This image originally appeared in the October 1989 issue of Rotor & Wing International
This article was originally published in the October 1989 issue of R&WI and has been edited to comply with current grammar and style guidelines. Look for our special 50th anniversary edition of the magazine in June 2017, where we'll celebrate the past 50 years — and look ahead to the next 50 years — of rotorcraft innovations.
Honeywell’s Defense Avionics Systems division, in Albuquerque, New Mexico, is no newcomer to producing digital map systems. Currently, it is applying its some 20 years of experience to develop a system of the U.S. Army’s Light Helicopter Experimental (LHX) program. It does so as a member of the SuperTeam in the LHX competition, led by Bell Helicopter and McDonnell Douglas Helicopter Co.
Honeywell is using as a baseline for its development work experience it gained from the U.S. Navy’s McDonnell Douglas AV-8B and F/A-18 Night Attack program. Its advanced moving map system, being developed under independent research and development funding, will be expanded to include terrain reference navigation, ground collision avoidance, perspective view, terrain following computations, threat intervisibility and sensor blending — the kinds of reference a helicopter pilots needs when flying low, in the much and looking for targets while remaining as concealed as possible.
The trick in developing a moving map display, especially for low-flying helicopters, is acquiring adequate, detailed reference data. To make the digitized map display and advanced functions for the system, Honeywell acquires from the Defense Mapping Agency Defense Logistics Management Standards (DLMS) level-one (elevation data every 100 meters) and level-two (elevation data every 30 meters) terrain-and-feature data. That information is derived from several sources, such as satellite surveillance, reconnaissance flights, etc.
Honeywell will have all this data stored on an optical disk that has more than 520 mb of capacity, or enough storage to file away 500,000 square miles of terrain information on a side. Data will be written to the disk by a laser diode in the head assembly A beam of light that is focused on the medium to produce a hole, which, during the “read” operation, is recognized as a bit of data.
Unlike magnetic media, which can be scratched by a head crash, data stored on the optical disk is written to a thin film encased in a protective substrate and clear, protective cover.
Honeywell’s map system also stores and displays current aeronautical charts, which are digitized and processed for storage on the militarized optical disk. Each side of the optical disk can store 400 square feet of aeronautical charts, with up to six different chart scales being selectable.
Along with the digitized aeronautical charts, the Honeywell system will store additional information, such as radar and Landsat data, emergency procedures, letdown and approach plates, mission data and flight plans.
Honeywell’s current AV-8B and F/A-18 digital video mapping system will include an overlay selection as well, which presents feature data (roads, streams, towers, etc.) in the DLMS mode. It will also show flight path waypoint symbols, text and threat symbols in the DLMS and digitized-chart modes. The video generator combines the background scene memory with the overlay memory to provide a composite video output.
Processing is distributed across several high-performance microprocessors rather than a single unit, and parallel processing is performed wherever possible. Thus one processor can process the map display, while another processes the overlays. Data is then pipelined through the digital map computer. The use of parallel processing provides fault tolerance since a failure in the map generation does not prohibit the graphics-overlay operation.
The digital map computer performs the map generation. On the Navy’s AV-8B, that computer contains 11 circuit cards as well as mother board, power supply and space to accommodate additional functions. Honeywell’s advanced system will be similar; however, it will have more than twice as many (25 to 30) circuit cards.
To achieve the performance, reliability, maintainability and supportability required for advanced platforms like LHX, Honeywell will integrate the digital map computer’s critical functions onto standard modules. Company engineers will then have to reevaluate the current interfaces and develop new ones to meet the program’s architectural requirements.
The digital map computer receives operational parameters that include aircraft state vector map scale, zoom factor, north up/track-up, database type, de-clutter select/deselect and video output mode from the mission computer via a MIL-STD-1553B multiplex bus. Data requests are then sent to the digital memory unit using a fiber-optic link.
What the pilot sees
For the pilot, all this memory and processing horsepower will deliver a full-color moving map that provides precise navigation and route selection to and from the point of target acquisition and weapons delivery. It will offer terrain reference navigation by combining the onboard terrain elevation data with readings from the radar altimeter to pinpoint the aircraft’s position.
By comparing DLMS elevation data to elevating limits relative to the aircraft’s altitude, the advanced Honeywell system will also provide ground collision avoidance. In this case, the terrain on the map display appears in four colors: green, indicating safe clearance of the terrain; yellow for terrain elevations that are up to, but not higher than, the aircraft; red, indication dangerous terrain elevation (higher than the aircraft); and blue, representing water. Variably spaced contour lines can be added, if required. Taking into account the helicopter’s trajectory, the Honeywell system will also alert the pilot when he appears to be heading toward the ground.
Indeed, according to Harry Waruszewki, a senior marketing representative for Honeywell, his company’s enhanced mapping system can do more than create a picture.
“It can input into the flight control system to become a flight management system, and actually fly the aircraft if require for pilot workload reduction.
“We can also input threats via the optical disk or data transfer,” Waruszewski said. Not only will the map display show where threats are located, he added, “it will show where the threats can and cannot see you, so you can thread your way through hills, etc. undetected.” This capability is called, “threat intervisibiltiy.”
More than a map display
In addition to a map display, the Honeywell system will present a perspective view of the terrain before the pilot. Colors will again be used to indicate elevation, and threats can be projected in the form of dome-like symbols.
The Honeywell digital map will assist in target handoff as well.
“Using a mass-mounted sight, [forward-looking infrared] — anything that is bore-sighted — a crewman can place a cursor on an acquired target,” Waruszewski explained. “The cursor position is sent to the digital map computer via the 1553 bus where the latitude and longitude as well as the target’s altitude are then processed and can be handed off to a ground unit or another aircraft.”
Honeywell’s advanced digital mapping system also provides senor blending. Like it sounds, this feature will blend, say, forward-looking infrared (FLIR) or low-level TV with ridgelines on the head-up display (HUD) or head-down display to allow for better depth perception.
Sensor blending also allows the LHX pilot to “manage” sensors for improved protection against threats. The pilot can, for example, choose to fly totally covert, using the map system’s database for terrain following information and not the terrain following radar. Or, he could minimize the radar output, sending out only occasional bursts and reducing power output for near range terrain verification. Radar information is then blended to the long-range terrain elevation database carried on the optical disk.
Of course, the lesser the terrain following radar is used, the higher the pilot should fix to ensure ground clearance. Conversely, the more the pilot can use the power-managed terrain following radar, the lower the pilot can safety fly.
In the business since ‘70
Honeywell’s experience with digital mapping systems began in 1970 when the first airborne digital map system was developed for NASA Ames for flight test on the STOLAND/VSTOLAND program. Development continued under the McDonnell Douglas F-15 Advanced Fighter Concepts Demonstrator program and in 1985, culminated with an award by McDonnell Douglas to provide the digital video mapping system for the AV-8B and F/A-18 Night Attack program. Honeywell also is under contract to provide the digital video mapping system for the U.S. Navy’s Bell Boeing V-22 tiltrotor.