Reduction in weapon's dependence on global positioning system and boost to in-flight retargeting flexibility sought

The US Navy is looking at a future precision navigation improvement to the Raytheon Block IV Tactical Tomahawk in a bid to reduce the new cruise missile's reliance on global positioning system (GPS)-satellite navigation and give greater in-flight retargeting flexibility.

The proposed upgrade to the legacy terrain-contour matching (Tercom) guidance system is one of several planned, but unfunded, improvements being considered for the Tactical Tomahawk. The modification would use the radar altimeter and a three-dimensional topographical map of the world. "We're starting to get significantly dependent on GPS. This would allow us to get the same level of accuracy, but not be dependent on GPS," says Steve Morrow, US Navy Tactical Tomahawk programme director.

A key Block IV feature is a datalink to allow the missile to receive targeting updates, loiter or be redirected to a new target while in flight. New target co-ordinates can be sent to a missile, but the current Tercom and digital scene-matching area correlation terminal guidance system relies on specific data produced during mission planning. A 3D topographical database would remove the need for pre-loaded maps and scenes and allow the missile to decide a new route.

Meanwhile, the USN plans to place the first low-rate initial production (LRIP) contract for 32 Tactical Tomahawk missiles, once the first of two demonstration test firings is completed. This is expected shortly. A second LRIP batch of 106 missiles will follow next year during the course of the technical evaluation (Techeval).

Techeval will comprise eight missile firings and a number of Block III missile shots to ensure compatibility with the new Tactical Tomahawk weapon control system (TTWCS) to be installed on ship and submarine launchers. An additional four missile firings are planned during a six-month operational evaluation due to start late next year.

Development work on a torpedo-tube launch version of Tactical Tomahawk has now begun, following agreement with the UK, says the USN. The UK will cover half the $50 million cost of developing a shroud for the missile compatible with pressurised tube ejection, along with flight-control software modifications. The UK will be responsible for its own submarine TTWCS modifications.

Source: Flight International