Sunnytech Low Temperature Stirling Engine Motor Steam Heat Education Model Toy Kit For mechanical skills (LT001)

This is a great gadget and a lot of fun. It comes fast, works well, and is easy to assemble, though you may want to have a tiny screwdriver or dull knife point to click the two little drive shafts in place. It's super easy and the instructions are good. It took me fewer than five minutes to set up. The great thing about this, which is better than other similar products, is that you don't have to light a fire or use a candle or anything like that. You simply place it on the top of your coffee cup. You can put it on a hot beverage cup you want to keep hot, and watch the little motor do its cool thing, or you can microwave some water in a cup for two minutes and set this gadget on top of the cup for lots of fun. Kids are blown away by this and it is a real conversation piece for adults. Any kid would love to get this as a gift--birthday or Christmas or whatever, because everyone drinks hot tea, hot coffee or hot chocolate at some point, and if not, just hot water--no open flame. Also it is great for teaching kids about external combustion engines and the principles of physics. I haven't had it long, but already its my favorite gadget to play with in the kitchen while I am waiting for the rest of my meal, and I can't wait to show my friends when they come over for dinner. Just a lot of fun without an open flame or any dangerous substances to ignite.

This is a little great machine! I remember seeing one of these years ago in grade school that used an alcohol flame and always wanted one. Of course now I am able to relive those days as back then it would cost a small fortune to acquire it back then, and of course there was no amazon back then either. Absolutely love being able to watch it run for quite some time on a heated cup of water. You do need to let it break in a little bit, and I found that I needed to tweak the arms a little bit (probably due to shipping) but aside from that it works great!!! Thanks!

I got this for my husband for Christmas. He loves it. It is fun to set over his coffee cup and watch it run. He said he will probably buy more of the Sterling engines that Sunnytech has for sale because this one works so good. It is a neat little gift. Thank you! Grandchildren thought it was fun also, power in the coffee cup.

I got this as a birthday gift for my engineer husband. He loves well made useful gadgets, but typically doesn't like gadgets that are just for entertainment. So this was a risk. He loves it. It's so well-made... and impressive. We heated up one of his Yeti mugs and then put the hot water in and placed the sterling engine on top. We waited a few seconds, gave it a wee nudge, and it went for three hours!!! (I got a kick out of Amazon's toy age selection box. It goes up to age 13 for this. Hubby is 68.) UPDATE: We still love this, and it still works, but it definitely slowed way down and got noisy. My son cleaned the little pump, and it works better, but still lasts only half as long. I wouldn't have taken a star off, except when it stopped working right, I ordered a different brand that works even better and cost ten bucks less. That one has been running over four hours for several months now. The video shows them at about an hour and a half, just before the Sunnytech one (on the left) died. You still enjoy both.

