Seeker electronics then convert laser intensity to determine target angle and guide the rocket to the target. The proportional navigational software maintains the closure angle for static and moving targets. Simultaneously, an Inertial Measurement Unit (IMU) senses roll, pitch, and yaw. An autopilot uses the IMU data and seeker data to calculate flaperon positions, which are then moved appropriately by CAS. Corey describes this as “a pretty innovative” way of solving the problem, adding that flaperons impart maneuverability to the missile as it engages moving targets.
High Precision = Minimal Collateral Damage
Disclosing that that operational testing (with about 50 shots) yielded an average CEP – or average miss distance – of 0.44 meters, with weapons being fired from 1,500 meters to 5,000 meters, Corey says, “Every rocket has hit the laser mark. The requirement was 94 percent success rate and we met it.”
A NAVAIR diagram of the APKWS II concept of operations. Image courtesy of NAVAIR
According to BAE, effective ranges are a minimum of 1,100 meters to 5,000 meters. Notably, the minimum range is significantly better than the threshold specification of 1,500 meters, although the objective requirement for minimum range for rotary wing aircraft is 500 meters. At minimum range, time of flight is less than 5 seconds. APKWS also has an off-axis capability of 0 to 14 degrees.
As far back as 2010, APKWS II met the 0.86 threshold requirement for system reliability – which is defined as guided reliability (0.95) X warhead reliability (0.91) X motor reliability (0.99) given the presence of a firing impulse.
In combat, the CONOPS is simple. The rockets, which are Lock on After Launch (LOAL) weapons, can be fired at targets illuminated by cooperative ground and air forces with handheld laser designators or be guided from a self-designator on the launch platform if so equipped or by ‘buddy lasing’ wherein one aircraft lases, the other fires. Multiple targets can be engaged as long as the laser Pulse Repetition Frequency (PRF) codes match.
Production Status
At present, the weapon is in LRIP (low rate initial production) with a unit cost of $28,500 for the guidance unit, while the rocket itself costs around $1,500-2,000 per round. Industry analysts expect costs to drop significantly with volume orders.
The first contract for 325 units has been delivered. A second contract for 600 shipsets is underway since FY11. As of mid-April, 2012, about 400 units had been accepted, with a production rate of roughly 80 units per month.
Full Rate Production is under negotiation, with a decision expected this year. It is expected to be in two lots of 1,000 units – one each for FY12 and FY13, with Lot 3 expected in FY14.
The APKWS II as fielded today is for older helicopters (the AH-1Z has more precision capability so it was more important to develop the weapon for the older helicopters) and slow, fixed wing aircraft like the AT-6C from which BAE has carried out test firings in a company-sponsored demonstration.