Hellmut1956 2 Report post Posted May 14, 2015 Dear friendsas a person past his professional career and carrying the loads of health problems I have dedicated my time to use o project of building a model sailboat from scratch to get in touch with the most diverse technologies. As I started my career as an application engineer in the semiconductor industry my affinity to electronics has strongly influenced my work on this project since nearly a decade. As part of this project I have developed a concept for a sheet control system that has as its objective to implement the some of the techniques used in the original sailboats of the beginning of last century, here the Endeavour.Now talking with experts in real sailboats and with those specialized in building models of sailboats I have been told that the friction of the rope between the sheaves of the pulley in a model scaled 1:20 is so big that the model ship becomes inoperable. Talking with people in physics forums i am told that there is no friction between the rope and the sheaves, only in the bearing of the sheaves! This contradiction made me contact the physics the physics institute at the Ludwig maximilian University, short LMU, here in Munich. The response I got was that physics have the tendency to view problems in ideal systems and as a result their responses are explainable. In the real world there actually is a friction between the rope and the sheaves, the Euler-Eytelwein-Formula. Unfortunately this is not an equation with an "=" sign, but one with =<, I think in english it is called an inequation? The friction issue in the pulley in my model is one were I need a proper response, for which the Euler-eytelwein-Formula is not enough!So, due to this aspect and a couple of other ones i decided to use the method of "Design by Modeling"! First issue I met was that after nearly 4 decades my mathematical skills had eroded and that a lot of advances have taken place, also in mathematics, that I needed to work on it to be able to pursue my objectives!After extensive investigations I do not want to bother you with details I decided to use the modeling and simulation language and environment called "Modelica", details can be found at "www.openmodelica.org", a language that defines itself as an object-oriented equation based modeling language and I decided to use the software tools from Wolfram Software, Mathematica and SystemModeler.Searching in the Internet I found a course from a swiss professor that gave an excellent introduction to Modelica using the tool from Dassault called "Dymola"! But also in this youtube based course he used another tool called "Berkeley Madonna" and referred to the fact that he introduced this tool in in another YouTube video series about "System Physics".This way I learned about System Physics and about the dynamic modeling and the tool he used for it called Berkeley Madonna. The dynamic modeling method was developed by the Sloan Institute of the MIT in the mid fifties of last century to model financial systems to reflect complex dynamic systems. Famous for insiders became this dynamic modeling i.e. the "Club of Rome" used it for its work presented in the famous book about the limits of growth! system Physics is based on research work done at the university of Karlsruhe, Germany, to develop a new didactical method to teach physics. Information about this can be found here.Summarizing the essential of it is, that the system physics found that by applying the methodology from the complex dynamic systems, different areas of physics can be dealt with using the same mathematical equations. In what is relevant for mechanics and therefor the reason why I have made this introduction is, that System Physics, uses the "Momentum" and "Momentum Flow" to deal with translational and rotation mechanics and that the principles of "recipients" and "flows" coming from the "complex dynamic systems" methodology originally developed at the Sloan Institute of the MIT, allow to use the modeling and simulation language "Modelica" to model and simulate physical assignment work!Now, the "sheet control system" concept that I have been developing combines effects and influences from the physical environment in which a sailboat is operated, as multidomain as it is, also covers other aspects that lead to achieve the objective of energy efficiency, thermal aspects, system control aspects and so on. So I decided to model the pulley shown in the above image from the original sailboat Endeavour and that I will implement on my model using system Physics and the Modelica language with the Wolfram Software tools mentioned above. This will allow me to find out if my concept can work with a pulley like the one shown in the picture from the Endeavour and to find out whether the physics were right, or the boating people were right or were between those contradicting positions the reality is! Obviously a model simulation is only as good as the quality of the models used, so that experiments will have to be defined and done to verify the quality of the models used!Finally, the reason I am presenting my project here is, that I want to gain access to the communities, not only of physics electronics and naval experts, but also of the mechanical engineering community. As extensive as this introduction is, I am aware of that it is still very limited to brief you my dear readers enough to capture what this project is all about. So, if you are so nice to start from assuming that what I am dealing with is well thought through, I would ask you to publish the questions that might come up, so that based on responding to those I can expand along the lines of interest you might have! 1 Share this post Link to post Share on other sites