Twice the Bang for the Buck

By David Jensen | November 1, 1999
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American taxpayers should be pleased. The U.S. Marine Corps has taken on an unusual upgrade program that is faithful to the service’s reputation of accomplishing more with less.

The program is unique because it concurrently modernizes not one, but two helicopter types, the UH-1N "Huey" and the AH-1W SuperCobra, both produced by Bell Helicopter Textron. These aircraft perform distinct missions, and they entered the upgrade program with distinct operational issues: performance, for the Huey, and cockpit integration, for the SuperCobra. Nevertheless, sufficient commonality—or "identicality," in Marine Corps jargon—was developed to combine two upgrade programs into one. The result is reduced costs in both acquisition and, subsequently, logistic support, not to mention a smaller price tag for research and development.

Time will have been saved, as well. The program’s development phase is to take no more than 3.5 years, yet it prepares for the Huey’s and SuperCobra’s effective service until FY2020—which is not bad for airframes that first entered the Marine Corps inventory in 1970. That’s 50 years of service!

According to Capt. Thomas J. Curtis, the Marine Corps’ H-1 program manager, the helicopters’ service prolongation will fill a time gap until the Joint Replacement Aircraft—likely a light tiltrotor—enters the service’s inventory.

The Marine Corps decided to modernize its Bell models—and give them new designations, UH-1Y and AH-1Z—in October 1996. A contract was signed with Bell, the upgrade program’s prime contractor, the following month. The two principal subcontractors are Litton Guidance and Control, Woodland Hills, Calif., providing the integrated avionics, and Lockheed Martin, Orlando, Fla., which developed the advanced Target Sight System (TSS), mounted on the AH-1Z SuperCobra’s nose.

Five flight test aircraft, three 1Zs and two 1Ys, currently are being assembled at Bell’s Fort Worth plant. The program schedule will proceed as follows: Tie-down tests begin next summer, and first flights are slated for early autumn 2000. Then, starting in 2002 and continuing through 2011, 100 Hueys and 180 SuperCobras will be taken from the Marine Corps inventory to the Bell plant for upgrade to the 1Y and 1Z standards.

Continued Kinship

A kinship between the Huey and the Cobra has existed from the start, when the AH-1G gunship derivative of the U.S. Army’s UH-1 Iroquois was developed in the 1960s. The Marines have simply maintained that sibling-like relationship by establishing 85% commonality in the latest upgrade, according to Curtis.

This commonality delivers to the Marines several space- and workload-saving benefits. For example, Curtis notes, it allows the volume allotted for spares for two aircraft to be reduced by about a third, from 3,978 cubic feet (112 m3) to 1,408 cubic feet (39.9 m3). That represents a critical advantage where many 1Zs and 1Ys will reside, on space-restricted aircraft carriers.

As well, the commonality means that two pilots trained for either type can fly one or the other of the aircraft’s two crew positions. It also allows the pilot trained in, say, the UH-1Y to ferry an AH-1Z, and vice versa—though, of course, the two aircraft’s distinct missions would preclude complete crew interchangeability.

But, more to the point, the combination of digital technology, open systems architecture, and Power Pc processing have delivered new cockpits for both a combat helicopter and a utility helicopter that are near unprecedented in terms of providing situational awareness to crewmen. The early AH-1G pilots in the early 60s could not have envisioned a Cobra outfitted with "glass" cockpit displays and controls; a moving map that provides routing, threats and terrain elevations; and a night-capable helmet-mounted display (HMD) that allows virtually continuous out-of-cockpit viewing. Such capability should comfort Marine Corps air crewmen when they enter areas of threat, often at night and/or in adverse weather conditions.


In both the 1Z and 1Y cockpits, crewmen will be looking at the same Rockwell Collins 6-by-8-inch flat-panel, color displays, instead of the usual cluster of steam gauges. The displays are commercial off-the-shelf (COTS).

