Lamina 2 - Lamina Flow Hot Air Engine


Here is the video commentary:

This is the 2nd lamina flow engine I want to show you. I'll call this engine Lamina 2 and the first Lamina flow engine I showed in previous videos I'll call Lamina 1. This is pretty much the same design as Lamina 1 with a few modifications. The piece of white tape on the flywheel is reflective tape for finding the rpms of the flywheel. And that red thing on the shaft of the flywheel is a broken LED light I'm using as a cotter pin to keep the flywheel from sliding out of it's bearings.

I added a small piece of brass tubing that fits tightly around the Pyrex test tube. This seems to improve the start up time and causes the engine to run a little faster over all. Brass is a pretty good conductor of heat so it's probably distributing the heat from the candle more evenly around the pyrex test tube. Pyrex, or Borosilicate Glass, is a poor thermal conductor. The flywheel on this engine is a lot heavier than the one on Lamina 1. Lamina 1's flywheel is 124 grams and this one weighs 212 grams. The piston in this engine is made of graphite and has a diameter of 5/8ths of an inch. The stroke of the piston is currently set at 9/16ths.

There it is topping out at 850 rpms. 850 is the fastest I've seen this engine go so far. From here it'll slowly work it's way down to 6 or 7 hundred rpm's and stay in that general speed range. I added a neodymium (rare earth) magnet to the flywheel to counter balance the weight of the graphite piston. I'm not sure how much this has improved the performance of the engine if it has at all. The magnet is held in place by it's own magnetic pull on the steel flywheel. Neodymium magnets are very strong and I haven't noticed any movement of the magnet (while using a candle for heat) . Another modification of this engine over the Lamina 1 engine is this adjustable crank shaft. This allows the stroke or distance the graphite piston travels to be adjusted from 1/4 inch (6 mm) to about 1 5/8ths of an inch (41 mm)

Here I am using a propane torch for the heat source. I wanted to see how fast the engine would go while running with propane. The engine makes it to over 1700 rpms and then the neodymium magnet flys off. I was a bit surprised when it happened. I have used neodymium magnets as counter weights before and used propane for heat but I've never had a magnet fly off until I recorded this video. Previous engines I have made did not run as fast but I also sanded the surface of this flywheel to a really smooth finish. Either way I don't recommend using propane to power this engine since it can melt the pyrex test tube and the potential for danger is all-around greater. A counter weight is not necessary for this engine to run but it's probably more efficient.

The stroke of the engine, for this run, is set to 1 inch. I adjust it from time to time to try to find the best setting. The magnet flys off at 1723 rpms, if you listen closely you can hear it. I tried for another minute or so to top 1723 but it never happened. Ok that's all for this video, I'll upload another video with all the dimensions of all the individual parts so check that out if you would like to try building one of these for yourself.

Click here for this Lamina Flow Stirling engine's plans.