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An X-47B Unmanned Combat Air System demonstrator launches from the aircraft carrier USS George H.W. Bush (CVN 77) May 14, 2013, in the Atlantic Ocean 130514-N-UZ648-182

The X-47B Unmanned Combat Air System demonstrator launches from the aircraft carrier USS George H.W. Bush (CVN 77) May 14, 2013.

An X-47B Unmanned Combat Air System demonstrator flies near the aircraft carrier USS George H.W. Bush

Unmanned X-47B with USS George H.W. Bush (CVN 77) in the background

The United States Navy's Unmanned Carrier-Launched Airborne Surveillance and Strike (UCLASS) program is to develop an aircraft carrier-based unmanned aerial vehicle to provide an unmanned intelligence and strike asset to the fleet. The UCLASS will be "an autonomous aircraft capable of precision strike in a contested environment, and it is expected to grow and expand its missions so that it is capable of extended range intelligence, surveillance and reconnaissance, electronic warfare, tanking, and maritime domain awareness".[1]


The UCLASS program currently has several competing designs and design bases:[2]


In June 2013, the USN released RFPs to the four competitors. The RFPs were individualized for each company, so the exact specifications were publically unknown. The RFPs were originally supposed to be issued in late 2012, but were delayed several times. Submissions were due in early July.[3]

The Navy expected to release a draft RFP for the technology development phase in August 2013, with a final version expected in 2014. The first RFP, released in June, is to mature the four designs up to a preliminary design review (PDR) over nine months and assess technical readiness. The following technology demonstration phase is much more rigorous. NAVAIR hoped to have an industry day for UCLASS competitors in September 2013. The Navy was to downselect one company and design in 2014 and begin development in 2015.[4]

The draft RFP for technology development was delayed from August to September 2013. There was continuing debate over requirements and stealth. General Atomics and Boeing are expected to de-emphasize stealth in favor of endurance and payload. Northrop Grumman and Lockheed are pitching tailless high-survivability designs. Although stealth is more expensive, Lockheed says the UCLASS "needs to be a fifth-generation capability," and that their experience with the F-22 Raptor, F-35 Lightning II, and RQ-170 Sentinel provided lessons on affordability. The Navy is expected to select a cost-plus contract to minimize risk put on the contractor in development, but it is unclear how the bids will be graded.[5]

On 14 August 2013, the Navy awarded four development contracts to Boeing, General Atomics, Lockheed Martin, and Northrop Grumman. Each contract was worth $15 million develop airframe designs. The preliminary design review assessment is to support the UCLASS “to enhance aircraft carrier/air wing operations by providing a responsive, world-wide presence via an organic, sea-based unmanned aerial system, with persistent intelligence, surveillance, reconnaissance, and targeting, and strike capabilities.” NAVAIR expected to have a competition for a final airframe design after January 2014.[6] The industry day was to be held in October 2013, with the final RFP released in the second quarter of 2014, and a vehicle selected in the first quarter of 2015.[7]

On 26 September 2013, the Government Accountability Office (GAO) issued a report calling for greater oversight over the UCLASS program. It said that the Navy was pursuing the program in a way that will limit the ability of Congress to hold it accountable for meeting goals on cost, schedule, and performance. In FY 2014, the Navy plans to spend $3.7 billion to develop, build, and field six to 24 aircraft as an initial complement of UCLASS. However, it does not plan to initiate a key review of the program until 2020, when the proposed aircraft would already be fielded. The Navy sees UCLASS as a technology development program. Instead of starting a formal review early on, it plans to take advantage of Defense Department flexibility to gather data so the program is ultimately successful. They say their approach conforms to requirements set forth in the 2012 National Defense Authorization Act. The GAO says work on the program goes well beyond technology development, and thus warrants oversight in relation to a major weapon system development program. The report advises Defense Secretary Chuck Hagel to direct the Navy to hold the review in FY 2015 to trigger key oversight measures. It also raises problematic risks, as the $3.7 billion cost estimate exceeds the funding the Navy expects to budget for the program through 2020. The Navy has scheduled eight months between the time it issues a request for design proposals to the time it awards a contract, a process which normally takes 12 months. The UCLASS relies on the successful development and delivery of systems and software, which creates additional schedule risk. Integrating all the systems associated with the program will require the service to manage 22 separate government systems, acting in an increased capacity that it does not routinely do. The Navy will do regular reviews and consult industry experts, but will still need to double the staff in the program office from 150 to 300.[8]