Each aircraft has two pairs of these active matrix LCD, multifunction displays (MFDs), appearing on the left and right sides of the 1Y panel and front and back in the 1Z’s two tandem panels. Two 5-by-5-inch displays and a keypad, with ARINC 429 interface, rest side-by-side in the center of the 1Y panel and are divided between the two 1Z cockpits. They provide standby flight instrumentation and some of MFD functions.

All displays are night vision goggle (NVG) compatible and offer high resolution. The MFD’s pixel count, for example, is 1,024-by-768, with added clarity courtesy of a direct digital Hot Link interface.

"By mechanizing the Hot Link portion of Fibre Channel protocol, we can drive the displays directly from the graphics processing in the mission computers," explains Bill Devlin, Litton’s director-integrated systems.

All information, whether it is generated by an on-board sensor or mission computer, is available to all display locations, and the mission avionics architecture minimizes latency for all data, with particular emphasis on critical flight parameters. Collectively, these features contribute to crew versatility—making the crewmen’s roles interchangeable. "Now we can fly and fight from either cockpit," says Curtis, commenting on the AH-1Z.

Equal to their commonality is the orderliness of the 1Y and 1Z cockpits. "It’s a radical cleanup," states Curtis, allowing the crewmen much better outside viewing."

"The cockpit has been made user friendly, adds Devlin. "We’ve worked with the Marines to come up with an intuitive system for all of the mission functions, whether these be navigation, flight planning, maps, communiction, weapons or sensors."

Indeed, for a year and a half, 13 Marine Corps pilots—members of an aircrew system advisory panel (ASAP)—worked in Bell simulators "seeking the most efficient interface," says Curtis.

Curtis describes the resulting user-friendliness in the 1Z and 1Y cockpits as "synoptic," meaning "the imagery is graphic rather than [relying on] words, for at-a-glance perception." For example, a SuperCobra pilot can quickly determine his weapons complement by viewing a color graphic that depicts the aircraft’s two pylons and their attached arsenal. Few words are needed. Keeping his head up as much as possible, the pilot controls his displays using the button groupings on the collective and cyclic, which are called the HOCAS, for hands on collective and stick.

Key to a successful 1Z and 1Y mission is good pre-flight planning and the ability to use data in the avionics system. This applies to all aspects of mission execution, including weapons inventory, communications, navigation, target management, and threat avoidance.

The Marines will use the Navy’s standard Tactical Aircraft Mission Planning System (TAMPS) as the source of mission plans for uploading into the mission computer, and their pilots will be able to conduct on-ground flight rehearsals and "what if" scenarios.

"Mission plans will be imported into the aircraft using a Pc MCIA card prior to takeoff," according to John Dowell, Litton’s technical director for H-1 programs, "and this augments the more permanent data base residing in the Tactical Aircraft Moving Map Capability (TAMMAC).

"It’s the digital map system that represents the most logical function extension of TAMPS," Dowell adds, "because of its ability to assist in real time display of geographical, target and threat situational awareness."

The map system stores types of data covering a large theater of interest. These include the Digital Terrain Elevation Data-base (DTED), which describes contour characteristics, and the electronic image version of aeronautical charts in the form of Compressed ARC Digital Raster Graphics (CADRG). Various registered photographic images from satellites or other sources can be stored and displayed as well, as Controlled Image Base (CIB).

The crew can exploit these data in many ways. Marine Corps pilots, for example, can use the data to take maximum benefit of the geography during ingress and egress through terrain masking with respect to threats and targets.

Linked to the mission planning process is the post-mission analysis of data, with emphasis on maintenance and, ultimately, lower life cycle costs. This includes, according to Dowell, "the real time monitoring of health parameters and the delivery of these through an extracted PMCIA medium."

This monitoring capability complements the 1Z’s and 1Y’s integrated mechanical diagnostic (IMD) system, made by BFGoodrich. The IMD provides blade tracking, plus drive train and engine monitoring. "The IMD could well give use-on-condition maintenance," says Maj. Paul Davidovich, the Marines’ chief engineer for the H-1 program.

