Zephyr Net

Old Weapon Gives Precision Punch to Helicopters
Aviation Week & Space Technology Feb 20 , 2012 , p. 50
David Fulghum
Washington

APKWS II to take on a new mission in Afghanistan
Printed headline: Precision Kills

What combat helicopters and unmanned aircraft in Afghanistan need in a hurry is an inexpensive, lightweight rocket that can be fired with enough accuracy to guide itself through a window-size target from outside the range of small-arms and light anti-aircraft fire.

The U.S. Navy believes it has the answer in a modified version of an unguided, Vietnam War-era rocket. The Advanced Precision Kill Weapon System (APKWS) II has already hit a basketball-size target at a range of 5 km (3 mi.).




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AT-6 Texan II with two pods of AKPWS precision rockets taxis at the beginning of a launch test. The pod (below) is extended to cover and protect the missile’s mid-body optics.Credit: JIM HASELTINE


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BAE Systems intends to deliver the next batch of its low-rate-production APKWS directly to the U.S. Marine Corps for shipment to operational units. The first 325 missiles had completed delivery to the Navy in December, and the second lot of 600 will be dispatched in early fiscal 2012. With the end of operational testing in January, a full-rate-production decision for 1,000 missiles a year is expected to follow soon.

There is a rapid-deployment effort to arm the MQ-8B Fire Scout rotary-wing unmanned aerial system (UAS).

“APKWS is what we plan to put on [the MQ-8B] in the near future,” says Navy Capt. Brian Corey, program manager for the missile. “We expect that to be the Navy Department’s first armed UAS. We could put a three-tube launcher on each of the two stations on a Fire Scout for a total of six rounds. The number of rounds actually on board depends on what other payloads are carried and the length of the mission.”

A Joint Concept Technology Demonstration also is underway to equip fixed-wing aircraft with the missile, which is being modified to survive a tougher, high-speed environment in the Air Force/Marine Corps project. The initial goal is to install the weapon on AV-8B and A-10 ground attack aircraft. The first operational launch of the missile from a fixed-wing aircraft, a modified AT-6 Texan II trainer, was made in mid-January. The combination developmental and operational test was conducted at Eglin AFB, Fla., using a lengthened launcher to protect the mid-body sensor system from damage by the firing of adjacent missiles. The APKWS rocket is usually bundled seven to a launcher. The Eglin tests also are part of a program to increase the firepower of light helicopters and fixed-wing attack aircraft.


“The future of light attack is not 0.50-caliber machine guns and 500-pound bombs,” says Derek Hess, Hawker Beechcraft’s director of AT-6 development. “We’ve always been interested in deep-magazine, standoff-precision weapons with low collateral damage. Certainly laser-guided rockets are front and center in that capability.”

The Marines’ aim is to field ­APKWS on the AH-1W and UH-1Y helicopters first. “Then we’d like to see it on the AH-1Z . . . for its first deployment,” says Marine Corps Lt. Col. Matt Sale, air-to-ground weapons requirement officer. “Depending on how long the legacy F/A-18s are going to be around, that could be the next logical step.”

Combat in Afghanistan is generating the pressing need for precise rapid-fire missile systems on Marine helicopters.

“What’s important to us is an appropriate target and weapons match,” says Lt. Col. Raymond Schreiner, lead H-1 test pilot for VX-31 at the China Lake, Calif., Naval Air Warfare Center. That means minimum collateral damage from small-yield precision weapons like the APKWS missile’s 10-lb., Mk. 151 and Mk. 152 warheads. Logistics also offer an advantage, since many 2.75-in. rockets and warheads are already in place in theater and only guidance sections have to be delivered.

“The capability that APKWS provides is well suited for current operations,” says Sale. “Marine Corps headquarters is confident of a fielding decision early in the year. With APKWS, you can increase the volume of precision fire by carrying 7-14 missiles on each aircraft. Depending on the success of the program in the next year or two, we’ll look at expanding envelopes and other material solutions.”

One idea is to adapt the package to the longer-range 5-in. Zuni rocket, which the Navy has in large numbers. However, it would be impossible for the larger rocket to be carried by UAS and helicopters in the same numbers.

As part of the APKWS’s operational testing, the missile was subjected to a number of variables including altitude, airspeed, range to target, laser code, lighting conditions, target type and movement. Evaluations involved a threshold range of 5 km and an objective range of 8 km.

“As far as operational availability, the current effort is integrated. Developmental and operational testers are working side-by-side and we are evaluating two aircraft simultaneously,” says Schreiner. “We’re minimizing the number of test resources required . . . that will answer both the developmental and operational requirements and minimize the schedule.”

The test program has yielded improvements including the ability to protect the missiles. The rocket pods have been extended to keep the mid-body guidance section out of the path of debris. Wing-slot seals have been added to keep particulate matter off the optics and protect them from blast damage.

“We worked with BAE about getting the wing-slot seals right,” says Corey. “That required a delicate engineering balance because we needed a seal that was affordable but rugged enough to protect the rocket and withstand the captive-carry environment on helicopters. Yet it needed to fracture to deploy the wings.”

The test results are promising.

“We had failures in testing, but when we put [the guidance units] on the flight line, they worked. They’re accurate and hitting well within requirements. The aircrew—if the targeting system camera is good enough—can put this thing through a window.” Targets included pickup trucks, lightly armored vehicles, walls of various construction types, moving targets and simulated gun positions.

