Eurocopter’s talking more than just weather

 - January 14, 2008, 11:28 AM

Eurocopter’s “all-weather helicopter” (AWH) demonstrator has flown from the manufacturer’s headquarters in Marignane, France. The proof-of-concept aircraft is an EC 155B fitted with systems that are expected to manage 3-D flight plans, help avoid collisions with terrain or obstacles, de-ice the airframe and allow the helicopter to perform steep approaches in zero visibility. The program also includes provision for dialog with civil aviation authorities encouraging them to study regulation changes that would take into account these new rotorcraft capabilities.

Daniel Bouheret, head of the AWH program, told AIN that the “all-weather” system, when mature, will be the core of the mission system architecture for all future Eurocopter products.

“Today, flight into poor weather is almost impossible with helicopters,” he said, noting that:

• Operations are often not possible in low-visibility conditions, such as fog.

• De-icing systems are available on only two helicopters–the Eurocopter Super Puma and the Sikorsky Black Hawk.

• Flight in IMC is not practical, as the rules have been designed for fixed-wing aircraft operations and they force helicopters to make flat, high-speed approaches whereas they are capable of steep, low-speed ones.

• Night VFR is allowed but helicopters are expected to follow specific paths. In this regard, rotary- wing aircraft are way behind their fixed-wing brethren, and Eurocopter engineers are using and adapting some technologies that have been widely used on the latter.

On the AWH demonstrator, a satellite-based navigation system– using GPS, its augmented variants EGNOS/WAAS or the future Galileo–and a terrain database provide the pilot with both a conventional moving map and a vertical situation display. On the latter, the pilot can see the helicopter’s current position and the terrain ahead. Colors (with red representing the higher level of danger) indicate how a mountain conflicts with the flight plan. This system is designed to help the pilot work out a safe flight path. Thales Avionics provides Eurocopter with the cartography.

Eurocopters philosophy in designing the flight deck shares some of the ideas manifested in Dassault’s EASy cockpit. “I went to see Dassault’s demonstrator, and we discussed PC-like, multi-window displays,” Bouheret said. On the EC 155 prototype, the cursor-control device is a joystick, but this could evolve into a trackball or a touchpad, he noted.

Takeoff and landing-aid design philosophy is “staying in a VFR scheme,” as Bouheret put it. In the first phase of the approach, six- or seven-degree descents would be performed by following IFR-like, curved trajectories. The virtual glide- slope and localizer would be computed by the navigation system’s database. An operator could even add the map of a hospital location into the database.

“Differential GPS gives us precision of a few meters,” Bouheret said.

The targeted decision height is approximately 100 feet. “This means that, for the second phase, you need to get visual contact as soon as possible,” Bouheret said.

HUD/EVS Evaluations
Under evaluation for display on the still-to-be-fitted head-up display (HUD) will be an enhanced vision system (EVS). Both an infrared camera and a light intensification camera (the same technology used in night-vision goggles) will be flight tested.

Some systems have not actually been fitted to the EC 155, although they have been tested on a flight simulator. After a first phase with IFR head-down systems, a second phase will lead to EVS/HUD systems testing in the second half of this year.

The Thales HUD will have “a field of vision of 30 degrees vertically by 40 degrees horizontally.” In the future, a color HUD, developed by EADS shareholder DaimlerChrysler, could bring better alarm differentiation. But since the HUD combiner is bulky and the field of vision is limited, an ideal solution would be a helmet-mounted display like those used on combat aircraft, “but prices are still too high,” Bouheret said.

A laser-based obstacle warning system, manufactured by Dornier, will detect trees, wires and other obstacles. As the database might not indicate some obstacles and pilots do wander from the flight plan, collision avoidance systems are still needed, Bouheret emphasized.

On the HUD, the obstacle warning system will show a “safety line,” above which the pilot can fly without any concern about hitting terrain. “But this is safety equipment, not a primary flight system,” Bouheret noted.

A laser cannot see through dense fog, since water droplets reflect the light. Therefore, Eurocopter is keeping an eye on millimeter-wave radars, which can penetrate fog. However, such radar cannot currently see wires, meaning further development is needed before it can be part of the all-weather concept.