By Courtney E. Howard
Whether a pilot is flying in a U.S. Army Apache Longbow helicopter over Iraq, flying a luxury business jet or just training in a simulator, he needs accurate, reliable, and real-time information available in real-time on his avionics display.
Yet, historically, systems designers and systems integrators have often invested little time and attention in selecting the optimal flight display; that is, until now. Today's engineer has a wealth of display options from which to choose, and an exponentially larger list of application and end user requirements to weigh in the selection process.
"The exact order of priorities depends on the specific application," says retired Navy Capt. Chuck Nash, chief executive officer of Combat Displays Inc. in Bowie, Md. In general, he says, military and aerospace end users must consider a display's ruggedness, which translates into mean time between failures (MTBF) and mission reliability; size and weight, which are critical especially in form/fit/function replacement; resolution, especially to take advantage of sensors; power consumption and thermal output, as most platform power and thermal budgets are already out of headroom; and brightness/dimness/contrast for daytime readability and night-vision device compatibility.
Aspect ratio is also an important trait in military and aerospace displays. "Most military systems output in a 4:3 or 1:1 (square) aspect ratio," Nash explains. As a result, commercial off-the-shelf displays, such as LCDs, which increasingly offer only a 16:9 aspect ratio, are a poor fit. "It causes the integrator to either spec a larger size to get the same viewable area as the legacy display (with large black bars down on each side), or to settle for a smaller viewable area than before." The ability to get the specific size and aspect ratio required for a specific application is a significant advantage of rear-projection displays, he continues.
Color is yet another important display consideration today. "Many of the mission essential applications, like maps and datalink presentations, are becoming more and more color dependent," Nash explains. "We have only scratched the surface of what color could bring to situational awareness for the warfighter."
Improved color and graphics helps improve the situational awareness for pilots, by replacing analog instruments with digital displays. Engineers at Sagem Avionics in Dallas upgraded the cockpit of the Sikorsky S-61 with such displays.
They provided the S-61 with four Active Matrix Light Crystal Display (AMLCD) 10-inch displays mounted in portrait mode and one in landscape mode. The system integrates Primary Flight Instruments, EICAS -Engine Instruments/Caution Advisory System and other Multifunction Display system functions such as moving maps, enhanced vision when linked to a camera, TOPS – Terrain Obstacle Proximity System, route information, etc.
For example in the art pictured with this story Sagem fitted the S-61 cockpit with 5 x 10 inch displays and a 6-inch display that is mounted in the console and shows the Caution Advisory System, which replaced the annunciators that were in the panel before," says Emmy Ansinelli, spokesperson at Sagem. This solution can be fitted on any Sikorsky S61 model which includes the SeaKing, she adds.
In flight simulation the displays need to be just as high-performance as those the pilots will use in the actual cockpit.
"Fast Jet training demands the ultimate in functionality and performance," Al Herman, North America business segment manager for the Simulation Division of Barco, Inc. "Image projection devices must provide smear-free images with high resolution, high contrast, and night vision fidelity. Fast jet mission training often requires an unobstructed, horizontal 360-degree viewing environment which in turn requires optically near-perfect rear-projected domes, either faceted or spherical.
"Rotary craft training requirements are similar to fast jet requirements differing primarily in fields-of-view. Resolution, NVG, smear reduction, contrast and time-of-day remain at the top of the performance criteria," Herman continues. In wide-body, or collimated systems, resolution, brightness, and contrast are important, but cost of ownership is also a key consideration. We are constantly working to improve lifecycle cost by improving maintenance tools and reducing maintenance requirements, e.g., by extending X-cube life and lamp life.
"The United States Air Force Distributed Mission Operations (DMO) requirements significantly increased visual system performance demands for aviation simulation, which in turn requires display devices capable of much more accurately depicting targets, friendly forces and non-combatants," Herman says. "Now we are seeing increased performance demands from all users. Not only are the operational requirements more demanding, military pilots also have exceptional eyesight, and poor visuals produce negative training. We recently shipped a system with 20/10 resolution and 1 percent blend uniformity. This level of performance in a training visual display was previously unknown. "
In commercial aviation simulation users typically want "multi-type, wide and narrow body trainers with collimating display systems, Herman continues. Users are seeking improved optical performance, improved reliability and reduced operating cost. Because much commercial aviation training is provided on a fee-for-service basis, there is constant pressure on the suppliers to reduce operating costs while retaining a very high uptime percentage. Again, the use of automated maintenance tools, more reliable products and technological advances are keys to success in this market."
Barco's most popular simulation display product is their Sim7 LCoS projector, which has more than 600 shipped to date, Herman says.
Portable computing is becoming more prevalent, notes Timothy L. Hill, senior product manager at General Dynamics Itronix in Spokane Valley, Wash. "In portable devices, such as notebook and tablet computers, the most important aspect is outdoor viewability, and then battery run time followed by ruggedness." Most companies simply increase the display brightness to compensate for the effects of direct sunlight, resulting in added power consumption (reduced battery run time) and a washed-out look that makes seeing fine detail difficult, he says. In contrast, General Dynamics Itronix patent-pending DynaVue display technology employs films to reduce the effects of direct sunlight without affecting battery run time.
"The most basic barrier of entry for any of the military mobile programs and applications is almost always MIL-STD-461 and MIL-STD-810G, which address both the environmental ruggedness and the EMI (electromagnetic interference) requirements," adds Richard Ridley, president and chief executive officer at Digital Systems Engineering Inc. in Scottsdale, Ariz.
"The display must also be able at accept and process the various video input signals available from the selected systems," Ridley continues. "The more flexible the display is in this area, the better. Customers are asking the display to do more than present an image. We are being asked to integrate controls for various sensors and systems through the use of programmable switches and potentiometers. We are being asked to provide application-specific graphic overlays and GUIs (graphical user interfaces), and even some limited use of touch screens."
"Touch screens will become even more prevalent in all computing devices, as will the desire for multi-touch gesturing," Hill says. Multi-touch touch screens are beginning to be desired in portable devices; yet, the challenge is enabling them to be used with gloved hands or in the rain.
"Touch screen is making its way into certain applications," Nash agrees, "but some operators find it difficult to use when the platform is moving erratically. Also, many platforms and weapons system controls are already established with techniques like HOTAS (Hands on Throttle and Stick), track ball, and joystick, which are operator-preferred."
Two technologies are showing some indications of viability in this area, however: Resistive multi-touch and CMOS (complementary metal oxide semiconductor) optical touch. "As touch screens become more popular, their surfaces will need to become more resistant to scratches," Hill explains, adding that it is likely to be accomplished through removable films and harder glass surfaces.
In the future, flat-panel displays will move from a basic terminal to "an intelligent, interactive display system allowing for interaction with and control of several systems, such as DVE (Driver's Vision Enhancer), FBCB2 (Force XXI Battle Command Brigade and Below), COMM, targeting, and so on," Ridley predicts. "Also, next-generation displays will need to be able to enhance images through internal processing and display several images at the same time."
John McHale also contributed to this story.