PART 1: Upcoming Chat
Tuesday, March 31, 10:00 a.m.- 11:00 a.m. Pacific Time: Andrew Hahn, Conceptual Aircraft Designer Andrew designs aircraft concepts. He uses physics every day in his job. Registration information is at http://quest.arc.nasa.gov/aero/chats/#chatting Read his biography prior to joining this chat. http://quest.arc.nasa.gov/aero/team/hahn.html Thursday, April 2, 1998 11:00 a.m.- 12:00 p.m. Pacific Time: Rabi Mehta, Senior Research Scientist, Rabi is an expert in the aerodynamics of sports balls from cricket balls to golf balls. This chat will also cover the topic of a new air pressure measurement technique for wind tunnel tests! Read Rabi's journal at http://quest.arc.nasa.gov/aero/team/fjournals/mehta/ Registration information is at http://quest.arc.nasa.gov/aero/chats/#chatting Read his biography prior to joining this chat. http://quest.arc.nasa.gov/aero/team/rabi.html Tuesday, April 14, 10:00 a.m.- 11:00 a.m. Pacific Time: Dave Korsmeyer, Senior Project Scientist Dave is a project manager who develops advanced information technology and systems like near real time remote access to wind tunnel data. Registration information is at http://quest.arc.nasa.gov/aero/chats/#chatting Read his biography prior to joining this chat. http://quest.arc.nasa.gov/aero/team/korsmeyer.html Thursday, April 30, 1:00 p.m.- 2:00 p.m. Pacific Time: Estela Hernandez, Flight Simulation Engineer Estela is a flight simulation engineer. She uses math to build computer models that simulate flying airplanes. This chat will be in English and Spanish. Registration information is at http://quest.arc.nasa.gov/aero/chats/#chatting Read her biography prior to joining this chat. http://quest.arc.nasa.gov/aero/team/hernandez.html
PRIZES FOR EARLY CONTEST ENTRIES
As you know we are holding two contests: "Draw a Picture of an Airplane" and "Write an Essay Describing the Airplane You Would Like to Design", http://quest.arc.nasa.gov/aero/events/index.html An early bird prize will be awarded to entries received by March 30, 1998. So far no one has earned an early bird prize.
[Editor's Note: Michael Wong is an aeronautical engineer and Computer Programer in the Military Technology Branch.He uses computers to see how aircraft will fly before they are actually built. Read his bio at http://quest.arc.nasa.gov/aero/team/wong.html ]
COLORFUL 3D ANIMATIONS
by Michael Wong
February 13, 1998
[Editor's Note: Rabi Mehta is an Senior Research Scientist. His research focuses on fluid flows as applied to aerodynamics. For fun he thinks about the aerodynamics of sports balls. Read his bio at http://quest.arc.nasa.gov/aero/team/rabi.html ]
PRESSURE SENSIVITVE PAINT TESTING AND TENNIS BALL RESEARCH
by Rabi Mehta
March 24, 1998 We just completed a wind tunnel test on a 40% commercial van model in the NASA Ames 7 X 10 foot low-speed wind tunnel. The main goal of the test was to identify noise sources --- a lot of the noise heard on the inside of a vehicle is aerodynamic noise generated by wind flow patterns around the vehicle. On this particular test, an array of microphones was installed on the test section side wall to measure the noise levels. This part of the test was run by another research group. The main task of our group was to measure the surface pressure distribution on certain parts of the van. The pressures on the surface are determined by the flow patterns and they give a good idea of the locations and strengths of the noise sources. The surface pressures on the van model were measured using a relatively new measurement technique which involves the use of a special "pressure sensitive" paint. The paint was excited by a special light source and by measuring the intensity of the emitted light, we determined the pressures on the model. Two high grade scientific CCD cameras were used to image the surface and the data were then processed on work stations. We obtained data over a speed range of 100 to 150 mph --- the relatively high speeds are needed to compensate for the fact that the model is scaled down. We investigated the effects of side mirrors and rain gutters on the pressure distributions. The preliminary results look very promising and we are particularly excited because this is the first time that this measurement technique has been used at such low speeds --- the technique typically works better at higher speeds (transonic to supersonic). The data from this test will hopefully help in designing quieter vehicles in the future. For more details of this new measurement technique and some sample data, check out the following website: http://sisko1.arc.nasa.gov/psp/homepage.html As part of my continued interest and research in sportsball aerodynamics, I am currently participating in a project on tennis balls. This project is mainly involved with the aerodynamics and dynamics of the tennis ball, although some studies also include the bio-mechanics of players in action. High-speed videos have been shot at professional tournaments generating data on the speed and spin rates of the ball at various stages of its trajectory. The bounce properties of the various balls used in Grand Slam events on the different surfaces (grass, clay, hardcourt) are also being investigated. A computational program is underway which we hope will eventually be able to predict the flight of a ball, given the initial conditions. A wind tunnel test program is also planned to study the flow features over a tennis ball and to measure the aerodynamic forces acting on the ball. Check out the following website for complete and regularly updated details of this research program: http://wings.ucdavis.edu/Tennis For the forthcoming web chat scheduled for April 2, 1998 I will be happy to answer questions on both topics (pressure sensitive paint and tennis ball aerodynamics). I have also studied the aerodynamics of other sportsballs (e.g. cricket, baseball and golf) and questions on these topics are also welcome.
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