Dassault Aviation to study greener airframe designs

EBACE Convention News » 2007
May 14, 2007, 6:08 AM

Dassault Aviation is about to start researching more ecologically friendly aircraft designs as part of the European Commission-funded CleanSky joint technology initiative (JTI). With several partners, the French business jet manufacturer will focus on airframes and systems under the e117 million ($155 million) Eco-design integration technology demonstrator (ITD) project. CleanSky is divided into six ITDs and will be spread over the period 2007-2014.

“Green airframe research will take into account the entire life cycle of an airframe,” Myriam Goldsztejn, Dassault’s vice president for European Commission business development, told EBACE Convention News. The company will build two major airframe subassemblies–such as wings–one made of metal, the other of composite materials. It will perform some ground trials–albeit with little fatigue testing–and then will dismantle the airframe.

“We want to conceive environmentally friendly airframes and materials,” Goldsztejn explained. The researchers first will endeavor to find significant energy and water savings in the manufacturing process. For example, they will develop one-shot processes rather than breaking them into several phases.

The Eco-design team will also try to reduce the amount of coating on an airframe. “Sometimes you will find up to four layers of primer and paint,” Goldsztejn pointed out. Simultaneously, they will try to make paint stripping easier and safer, as current chemical stripping is dangerous for human health and the environment.

Turning their attention to the end of an airframe’s life, the researchers will study recycling those materials. Estimates from one major airframer call for the dismantling of 200 to 300 commercial aircraft each year over the next 15 to 20 years. That could lead to some serious difficulties in disposing of composite materials. “Composites are good for lightening an airframe and therefore reducing fuel burn, but when it comes to recycling, they are a huge problem,” Goldsztejn said. Accordingly, Dassault will explore composite recycling since aluminum recycling processes are already well understood.

The second part of the Eco-design project is about systems. “We are going to study all-electric architectures for business jets, regional aircraft and helicopters,” Goldsztejn explained. The idea is to eliminate polluting liquids, such as hydraulic fluids, currently used in brakes, landing gear and flight controls. Even the control surfaces of fly-by-wire flight controls are moved by hydraulic actuators, she noted.

Electric Systems Pose Problems
However, a major issue with an alternative to hydraulic systems–electric power–is heat management. One advantage to existing hydraulic systems is that fluid circulation keeps heat under control; excess heat generated passes into a heat exchanger where it is drained and cooled. However, in an electric aircraft architecture, excess heat is not directly drained.

“To avoid temperature spots and overheating with electric architecture, we must create a new concept for thermal management in aircraft,” Goldsztejn said. Greater use of electric-driven systems are planned for aircraft due to enter service around 2015-2017, she said, insisting that this will require the development of new computational design tools.

Goldsztejn noted that a new technology can be heavier than the current one and still result in a lighter aircraft. So the benefits of both approaches must be analyzed for each particular aircraft. For example, if a new, heavier system reduces fuel burn, the amount of fuel required for any given mission is reduced and thus the size of the fuel tanks can be reduced, resulting in a smaller aircraft with better aerodynamics.

In the final analysis, heavier technology can be more environmentally friendly than a lighter alternative. This is often the case when transitioning from hydraulic or pneumatic power to electricity.

Dassault is involved in another CleanSky ITD, the so-called smart fixed-wing aircraft, a program that may involve a Falcon 900 becoming a flying testbed for an active-wing concept.

Micro electromechanical systems (MEMS) sensors and actuators will be employed in this project, whereby the active wing will sense the surrounding airflow, analyze it and modify it to continuously seek optimum efficiency. The company hopes the application of MEMS will defer the onset of turbulence.

Previous experiments in active flow control seeking the same goal have used boundary-layer suction via tiny holes, and another modified the wing profile.

Eco-design Partners

• Dassault and German-based research center Fraunhofer are joint project leaders on Eco-design.

• Other partners include AgustaWestland, Airbus, Alenia, EADS, Eurocopter, Granta, HAI, IAI, Liebherr Aerospace, MBN Nanomaterialia, Ruag Aerospace, Rolls-Royce, Safran and Stork.

• Israel and Switzerland both contribute to the European Union’s seventh framework program for research and development–even though neither is an EU member state.

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