SOW S76 Visual System 06-29-23 final.docx

Statement of Work Wide Angle Visual System S-76D Cockpit Simulator

1.0 Background

The Federal Aviation Administration (FAA) has a requirement for a visual system for the S-76D cockpit simulator maintained by the Cockpit Simulation Facility (CSF) of the Laboratory Services Division (ANG-E16). The CSF S-76D cockpit simulator provides the worldview out of the window as seen by the pilots, and depicts any visual object that could be encountered in all phases of flight of the aircraft.

The CSF S-76D simulator is being used for flight safety research in helicopter operations. While the accident rate of commercial aircraft is extremely low, the accident rate of helicopters continues to increase. From 2016 to 2019, the accident rate per 100,000 hours of flight increased from 108 to 122; (of these totals 17 were fatal accidents in 2016 versus 24 in 2019) – Source: US Helicopter Safety Team.

Helicopters are used in applications where fixed wing aircraft are not feasible such as search and rescue, emergency medical services or operations to offshore oil rigs. Unfortunately, there are causal factors associated with these types of operations including poor environmental conditions – e.g. low visibility (darkness, weather), and operating the aircraft outside of its operational limits. In order to reduce the accident rate, these factors must be mitigated. Improper flight planning and/or pilot training (decision making) are also accident factors (Source: Medical Helicopter Accident Review [CAMI May 2021]. Therefore, these factors must also be addressed.

Results of the research performed in the S-76D simulator may lead to rulemaking, so any information gathered must absolutely be based on real world conditions. Due to the importance of the visual cues provided by the environment outside the aircraft, it is imperative that the visual system procured for the S-76D simulator must meet the specifications in this SOW. For example, the contrast specification included herein determines the amount of light emitted from the screen in night/darkness conditions. If this specification is not met, excess light in darkness conditions may be present which could blind vision augmenting equipment and invalidate any research results.

For these reasons, minimum performance specifications contained in this specification are taken as invariant.

2.0 Scope of Work

This specification provides minimum performance specifications for a visual system for the CSF S-76D simulator including display surface, image projectors, and any optics needed to focus the image, or achieve the required field of view. This specification does not include the image generators.

2.1 Description [Method/Approach]:

2.1 Constraints:

There are several hard constraints that the visual system designs must consider:

1. The first constraint is that pilot access/egress is through the standard helicopter side doors. Access/egress through the rear of the fuselage is not possible because the simulator is built using an actual aircraft nose section that contains structure for the broom closet and occupant seats.

Note: The implication of this constraint is that sufficient room between the image surface and the helicopter fuselage must be allowed to allow occupants access to the side doors for access/egress to/from the cockpit. With both cockpit doors opened to their full extent, the width of the cockpit is approximately 14’ wide. Therefore, the projection dome cannot be smaller than 14’ in diameter to avoid contact with the doors when fully opened. It should be noted that removal of the cockpit doors to accommodate smaller projection screens is not an option. To obtain the highest degree of fidelity possible occupants will enter the cockpit, close the doors, and then begin their flight trials, just as they would in live operations.

2. The second constraint is the mounting structure beneath the fuselage. The helicopter fuselage is currently mounted on a frame that provides approximately 12” of clearance to the hard floor. The fuselage will require additional height to accommodate the new visual display.

Note: The implication of this constraint is that a new mounting frame will be needed to raise the helicopter fuselage a sufficient amount to place pilot’s eye point at the proper height relative to the screen. The simulator has unique dimensions. If vendor design does not provide the new mounting frame, the FAA would require vendor screen design information so that the FAA can engineer the mounting structure to be compatible with the display screen and screen support structure.

3. The third constraint is the room size where the visual system must fit. The space allocated for the visual system is a maximum of L24’ x W20’ by H19’. The absolute ceiling height of 19’ within the simulator bay is the clearance from the floor to overhead building structure. As a result, the height of the dome, including support structure, cannot exceed 18’ 10” to allow for clearance.

2.2 Visual System Specifications:

2.2.1 Image type: The image seen by the pilots must be direct view; no collimation is required.

2.2.2 Screen Surface: The surface of the reflecting screen must be finished so as to exhibit Lambertian reflection. (An ideal Lambertian surface reflects light in a diffuse pattern rather than specular reflection according to Lambert’s cosine law). The reflecting surface must not have ‘hot spots’ or cause light to be reflected from the screen that would dilute dark scenes and increase the black light level.

2.2.3 Parallax: The visual system must provide for a maximum parallax of 10° per pilot.

2.2.4 Field of View: The horizontal and vertical field of view as seen by each member of the flight crew must be a minimum of + 110 degrees horizontal (relative each pilot’s eye point) by 90 degrees vertical (65 degrees down by 25 degrees up relative to the pilot’s design reference eye point).

The visual image viewed by each pilot must be continuous and uninterrupted. Therefore, no part of the S-76D fuselage must cause occluding of light from any projector to the projection surface. Shadowing in the projected image must not be visible from either of the pilots’ eye reference points.

