Precision weapons give the next-gen F-35 its sting

When Australia’s F-35 Lightning aircraft enter operational service, they will be equipped with a range of highly capable weapons, enabling the aircraft to perform a range of missions from the outset.

Integrated onto the F-35A Lightning is an initial basic weapons fit of a range of advanced air-to-air and air-to-surface weapons common to many western air forces and already in service with the RAAF.

These include the Raytheon AIM-120D AMRAAM beyond visual range (BVR) air-to-air missile, the Raytheon AIM-9X within visual range (WVR) air-to-air missile, Raytheon GBU-12 Paveway laser-guided bomb, Raytheon GBU-53 small diameter bomb (SDB), and the 2,000lb Boeing GBU-31 and 500lb GBU-38 GPS-guided JDAMs and their dual-mode and penetrator variants.

Then there’s the internal General Dynamics GAU-22/A 25mm gun.

All of these US weapons are already integrated to the F-35, and are in service or entering service with the US military. Thus, they present minimal risk for the RAAF achieving initial operating capability (IOC) in 2021 and then full operating capability (FOC) with 72 aircraft at the end of 2023.

Raytheon said it provided a number of advanced weapon systems for the F-35A platform, enhancing the capability and lethality of this class of aircraft.

“These weapon systems will deliver for the RAAF a new combat advantage while also providing the opportunity for greater interoperability of systems with allied forces,” a company spokesman told ADBR. “The current weapon systems provided by Raytheon for the F-35A platform include the AMRAAM, which is currently the only radar-guided air-to-air missile that is cleared to fly on the F-35A.

“As the leading manufacturer for a number of weapons systems across the ADF, Raytheon also has the opportunity to provide future weapon systems for the F-35A variant, including the Joint Strike Missile and our AIM-9X Sidewinder missile.”

So far Australia has opted weapons of US origin. But the US and Australia aren’t the only operators of the F-35, and other nations have their own weapons which will be integrated onto F-35. And that offers opportunities for Australia to acquire advanced weapons with capabilities well in excess of those now in service.

Andy Watson, managing director of MBDA Australia, the local subsidiary of the European missile firm, said once the RAAF’s F-35A aircraft are bedded in, it would be natural to look for the next step in air-to-air missile capability.

One option is the MBDA Meteor, a BVR air-to-air missile which has been integrated onto the Saab Gripen, Eurofighter and Dassault Rafale, and is being integrated onto the UK’s F-35B. Meteor would appear to do what the much-vaunted AIM-54 Phoenix promised as a long-range interceptor but never actually demonstrated. 

The US only fired three Phoenix missiles in anger – all over Iraq in 1999 – and none hit their target. The only other Phoenix user, Iran claims multiple successes against Iraqi aircraft, though few details have been revealed.

The 190-kilogram 3.7-metre Meteor features active radar homing and ramjet propulsion. The actual range is classified, but is reportedly more than 300 kilometres. Watson said Meteor’s advantage is its ramjet which can be throttled to optimise the flight profile.

With other missiles which are rocket powered, once the solid fuel sustainer motor runs out after a few seconds, the missile is coasting and decelerating. Thus at longer ranges, the target has a better chance of escaping. 

“Once you have the ramjet going, you are powering all the way to the target,” Watson said. “Meteor has over three times the no-escape zone compared to current BVRAAM’s. We are not talking about a 10 per cent difference here – it is a significant game changing capability at range.”

The UK and Japan are also jointly researching an even more advanced version of Meteor which would add a a Japanese-developed AAM-4B seeker to the airframe. In the meantime, the UK is specifying three European weapons as its baseline loadout for the RAF’s 138 planned F-35Bs – Meteor, the MBDA ASRAAM, and SPEAR, a 100-kilogram precision surface attack missile.

MBDA regards ASRAAM as a superior alternative to the AIM-9X, while SPEAR roughly compares to the SDB. But SPEAR is powered which not only gives it greater range but with sufficient power for a sophisticated radio-frequency/semi-active laser (RF/SAL) seeker.

Watson said the UK was buying MDBA’s weapons not just because it liked having UK products. “What we have tried to do in the UK is broaden the utility and gain overmatch through having more capable weapons. This allows us to stand off further and make the jet more survivable.”

Watson said that was certainly the case with Meteor and SPEAR, and to an extent ASRAAM. In terms of weapon maturity, ASRAAM is in service with the UK and is so far the only non-US weapon integrated to F-35. It is also in service with the RAAF, having been acquired in the early 2000s to replace the older version of the Sidewinder, the AIM-9M on the classic Hornet.

While Meteor is in service on other types, so far it has only undergone fit trials on the F-35, while SPEAR is still undergoing development which will conclude in early the 2020s. So, if Australia opted for a non-US weapon for the RAAF’s F-35A, most of the integration work with the F-35’s combat system is likely to have already been done by the JSF program. 

Watson said the principle with the JSF block upgrade program was that integrating a weapon onto one F-35 variant meant it was effectively integrated into the mission systems of all three versions. There will, however, likely need to be a weapons clearance test program as the F-35A’s weapons bay is larger because it lacks the lift fan of the B model, and therefore has different airflow characteristics.

“There is some work to be done but it is nowhere near the total magnitude of work,” he said. “Once you have integrated onto one version, if you want to then migrate it to another variant it is not starting from scratch by any means.”

Then there’s the low-observable aspect. In order to present the lowest possible signature, the F-35 needs to carry all of its weapons internally. So until air superiority has been gained, that precludes the use of heat-seeking missiles such as AIM-9X and AASRAAM. These weapons can only be fired from a wing-mounted rail, and cannot not be employed from the F-35’s internal weapons bay.

But once the aircraft’s signature is no longer a major factor, the F-35 can carry more weapons externally on up to six under wing hardpoints. 

In the meantime, most of the weapons to be employed by the baseline F-35A are already familiar to the RAAF. AMRAAM and AIM-9X are already in the inventory, as are the various versions of JDAM and Paveway. 

MBDA operates an ASRAAM maintenance facility at the Orchard Hills depot in Sydney, where missiles can be placed on a test rig (minus the energetics), problems diagnosed down to sub-system level, repaired, re-certified and returned to the squadrons.

AIM-9X and ASRAAM are broadly comparable, though the fine details of performance aren’t available in the public sphere to make a definitive comparison. MBDA claims ASRAAM is significantly faster, has much greater range thanks to the lifting-body properties of its airframe, and an extremely high off-boresight ‘over-the-shoulder’ shot capability. 

The mainstay beyond visual range missile for the US military and the RAAF for the foreseeable future will be the AMRAAM which is in service in the AIM-120C5, C7 and the longer-ranging AIM-120D forms in the RAAF.

Raytheon says AMRAAM’s capabilities have been fully demonstrated in more than 4,200 test shots and 10 air-to-air combat victories, although the latest versions have a much high probability of kill (pk) than the earlier versions which entered service in the late 1980s.

“In the air-to-air role, no other missile compares to the AMRAAM missile,” Raytheon says. “The weapon’s advanced active guidance section provides aircrew with a high degree of combat flexibility and lethality. Its mature seeker design allows it to quickly find targets in the most combat challenging environments.”

Australia has already been approved for a very substantial investment in AMRAAM. In April 2016, the US Defense Security Cooperation Agency announced a proposed US$1.2 billion foreign military sales deal for up to 450 of the latest AIM-120D to equip the RAAF’s classic and Super Hornet, Growler, and the F-35s.

The SDB emerged from the success of the GPS-guided JDAM after it was realised that precision meant a large weapon wasn’t always required to destroy or damage a target. It also meant more munitions could be carried per aircraft – typically four SDBs can be carried in the space of one Mark 84 2,000lb JDAM. 

The latest GBU 53/B SDB II is a bit smaller but adds a tri-mode seeker to the SDB’s GPS/INS plus a tri-mode seeker, with millimetric radar to detect and track targets, and IR/SAL guidance to home in on a target illuminated by an airborne or ground laser designator so it can hit moving targets such as a single vehicle in a convoy. When employed from altitude, the SDB II’s range is up to 100 kilometres. 

Like AMRAAM, Australia has been approved to buy the SDB II from the US, with a proposed FMS deal announced last year for 3,900 units at an estimated cost of US$815 million.

By comparison, the SPEAR – an acronym for the UK’s Selective Precision Effects At Range program – is roughly equivalent to SDB II, But with the addition of a small turbojet, it has significantly greater range in excess of 130-kilometres. There is also a feature that allows a brace of SPEARs to fly in formation or to attack from different tangents for simultaneous time-on-target. A datalink enables the missile to be launched from one aircraft and targeted by another.

The UK is even considering SPEAR as an anti-ship missile launched from the F-35B, and may provide a useful capability against smaller vessels. 

For larger vessels, a larger missile such as the Kongsberg/Raytheon Joint Strike Missile (JSM) – a derivative of the Kongsberg surface-launched Naval Strike Missile (NSM) which is in service with the Norwegian Navy and has been ordered by the US Navy aboard its Littoral Combat Ship (LCS). In 2014 Raytheon partnered with Kongsberg to develop JSM and to market and produce it in the US.

The NSM is four metres long and weighs about 1,000lbs. The JSM program aims to adapt it for air launch, with two able to be carried in the larger F-35A and F-35C weapons bays, and externally on all three variants. 

Depending on aircraft flight profile, the JSM’s range could exceed 500km, more than four times that of the older Harpoon missiles. Raytheon said JSM is the only 5th generation cruise missile that will be integrated onto F-35.

With no anti-ship missile initially planned for the F-35, Australia showed immediate interest in JSM. So much so that, in 2015 it was announced Australia would contribute to JSM development with funding for a passive radio frequency seeker to complement the missile’s imaging infrared seeker.

JSM also has an ability to hit land targets at standoff ranges, as do a couple of other weapons familiar to Australia – the unpowered Raytheon AGM-154 C-1 JSOW (joint standoff weapon) which can be employed against maritime and land targets from the RAAF’s Super Hornets, and the jet-powered Lockheed Martin AGM-158 JASSM (joint air to surface standoff missile). 

Integration of JSOW to the US Navy’s F-35C is well under way, so integration with the F-35A should be little more than a formality. In 2006 Australia picked JASSM to equip its F/A-18 classic Hornet under the Project AIR 5418 stand-off weapon program, and Lockheed Martin says it plans to integrate JASSM onto the F-35A. 

The JASSM has also been developed into the longer-ranging 1,000km range JASSM-ER, and the anti-ship dual-mode LRASM. 

This article appeared in the November/December 2018 issue of ADBR.