC-135 refueling tanker of technologies that could be refitted on planes as old as the 1950s-era KC-135 and as new as the KC-46. A modified KC-46 would bridge the gap until the KC-Z procurement can begin and allow to skip a KC-Y procurement program. The KC-46’s 179 units planned purchase is slated to end by 2028 while the KC-Z is expected to be available by 2035.
The study also discussed fielding a defensive laser weapon on the aircraft. Different from current defensive systems such as DIRCM and LAIRCM, which use laser beams to blind an incoming missile’s heat-seeking warhead, the system would directly destroy missile. Mark Gunzinger declared to Breaking Defense it is “possible in the near term to develop and field the next generation of laser defenses that will burn out, not just blind, sensors on SAMs and air-to-air-missiles. In fact, lasers would be especially effective against the most advanced missiles, those with sensitive multi-mode sensors.” The Air Force is currently focussing on three programs, a Self-protected HIgh-Energy Laser Demonstration (SHIELD) defensive system, a 100kW longer-range defensive system and a 300kW offensive system. If they were first destined to be integrated on fighter planes, the Air Force decided earlier this year to demonstrate the system first on a mobility platform, which offered more favorable size, weight, power and cooling constraints and don’t require the beams to fly through faster, or transonic, airflow. Air Combat Command Chief Gen. Mike Holmes also advocated for increased investment in shared situational awareness across platforms. This type of information would “helps tankers know which airfields are safe to land in, what threats are nearby and whether the assets meant to protect them are nearby.”
The US Navy faces similar challenges. Its $13 billion Ford-class carriers will face sophisticated hypersonic missile designs and the Navy announced China already fields an anti-carrier Dong Feng-21D ballistic missile with a 900mi range. Just as these weapons would force the carriers farther from shore, the Navy’s strike range from its carrier wings has actually dipped by 50 percent, below 500 miles, according to Center for a New American Security (CNAS) analyst Jerry Hendrix.
The tanker role is currently carried by F/A-18E/F Super Hornets equipped with two 480-gal. auxiliary tanks and a centerline aerial refueling system an “inefficient use of combat-rated strike fighters” for Rear Adm. Mark Darrah, program executive officer for unmanned aviation and strike weapons at Naval Air Systems Command (Navair). As such, the Navy decided for an UAV to serve as its next aerial refueling tanker. The MQ-25A Stingray, which would also serve as an ISR platform, evolved out of a now-cancelled carrier-launched ISR and attack drone program called Unmanned Carrier Launched Airborne Surveillance and Strike system (UCLASS). The program calls for 72 aircraft able to deliver 14,000 lb. of fuel starting at 500 mi. from the carrier at sea, with the first to enter service by the early 2020s.
Northrop, which designed the UCLASS demonstrator X-47B, withdrew from the competition, leaving Boeing, Lockheed Martin and General Atomics Aeronautical Systems as the sole contenders. The Stingray is not supposed to integrate stealth technology. In August 2016 Naval Air Forces Commander Vice Adm. Mike Shoemaker said that tanker and stealth concepts “don’t go together”. This would reduce its value as an ISR platform, although it will have an electro-optical/infrared sensor ball and provisions for a potential maritime surveillance radar. For CNAS technology and national security program director Paul Scharre these changes a part of the Navy’s “muddled view on range”, saying the service still “hasn’t specified whether the MQ-25’s precise role would be as a mission tanker to accompany fighters on combat strikes, or merely as a recovery tanker loitering near carriers for pilots who miss approaches and are low on fuel.”
Written by ADIT – The Bulletin and republished with permission.