Crest of the Royal National Institution of Naval Architects - Click to return to the homepage

The Royal Institute of Naval Architects

Alfa Laval March 18 (updated)

NexansSept17

High cost prompts review of aircraft carrier alternatives for the US Navy

Warship Technology: January 2018

 

The US Navy is facing financial challenges that require it to evaluate potential lower-cost options for its most-expensive platforms, and recently commissioned Rand Corporation to look at aircraft carriers.
In the study, Rand examined potential alternatives for replacing later Nimitz-class nuclear-powered aircraft carriers (CVNs) as they reach the end of their planned service lives in 2030 and beyond.

 

Some in Congress – among others – have criticised the Gerald R Ford-class nuclear aircraft carriers (USS Gerald R Ford [CVN 78], USS John F Kennedy [CVN 79], and USS Enterprise [CVN 80]), which are now in construction or early long-lead procurement, for their high acquisition cost, and the US Navy has been directed to consider lower-cost alternatives. The study was an effort to consider those alternatives by asking what platform options should be considered, how different platforms would perform in various operational environments, and the costs of alternative platforms.

 

So great is the level of concern that it has been suggested that continuing the Ford-class carrier programme might unduly affect the whole of the US Navy shipbuilding budget. The Senate Armed Services Committee noted that alternatives could be developed for less cost and potentially with sufficient capability.

 

The US Navy asked Rand to provide procurement cost and effectiveness analysis comparing the Ford-class programme with potential alternatives in order to examine a potential future transition to a lower-cost carrier replacement in long-range shipbuilding plans if the findings support further US Navy or congressional actions to that end.

 

Rand analysed four carrier variants and their capabilities against anticipated future warfighting requirements as part of the overall carrier fleet architecture. The alternatives represented reasonable and technically achievable variants that provided at least some part of required warfighting capability and were developed them in consultation with a US Navy-led executive steering committee.

 

Among the aircraft carrier variants examined in the report were two large-deck carrier platforms that would retain the capability to launch and recover fixed-wing aircraft using an on-deck catapult and arresting gear system and two smaller carrier platforms capable of supporting only short takeoff and vertical landing (STOVL) aircraft.

The four concept variants are as follows:

  • A follow-on variant continuing the current 100,000ton Ford-class carrier but with two life-of-the-ship reactors and other equipment and system changes to reduce cost (we refer to this design concept as CVN 8X)

  • A 70,000ton USS Forrestal–size carrier with an updated flight deck and hybrid nuclear-powered integrated propulsion plant with capability to embark the current large integrated air wing but with reduced sortie generation capability, survivability, and endurance compared with the Ford-class (referred to as CVN LX)

  • A 43,000ton variant of the USS America-class, fossil fuel–powered and arranged to support only STOVL operations but at a higher tempo than the current LHA 6 (USS America) (referred to as CV LX). This variant would incorporate the larger ship’s beam excursion the US Navy examined in the LHA 8–class flight 1 studies.

  • A 20,000ton variant that will resemble escort carriers that some allied navies currently operate (referred to as CV EX). Similar to the 43,000ton variant, it will be conventionally powered and will operate STOVL aircraft.

 

For each alternative, Rand evaluated the operational effects and the rough comparative costs. The latter two options would require major changes in US Navy concepts of operations for the US Navy’s carrier strike group (CSG), require changes in the Navy’s aircraft procurement plans, and create capability shortfalls that would need to be supported elsewhere in the joint force.

 

The analysis was based on a carrier being able to generate sufficient tactical air capability and the capacity to support a joint campaign in the most challenging scenario (which includes capability, a specific number of aircraft, and an ability to rearm and sustain these aircraft); support an integrated air wing, including airborne early warning (AEW) and electronic attack (EA); and operate at ranges where tactical air can carry out its missions. These requirements imply specific capabilities a carrier must possess, which will, in turn, drive equipment and design:

 

  • The ability to support organic aircraft capable of providing AEW and EA, which currently are the Advanced Hawkeye (E-2D) and Growler (EA-18G). Both are fixed-wing aircraft requiring catapult-assisted takeoff and arresting gear. Rand considered aircraft carrier variants (the CV LX and the CV EX) without this capability and noted the resulting limitations.