Helmet-Mounted Display

To further enhance the AH-1Z pilot’s situational awareness, the Marines selected the Integrated Helmet Display and Sighting System (IHDSS), which Marconi Electronic Systems adapted from its Viper 2 helmet. Providing crewmen with sighting and cueing, the IHDSS consists of three main components: the HMD, which includes a visor projection system; a head tracker, to follow the crewmen’s head movements; and two clip-on image intensified cameras with video signal conversion, made by Ball Aerospace. The processed and intensified image provides 40� horizontal and 30� vertical fields of view inside the visor.

No longer need direct-view night-vision goggles hang before the pilot’s eyes. Rather, the image from the intensifiers is displayed on the helmet’s visor by means of two high resolution minature projection CRTs. To enhance the helmet’s utility, particularly in urban terrain warfare, the intensifiers employ low-halo tubes, by Litton. In the future, the Marines hope to have TV and forward-looking infrared (FLIR) imagery projected on the visor.

For true head-up operation, both crewmen can overlay navigational, threat and weapons information on the IHMSS and can independently control the sighting system or engage the weapons—another example of the AH-1Z’s total electronics integration. In daylight, the target, weapons and flight instrumentation data projected on the visor remains fully readable—even in bright sunlight.


The primary navigational sensor for the 1Z and 1Y is the Enhanced GPS Inertial (EGI). GPS data and inertial sensor data can be used together or separately. The aircraft also have the APX-100 identification friend or foe (IFF), the ARN-153 TACAN, and a back-up air data computer and attitude sensor. For the 1Z, a low speed air data system supports accurate weapons delivery while the aircraft is in a hover.

The new H-1s’ primary communications unit is Rockwell Collins’ DCS-2000/RT 1794 with fully integrated VHF/UHF, modem and encryption capability. Two of the com systems are installed in the 1Z and three are in the 1Y. The added com unit, as well as a satcom expansion, are critical for the Huey’s command and control mission.

The the com unit also mechanizes a tactical data communication capability, featuring variable messaging formatting. These are the emerging message types and protocols, says Devlin, for inter- and intra-service communications. Maintenance of the UH-1Ys avionics has been made easier, as well. Rather than storing black boxes in various nooks and crannies, the Marines had the Huey fuselage stretched 18 inches (45.7 cm), giving room for avionics racks behind the two pilots’ seats.


Situational awareness in terms of target acquisition in the AH-1Z derives from the Lockheed Martin TSS, which includes low-light color TV; third-generation FLIR; and a laser designator for targeting. "The laser designator is better than with previous generations," says Davidovich. "It is the same as in the LANTIRN (Low Altitude Navigation and Targeting Infrared System for Night) program for the F-14 and F-16."

The Sony color TV camera has an 18x zoom lens, and the FLIR is third generation. The Marines prefer target detection using the FLIR, with its auto tracking feature, over a millimeter wave radar, such as in the U.S. Army’s AH-64 Longbow Apache.

The FLIR is passive, Curtis explains. A signal emitting radar poses a threat because the enemy can detect it.

Perhaps most impressive is the TSS’ stabilization—thanks largely to the gimbal system, which was taken from the Wescam P-3C system. "The stabilization controls ‘the jitters’ to within five miliradians," says Curtis.

What makes all the electronic wizardry in the AH-1Z and UH-1Y work are two (for redundancy) ruggedized mission computers with muliple Power Pc processors with an open systems architecture based on the 6U-VME standard. Chipsets in the computer have been "de-rated" from 233 Mhz to 150 Mhz, "for better heat management," says Curtis. The expandable computers each have 14 bus slots: The Huey uses just three high-functional-density modules fitted in slots, while the SuperCobra employs eight because of its weapons systems and HMD. The vacant slots allow for growth.

Two 1553 data buses exist in the UH-1Y and three in the AH-1Z, the third mechanizing the 1760 protocol, which allows interface to the available weapons and any future weapons.

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