ARCHIVED - New technology for fly-by-wire helicopters gives pilots better control

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July 01, 2011— Ottawa, Ontario

Imagine the stress of flying a helicopter in rapid combat or in high crosswinds and low light. Picture yourself fighting gravity in tight turns over rough terrain. One small mistake when operating multiple control panels could mean a quick end to your career. 

Now, a major breakthrough in advanced aircraft control systems will change all that. A unique technology developed by NRC Aerospace will give helicopter pilots far better control, especially in conditions that could put their life at risk. 

The new technology is for rotary-wing aircraft in which an electronic interface replaces manual controls, hence the name “fly-by-wire.” Available since the 1970s, fly-by-wire systems are becoming more and more prevalent in both fixed and rotary-wing aircraft.

The new technology was tested at the NRC Flight Research Lab, using its Bell 412 Advanced Systems Research Aircraft.

The new technology was tested at the NRC Flight Research Lab, using its Bell 412 Advanced Systems Research Aircraft.

In a fly-by-wire system, the pilot’s control stick movements are converted to electronic signals and transmitted to computers. The computers determine how to move the actuators at each control surface to provide the best response. The computers also enhance performance by issuing commands without the pilot's knowledge to stabilize the aircraft and perform other tasks. 

This revolutionary technology simplifies the fly-by-wire control system so that, in critical moments, pilots can focus on flying rather than on managing multiple control system modes.

“Compared to traditional manual controls, fly-by-wire technology has dramatically increased stability and responsiveness,” says Stewart Baillie, Director of the NRC Flight Research Laboratory. “However, our technology enhances fly-by-wire control systems to a degree never seen before.”

Super-TRC control system 

Bill Gubbels and Kris Ellis are the NRC Aerospace researchers who developed the new technology — a control system architecture they have dubbed “super translational rate command” or super-TRC. 

Kris Ellis is one of the NRC Aerospace researchers who developed the super-TRC control system for fly-by-wire helicopters.

Kris Ellis is one of the NRC Aerospace researchers who developed the super-TRC control system for fly-by-wire helicopters.

Fly-by-wire helicopters that are in production or under development employ multiple dedicated flight control modes that are optimized for either stability or maneuverability. These systems require a pilot to manually select the appropriate mode for the given task and condition, using control panel switches. But this can become a problem in environments where visibility rapidly degrades, such as in blowing sand. To switch control modes, a pilot must look inside the cockpit rather than focus on the situation developing outside the cockpit windows. 

The Super-TRC system allows both stable and manoeuverable control systems to be active simultaneously. The blend between stability and agility is determined by how the pilot moves the control sticks. Slow, deliberate stick motions are channeled to a stable control system, whereas fast stick inputs are channeled to more manoeuverable control systems. 

“Given how much it will improve operational effectiveness, every new and retrofit fly-by-wire aircraft should have it installed,” says Gubbels. 

“It will make helicopter control so much easier, especially for military or rescue applications where the visual environment can change rapidly, such as at low altitude over dust, sand or snow,” adds Ellis. 

Limitations of current technology 

Helicopters require the ability both to manoeuvre aggressively and be very stable, depending on situations that change by the minute. When configured for stability, a helicopter tends to be sluggish to manoeuvre. When configured for agility, it tends to be “twitchy” when no manoeuvering is required. Current technology requires pilots to manually change the flight control mode as the situation changes. Pilots choose higher stability settings in poor visibility, but these settings reduce their ability to more aggressively manoeuvre the helicopter. 

The NRC technology will allow pilots to handle these situations with a single interface that integrates high manoeuverability with stability. Pilots will no longer have to manually transition between different modes ― a significant advantage when they must concentrate on other important tasks. The NRC technology tailors the aircraft dynamics based on the character of the pilot’s control inputs. 

“Pilots can be fast and aggressive with the stick when they need agility. At the next instant, they can be slow and cautious, using tiny movements when they need stability,” says Gubbels. “They get the best of both worlds without having to change modes at the control panel,” adds Ellis. 

NRC will license this technology to a Canadian firm that aims to be at the forefront of aerospace innovation and has the means to commercialize it.

Related information 

Enquiries: Media relations
National Research Council of Canada

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