A halo effect due to diffraction of light from the simulator or its support structure is not permitted. Reflected light from vendor provided equipment or structures is not be permitted.

2.3 Minimum Performance Specifications – Image Quality:

2.3.1 Image Resolution: The visual system must have an average image resolution of not more than 5 arc minutes/OLP over all conditions of dynamic motion in the visual system.

2.3.2 Display brightness: 40 Foot Lamberts minimum when measured at a distance of 1 meter from the screen. Note: This brightness condition is for bright sunny day conditions in an environment with medium ambient light.

2.3.3 Image Latency: Not more than 100 milliseconds from control input to visual indication of actual control response.

2.3.4 Dark Levels: The amount of light reaching the pilot eye point in dark conditions must be no greater than .003 Cd/M2. This is measured using an unaided photometer located at the pilot’s design eye reference point[endnoteRef:1]. [1: ]

2.43.5 IR Channel Illumination: Each projector must be equipped with a separate Infra-Red (IR) input in order to stimulate NVGs. The light emitter must operate in the 740nm range. The projector must be capable of projecting RGB images and IR images simultaneously.

2.3.6 Projector Frame Rate: Projectors used in the projection system must operate at 120 frames per second minimum, and must be able to achieve native WQXGA resolution at this frame rate.

2.4 Surface Contrast Ratio: The contrast ratio of a checkerboard pattern of white and black squares must be greater than 100:1. The size of the squares must subtend an angle of 5 degrees when viewed from the pilot’s eye reference point. Light levels must be measured at the screen at the center of two adjacent squares. The ratio of light levels at the center of the light and dark squares must not be less than 100:1.

2.5 Screen Surface Characteristics:

2.5.1 Gain: The projection surface of the visual screen must have a gain of not less than 0.7 and not more than 1.0.

2.5.2 Cross Reflection Reduction: The projection surface must be designed with a surface finish to minimize cross reflections from multiple projectors.

2.5.3 Projection Surface Finish: The projection surface must be finished in a color that results in the highest black levels.

2.5.4 Image Blending: Image blending must be used to create a seamless image in the overlapping region between projectors. There must be no variation in image brightness across the blend region visible to the cockpit occupants.

Image blending must support a minimum of 4K in the Image resolution; the image must be seamless for all lighting conditions from full daylight to total darkness and must include the infra-red region for night vision operations.

After initial adjustment, Image blending adjustment must be automatic and continuous and must not require manual adjustment. Offerors must indicate their methods of blending adjustment in their response.

Compatibility: Iimage blending software must accept any video input using industry standard video interfaces such as HDMI. Dual Link DVI, etc.

2.5.5 Cabling: Video cabling must be provided for each projector (IR and Visible spectrum). The cabling must be sufficient in length to reach an image generator located not more than 50 feet from the projector mounting structure.

2.6 Night Vision Device Compatibility: To support enhanced/synthetic vision research the visual system must be able to produce imagery in the infra-red region simultaneous with imagery in the visible region. Pilots must be able to wear Night Vision Devices (NVDs) in the simulator and perceive accurate renditions of infra-red illuminated terrain features in all-weather operations.

2.7 Visual System Field of View: The visual system must be immersive with a wide field of view. To create the sensation of flight movement, the imagery must fill the pilot’s peripheral field horizontally, and provide a downward looking image to permit visual approaches and landings. The simulator will be used for several operational profiles including oil rig operations, search and rescue, steep angle and curved approaches, and edge-of-the-envelope operations. For these types of operations, motion cues in the visual system are critical to give the pilots the spatial information necessary to complete the operation. Therefore, the horizontal field of view must be sufficiently large to immerse the pilot’s peripheral vision completely in all head-forward operations, and the vertical field of view must allow visual approach and landings.

2.8 Shadows and Reflections: No portion of the helicopter fuselage or mounting structure is permitted to block the light from any projectors or occlude the image seen by the pilots. Therefore, the image must be continuous and uninterrupted, free of shadows across the field of view from either of the pilot’s eye reference points. Similarly, reflections from any mounting structures that would cause screen glare are not permitted. Any structural components must be finished in a non-reflective black coating to eliminate reflections.

2.9 Direct Projection: The visual system must be continuous in the near field and far field imagery. For this reason, the projection method must be direct projected; collimation is not desired in near field operations and is therefore not permitted in this procurement. The visual image must also be continuous in the forward view above the horizon down to the view through the chin windows and through the side view from the horizon downward. This continuity requires the use of a continuous spherical projection screen of sufficient geometry to cover the entire viewing volume. The use of auxiliary displays to fill-in gaps is not permitted in this procurement.

2.10 Image Resolution and Detail: The required richness in scene detail requires high resolution projectors. The simulated helicopter will be operated in all weather conditions, over all terrain types, and in all day/night lighting conditions. Scene detail is required, however, projector resolution is not specified in this procurement. The specification for resolution in the visual scene for Level D simulator qualification compliance is required.