The of the last remaining significant technology challenges in high-fidelity simulation is the visual system. Most of the visuals fielded with aircraft simulators have been high-cost, low-fidelity, and low-resolution systems. Many of the designs in the field today originated in the early to mid-1970s. They have also been large and immobile, such as a domed visual system, and most have included six-degrees-of-freedom motion bases. Although a dome provides a full 360-degree visual scan, the brightness and resolution has always been among the lowest of any approach. Most of the other visual systems fielded today that are not domes are aircraft simulators with a very limited field of view, usually 120 degrees horizontally by 30 to 60 degrees vertically. One of AFRL/HEA’s simulator development program goals has been to develop high-fidelity, low-cost, deployable, and upgradeable training system prototypes, which encompass the cockpit and the visual system. The field of view included in the training system design has been varied to meet the users’ training requirements and budget. The display systems have ranged from a single screen to a full 360-degree, eight-channel, full-color visual system.

With this in mind, AFRL/HEA’s visual system development program produced the Display for Advanced Research and Technology (DART), which was designed to replace domes. The DART was followed by the Mini-DART, which was developed for SCUD missile hunting research during Desert Storm. Next came the Deployable DART, which was built as a prototype for the Air Force Reserve F-16C Block 30 simulator. The newest, the Mobile Modular DART (M2DART), was designed to eventually contain the advanced super high-resolution projection system capable of 20/20 visual acuity currently under development. The DART program was designed to develop and demonstrate a significantly more cost-effective display capability with the flexibility to address a variety of weapon system simulation visual requirements. The DART series of visual displays at AFRL/HEA evolved as an alternative to the early domes and continues to evolve as technology improves. Each iteration of the DART combines the strengths, and improves on any weaknesses, of the previous system.

The original DART was configured as a rear-projected dodecahedron screen system with nine channels of imagery surrounding the warfighter’s eyepoint. The result was a wraparound, real-image display presented 37 inches away from the pilot. The DART is significantly brighter than previous domed systems. A rear-mounted green monochrome projector in the DART provides an effective representation of the aircraft heads-up display (HUD).

Because of the high per channel cost associated with multiple channel, high-end, image generators (IGs), AFRL/HEA developed a head-tracking system that reduces the required number of live video channels required to be output at any one time. As a result, not all of the screens have to be illuminated in a 360-degree visual system, depending on the screen geometry of the system. The head-tracking system follows the pilot’s head movement to determine where the pilot is looking. The head tracker then switches on the channels that are in the pilot’s field of view and turns off those that are not. This system enables the available IG channels to cover all the projectors in each channel of the display system without compromising pilot performance or limiting the field of view. In the M2DART design, AFRL/HEA determined that six channels were sufficient to prevent the peripheral perception of projectors blinking on and off, which can be distracting to the pilot.

The Mini-DART evolved from the original DART to meet the users’ need for a simulator system that fit into a room with a 10-foot ceiling. As a result of the ceiling restriction, the Mini-DART used a series of rectangular and trapezoidal screens each with a different surface area. The eyepoint was a 24-inch screen distance to the front screen. This was significantly closer than the 37-inch screen viewing distance demonstrated with the DART. This design used only four channels of the IG system and head tracked the other four for a total of eight channels and 360-degree horizontal field-of-view. One of the severe limitations caused by the significantly different surface areas (driven by the ceiling height restriction) was that each channel had a noticeably different resolution. Seven of the eight channels could be made to match in brightness but not in resolution. The front screen, which was the smallest, was brighter and had much higher resolution than the rest. The Mini-DART is no longer in service at the Lab.

The next generation of the original DART design provided the user with a modular four-screen system that could be deployed to forward operating locations to conduct mission training and rehearsal. AFRL/HEA developed the four-screen system and called it the Deployable DART. The design of the Deployable DART is similar to the front half of the Mini-DART except that the screen geometry was controlled so the surface areas matched more closely. The field of view of the display is 240 degrees horizontally by 90 degrees vertically. This system is currently mated to an A-10A Multitask Trainer prototype.

Recently, a new DART has been developed which uses the most desirable aspects of the previous DART displays to achieve maximum visual fidelity. Dubbed the Mobile Modular DART (M2DART), it is a flight simulation rear-screen, real-image, display system that uses commercially-off-the-shelf (COTS) cathode-ray tube (CRT) projectors to provide out-the-window (OTW) visual imagery to the pilot with a full field of view. The M2DART has eight flat projection screens mosaiced together to display eight channels of full color imagery. The projectors can be controlled via an infrared remote control and a laptop computer for ease of maintenance and repair. The view screens are the diffusion type, made of a 3/8" thick acrylic substrate. The fold mirrors, used to make the system more compact, are very lightweight and are fabricated from mylar film stretched around aluminum frames with a styrofoam core. The screen frame support structure is designed such that the front and two side windows can be easily modified to accommodate any fighter-sized cockpit while the two rear screens, mounted on hinged frames, allow ingress/egress to the system. Due to the relatively small surface area on these screens in comparison to large dome displays, the imagery is significantly brighter with much improved contrast.

While the current design uses COTS projectors to provide high contrast imagery, the M2DART structure is designed to also accommodate the super high-resolution projection systems currently being developed with AFRL/HEA’s oversight. These projection systems will be capable of extremely high resolutions, with 20/20 visual acuity being the goal.

NOTE: These features are not possible with a DOME display system!

The M2DART is designed to be modular to facilitate transport and assembly and, in fact, has been deployed a number of times without failure. There are three towers that physically house the projectors. The tower positioned forward of the cockpit holds five projectors (four OTW, and one HUD projector). The two remaining towers, positioned aft of the cockpit, each contain two projectors. All projector towers are equipped with casters and leveling feet to facilitate transport and setup. The rear projection towers are designed to transport in a lowered condition, and then raise telescopically (with gas-charged struts) into position during setup. Projectors in the front tower are mounted on trolleys and have hinged frames for positioning. A seven-sectioned fiberglass cover, designed for the system, will block out extraneous light and minimize debris and dust. All modules are made to fit through the door of a standard eight-foot high truck.

The modularity and flexibility of the design of the M2DART allows this system to remain an excellent testbed for many important technology insertion projects such as improved projection systems, refined screen materials, advanced image generators and high-fidelity, target-inset systems. The M2DART design provides an enhanced ground training device, which will provide the warfighter with a much broader training capability in the advanced Distributed Mission Training environment.