 

  • The ability to support current tactical air strike aircraft, principal among which is the Lightning II carrier variant (F-35C), which requires catapult launch and arresting gear recovery and a flight deck that is approximately 1,000ft long. Although the numbers of tactical aircraft required to support future operational scenarios are not expected to diminish, Rand analysed smaller carrier variants (the CV LX and the CV EX) that can support only the F-35B (STOVL-capable Lightning II) and rotary-wing aircraft. Again, these smaller alternatives depart from the US Navy’s current aviation programme plans.

 

  • The propulsion systems must be able to support speed requirements, provide redundant propulsion capability, and meet electrical power generation requirements, which could include the potential to support an electric, integrated propulsion system.

 

  • Magazine size must be adequate to support sustained operations, with replenishment occurring not more frequently than every 7-10 days during combat operations. This capacity will be proportionate to the size of the aviation element embarked; a carrier with a smaller number of aircraft will not need the same size magazine as one with a larger complement.

 

Operational impact
To assess operational feasibility, Rand used generalised threat scenarios resembling those that fleet commanders use in Joint Task Force Exercise certifications to assess CSG readiness for deployment but also identified where missions are likely to change in the future. One major operational key performance parameter for the Ford-class carrier is sortie generation rate (SGR), which is a measure that “includes the ability to launch, recover, service, load and prepare the aircraft in all ways for the succeeding mission.”

 

Accordingly, its initial assessment of operational impact was oriented toward impact of the alternative variants on force sortie generation in varying scenarios with varying force flows, while considering other relevant factors as well. It noted, according to future planning scenarios, that an SGR consistent with the Ford-class key performance parameter might not be necessary given the anticipated longer sortie durations caused by increased standoff.

 

Analyses of the carrier variants illuminated capability shortfalls in some instances:

  • The CVN 8X, the ‘de-scoped’ Ford-class carrier, offers similar warfighting capability to that of the Ford-class carrier today. There might be opportunities to reduce costs by eliminating costly features that only marginally improve capability, but similar trade-offs are likely to be made in the current programme as well.

 

  • The CVN LX concept variant offers an integrated, current air wing with capabilities near current levels but with less organic mission endurance for weapons and aviation fuel. It will not generate the same SGR as the Ford-class carrier, but this is not a significant limitation for the most challenging warfighting scenarios. It will be less survivable in some environments and have less redundancy than the Ford programme-of-record ship, and these factors might drive different operation concepts. “Although we do not characterise the impact of decreased survivability, this is an important limitation that will have to be weighed against the potential cost savings,” said Rand. “The major means of reducing cost is through engineering redundancy, speed, and air wing fuel capacity, and these could affect mobility and theatre closure.

 

  • The concept variant CV LX, which is a version of the LHA 6 platforms, might be a low-risk, alternative pathway for the US Navy to reduce carrier costs if such a variant were procured in greater numbers than the current carrier shipbuilding plan; Rand’s analysis suggests a two-to-one replacement. Over the long term, however, as the current carrier force is retired, the CV LX would not be a viable option for the eventual carrier force unless displaced capabilities were reassigned to new aircraft or platforms in the joint force, which would be costly. This platform would be feasible for a subset of carrier missions but, even for those missions, could require an increase in the number of platforms. This concept variant might, if procured in sufficient numbers, eventually enable the US Navy to reduce the number of Ford-class carriers in the overall force structure, but more-extensive analysis of missions, operations, and basing of such a variant and the supported air combat element is required.

 

  • The smallest concept variants reviewed, the CV EX 20,000ton sea-based platforms, do not provide either a significant capacity or an integrated air wing and, thus, force reliance on other legacy platforms or land-based assets to provide key elements of capability – in particular, AEW. As a result, this concept variant is not really a replacement for current aircraft carrier capability and would require other platforms, aircraft, weapons, and capabilities in the joint force. These platforms would be a viable pathway only in broad fleet architecture transformation providing a narrow mission set, perhaps regionally, and would require extensive analysis. Given that such a concept variant is not a viable replacement for an aircraft carrier, such analysis would be required to see whether any adjustment on the current aircraft carrier programme would be feasible.

