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Brian does Ridders flame eater

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  • Things are reassembled with the machineable graphite valve and piston. I hate to say it, but the engine is no different now than it was with the cast iron valve and piston. It spins very freely, it acts as if it wants to run, but it is very difficult to find that "sweet spot" where it will pick up and keep on running by itself. I know that if you do find that "sweet spot" the engine will set there and tick over beautifully for about 20 minutes until the cylinder heats up to a point where there isn't enough temperature differential to keep it running. I may dick around a bit with different fuels, but unless changing to a hotter fuel does something remarkable, I'm done with this engine.
    Brian Rupnow
    Design engineer
    Barrie, Ontario, Canada

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    • 316 stainless steel has about one third the thermal conductivity of plain carbon steel or cast iron.
      10 vs 30 Btu/(hr-ft-F)

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      • Makes me think that a thin stainless sleeve to aid with avoiding any corrosion from condensation with an aluminium cooling jacket would be a nice option. Much like a model airplane engine has a steel liner in a finned casting. But in this case I'd likely shrink the jacket to the liner.

        Thoughts?
        Chilliwack BC, Canada

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        • Yes.

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          • Originally posted by brian Rupnow View Post
            Things are reassembled with the machineable graphite valve and piston. I hate to say it, but the engine is no different now than it was with the cast iron valve and piston. It spins very freely, it acts as if it wants to run, but it is very difficult to find that "sweet spot" where it will pick up and keep on running by itself. I know that if you do find that "sweet spot" the engine will set there and tick over beautifully for about 20 minutes until the cylinder heats up to a point where there isn't enough temperature differential to keep it running. I may dick around a bit with different fuels, but unless changing to a hotter fuel does something remarkable, I'm done with this engine.
            When you say it "spins very freely" , does it meet the very specific tests that are given on Ridders website for the engine? He goes into great detail and its gives very specific measurements of how free the engine should spin. He also is very specific about recommended fuels. Its a well proven design so the problem does not lie there.

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            • Yes Sparky, it does meet all of the requirements as set down by Jan Ridders, and it does run. It runs on methyl hydrate and it runs on 99% alcohol from the pharmacy. It does not start consistently, and once running it doesn't stay running consistently. It may be a proven design, but many others who have built this engine have either had the same results as myself, or been unable to get the engine to run at all. It was a fast and interesting build, but I'm not impressed. I have many other types of engine "under my belt", but had never built a flame licker before. I don't think I would advise someone to build this engine. If I had it to do again I would probably favour the "Poppin" engine, which seems to be much more forgiving.
              Brian Rupnow
              Design engineer
              Barrie, Ontario, Canada

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              • I've been thinking--which is probably a dangerous thing. I made my cylinder from 316 stainless to prevent any rust buildup inside the cylinder. (alcohol releases water when it burns). These flame licker engines depend on the heat differential between the flame they suck in and the cooler temperature of the cylinder to cool off the flame and create a vacuum. Someone pointed out that the thermal conductivity of stainless is only about 1/3 of the thermal conductivity of cast iron. I wonder if the poor performance of this engine could be caused by the cylinder material?--And yet Jan Ridders specifies stainless for the cylinder.
                Brian Rupnow
                Design engineer
                Barrie, Ontario, Canada

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                • My atmospheric engine uses a stainless cylinder and a graphite piston without any issues I think you must have something else going on. Keep at it OD you’ll get it.

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                  • A little internet searching shows that "stainless" covers a range of thermal conductivity, with 316 being in the middle of the range. I wonder if a different alloy was used by Ridder.


                    Dan
                    At the end of the project, there is a profound difference between spare parts and left over parts.

                    Location: SF East Bay.

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                    • Brian, it seems this little engine operates on very fine margins!

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                      • I want a dependable flame eater style engine. I modelled Mr. Senfts "poppin" engine today---
                        Last edited by brian Rupnow; 03-11-2018, 08:28 PM.
                        Brian Rupnow
                        Design engineer
                        Barrie, Ontario, Canada

                        Comment


                        • Originally posted by brian Rupnow View Post
                          Someone pointed out that the thermal conductivity of stainless is only about 1/3 of the thermal conductivity of cast iron. I wonder if the poor performance of this engine could be caused by the cylinder material?--
                          The performance has to suffer from the relatively high thermal resistance of SS compared to cast iron. In fact, why not make the cylinder out of aluminum?

                          I hope you can still find an icicle, now that summer is here (in Phoenix, at least). What happens when you drape one of those across the cooling fins?
                          Allan Ostling

                          Phoenix, Arizona

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