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[ta0]

We know about mechanical (e.g. whip) powered tops, electric powered tops, air (blown) powered tops, etc. What about steam powered tops?

Grand Illusions sells a German "Steam-Gyro" (Der Dampf-Kreisel), which they call a top, although it's not really one as it doesn't stand up to gravity:



I was not planning to get one, but I finally added it to a small order I placed for a Pirouetto top and an optical illusion (it's only $10, but no candle or bowl included). It worked as described, with a typical but erratic rotation rate of 30 RPM, and bursts of up to 60 RPM (1 turn per second). It can go for a long time, specially if the pipe is out of the flame and doesn't get covered by soot, which is a heat insulator. It would be easy to make a homemade version. The "top" comes with a brochure where it mentions that the first know description of a steam engine was the Aeolipile or Hero's Engine, which was a rotating ball with tangential steam jets from the 1st century AD:



But, has there ever been a true steam top? Well, at least there was a patent for one. Philip Eley of New York city obtained US Patent #114,781 on May 16th, 1871:



The patent explicitly mentions that it works as the Hero's Engine. The heat is provided by flames on the base. There is a movable arm that is used to hold the top until it reaches sufficient speed to stand up by itself. This steam top would also be relevant to the current discussion of Tank Tops, as it's filled with water. Was it ever built?  Did it work? Was it stable when filled with water? This is a very early patent and I believe at that time you had to send a working prototype of your invention, so perhaps the answer is yes . . .

[Jeremy McCreary]

But, has there ever been a true steam top? Well, at least there was a patent for one.... Was it stable when filled with water?

Very cool steam top, and I'd like to know that, too. Product liability must have been invented later.

[ta0]

If found out that patent models were required by the Patent Office until 1880. Models had to be smaller than a cubic feet, so many were miniature models of the invention, but in this case it would have been full size. And I imagine it would have had to work.    Unfortunately, a 1877 fire at the patent office destroyed 75,000 models. By the way, the Patent Office still requires a proof-of-concept model if you apply for a perpetual motion patent. 

[Jeremy McCreary]

The more I study Eley's steam-driven tank top, the more I want one to tinker with -- once my bomb squad suit arrives. Really like his air-cooled support and release solution.

Visually, great pattern formation potential here -- if only you could watch the spin and the free surface and the internal flows all interact. And with a clear tank, some carefully chosen glittery tracers, and the right lighting, you might at least get a glimpse.

The blacklight version could be pretty psychedelic.

Dynamically, a fascinating system. Inside the spinning water tank, a wonderfully complex speed-dependent clash of mechanical, fluid dynamic, and thermodynamic processes. This clash shapes both the water's free surface and its internal flows. The clash shaping our planet and its weather, or Jupiter's swirling visible cloud deck isn't much different.

And what a line-up of major players: Gravity (including buoyancy), inertial forces (esp centrifugal and Coriolis), viscosity, surface tension, pressure-gradient force, and thermal convection.

Duking it out like superheroes armed with interfering transient and standing wave systems!

Sorry, I lost control for a moment.   

[ta0]

I found on youtube several videos of home made Hero's Engines and most have a vertical axis, so very close to a steam top!



It just needs a tip and a release mechanism! 
The maker of that one claims that it was easy to build. It was made from a copper water level float and copper pipe from the hardware store.
Everything is soldered with bearing solder.

I think I'll make a steam powered top sometime in the future 

I also found that Gyroscope.com sells one one ($111):



It only takes 12ml of water and spins at 2,500 RPM.

[Jeremy McCreary]

Getting very close, indeed! Yes, and seat the tip on a bearing surface allowing the top to tilt as well as spin while discouraging tip travel, as in patent drawing.

On a separate matter, wondering if Eley's rotor is balanced enough for safe high-speed operation as shown. If not, you have a potentially dangerous failure mode.

Not a deal-killer, though. You could probably balance it by dialing in the mass, length, and pitch of the  steam outlet tube's upward spiral from tank to exit nozzle.

[Kirk]

I have built several model boilers for locomotives and stationary engines.  This Hero type would have a high degree of safety as it can never be fully closed.  2 steam jets make the whole affair easier to operate. (and balance) Tilt the top to the "correct" angle squirt water into one jet until it comes out the other.  Eley's machine looks like a fun project. Getting enough speed seems pretty tough.

[Jeremy McCreary]

Not sure, but seems like anything less than 3 evenly spaced jets would invite a potentially serious instability in a steam top, even if perfectly balanced.

[Iacopo]

Not sure, but seems like anything less than 3 evenly spaced jets would invite a potentially serious instability in a steam top, even if perfectly balanced.

I believe that if the two horizontal axes of inertia of the top are equal, there should be no problems with two symmetrical jets. It should be stable.