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Aviation History
2003
2003 - 0153.PDF
TECHNOLOGY PROPULSION GUY NORRIS /LOS ANGELES Cash sought for forward-swept prop Initiative promises more performance and less noise for general aviation, say researchers at Miami University A University of Miami research team has successfully completed initial studies of a forward-swept propeller blade and is seeking industry support to continue full- scale tests for applications on gen eral aviation, utility and other pro peller driven aircraft. While aft-swept blades are in use, forward-swept blades have proved more challenging to develop, des pite promising better performance. Although General Electric halted work on a NASA contra-rotating propfan project in 1994 after the blades suffered instability, GE later proved the concept's viability. In 1998 it developed a forward-swept, two-stage fan with improved effi ciency and greater stall margin. Theoretical benefits of forward- swept blades are that the tip encounters undisturbed air first, which generates greater mass flow with higher kinetic energy, and lower noise due to reduced tip tur bulence intensity. The Miami team designed the blades by leaning the leading edge forwards rather than by adding axial A Straight blade B Outer section 15° forward sweep C Blade with 20° backward and 30° forward sweep FLIGHT uaniniLMi TIM 8ROWN 2003 sweep. This approach is believed to be advantageous as it does not cre ate additional axial space compared to a conventional radial blade. Eight 155mm (6.1in)-diameter aluminium propellers were made for the tests: a baseline straight blade and seven with different degrees of sweep. The swept designs include four with an aft-swept inner region and a forward-swept outer section, one with an unswept inner region and a 15a forward-swept outer section and two examples forward swept by 10a and 15s, respectively, along their entire lengths. The four aft forward-swept blades are designated 5-10, 10-15, 15-20 and 20-30, the first number denot ing the aft sweep angle of the inner section in degrees and the second denoting the forward sweep of the outer section. Windtunnel tests and computa tional fluid dynamics (CFD) simu lations show the swept blades are more efficient and have higher stall margins than straight blades. The 20a forward swept blade gave the best results, but the team is uncertain why. "It is possibly because this configuration has the greatest aspect ratio, which may help reduce induced drag and downwash, or the profile drag may be cut because the velocity component and chord length nor mal to the leading edge are reduced," it says. "Another possible cause is the greater mass flow in the tip region." The team acknowledges that the forward-swept designs have greater stress at the blade root, but noted no structural problems during tests. Further tests are planned on larger blades and variable pitch versions. SPACE EXPLORATION MICHAEL PHELAN / LONDON Qinetiq looks at nuclear powerplants on Mars UK research agency Qinetiq is to study power generation on Mars as part of the European Space Agency's (ESA) Aurora programme. The pro ject seeks to identify power genera tion and storage technologies to support exploration on the planet's surface, and is focusing on the use of nuclear reactors as the most appropriate solution. ESA last year began the Aurora technology development project to outline Europe's robotic and human exploration of the moon, Mars and the asteroids over the next 30 years, and Mars is the primary target for future human missions. Qinetiq estimates that astronauts and equipment on Mars would need 50-100kW of consistent, reli able power for conducting experi ments, exploring the surface in rovers and other units, and running critical life-support systems. Hazel McAndrews, project man ager and space scientist at Qinetiq, says a nuclear solution is being studied, after other systems have been discounted as impractical. "Atmospheric dust and low solar energy intensity at such distances from the sun mean that solar power generation would be impractical on the planet's surface," she says, "and wind turbines would provide inconsistent power output." Qinetiq will lead a consortium comprising AEA Technology, nucle ar technology expert Serco Assur ance, small satellite developer Surrey Satellites Technology and nuclear propulsion specialist Tech- nicatome. Qinetiq will provide spe cialist space knowledge as well as outline a technology development roadmap for ESA. The project's ini tial phase runs until year-end, by which time Qinetiq will advise ESA investigated "at a top-level only" is the logistics of getting a reactor into space, and the consequences of a launch failure or loss of the payload in the sea. SEE SPACEFLIGHT P26 on the feasibility of power genera tion on Mars using current technol ogy available within Europe. Potential future applications include power generation and stor age in space. One aspect also being TEST STANDARDS Europe in drive to improve quality of space parts Qinetiq has been contracted by the European Space Research and Technology Centre (ESTEC) - part of ESA - to expand the range of European Space Components Co-ordination (ESCC) specifications. These define requirements for approval of European assembly and test houses for electronic components used in space applications. Qinetiq will produce specifications for applying the ESCC requirements to a component quality assurance system during assembly and testing. Assembly and test houses procure semiconductor die and piece parts from manufacturers, create their own designs, and manufacture and test the elec tronic components. Many commercially available components used in space equipment are not approved within the existing ESCC system, and are pro duced by third parties rather than the original semiconductor manufacturer. www.flightinternational.com FLIGHT INTERNATIONAL 28 JANUARY - 3 FEBRUARY 2003 23
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