The Navy plans to arm the proposed UCLASS with weapons currently in the carrier air wing's inventory. Weapons requirements will be outlined in final proposals and will be influenced by specific proposals. With the priority of the aircraft on ISR, the airframe will accommodate a fifth-generation AESA radar. It will have multiple intelligence (multi-int) sensors to include electro-optical/infrared sensors and full-motion video cameras. The sensor suite allows for detection and tracking of targets on land or at sea. Integrating weaponry is still being planned, but will include Joint Direct Attack Munitions. A draft RFP was to be released in December 2013, with the final technology-development phase RFP submitted by spring 2014.[9]

In January 2014, the draft RFP was pushed back to "the end of this quarter." The delay continued to be on the cost of the system compared to desired performance. Congressional actions also restrict the Navy's approaches. The original plan was to build four air wings with the UCLASS aircraft during the technology development phase. Congress has prohibited downselection of a contractor until a preliminary design review is complete, and will not allow them to acquire more than six air vehicles prior to Milestone B approval to enter Engineering and Manufacturing Development (EMD). Some in the Navy are recommending temporarily halting the program to better plan it out.[10]

The Navy has hinted at the possibility of using the UCLASS in air-to-air engagements. Though its primary roles will be ISR and strike, there is the potential to use it as a "flying missile magazine" to supplement the F/A-18 Super Hornet and F-35C as a type of "robotic wingman." Its weapons bay could be filled with AIM-120 AMRAAMs and be remotely operated by an E-2D Hawkeye or F-35C flight leader. Unmanned aircraft have no judgment or onboard systems to perform the mission, but if teamed with a manned fighter that uses it sensors and human judgment to detect and track an enemy aircraft, the UCLASS could then be directed to engage. The Navy is ahead of the U.S. Air Force in unmanned air-to-air fighting capabilities, as its Naval Integrated Fire Control-Counter Air (NIFC-CA) concept gives a common picture of the battle space to multiple air platforms through data-links. Under the concept, any aircraft could fire on a target in their range that is being tracked by any sensor, so the forward deployed UCLASS would have its missiles targeted by another controller. Using an unmanned aircraft as a missile platform is not without difficulties, as manned air superiority fighters like the F-22 and F-15 Eagle use high altitude and supersonic speeds to impart the greatest amount of launch energy on missiles. The subsonic UCLASS would generate even less energy than the low speed and low altitude F/A-18 Hornet, resulting in decreased missile range. Even so, most missile engagements have taken place at subsonic speeds and medium altitudes. Although the UCLASS' expense will not make it an "expendable" asset, one getting shot down in air combat would be preferable to losing a pilot. With manned-unmanned teaming for air combat, a dedicated unmanned supersonic fighter may not be developed, as the greater cost of high-thrust propulsion and an airframe of similar size to a manned fighter would deliver a platform with comparable operating costs and still without an ability to engage on its own.[11]

NAVAIR planned to release the draft RFP by the end of March 2014. The Navy is optimizing the UCLASS for ISR and limited strike rather than long-range strike, along with a potential tanker role. On 18 February 2014, Congressman Randy Forbes, senior member of the House Armed Services Committee and chairman of the Seapower and Projection Forces subcommittee, wrote a letter to Secretary of the Navy Ray Mabus. The letter advocated for the UCLASS to have aerial refueling, survivability, and payloads to make it effective in future contested air environments. Forbes requested the aircraft have broad-band stealth to survive integrated air defense systems and have the payload capacity to simultaneously support land and sea missions. Aerial refueling was also cited as a needed capability for responding to far-off threats and conducting missions outside the envelope of long-range threats, particularly the Chinese DF-21D anti-ship ballistic missile.[12] The first flight of the UCLASS has been delayed from early 2017 to mid-2018.[13] The draft RFP was expected near the end of April with the final RFP released in July 2014. After the final RFP is released, industry has 60 days to respond, followed by a 10-month source selection. One contractor and aircraft design is to be downselected in early 2015.[14][15]

Requirements controversyEdit

Navy officials expressed concern that the original requirements of the UCLASS program had been so degraded that it could be cancelled as part of budget cuts. The original concept called for a stealthy, carrier-based, long-range unmanned combat aerial system (UCAS) with a large payload that could be refueled in-flight. The current version calls for an UCAS that is modestly stealthy and emphasises intelligence, surveillance, and reconnaissance (ISR) missions over lightly contested airspace, with a light secondary strike mission. It promotes affordability, which calls for a design that is less survivable and has less endurance. Some think it is better to create an aircraft that although more expensive, adds greater capabilities to the fleet, rather than a cheaper platform that adds little. The lessened stealth capabilities and lower numbers proposed may have made the program decline in worth. The office of the Chief of Naval Operations said the UCLASS will support missions in permissive and low-end contested environments, while providing enabling capabilities for high-end denied operations. Current requirements were written to fill a gap in persistent, sea-based ISR. The original concept was to evolve the X-47B demonstrator into an operational aircraft with aerial refueling. The Joint Requirements Oversight Council dropped the air refueling requirement, reducing its flexibility. NAVAIR said although aerial refueling was not an initial requirement, it may be re-added in the future pending early operational capability performance and fleet feedback. The UCLASS was to have low-observable features, running from "marginal stealth" to F-35 Lightning II levels. Stealth requirements have been sharply reduced to lower costs, reducing its ability to penetrate anti-access/area-denial environments. Original payload requirements called for weapons bays to carry as many as 24 GBU-39 SDB 250 lb bombs, totaling a 6,000 lb weapons payload. Current requirements call for a total payload of 1,360 kg (3,000 lb), with only 454 kg (1,001 lb) of weapons.[16]

Senior officials denied that changes to the UCLASS requirements were made by the JROC on behalf of the White House. The JROC also did not consider the requirements to be "relaxed." The Pentagon said that the requirements were modified by the JROC during an 18 December 2012 meeting. The UCLASS requirements were changed to consider "within the broader unmanned aircraft portfolio and included an assessment of the platform's performance, capability, survivability, and basing." They claim its capabilities were not reduced, but were shifted to increase some performance areas and decrease others to get a mix. Trade-offs were made to consider the needs of fighting forces across a range of national security interests.[17] JROC was reported to have changed the requirements in order to produce a replacement for the current drones used for Disposition Matrix missions that would not require host nation basing or permission. While the Navy's initial aim of creating a UAV capable of striking defended targets, the focus was changed to keep costs down and maintain unmanned counterterrorism missions as a U.S. military option. Flying missions from sea-based carriers would have fewer restrictions than operating inside foreign countries, and irregular warfare missions would continue in the future to warrant further attention. The Navy disagrees with this focus, as there are many assets that can operate in non-contested airspace with few stealthy-type penetrators, and expensive carrier forces and air wings would be used to find individual high value targets.[18][19] DoD director of unmanned warfare Dyke Weatherington confirmed that the change was made because of fiscal pressures.[20]

In September 2013, several lawmakers wrote a letter to Navy Secretary Ray Mabus to ask the service to consider a broader scope of requirements and capabilities and a wider range of mission possibilities for the UCLASS to make it an “integral part of the Carrier Air Wing.” The letter stated that Congress believes the narrow ISR role limits the capability growth of the system, and that it should be designed to be an integral part of the air wing and be employed in the full-spectrum of the Navy’s power-projection mission. The letter asked Mabus to work with the program on the technology development RFP to not focus on just one particular key performance parameter, but to enable competition and capability tradeoffs on a spectrum of attributes such as range, payload, survivability, and affordability. A more broadly scoped set of missions would allow industry the flexibility to develop a range of solutions able to meet requirements for the UCLASS in both the near-term and longer term. The main argument of the letter was for establishing broad requirements so that the platform can grow, change, and evolve over time as technologies mature. Advocates for a wider set of mission roles say it will not lessen the core ISR function, but rather add to it with additional capability.[21]

