On the enlargements, the few traces that can be seen are due to a long and busy life ...
Here is a little odd job not too difficult to do. You should enjoy it (We did !). The purpose is to build a small boat propelled by means of a steam engine.
100 years B.C. Hero from Alexandria built a sphere filled with water, provided with elbow-like pipes, and rotating above a fire thanks to the reaction involved by the steam exhaust. The pop-pop engine works slightly like this, but the exhaust is inside the water. This should look like this:
In the nineteen eighties, the popular scientific magazine "La Nature" detailed the realisation of such an engine. In 1914, the German toys manufacturer Ernst Plank proposed on his catalogue some models of boat fitted with pop-pop engines. You can made some research on the web in order to have a more detailed histrorical.
Pop pop ... pop pop ... is the sound emitted by pop-pop engines that are a little bit more complicated that the one described in this article. In fact we will look into coiled-pipe engines that are quasi silent. Those which emit a pop-pop are (very likely) based on the same principle, but they look more or less like the hereunder sketch :
The lower face of the dish is a rigid metallic disk, while the upper part is a diaphragm made of thin metal so that it moves depending on temperature or pressure changes… or both. (For me the question remains wide open). I didn't buiuld this type of engine (thouhg with a few pieces of brass or copper and a soldering iron, it's relatively easy) and then I would suggest you to go to other web pages, like this one for example.
Before going deeper into it, let rush to the nearest hardware store to buy a brass pipe of 3mm external and 2mm internal diameters. While you are at it, add a tube of epoxy glue. Then, back at home, after a deep breath, look for a small Styrofoam tray for meat (without meat ...) and for a metallic screwing cap as there are on some bottles of alcohol. (If you don't use to recover this kind of things, wait until… or grill a steak with alcohol !...). Once you have collected the requested raw materials, you are ready to start !
Both shapes are possible, the right side one being perhaps better for heat spreading and for excess heat evacuation.
Covering is not needed if you intend to use the engine at places where Eole doesn't blow… As this is not common, even inside, here are some suggestions.
If you are the sort of guy who throws away everything, take an aluminum foil and fold it as you can… Elsewhere…
You drill two holes for the pipes going through, and it remains to glue the boiler at its final location. On this float, it is useful to add a rudder: a tooth-pick and a little piece of tray will suit. Now, theoretically you should have in hands something looking like this :
Principle and operation :
To do it runs, the pipe is to be filled with water by means of a syringe (for instance) and to put the boat on the water, taking care not to empty the pipe. Therefore, put a finger on one of the pipe ends until the boat is on the water. There, the atmospheric pressure exerted on the water is high enough to avoid the water exhausts from the pipe. (Insofar as you don't use a coil more than 10.33 meters high you should not be in trouble !!)
The final word :
Here are some ideas, rather definite I admit, to build a simple device allowing to testing a propelling mode. However, it is obvious that nothing is fixed, and you can (you must !) let your imagination run free. You could for instance put several engines in the same and more realistic hull, and (why not?) add a radio control ...(as R. Lefèvre, to whom I borrowed the small historical of the beginning of this page, did it).
Translated by Jean-Yves. Thanks.
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