Vincent,
I read your question several times and went away and came back to it and went away .......... and now I will try to fashion a reasonable answer.
I wish that selecting components for an electric power system was as easy as saying use XXX for a .60 size replacement or YYY for a .40. In the electric power department you could probably use either of those setups for each plane. Therein lies the problem.
Without being flip, the simple answer is to avail yourself of the postings by Mike, Dean, myself and others and "do the math". Yet even if you do do the math, you may not get it right. You will certainly be close but perhaps not where you wanted to be. We have almost eighty years of development and usage experience with IC engines. This has over time led to someone being able to ask your very question and yet even then you may not get it really right unless you pay close attention to the details. The devil is in the details.
Before you set pencil to paper, you need to determine the level of performance you want to achieve, the wing loading of the plane, the weight of the power train complete, the physical distribution of the components within the airframe, the minimum weight at which you personally can build a model of a specific size, the size and type of propeller, wether high or low pitch, line length, battery size and weight, motor mounting requirements, cooling requirements, access requirements, battery retention requirements, budget requirements, your particular level of flying experience, etc. All of these variabes are inter-related to one another and result in an equation with many unknowns. Take just the topics I have listed and fill in the blanks then go and find out the details of each parameter i.e. just how much does a Plettenburg Orbit 30-12 weigh? how much does the collett weigh? How much do the mounting bolts weigh? How much does the prop and spinner weigh? What is the actual physical size of the battery and how would you propose to hold it in the airframe?
As you begin to refine one selection you will find that other selections must of necessity change. So change them and see if there are any downstream impacts (or IMPACTs?
). Sorry, couldn't resist. They will change. Your budget will also dictate what you can and can not do. It is not a simple or qick process. In my case, I wanted a plane that would perform well enough to win a W/C's and nothing less. Money was not an object. Time was not an object. I had professional engineers guiding and evaluating every choice we made. I do not expect you to go to this extreme but the point is that the reason I can now say to you that to compete at the world level you need a particular setup (mine for example) was the result of all of the above and "proving" the setup in competition. Subsequent efforts by others have further proved the validity of the choices we made. So now if I tell you that you should use the setup I am using to compete at the highest level you will (I hope ) believe me.
All of that effort has resulted in "one setup" being proven and verified. In the IC world we have multiple setups for every size and type of engine that exists. They exist because someone took the time and put forth the effort to establish each setup as being valid. I do not fly .40 size planes and so am not likely to go through the same effort to establish a standard for that size. That is what you must do. You or someone else must risk time and money to "prove" a complete package to the extent that someone such as yourself could say without hesitation is the "right" setup for such and such a size model. The issue as I see it right now is that if I suggest to you that you should purchase components X, Y and Z to achieve a particular goal, I better have it right or you may be significantly out of pocket and regretting my Irish ancestry. So to make a long reply short, "do the math" and when you need advice on which of several directions to go with a particular issue I and others can help you make an informed choice. You will not find the answer unless you put in the legwork as well.
Kim.
Topic: PUTTING A SYSTEM TOGHETHER (Read 971 times)