The letter from Congress also showed that they were concerned about the UCLASS acquisition strategy. The Navy's established plan to field four carrier air wings worth of aircraft before the completion of operational testing, or even a formal “Milestone B” decision to enter engineering and manufacturing development, was described as "atypical." Congress and industry both agreed that the Navy has deviated significantly from the normal process for developing a new aircraft. Normally, industry would develop solutions over two years based on initial issued requirements. The specifications would be refined and updated as needed, based on various industry-informed trade studies. This procedure is likely to yield more relevant industry investment, more affordable requirements, and a better overall competition. For nearly three years, companies developed their candidates with company funds based on assumptions about the Navy’s requirements without any guidance from the service. The Navy did not issue any aircraft performance specifications or draft requirements until the spring of 2013, so competitors tried to refit their aircraft for the preliminary design review phase. This required more company investment, which may lead contenders to drop out of bidding. The lack of feedback was compounded by the shift of mission statements, from a long-range penetrating strike platform to long-duration orbits over permissive airspace. Endurance requirements of over 12 hours is especially hard to meet, as there are limitations of an aircraft's wingspan for holding fuel on the confined space of an aircraft carrier. The aircraft must have a higher aspect ratio wing (longer wingspan), but the maximum wingspan for the UCLASS is around 70 ft (21 m) to meet size and weight requirements. With aerial refueling no longer a capability, designers must make aircraft as light as possible, holding as much fuel as possible. The UCLASS must maintain two 600 nmi (1,100 km; 690 mi) orbits around the ship, or one orbit at a range of 1,200 nmi (2,200 km; 1,400 mi), with the ability to attack lightly-defended targets out to 2,000 nmi (3,700 km; 2,300 mi). The endurance requirement is so strenuous that a turbofan engine may not be a "viable option." Boeing and General Atomics appear to have selected a wing-body tail design, while Lockheed and Northrop Grumman have flying-wing concepts.[22]

After pressure from Congress, industry, and the GAO, the Navy took another look at the draft requirements for the UCLASS. They were scheduled to be released in October 2013 but were delayed. Industry sources said the struggles with the program were because of the budget environment. The Navy wanted to run its own budget priorities, while JROC recommended otherwise. The main reason behind the internal strife was indecision over the future of the aircraft carrier fleet and the air wings that operate from those ships. JROC and some naval officers believe the U.S. military needs better UAV-based ISR coverage around the globe, and that the capability must be integrated on board carriers in the near-future. Examples are drawn from the French experience during Operation Serval over Mali, where they needed permission from a host nation to use their airfields to deploy unmanned assets. They feel the first priority should be to get UAV operations normalized on board carriers and get more value out of the vessels, and more capability out of the aircraft could be added later. Most others inside the Navy believe that their multi-billion dollar carriers, air wings, and accompanying strike groups have better uses. Even though a UAV's benefits are not essential for the service to operate, they feel any new unmanned aircraft integrated into the carrier air wing should be focused on making the carrier a more effective strike platform.[23] In November 2013, the draft RFP was pushed back to December for what was said to be "cosmetic" changes,[24] but Rear Admiral Mat Winter said that he was requiring all the bidders to show how their designs would perform in contested airspace.[25]

By December 2013, the UCLASS concept aircraft had shifted around significantly. Original requirements that were for a relatively simple ISR platform, have now changed to a "heavy-end" ISR and strike aircraft with growth for weapons and sensors. It is now planned to weigh 70,000 to 80,000 lb (32,000 to 36,000 kg), about the size of the F-14 Tomcat, and much larger than the 44,000 lb (20,000 kg) X-47B. Some proposed designs are 68 ft (21 m) long, 8 ft longer than the F/A-18 Super Hornet. Size and weight projections may require a twin-engine design or a version of the Pratt & Whitney F135 which delivers 28,000 lb (13,000 kg) of thrust. Endurance may be up to 14 hours. Other roles are now being considered for the aircraft. The UCLASS may be used as an aerial refueling platform to extend the range of fighters like the F-35C. It could transfer 20,000 lb (9,100 kg) of fuel and still stay airborne for up to 7.5 hours. Stealth features are still being debated, but it is not expected to be as stealthy as the F-35C. By 2030, the Navy will have operational experience with the UCLASS and have a better understanding with what an unmanned aircraft can bring to a carrier air wing.[26]

