Latest Sikorsky S-70B Can Perform Varied Naval Warfare MissionsJun 15, 2008
By David Hughes
With its latest S-70B, Sikorsky Aircraft has created an anti-ship and anti-submarine warfare platform with a glass cockpit and automated mission avionics system designed to meet a wide range of needs for navies around the world.
Aimed at the international naval market, this version of the Seahawk has a Sikorsky-developed mission avionics package. It competes against other new helicopters being offered to navies, including the Lockheed Martin-developed MH-60R Romeo, an advanced version of the Seahawk now entering service with the U.S. Navy, and Europe's NFH90 (see pp. 50-52).
Interest in new naval helicopters is high in part because the current global fleet, mainly Sea Kings, is aging and also because of growing threats to vital sea lanes and offshore resources from quiet diesel submarines and fast attack boats. Sikorsky has developed the new S-70B to offer an exportable combination of anti-submarine and anti-surface warfare capability. The latest version of the S-70B has been in development since 2004, and work on it is nearly complete.
In 2005, the Singapore defense ministry reported it ordered six S-70Bs to operate from its navy's new class of frigates, with deliveries starting this year. Turkey reportedly increased its order for new S-70Bs to 17 aircraft in 2005; first deliveries are to begin next year. The value of the contract is expected to exceed $500 million.
The S-70B can carry a variety of sensors and weapons, including the Penguin anti-ship missile, dipping sonar and homing anti-submarine torpedoes. Just how the helicopter will be configured with weapons and mission systems will depend on the customer, but it is intended to be versatile enough to handle a wide range of requirements. The underlying architecture includes five multifunction displays. There is no separate mission computer; some of the PowerPCs for the displays do that job.
Sikorsky's engineers realized that the new S-70B mission system needed to be highly configurable to adapt to the various needs of international customers, so they set about creating a federated avionics system that can manage large amounts of flight and mission data while helping the crew with newly automated functions.
The effort took advantage of a third-generation system and software development laboratory here to develop the complex avionics and new flight control features. All of the aircraft's subsystems are resident here and have been evaluated individually and as part of an overall replica of the cockpit, the integrated bench test facility.
The cockpit is equipped with four Rockwell Collins 10-in. diagonal multi-function displays. A fifth display is mounted in the helicopter cabin in the tactical sensor operator (TSO) station. Each multifunction display (MFD) has two independent PowerPC processors. These processors are more powerful than their predecessors used on the Seahawk line. They were developed for use in personal computers but have become popular embedded processors for avionics applications.
The first processor card on each outboard display in the cockpit drives the primary flight display (PFD). All the basics are there on the PFD including aircraft attitude, altitude and airspeed as well as an engine-indication and crew-alerting system (Eicas). The PFD also has a map mode with an active flight plan feature. Pilots can elect to have the PFD shown on any of the four up-front MFDs.
The second PowerPC built into the two outboard displays remains unused at the moment and can pick up additional tasks as customers expand the missions they want the helicopter to handle. Half the capacity of the processors that are being used also remains untapped.
The second PowerPC in the pilot's inboard MFD serves as a mission computer. The second PowerPC in the copilot's inboard MFD and the one at the TSO station work in shadow mode to back up the primary one. The mission processors manage a suite of sensors including radar and forward-looking infrared (Flir) as well as a data link and electronic support measures. These sensors are controlled via Arinc 429 and Mil-Std-1553B data buses. In addition, an Ethernet data bus allows the mission processors to maintain a synchronized tactical situation display that can be presented on the inboard MFDs for the pilot and copilot or on the one at the TSO station.
Sikorsky engineer Dave Adams says the advantage of the Ethernet local area network in updating the tactical situation is that it is 100 times faster than the 1553 bus used in earlier versions: Tactical displays on three screens now update in 3-4 millisec., compared to 30 sec. previously.
A typical operation would have both pilots showing PFD information on their outboard displays. The copilot might then select the tactical plot (such as a Penguin or anti-submarine torpedo engagement scenario) on his inboard display, while the pilot's inboard display would show sensor video or electronic support measures data. These displays show the attack sequence in a plan view (top-down) format with key waypoints and all engagement parameters presented for easy assimilation by the crew. This would allow the crew to examine the tactical plot situation, cue the Flir to pick up a specific target being tracked on the tactical plot, and observe on the pilot's inboard MFD the infrared image of the target - all without having to reconfigure any displays.