The Navy took over the APKWS program from the Army in 2008 to fill the gap between the service’s short-range airborne cannon and machine guns and Lockheed Martin’s long-range, high-precision Hellfire anti-armor missile carried by helicopters. Hellfires cost roughly $68,000 each and weigh 100 lb. In comparison, the mid-range APKWS has a 10-lb. warhead for low collateral damage, is estimated by non-BAE analysts to cost $10,000 per missile, weighs roughly 32 lb. and has the precision to go through a window 5 km away. Moreover, the weapon is a threat to moving targets since it has flaperons to make high-speed flight corrections.

During this initial phase, BAE Systems developed a simple guidance package that did not require communications with its launch aircraft.

“Any airplane that can shoot an unguided 2.75-inch rocket can shoot an APKWS,” Corey says. “The only thing required to launch it is a 28-volt fire signal from the airplane. All the precision takes place after the rocket is launched. No integration with the platform, no signal transfers, no software updates are required.”

Vietnam Dumb Rocket Becomes PGM in Afghanistan
Aviation Week & Space Technology Feb 20 , 2012 , p. 52
David Fulghum
Washington

Venerable Hydra missile takes on precision missions
Printed headline: Mini-PGM for Helos



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An unguided, Vietnam War-vintage missile has been transformed into an air-to-ground precision-guided munition (PGM) that will be introduced into combat in Afghanistan this spring.

The 2.75-in. Hydra rocket was the keystone weapon of the U.S. Army aviation’s aerial artillery. Now BAE Systems has turned it into the Advanced Precision Kill Weapon System (APKWS) II that does not require communications with its launch aircraft. All the precision is introduced after the rocket is launched.


The APKWS has guidance optics on its mid-body airfoils to protect them from launch blasts while providing sectored inputs for precision guidance.Credit: BAE SYSTEMS


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“On the AH-1W Cobra [APKWS II] will fill the weapons gap between guns and the Hellfire,” says Maj. Ryan Schiller, former lead operational test director for Air Test and Evaluation Sqdn. 9 (VX-9) at China Lake, Calif., Naval Air Warfare Center.

“On the UH-1Y it will introduce a precision-guided missile capability that is new for the Huey side of the house,” he adds. “The overall result is going to be a higher number of precision kills per sortie, and it will improve aircrew survivability due to increased standoff ranges. It also offers a low-yield weapon for urban conflict where collateral damage has to be minimized.”

So how does the magic work with a missile that is 29% of the weight and 15% of the cost of the benchmark AGM‑114 Hellfire? Part of the answer is lots and lots of warehoused missiles that are already paid for and can be easily modified.

BAE Systems came up with a mid-body addition—the WGU-59/B guidance section—that can simply be screwed into place between the existing warhead and the Mk. 66 Mod. 4 rocket motor, says Lt. Col. Raymond Schreiner, lead test pilot for VX-31 at China Lake.

The mid-body guidance section has four small wings with flaperon flight-control surfaces on the trailing edge and an optical sensor on the leading edge of each.

“The wings provide heavy, stable platforms,” says Dick Venuti, BAE Systems’ technical director for missiles and munitions. “When they open and lock, they become an optical bench. The missile’s accuracy depends on how much each wing doesn’t move.”

Development of the Distributed Aperture Semi-Active Laser’s electronics stack and optics is key to the mid-body design. The package is about the size of a soda can with guidance, seeker, computers and receiver electronics all connected through four fiber-optic bundles to the optical sensors on each wing.

During production, the wings and “eyeball” optics are folded and stored inside the missile, where they are insulated with a “wing-slot seal” against weather, heat and blast damage. Before the missiles are loaded, they are updated with the laser code of the day.

During the launch is where a mid-body sensor array shows its value.

“Rockets with nose-mounted seekers have a tough time with adjacent rocket fire,” says Venuti. “Launch takes all the output of the rocket motor with its very corrosive, high aluminum content and puts it on the face of any exposed seeker. Inside the launcher, the overpressures were more than anyone expected. With APKWS, the missile interior is water-, pressure-, carbon- and aluminum-tight.”

Three-tenths of a second after the missile is fired from its protective launch tube, its battery is turned on by a switch that senses acceleration. At 0.4-0.5 sec., the missile’s computer commands it to deploy its wings through the wing-slot seal, lock the wings and free the flaperons. The motor burns for roughly 1 sec. while the missile spins to avert wobbling. The target is already being lased, so when the wings deploy, the missile immediately starts receiving target information.

“In flight tests, we have always seen the target immediately,” says Venuti. “Just before rocket burnout, we stop the missile from spinning with a de-roll maneuver, then we go into tactical guidance.”

The optical sensors, described as eyeballs, are made of a glass-like material. Each is connected to bundles of fiber optics that provide seven channels of data. That information is relayed to the guidance section. If there is a target in one of the channels, all the energy is routed through that single conduit. As the target moves, the energy shifts from one channel to the next. If it is split equally between two channels, the target is halfway in between. If there is no target, the missile goes into an attitude hold and continues looking across a 40‑deg., instantaneous field of regard.

“With this weapon, lock-on before launch is not necessary,” says Venuti. “In all the tests, we acquired the target within one second of firing.”