Power and efficiency of Hero's engine or aeolipile has been put to the test by having it lift a weight. This is the first time in the modern era that the power and efficiency of Hero's engine have been measured, although there has been a lot of speculation.
I built a model of Hero's steam engine designed over 2000 years ago by the Greeks. The measured power and efficiency were very low. This video is a 4 minute quick presentation of video clips showing carious versions of the machines including Version 1 which was built by my grandfather 100 years ago.
This YouTube video is imbedded in the web site (HeroSteamEngine.com) presenting this work and its conclusions. There is extensive discussion about every aspect of the build and its design with many photographs. There is also research into the history of Hero himself and his inventions described in the English translation of Hero's manuscripts in Greek.
This exposes a few myths about Hero (Heron of Alexandria).
CORRECTION: There is a typing error. Version 3 produced 0.055 Watts not 0.55 Watts. The best power output measurement with the model was 0.1 Watts or 100 milliWatts.
Extensive theoretical calculations before the model was built, suggested that it would produce 1 Watt at 600 RPM. Version 4 ran at 5400 RPM without a load, and ran at 3000 RPM lifting a weight with a small spool (circumference 25mm) but dropped to an average speed of 660 RPM under load using a large spool (80mm) on the crane and produced 0.060 Watts. This is only 6% of predicted and it is thought that there must have been large losses due to friction and air resistance.
Efficiency was only 0.0128%, but might have been improved with higher steam pressure. Interestingly the efficiency of the first Newcomen engine in 1712 was only 0.2%, but it led to a commercially viable engine. See the web site HeroSteamEngine for further discussion.
Thrust or force from the escaping steam is calculated in the Appendix on the web site HeroSteamEngine.com. At about 10-15 psi the escaping steam reaches the speed of sound and cannot go any faster. Although the velocity remains constant at higher pressure, the density of steam inside the sphere increases in direct proportion to the pressure. Since the thrust is determined by the momentum of escaping steam it is proportional to velocity times density. So the thrust continues to increase as steam pressure increases.
Several people have suggested adding a flywheel. There would be no advantage in using a flywheel because the thrust from the jets is continuous. Flywheels are used on piston engines such as steam engines and internal combustion engines to smooth out the intermittent torque produced by power strokes followed by strokes that produce no power.
My playlist about using the Boxford metal lathe has several episodes about how the model was constructed including spinning copper, flaring copper before brazing, and making various accessories and attachments for the lathe as well as overhauling several parts of the lathe.
Playlist:
[ Ссылка ]
Season 3 Episode 9 of the playlist
"How to use a general engineering lathe" by Evan Lewis (evan-e-cent now evanecent).
INDEX:
00:10 Hero's engine version 1 is shown in operation. Built by my grandfather
00:27 Version 2 is running well
00:40 Version 3 with an improved boiler and large jets
01:00 Version 3 lifting a weight on a small crane
02:00 Version 4 with spherical rotor ran up to 5400 RPM
03:54 END
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