In early February 2014, four Washington think tanks held a public event on recommendations of how the Pentagon could develop future military capabilities while staying within budget caps. All embraced an option to shrink the U.S. Navy's aircraft carrier force by two or more carriers. They see this not as an end to the class of ships, but as a rebirth, with two teams choosing to develop a stealthy unmanned combat aircraft system to perform long-range strike and surveillance missions. Future adversaries are likely to employ anti-access threats like anti-ship ballistic missiles, cruise missiles, and submarines that will require carriers to operate further from coastlines, limiting the ability of short-range strike fighters to reach targets while being met by advanced air defense systems. Strategic bombers and nuclear submarines can strike targets in these environments, but rely on fixed land bases that are vulnerable to attack. A multi-mission UCAS can operate from the mobile base of a carrier and perform long-range ISR and strike missions against sophisticated air defenses. The UCAS would require three key features: broadband stealth to penetrate contested airspace; a range on internal fuel double that of a manned fighter to take off beyond the range of land-based missile threats, as well as in-flight refueling to extend its endurance up to 20 hours for patrolling inside enemy airspace while needing fewer aircraft; and an internal weapons payload of 4,000 lb (1,800 kg) (similar to the F-35C) or greater to attack the same number of targets as its manned counterpart on contested areas. The Navy's course of pursuing the UCLASS without broadband stealth, a small weapons load, and no in-flight refueling would relegate the platform to providing surveillance outside the combat zone. This would make it as unusable as other non-stealthy unmanned systems like the MQ-4C Triton and MQ-8C Fire Scout and be a lost opportunity to sustain sea-based strike advantages.[27]

NAVAIR planned to release the draft RFP at the end of March 2014, but was further delayed by OPNAV debating whether to develop a basic airframe that can be upgraded over time or an immediate highly capable platform. The four industry teams pushed back against the idea of a more capable UCLASS because the specifications would be significantly different from aircraft they developed for the PDR phase. Cost per aircraft would also increase from $35-$50 million to $100 million, which may be unaffordable given the fiscal environment. Some within NAVAIR advocated the air vehicle to be modular, with a basic airframe to gain the experience of flying a UAV from a carrier before creating a deep penetrating strike aircraft, which would be simpler to build as a follow-on. Top-level UCLASS requirements of providing 24-hour persistent ISR coverage from the carrier at “tactically significant” ranges with limited strike capabilities at mid-to-long ranges remained fixed since spring 2013, though detailed specifications had been refined. The draft RFP was to be released in a few weeks.[28]

Cost constraints are driving Navy requirements for the UCLASS. One requirement that has remained constant is for the aircraft to conduct ISR orbits at tactically significant ranges for $150 million, meaning two air vehicles costing $75 million each can cover one orbit if they have an endurance of 14 hours. Survivability features are expensive, but cost is ultimately driven by the size of the airframe. Growing the list of desired capabilities including payload, range, and endurance could increase the UCLASS cost. Payload is a large driver of cost because the aircraft has to be designed from the outset to carry a required amount, so a heavier payload leads to a larger plane. Propulsion is also a factor; if space is available for only one type of engine and it has a higher fuel consumption rate, a greater fuel capacity has to be added, which increases size, weight, and cost. For low-observability, turbofan fuel consumption rates have to be weighed with the physical diameter of the engine; a high-bypass turbofan has is large but uses less fuel, while a low-bypass turbofan is narrower and provides greater thrust but uses more fuel. No current carrier-based aircraft can stay aloft for 14 hours and a new engine cannot be designed for the UCLASS.[29]

