Stirling Engine Kit Hot Air Engine Motor Model Review #stirlingkit
I was very impressed with the overall quality and "fit and finish" of this model. There is very little I can find to complain about in this regard. Despite some of the minor negatives I'll discuss in a moment, my overall impression is very positive and I would not hesitate to recommend this model to anyone who has an interest in these things. The asking price is a bit on the high side, but given the niche market this appeals to, along with the high quality and solid construction of the unit makes me think that I got a fair deal for my money.
I found all of the manufacturer's claims in the product description to be accurate. It comes equipped with everything shown in the pictures.
Packaging was quite adequate for any form of shipment. The main engine was securely wrapped in bubble-wrap, and the spare parts were separately foam-wrapped. Everything was placed in a small medium-weight cardboard box, which was then in turn shipped in a larger Amazon heavy cardboard box with extra protective packing.
One of the features of this product that I appreciated the most was the heavy, solid, brushed-metal base that the engine is mounted on. At least 2/3 of the total ~1Kg weight of this engine is in the base. Unfortunately, even this heavy base is not enough to prevent the engine from "walking" across a smooth flat surface when it's running, even with the (included) rubber "feet" on the base.
Unloaded, this engine flywheel runs around 1800 RPM when powered with alcohol fuel. The mfr. recommends 95% ethanol, but I did not have any on hand so I used 91% isopropyl alcohol, which works just fine. I would not recommend using anything with a <90% alcohol content (such as common 70% "rubbing alcohol").
The tricolor flashing LED supplied (which you hook up to the attached generator) looks cool when the engine is running, but given its dynamic nature, it places a constantly varying load on the generator, which can result in the engine speeding up or slowing down as the LED runs through its display pattern. The generator outputs a bit over 6V unloaded (6.2V is what I measured). I've not yet had a chance to test/measure the generator output operating under a constant-current load (the included LED is definitely NOT a constant current load).
Some (minor) negatives - things that could be improved.
Note that I did not regard any these issues serious enough to detract from my overall high rating.
The provided fuel bottle and cap/wick arrangement is something of a safety hazard. The cap does not screw on or sit on the bottle mouth securely, which means that if the bottle is tipped or jarred hard enough during operation, fuel (alcohol) could escape from it. The fuel bottle does not fit securely in the indentation for it on the engine base, so it is free to rattle around as the engine operates. Having said this, the fueling arrangement is 'safe enough' if it is supervised during operation. Adding a simple (heat resistant) silicone rubber O-ring around the metal wick cap so it would sit in the bottle mouth with a liquid-tight seal would make this a lot safer. A smaller diameter holder (on the engine base) for the fuel bottle, with more sharply beveled sides, should be used so the fuel bottle has less freedom to move around during operation.
The operating instructions that come with the engine are poorly written, badly translated, and do not provide any significant detail on engine construction or maintenance (e.g. how to replace a broken cylinder, or remove it for cleaning). I did not find any instructions or contact info for ordering replacement/repair parts. A more detailed manual, showing a "blow up" diagram of all the engine's parts, along with care and maintenance instructions, which has been properly proofed and translated would have been appreciated, esp. since this is the sort of "toy" that someone who is mechanically-minded (and thus have an appreciation for design details) is going to have an interest in. I would have also appreciated some electrical specs on the attached generator - not the whole datasheet, just some basic details such as rated output voltage and current when used with this powerplant.
I found one _very_ minor "fit and finish" flaw after a close examination of the entire engine - the pilot hole in the flywheel, where the setscrew that secures the flywheel to the drive shaft is inserted, was drilled a bit unevenly - it is not perfectly circular on my model. However, this very minor flaw does not adversely affect the operation of the engine or appear to have any notable effect on the flywheel balance.