Satellite Application for PTFE propellant

Earth orbiting communications satellites are essential to the modern world. Each satellite carries thrusters to keep it precisely positioned in the orbit. One possibility to guarantee precise attitude and orbit control are electric thrusters. Instationary pulse magneto-plasma-dynamic thrusters (I-MPDs), also referred to as pulsed plasma thrusters (PPTs) use Teflon® PTFE as solid propellant. These thrusters distinguish through robustness and compactness and are particularly suitable for small satellites where power is one of the tightest constraints. Because of their high exhaust velocities and the resulting high overall efficiencies of the thrusters they are foreseen as main thrusters on the lunar mission BW1 (BW stands for Baden-Württemberg, a State in Southern Germany) scheduled to be launched by the end of this decade. The mission development and coordination lies in the responsibility of the Institute for Space Systems, IRS in Stuttgart, Germany. One of the major challenges within this project is the storage of the solid Teflon® PTFE propellant. Over 50 kilograms need to be stored efficiently and must be available to the thrusters.

Based on the IRS design, ElringKlinger Kunststofftechnik GmbH, based in Bietigheim Bissingen, Germany, has developed a manufacturing process for solid propellant with Teflon®PTFE helix shape that is perfectly suitable for this mission.

The system fulfils all requirements regarding internal stress minimization and dimensional stability in harsh environments. Due to its helix shape it is possible to feed the propellant into the thrusters using a torsion spring. To store the propellant space-efficiently, IRS designed the propellant to be fed into the thrusters bi-directionally. IMPDs using solid Teflon®PTFE propellant significantly extend the overall lifetime and function of a satellite. They can either be used to maintain satellites in orbit in the correct position or as primary propulsion system on long term missions. "Our joint IRS development is totally new, with a possibly big impact on the future," says ElringKlinger Sales Director Martin Schuster. "The thrusters makes multi-time ignition possible and allows for thrust control. With the helix shaped Teflon®PTFE propellant, they will be able to fulfill their mission for a much longer duration of time. For satellites in general, the new helix-shaped system is applicable for positioning systems, and makes minor orbit corrections possible. It can be used as the main engine for smaller satellite."

The first test units of helix shaped solid propellant Teflon®PTFE were produced in early 2006 and are currently running successfully in tests conducted by the Institute of Space Systems. The first satellites to utilize the new positioning system will be launched by the end of this decade. ElringKlinger expects all nations engaged in space satellite technology to use the system in future. In addition to that, the system offers application possibilities in other industries, such as the adoption of high speed PTFE plasma for laser functions.

Furthermore, PTFE and a more versatile form Moldflon®, commercialized by ElringKlinger, have become the most important substances for seals, guides and engineering parts. With its seals and engineering design equipment ElringKlinger has been one of the technology leaders in is field for over 40 years now. The company develops shaft seals used in centrifuges and screw compressors, spring-energised seals for piston rods and piston rings for oil-free piston compressors. It also manufactures PTFE laminate materials, which are used in metal foils, glass and elastomer films. Typical applications include linings for chemical industry requirements, high strength compounds, guides and bearings, composite membranes, base materials for printed circuit boards and also conveyor belts. The company's use of Moldflon® on components allows more versatile application of PTFE even into extruded products, injection moulding and transfer moulding. Moldflon® is less likely to be subject to 'cold flow' or 'creep' where such a property could be a disadvantage. The company's growth has been steady and spectacular. While in 2003, turnover was 44 Million EUR, the company reached 60 Million EUR in 2006. "We develop and produce individual, market driven solutions from high-performance synthetic materials such as PTFE compounds and composites," says Mr. Schuster. "We make anything from semi-finished to complex end-user products and from standard seals to complicated system solutions. We meet the toughest standards with economy and reliability guaranteed."

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Further Information
For further information relating to any of the above products, please contact Tony Snowdon on 0113 252 1061 or e-mail tonys@ftltech.co.uk