 

Cost comparison
The cost assessment reflects a comparison between the alternative concept platforms and the current Ford-class programme-of-record budget data based on weight changes but also includes the nonrecurring engineering expense incurred for new design, the cost associated with different equipment, the potential loss of learning resulting from new designs for a new lead ship, and, to the extent possible, any force structure changes needed to support new platforms (such as the need for more carriers or replacement ships).
The overall results of the cost comparison are as follows:

 

  • The de-scoped Ford-class carrier, the CVN 8X, might generate fewer sorties than the current key performance parameter values for the Ford-class and might have only incremental reduction in overall platform cost. The analysis examining cost reduction with transition to a life-of-the-ship reactor, such that being done on submarine programmes, does not appear to be cost effective. Between the developmental costs and a reduced service life, there is little cost advantage in this variant.

 

  • The CVN LX concept would allow considerable savings across the ship’s service life and appears to be a viable alternative to consider for further concept exploration. Construction costs would be lower; design changes and life-cycle costs would reflect the lessons already applied in the Ford-class. The reliance on hybrid drive with fewer mechanical parts than legacy platforms is likely to further reduce maintenance cost. However, CVN LX would be a new design that would require a significant investment in non-recurring engineering in the near term to allow timely delivery in the 2030s.

 

  • CV LX, although it requires a larger force structure to maintain air capabilities, might still reduce overall construction costs if large carrier numbers were reduced. However, as described in the report, reducing carrier numbers with the resulting loss of capability should not be pursued without extensive further analysis for all displaced missions in the joint force execution of warfighting scenarios and, potentially, regional basing and narrowly focused missions for these platforms. Any cost savings would likely be offset to an unknown degree by requirements for additional systems to mitigate loss of capability associated with this variant.

 

  • CV EX, the smallest variant, is not a practical variant at all without considerable revision of the US Navy’s warfighting concept of operations. Although the same is to a degree true with CV LX, the impact of an even larger number of low-sortie ships with small and limited air wings is even more pronounced with this variant. CV EX has all of the shortfalls of CV LX and will pose even greater issues of mutual support and logistics sustainment.

 

Conclusions
Rand’s analysis points to potential options for replacing the Nimitz-class carrier, as these ships reach expected service life, that have lower procurement costs than the Ford-class carriers. However, most of these options come with reduced capability that might require changes in the concept of operations to deliver sea-based aircraft capability comparable to that of carriers in the fleet today.

 

If a new platform is introduced in the mid-2030s, the US Navy’s force structure will still contain a large legacy force of Nimitz- and Ford-class carriers, at least until the mid-2050 time frame, which might lower the risks of introducing a new carrier for some period of time.

 

Ultimately, if a new carrier variant is selected, it will define the carrier force and constitute the supported capability available to the US Navy. Capability shortfalls can be mitigated, to some degree, with changes in operational concepts or by adding additional platforms to the force structure – which introduces additional cost that might offset anticipated cost savings. In addition, if the US Navy stops procuring large-deck nuclear carriers, the ability to reconstitute the industrial base at some time in the future comes with substantial risk.

 

Although SGR was a central variable in comparing the carrier variants, Rand’s analysis suggests that there is room to make trade-offs in aircraft sortie rate capacity between the Ford-class carrier and lower-cost platform. However, it is important to consider that, whatever threats complicate carrier operations, they might even more significantly affect land-based tactical air operations. Carriers can move; have defensive support from escorts; can readily replenish; and might, in fact, be more survivable than their land-based counterparts. This is an important factor for Congress and the Department of Defense to consider before a trade-off is made to give up the supported air wing sortie generation capacity in the overall sea-based force.

Survitec ( from 8th Dec )

Bentley Systems

Posidonia

Furuno June 2018

IQPC Smart Ships

METSTRADE

UBM April 4th 2018