From: "Jörg J. Buchholz" Subject: Stunt Kite Simulator Date: Sun, 28 Apr 1996 19:15:24 -1000 Organization: Hochschule Bremen Message-ID: <3184506C.4B97@fbm.hs-bremen.de> This is a forward from Gijs van Oort who cannot post. I will forward all rec.kites replies to him. >>>>>>>>>> Begin of forward <<<<<<<<<< The Stunt Kite Simulator At february 2, 3 and 4 1996 the National Contest for Young Scientists was held. Each participant had invented or made something. Gijs van Oort (17) made a stunt kite simulator. He won the 2nd prize in the category "Project" (ages 15 to 20 years), a trip to the Nobel Prize Ceremonies in Stockholm. The National Contest for Young Scientists was the reason for me to start the development of the stunt kite simulator, a system that allows you to learn to fly the kite on the computer. I started programming in March 1995, and just before the contest it was good enough to be demonstrated. The most important part of the stunt kite simulator is the computer program. But also some mechanics and electronics are needed to make it more realistic. The mechanics contain lines and handles and are used to control the movements of the kites by pulling the 2 handles. At this moment I have only one piece of mechanics, to control one kite with the handles. However, up to 5 kites can be controlled with the keyboard, the mouse and some simple rotary knobs, but this is less realistic. The electronics are needed to interface the mechanics and the rotary knobs to the computer. The stunt kite simulator roughly works as follows: The computer constantly reads the position of the lines and then calculates the position of the kites using a mathematical model. Finally the computer displays the kites on the screen. The figure (not included, J. J. Buchholz) shows the principle of the handle-mechanism. When you pull the handle, the lever rotates around the axis. With the lever, also a variable resistor rotates. The value of the resistor is read by the computer via an Analog-to-Digital convertor. This electronic device is connected to the computer via the printer port. The rotary knobs are read in the same way. The computer also reads the keyboard and the mouse. After reading all these data, the computer can calculate the positions of the kites. For the calculations, the computer can use different mathematical models. The simplest model is the Constant-Speed model. At all positions the kites have the same speed (just as in KiteFlight). This model is very useful to practise things such as "follow the leader". Another important model is the one that decreases the speed of the kites, when they come near the edge of the flight-range. This model allows you to test if your routines are practicable. I also tried to make a more realistic model. This model takes the kite position and orientation with respect to air speed, kite speed and rotation and the movement of the lines, and then calculates the forces on the kite. These forces are used to calculate the new speed and position of the kite. This model is only a rough guess of the dynamic behaviour of the kites, because very little is known about the aerodynamic behaviour of kites. Also my own knowledge about physics was not sufficent. The goal of making a realisic model has only been partly reached. However, this model has some nice features that are also present in real kites. For instance, the virtual kite reacts as expected when you pull both lines. After the computer has calculated the positions of the kites, it draws them on the screen. the kites are drawn as small triangles in different colours. The "virtual kite space" is very similar to the kite space of KiteFlight. The rectangle in which the kite contests take place is drawn on the screen too. During flight you can turn the trail of the kites on and off. What is the use of the stunt kite simulator? First you can learn the principles of team kiting. You can practise your figures endlessly and try to keep the distance between the kites constant, without walking to your crashed kite only once! Second, you can simply devise a team routine, and rehearse it as many times as you want. Some other advantages of the stunt kite simulator above normal kiting are: you are totally independent of the weather, it does not matter if you live far from the beach, and you cannot damage your kite. The program has not yet been finished. I am still trying to improve it. I am also making a Public Domain-version of the stunt kite simulator. This version has fewer possibilities and therefore has simpler menus for adjustments. But it is not sure if this version will ever be released. Gijs van Oort Romuluslaan 43 5631 JT Eindhoven The Netherlands E-mail: gijs@djoe.iaf.nl >>>>>>>>>> End of forward <<<<<<<<<< -- buchholz@fbm.hs-bremen.de (Jörg J. Buchholz) = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =