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| NickG:
Thanks Stew, will have a read of that. Your idea about the walshart type valve linkage for a flame gulper sounds intriguing too - will definitely be watching for further developments on these two. Nick |
| madjackghengis:
--- Quote from: cidrontmg on December 26, 2010, 05:14:21 PM ---Changing (=increasing) the weight of governor balls will not make them hang at a lower angle. In a carousel, with seats on chains, empty and occupied seats hang at the same angle. Adjusting spring tension works, so will adjusting the rotation speed. Thanks for the plans, much appreciated! :wave: --- End quote --- Hi Oli, I believe you are looking at it from a static perspective, when turning, the greater the mass the higher the rotational velocity necessary to reach the same height, and the spring pressure works in inverse proportion. Once the carousel starts rotating the empty swings achieve higher heights, and thus greater distance from the rotating center and higher velocity due to the increase in radius, so the velocity difference calculated from the differing total circumferance of the path, squared, times the mass of the empty swing, will equal the lower height of the swing with a person, and thus the smaller circumferance of the circle traced, thus the lower velocity squared, times the greater mass, will equal the empty seat. With the governor, the critical issue is to have both ends of the engine speed keeping the flyweights of the governor in the middle third of the spring pressure as that is the most linear part of the spring pressure curve, and the weight/height curve of the flyweights is a logrythmic curve, with the balls moving the most vertically relative to rotating velocity at the higher speed of the engine. Weight of the balls must be balanced against the dynamic forces of both the spring chosen, and with consideration of the different curves as the lift of the balls is a constantly changing curve, while the spring force is close to a straight line in the midsection of it's curve, but alters substatially at either end. In reducing the size of the engine, both an increase in natural running rpm must be accounted for, and the mass and spring factors must take into account the non-linearity of the respective curves so the governor can't be reduced by simply sizing it according to the scaling down. I would strongly recommend some research on Kozo Hiraoka and his tables on springs and such, as he has probably the best set of tables for such I know of in the modelling world. If I'm not mistaken, he has taken on this subject exactly in at least one of his steam locomotive books, and deals with setting up model engine governors and their weights and springs. :headbang: mad jack |
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