"What really sets the S-70B apart is the attention we have paid to cockpit ergonomics and human factors design to optimize the availability of information to the operators while minimizing their workload," says Richard Lammers, a principal engineer on the project who is responsible for weapons integration.
The mission processor also enables the S-70B to handle dipping sonar operations smoothly with a pull-down menu that allows a flight plan to be displayed on the tactical plot. Such a "dip-to-dip" flight plan indicates the flight path the helicopter would follow as it flies to one location to put the sonar transducer into the water. After the transducer is hoisted back out of the water, a second location can be designated for the next dip.
Once the mission processor calculates the flight plan needed, it sends it to the flight management system's control display unit. The special flight plan then supersedes the civil flight plan being flown and is presented on the PFD so the pilot can maintain course using the new lateral deviation indications. The autopilot can also be coupled to the FMS to fly from one dip location to the next automatically.
The tactical operator can run a coupled sequence with the "automatic sonar navigation mode" simply by putting a graphical icon over the targeted dipping location and clicking on it. The helicopter can be flown hands-off into the wind to slow down and decelerate to the correct altitude and hover so the transducer can be dipped into the water.
Sikorsky has also developed new coupled modes for anti-submarine warfare scenarios and for search-and-rescue (SAR) ones as well. The S-70B can perform other utility missions such as vertical replenishment using a cargo hook to carry 6,000-lb. loads. When transporting personnel, the aircraft can carry 12 troops and one crew chief in addition to the two pilots.
The S-70B's new flight control computer and redesigned control panel ease pilots' use of coupled modes, some of which haven't been offered before on a Seahawk. The new control panel combines what used to be three separate units: The automatic flight control system panel, the mode select control and the sonar cable angle control. It is critical to control the angle of the cable when the sonar transducer is in the water by keeping the helicopter vertically positioned directly over the transducer. If it starts to drift off center and drag the transducer through the water, then the cable might break.
Lammers notes that one of the types of sonar transducers used is like a "spider in the water" with arms that extend out 20 ft. and can create substantial drag if the helicopter moves off center.
The latest version of the S-70B can carry a variety of weapons and sensors authorized for export to customers who receive U.S. government approval. Among these are:
# The high-subsonic AGM-119B Penguin missile that uses a passive infrared seeker for target detection, validation, tracking and homing. After performing random and pop-up maneuvers, the missile dives so it can hit close to the target's waterline. It carries a 120-kg. (264-lb.) warhead to a range of at least 34 km. (18 naut. mi.), and uses a delayed fuze mechanism to maximize damage.
# The Raytheon Mark 46 lightweight, anti-submarine torpedo that can home in on its target with acoustic sensors. This weapon has been upgraded over the years with a variety of improved guidance and countermeasure capabilities.
# The U.S. Navy's Mark 54 lightweight torpedo that uses commercial digital signal-processing technology. Its advanced guidance and software optimizes shallow-water engagement capability.
# The laser-guided AGM-114 Hellfire missile that can engage surface ships and targets on shore.
# The AQS-18A mid-frequency dipping sonar system that can be used in both shallow and deep water.
# The L-3 Oceans Group's low-frequency DS-100 Helras dipping sonar system, for both shallow and deep water, that has a vertical transmitting array and a receive array with eight hydraulically driven arms that deploy to a diameter of 2.6 meters (8.5 ft.) when underwater. This 155-kg. underwater device can operate at depths up to 500 meters.
The S-70B can carry up to three weapons at a time on its three hard points - two inboard stations and an outboard one on the left side.
The aircraft is powered by two fully marinized GE Aviation T700-GE-401C turboshaft engines with a combined shaft horsepower of 3,426 for takeoff. It has a maximum gross weight of 21,884 lb., maximum payload capacity of about 6,680 lb., maximum cruise speed of 146 kt. and endurance of approximately 4 hr.
"We are seeing quite a few international maritime helicopter requirements - more than usual," says Keith Harrison, an avionics manager who supervises the integration of mission systems into the S-70B.
Source
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