|MadSci Network: Engineering|
Greetings: Airfoil design has been a continuing topic for study ever since the Wright brothers first aircraft. Also the ability to use models to test designs has always been part of aerodynamic engineering so your experiments are following in the foot steps of all of the great aeronautical engineers. It turns out that maximum lift and maximum distance are not the same thing. Many factors influence the design of an optimum airfoil. These factors include the weight of the payload and fuel load. The speed and range desired for the aircraft. Takeoff and landing lengths and so on. Each wing design must be optimized based on these factors. Thus it is difficult to answer your question directly for each wing that you tested had a different weight, lift to drag ratio and they probably flew at a different velocities. Also modern aircraft have the ability to greatly modify the shape of the wings during different portions of the flight. Thus we have flaps and slots for takeoff and landing and swing-wings for changing between subsonic and super sonic flight. From your note you are measuring only distance as an experimental parameter. The key parameter in your experiments is the glide ratio. That is for each meter (yard) of height at launch how far in meters (yards) will the aircraft fly. Glide ratios can be more than 20 to 1 for gliders and as little as 1.5 to 1 for the Space Shuttle. Airliners with trimmed wings (no flaps or wheels down etc) have a glide ratio of about 10 to one. If flaps are used for increased lift, the aircraft will land with a lower velocity but will also have a decrease the glide ratio. That is they land in less distance and at a slower speed, which is what you want to do for landing. The optimum design for maximum glide ratio is the long thin wing used for gliders, and the U-2 and TR-2 reconnaissance aircraft. The solar electric Pathfinder aircraft now being flown by NASA is all wing and it carries a battery and solar cell payload. This design for a slow aircraft that will fly at great heights for many days or weeks is a very interesting compromise between gliders and payload carrying airfoils. You can read about this project at: http:// erast.arc.nasa.gov/erast/erast4.html You will find much interesting information on experiments similar to yours on the following web sites. The one on flying squirrels and other animals is quite interesting: http://muttley.ucdavis.edu/Book/Nature/instructor/gliding-01.html a> http:// muttley.ucdavis.edu/Book/Fundamentals/instructor/ http://www.glenbrook.k12.il.us/gbssci/phys/projects/yep/ flight.html Good luck with your future experiments. Your Mad Scientist Adrian Popa
Try the links in the MadSci Library for more information on Engineering.