The development Team will develop a new set of wings this semester. The first step toward this goal was determining airfoils for further Computational Fluid Dynamics (CFD) Analysis. The team researched a variety of airfoils in XFLR5 in September and determined six airfoils to test in Star-CCM: The NACA airfoils 1412, 2211, 3510, 4413, and 6410, as well as the Clark-Y. The end of September and beginning of October will be dedicated to utilizing the AL-37 CAD model from last semester to gather lift, drag, and moment data from Star-CCM. The team will then decide the most optimal airfoil for manufacturing.
The team will then enter its rapid prototyping phase. The team will manufacture blue foam wings of the selected airfoil to test connection systems to the AL37 fuselage. The team will also experiment with carbon fiber spar placement to determine the ideal structural setup of the wing.
Development Schedule (tentative):
-October 1st-31st: Selection of the airfoil, rapid prototyping of blue foam wings of the selected airfoil
-November 1st-30th: Begin manufacturing of final wing, prototyping, and finalizing AL-37-to-selected-airfoil adapter
-December 1st-January 30th (Spring semester), Conduct final assembly of the wing, post-process
The development team conducted CFD of the aforementioned airfoils, as well as the NACA 2412 and the YS-930 from last semester, and compared results. The NACA 1412 and NACA 2211 were found to be unstable after CFD testing and were thus removed from further analysis. The NACA 6410 was found to have erratic results and was removed as well. The remaining airfoils were compared in MATLAB. Shown below from the top graph to the bottom graph, the angle of attack ranging from -5 to 10 degrees was plotted versus lift (lbf), pitching moment (lbf-ft), and the ratio of lift divided by drag. The NACA 3510, NACA 4413, and Clark Y were found to have the highest lift and lift over drag but also produced the largest pitching moments.
The YS-930 and NACA 4413 were found to be overwhelmingly stable, with a static margin of 53.1% and 54.0%, respectively. A desirable static margin is between 5% and 25%. The NACA 2412 was shown to give a static margin of 3.71%, which is also outside the range. For these reasons, those three airfoils were removed from consideration, leaving the NACA 3510 and Clark Y airfoils. The Clark Y gave slightly better results but is more difficult to manufacture as it is a non-NACA airfoil, whereas the NACA 3510 can be easily modified with airfoil tools and is built in into other programs, such as XFLR5. The team determined that the NACA 3510 would be ideal with these aspects in mind. Prototypes of the NACA 3510 were then manufactured, and are shown below.
The team will use one wing for testing control surface placement and one wing for rigidity testing, with the third wing as a backup. The wings were found to be smaller in thickness than originally expected, and a new version of the prototypes is currently in manufacturing, while one wing was layed up with fiberglass. The team in the meantime compiled a full report of the CFD analysis process and the results gotten from it, which will be displayed at the Symposium. The first version of the report is also uploaded below.
Moving forward, the team will continue to work with the NACA 3510 wing and finish assembly by the end of January and move into work on the next truss-braced wing utilizing the airfoil.Star_CCM_Analysis_Report