toc1955's video: Fluidyne liquid piston Stirling engines

(Adolf Cortel, july 2020). In the video you can watch the working and some details of the building of 3 fluidyne engines made of plastic.The fluidynes (liquid piston Stirling engines) were invented by Colin West; in his book “Liquid piston Stirling Engines” he describes how they work and some models thay can be built. This book can be read online in the web: https://archive.org/ . Since I have built the engines during the Covid pandemia the materials I used are the ones I had available at home. I have added some drawings to help those who want to build his own engines; please, consider that there is a big margin for improvement in all the designs. 1. The first is the simplest one proposed by West. It is made of plexiglas and it is heated by means of a resistor in the water. The working of this one can be seen in youtube: https://www.youtube.com/watch?v=SNxR-lEZXoQ (Aussie JimG channel). Watching this video stimulated me to build my own gadget. Instead of gluing all the pieces, I machined a block of plexiglas in a milling machine, everything with the same size proposed by West. It works very well but the problem is that when everything is glued if something goes wrong with the resistor it can not be replaced easily without breaking the block. I checked that it runs at sunlight concentrated with a concave mirror or a Fresnel lens on the resistor; however, this is not a good idea: since plexiglas endures only 90ºC some deterioration was observed. The resistor used should be inside a ceramic or aluminum block (In the first model I built I used a resistor with wounded wire visible) 2. I modified the previous design using plexiglas tubes glued by elbows made from a block of plexiglas. The resistor is glued to a stopper and can be removed if necessary to replace it or to clean the inside of the tubes. The resistor you'll see in the video was too big (10 ohm, 25W) and I had to reduce its size to fit in the plexiglas tube: a 10 ohm 15W resistor should fit in the tube without manipulations but I did't had it available. After checking that everything went fine I added a couple of 3 way luer lock keys which simplifies filling o empying the engine. 3. The third engine shown in the video comes from an idea of Max Manfred Piendl which can be seen at work in https://www.youtube.com/watch?v=2HoyAgELfbw and in http://www.maxpie.de/Fluidyne.htm It is heated from outside ( hot air gun, fresnel lens and sunlight, alcohol burner or electric bulbs). Once properly tuned (this can be a bit tricky!) it works very well. At 85ºC in the hot side the strokes have an amplitude of only a few centímeters, but they are much bigger if the temperature is raised to 160ºC with a hot air gun. I connected a pressure sensor to check the working of the engine. About the music: “Southern nights” by The Petersens. I've no rights on this music and I'm using it only for the educational purposes to which this video is aimed