Program continuationEdit

The U.S. Navy released the long-delayed RFP for the UCLASS on 17 April 2014, with Navy Secretary Ray Mabus signing-off on the draft the previous day. The draft RFP was planned to be released in mid-2013, but was repeatedly delayed from disagreements over the proposed aircraft's stealth levels, ability to survive in contested airspace, and inflight refueling ability. This RFP is classified and available only to the four contractors involved in the PDR, with the purpose of "designing, developing, assembling, delivering, testing, and integrating the air segment into the UCLASS system." Though classified, details available show original UCLASS specifications of providing two ISR orbits at range for 24 hours, 7 days a week over uncontested airspace with a light strike capability to eliminate targets of opportunity. The airframe will also have an open architecture design to be easily upgradable.[30][31] At the Navy League’s Sea-Air-Space conference earlier in April, program executive officer for unmanned aviation and strike weapons Rear Admiral Mathias Winter laid out UCLASS capabilities and missions as collecting ISR continuously through EO/IR cameras and SIGINT, limited ability to strike ground targets, and ability to refuel other aircraft while itself also being able to be refueled in-flight. The Navy is pursuing a path to at first use the UCLASS as a reconnaissance asset with proven standoff sensor technologies to observe targets in uncontested international airspace, while building in excess weight, space, and power capacity to add sensors and weapons and modify it later for use in contested airspace if needed. Increased stealth requirements would have added risk and expense to an unprecedented naval concept, which had a greater chance stalling the program.[32]


  1. Mabus, Ray (January 21, 2014). "Future Platforms: Unmanned Naval Operations". War on the Rocks. 
  2. One of These Bots Will Be the Navy’s Next Killer Drone -, 27 March 2013
  3. "US Navy releases requirements for carrier-launched UAV". Flightglobal. 17 Jun 2013. Retrieved 28 Jun 2013. 
  4. USN to release draft RFP for next UCLASS phase in August -, 10 July 2013
  5. Uclass Draft RFP Slips As Stealth Debate Continues -, 13 August 2013
  6. US Navy Moves Ahead To Develop Unmanned Carrier Aircraft -, 14 August 2013
  7. US Navy awards UCLASS preliminary design contracts -, 15 August 2013
  8. GAO cites concerns on Navy unmanned aircraft program -, 26 September 2013
  9. Navy Plans to Arm UCLASS with JDAMs -, 21 November 2013
  10. Majumdar, Dave; LaGrone, Sam (22 January 2014). "Navy Delays UCLASS Request for Proposal Amidst Requirement Evaluation". U.S. NAVAL INSTITUTE. Retrieved 22 January 2014. 
  11. Navy’s UCLASS Could Be Air to Air Fighter -, 13 February 2014
  12. Forbes Writes in Support of a High End UCLASS -, 19 February 2014
  13. UCLASS RFP expected by the end of March -, 19 March 2014
  14. New X-47B Ship Goal: Clear Deck In 90 Sec. -, 7 April 2014
  15. UCLASS draft RfP expected within weeks -, 9 April 2014
  16. Reduced capability leaves UCLASS vulnerable to budget axe -, 9 August 2013
  17. Official denies White House link to UCLASS revision -, 12 August 2013
  18. "Why the JROC neutered the Navy’s UCLASS program." -, 30 August 2013
  19. "Pentagon Altered UCLASS Requirements for Counterterrorism Mission." -, 29 August 2013
  20. "UCLASS Acquisition Raises Questions in Congress." -, 18 September 2013
  21. Lawmakers Seek Broader Roles for UCLASS -, 20 September 2013
  22. ANALYSIS: Industry concerned about US Navy UCLASS requirements -, 23 September 2013
  23. US navy grapples with different UCLASS philosophies -, 29 September 2013
  24. Majumdar, Dave (18 November 2013). "Debate Continues Over UCLASS Requirements". U.S. NAVAL INSTITUTE. Retrieved 18 November 2013. 
  25. Axe, David (15 November 2013). "Bad Guys Beware—The Navy’s Killer Drone Is About to Get a Lot More Dangerous". War is Boring. Retrieved 18 November 2013. 
  26. Navy: UCLASS Will be Stealthy and ‘Tomcat Size’ -, 23 December 2013
  27. Commentary: The Next Carrier Air Wing -, 24 February 2014
  28. Majumdar, Dave (March 24, 2014). "Requirements Debate Continues to Delay UCLASS RFP". U.S. NAVAL INSTITUTE. Retrieved March 24, 2014. 
  29. Cost Will Drive UCLASS Designs -, 2 April 2014
  30. US Navy releases draft of UCLASS RFP -, 17 April 2014
  31. Navy Issues Restricted UCLASS Draft Request for Proposal -, 17 April 2014
  32. Confusion Surrounds Navy’s Carrier-Based Drone -, May 2014

See alsoEdit