Composites firm nets big contracts for solar space arrays

Airborne International is developing conductive composites for heat-conductive structures on satellite platforms, fiber steering to optimize structural efficiency and resin transfer molding (RTM) for highly-loaded launcher components for the Galileo program.

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Airborne International BV (The Hague, The Netherlands) has been awarded contracts to manufacture the solar array panels for the first 14 satellites of the European Union’s (EU) GALILEO project, as well as for two flight models of the AstroTerra/AS250 satellite, a commercial satellite platform from Astrium SAS (Saint Médard en Jalles, France). Combined with existing contracts for the European Space Agency’s (ESA) Earth observation satellites, designated Sentinel 1 and Sentinel 2 (the latter is pictured on p. 22), the company’s order book commits Airborne to produce more than 100 solar array panels over the next several years. Airborne says the contract awards are a result of an extensive qualification and facility upgrade program that started in 2007.

The GALILEO project is an EU-financed global navigation system initiative supported by the ESA. Currently, Europe has no system of its own. It shares data with the U.S. GPS satellite system and the Russian GLONASS system. Initiated a decade ago, the project aims to deploy a system of satellites and ground stations under European control. Airborne is a subcontractor to Dutch Space (Leiden, The Netherlands), an EADs Astrium company, formerly part of Fokker Aerostructures BV (Hoogeveen, The Netherlands). Airborne will produce the composite panels to support the solar cells, and several other subcontractors will be responsible for electrical connections and the panel unfolding mechanisms.

According to Sandor Woldendorp, business manager for space composites at Airborne, the built-to-print panels are 1-inch/25-mm-thick sandwich constructions made with carbon/epoxy skins and an aluminum honeycomb core for heat dissipation.

High-stiffness/high-strength polyacrylonitrile (PAN) fiber is used to ensure panel bending strength. A thin layer of Kapton polyimide film manufactured by DuPont (Wilmington, Del.) is cocured with the top skin to electrically insulate the carbon composite from the solar cells, which are bonded to the upper surface of the sandwich panel.
The first two flight sets of solar panel substrates will be delivered early this year. Subsequent deliveries will take place every three months until the end of 2012. Each set of solar panels consists of two wings, and each wing has two panels with a surface area of 2.75m2/30 ft2.

For the Sentinel satellites, the first two flight sets are in final assembly at Airborne, with a launch date scheduled for the end of 2012 aboard an Ariane 5 rocket. The panels for AstroTerra/AS250 will be installed on the SPOT 6 satellite (scheduled launch 2012) and SPOT 7 satellite (scheduled launch 2014).

According to Airborne, these contracts are important milestones in its strategy to become a leading European provider of composite space structures. To reach this goal, Airborne reportedly will continue to develop new technologies, including conductive composites for heat-conducting structural satellite panels. These panels are said to be lighter in weight than aluminum skin panels and, therefore, will reduce satellite mass. Airborne says it also has developed more cost-effective fabrication strategies, including automated fiber placement and fiber steering as well as resin transfer molding (RTM) for highly loaded launcher components, enabling further mass reduction and performance improvements. The company intends to reduce part costs for composite sandwich panels and launch-vehicle structures, using automated production processes wherever possible, says Woldendorp.

Airborne has been in the news recently for its design of a carbon/epoxy composite main propeller, supplied to the Royal Netherlands Navy for an Alkmaar-class mine hunter in September 2010. It’s the first application of composites for a main propeller, with power output of approximately 1,400 kW. Testing of the propeller design will continue throughout 2011.

“Erosion is a big problem in bronze propellers because it damages blade surface geometry, giving rise to turbulence and hence to vibration and noise that produces an acoustic signature, endangering the vessel,” explains Wiard Leenders, Airborne’s managing director. “The use of low-signature composite propellers reduces inspection and maintenance needs and offers a way out of this impasse.”

Airborne also is part of a European project known as SmartFiber. The company is developing smart composites with embedded sensors that will facilitate continuous health monitoring of on-duty composite components, including wind turbine blades and aircraft and satellite components, using photonic integrated circuits (PICs).