Analysis of FC-31 stealthy naval fighter

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There has been a recent upsurge in social media attention to the Shenyang FC-31, prompted by the release of a photograph of a new carrier-capable variant, with what appears to be folding wings, and a nose undercarriage compatible with a carrier catapult system.

The FC-31 has been variously described in the past, as the J-31 and J-35, designations generally reserved for aircraft in production for the PLAAF or PLANAF. F-60 has also been used, in presentations suggesting that the aircraft would be available for export to Nations unwilling or unable to acquire the Lockheed Martin F-35 Lightning II.

The FC-31 designation is that used by Shenyang, and may change, should the aircraft be ordered into Chinese service. It is used in this article to describe both the prototype aircraft, and the recent carrier-capable variant.

On its first appearance, the FC-31 was greeted by a chorus of suggestions that it was simply a copy of the F-35. I’m not going to weigh into that debate – there are a number of twin-engine concepts and projects, as well as the FC-31, which share common features with either, or both of, the US F-22 and F-35. How much of this is convergence in design given similar requirements, and how much is replication seems, to me to be a moot point.

In the end, the external lines of these aircraft will have a relatively minor impact on their performance as air combat systems. The propulsion system, radar and other sensors, air-to-air and air-to-surface weapons, and their integration, along with external data feeds, into the man-machine interface will be the key to combat effectiveness. Similarly, the integration of defensive aspects, including signature, electronic combat and protection systems, and missile warning and countermeasures systems will be critical in determining survivability. While the aircraft shape will influence its signatures, the electromagnetic tailoring of the aircraft, including treatment of its surface, its intake and exhaust system, and the integration of its sensors and apertures, will all be critical if low signatures are to be achieved.

How does the FC-31 stack up on all these aspects? Well at this stage, I’d suggest much attention is likely to be required. How much, depends on how closely the PLAAF and PLANAF have been engaged, in what has been presented as an independent design by Shenyang. That said, it should also be noted that the development program for the J-20 aircraft appears to have been relatively rapid, although perhaps its operational capabilities have still to be fully revealed.

Since the appearance of quality photographs of the prototype FC-31 appeared, there has been some evidence of ongoing design refinement, which, in this case, may have been spurred by the PLAAF decision to adopt the J-20. This decision may have prompted Shenyang consideration of the development of a carrier-compatible aircraft for the PLANAF, or a version that might be exported.

Carrier-compatible FC-31

The recent photograph shows a new variant of the FC-31, with modifications including a catapult launch bar and folding wings. An Electro-optical Targeting System (EOTS) has also been fitted below the aircraft nose. The modifications are clearly directed at achieving aircraft carrier compatibility, presumably with the new Type 003 carrier, and its systems including the Electro-Magnetic Aircraft Launch System (EMALS) which is fitted, aircraft lifts and hangar spaces. 

The changes to strengthen the undercarriage for carrier launches and landings, and the introduction of folding wings, have increased the weight of the aircraft, and other increases in weight are likely as additional operational capability is introduced in development. As a result, the maximum take-off weight (MTOW) of the aircraft is reported to have increased from 25 tonnes to 28 tonnes. This 12% increase in MTOW is perhaps less than might have been expected, suggesting that provision for some navalisation has been included in the initial design. The twin nosewheels of the prototype may be an example of this, as this design is compatible with a catapult launch bar.

The aircraft, in its development,  is also reported to have had a change in engine from the 86 kN Guizhou WS-13 to the 110 kN WS-19 engine, a significant increase in thrust. Looking at the impact of this, we can compare the Thrust to Weight ratio (T/W) of the earlier and latest aircraft. Given the reported weapons load capability of 8000 kg, 2000 kg of which is internal, and making the assumption that a realistic strike configuration would have maximum fuel and carry only internal stores, we can compare the prototype with WS-13 engines to the carrier-compatible aircraft with WS-19 engines. With these assumptions, the T/W of the prototype is 0.92, and for the heavier and more powerful carrier aircraft, T/W is 1.02. With a lighter air-to-air loadout, the WS-19 powered aircraft would have a T/W in the region of 1.07.

These figures suggest reasonably competitive performance should be achieved, bearing in mind that the figures assume full internal fuel, and internal weapons carriage. Considering the systems aspects, with an Active Electronically Scanned Array radar, the EOTS, and a weapons loadout which is likely to include the long-range, Meteor-like, PL-21 Beyond Visual Range AAM, or a variety of air-to-surface or anti-shipping weapons, an FC-31 carrier-compatible aircraft could well be a very attractive option to equip the new Type 003 carrier.

The work still to be done to develop the full operational capability of the aircraft and its systems, and then to integrate that capability into the broader maritime battlespace would be considerable. That said, such a system would be a very useful asset if required to provide tactical Air Defence and Control over an area such as the South China Sea, or to project power elsewhere, if required.

The time taken to fully realise this potential will depend on how closely Shenyang has been working with the PLANAF in the development of the aircraft. Given the need to complete, fit out, integrate and trial the Type 003 carrier, the FC-31 would appear well placed to equip that vessel, should the PLAN decide to select the FC-31.

In the absence of such an order, the future of the FC-31 does look questionable. A land-based export version would appear to be a better option, given the small number of aircraft-carrier-equipped Navies that would be likely to select a Chinese combat aircraft as their primary Naval Air capability.

Or, to put it another way, the extensive work, and the cost, required to develop the carrier-compatible version of the FC-31, suggests that the PLAN is anticipating ordering the type, and might already be contributing to its development.

– Jim Smith


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