This an elegant engine, both in appearance and in its functioning. You can see all the parts moving. Of my five Stirling engines, it is the best performer at low temperatures. The Stirling engine is a heat engine, just as are steam engines, gasoline engines, hurricanes and the "drinking bird" toy busily bobbing. The large cylinder at the bottom contains the displacement piston. I will call it the displacer. It is driven by a crank on the flywheel. In the small cylinder, the power piston cranks the flywheel twice each revolution, making everything move. The displacer moves the air in the displacement cylinder, alternately to the bottom plate to be heated and then to the top plate to be cooled. This air is confined to the interior of the engine, so that when heated (or cooled), it cannot expand (or contract) but instead must increase (or decrease) its pressure compared to the air outside in the room. The pressure differences cause two power strokes per revolution, one in which the pressure in the engine is below room pressure so the power piston is pushed down, and the other in which the greater pressure inside the engine pushes upward on the power piston. Crucial to a Stirling engine is that the cranks control the pistons so that the power piston is always a quarter of a turn behind in its motion compared to the displacement piston. Here is how this offset between piston motions causes the needed pressure changes. The downward power stroke begins when the power piston is at the top of its cylinder and the displacer is at the middle of its downward stroke. At this point in time, the air is divided evenly between the cool upper region and the warmer lower one. The turning flywheel pushes the power piston to start the power stroke. As the power stroke continues, the displacer pushes more air into the cool upper region, and the overall pressure in the interior drops below room pressure. When the power piston reaches half way down in its power stroke, the displacer is all the way down, so all the air is in the cooler part of the interior space. The pressure in the interior of the engine is at its lowest point so the room air is pushing hardest downward on the power piston. This is the most powerful part of the power stroke, the more so because here the power crank is oriented to furnish its highest torque. The power piston continues downward, reaching the end of this power stroke. The upward power stroke now begins, and the explanation as to how it functions mirrors that of the downward stroke. You can see the two power strokes, one down and the other up! Start the engine on a hot cup. After it is moving at about 1 rps (60 rpm) take it off and set it on the table. Watch as it slows to a stop. In the last 2 or 3 revolutions the flywheel moves with an easily seen jerk at every power stroke. I find it easiest to see this by watching the power crank. The up stroke is harder to see because the engine is not rotationally balanced. The flywheel probably is balanced, but the combined weight of the pistons pulling down unbalances the system. This explanation raises some questions. The main one is that we know that the heat flow between the air and its nearby plate is not instantaneous. But there is a hint that it does happen very quickly. As the engine runs, the rim of the top plate becomes much hotter than the center of the plate. (I measured the plate temperature with one of those thermometer "guns" whose laser pointer shows a red dot showing just which spot is being tested.) The rim is the place that the hot air from below the displacer enters the top space. So for that place to be much hotter than the rest of the plate indicates that much of the heat from below gets dumped here quickly, before the air moves further into the cold region. Another point: the engine leaks air from the space between the power piston and its cylinder wall. This leak is slow enough that it does not affect the efficiency of the engine. But the leak is crucial! If the engine did not leak, it would soon not run at all! The air inside the engine becomes much hotter than outside, and its pressure therefore would be enough to push the power piston all the way up and lock it there! But this is avoided because some interior air leaks out, restoring the interior pressure (averaged over a cycle) to match the outside pressure. You can observe this leak yourself. Hold your cold engine with its power cylinder horizontal. Turn the flywheel so that the power piston is at one end of its motion, and hold it there for about 20 seconds. Then turn the flywheel so the piston is at the other end of its allowed motion, and release it. You should see the piston move back close to where you had held it! Repeat, starting this time with the piston at the other end.

Excellent. Easy to assemble. Worked first time. Well packaged.

These Sunnytech scientific toys make great conversation pieces, and are educational demos of working Stirling engines. The price is excellent -- $40 for a choice of four models. Three of the models, the LT001, LT002 and LT003, are identical except for their color scheme. These three models come mostly assembled, but one needs to place the flywheel/camshaft assembly into the supporting columns, and press the connecting rod clips onto the camshaft. These three models are beautiful kinetic art sculptures, and make wonderful gifts. Their large, curved-spoke flywheels suggest motion even when still. They are also the best models for educational purposes: The flywheel is mounted on a crankshaft, with two throws, one on either side of the flywheel. One throw is connected to a power piston rod, which drives the wheel. The other, which is at 90 degrees from the first, drives a connecting rod that positions the air displacer disk. The clear chamber wall allows one to observe the internal action of the engine, and to clearly understand its workings. The other model, the DWCL-01, is far more efficient and quieter, but less aesthetic and less understandable. The flywheel is smaller, and accurately balanced. It is side mounted, with bearings, on a single, supporting column. The power piston is centered on the upper heating/cooling plate. The flywheel is directly driven by a power piston side rod (such as you would picture on an old steam locomotive). There is are no visible mechanical connections to the displacer disk. Is it moved by air pressure from the piston? Perhaps also from thermodynamics? When moving the flywheel gradually by hand, one can observe a point where the displacer sudden shifts from high position to low position. When turning the wheel in reverse, the displacer reverses position at exactly the same point. This change must be 90 degrees out of phase with the piston action, or else the Stirling engine would not work. There are no English instructions with this model, and I seem to be missing something in my understanding. The DWCL-01 comes fully assembled, ready to use just out of the box. Note that, even though less efficient, the LT001 model can achieve high speeds. The attached video was made by my 10-year old granddaughter, who is maximizing the speed by powering her engine with hot water below, and metal ice cubes above.

As others have said, the stirling engine from Sunnytech is well-made, and fun to watch. I got this as part of a bundle with their mini hot stirling engine. It works from heat from the bottom, usually sat over a cup of boiling water. However, I decided to buy a mug warmer from Amazon. I found a mug warmer with a limiter time deal, for $10. The warmer has 3 temperatures, the highest being 176°F. It also has a timer. As you can see from the video, the engine is running nicely over the mug warmer. I have the Warner set at 176° with the timer at 4 hours. It's been running for 1 1/2 hours now at a good speed. This is a nice safe alternative to hot water (and there's no condensation. UPDATE: I set the mug warmer at the lowest temperature. The engine ran great. The lowest temperature on my unit is ~ 135° F.