Gravity-Water-Air Powered Engine

the water gravity air powered engine running

Air engines are a common occurrence here on Hackaday. They’re relatively novel and reasonably easy to 3D print without requiring any fluids or supporting machinery. For example, [Tom Stanton] took a previous air engine design, did away with the air compressor, and instead used gravity and water to create just a few PSI to run the engine.

The basic setup is to have a large jug of water up somewhere high. Flexible tubing runs down to [Tom’s] custom acrylic pressure chamber. A little CNC-ing and some epoxy made a solid chamber, and we’re happy to report that [Tom] did some initial simulation before construction to make sure he wasn’t accidentally building a bomb. Some back of the napkin math showed that he could expect around 0.6 bar (around eight psi) with his setup. His first test showed almost precisely that. Unfortunately, [Tom] ran into some issues despite the early success. His engine would stop as it drew air and the pressure dropped, and the replenishing rate of the pressure was limited by the relatively small inlet hole he had drilled.

To fix this, he printed a larger diaphragm for the engine, so the lower air pressure had more to push against. This allowed the engine to run for a good while before the tank filled up. Additionally, he smoothed and polished everything, so it was as low friction as possible. We know we often state it here, but it is incredible what can be achieved with 3D printed parts these days.

We love seeing the iteration evident in this video. The various engine versions splayed across the table offer a powerful story about [Tom’s] persistence. Powering an engine is a small step to powering your whole home.

19 thoughts on “Gravity-Water-Air Powered Engine

  1. Interestingly I just watched a YouTube video on a dam in Canada that was used to supply early twentieth century mines with pressurized air.
    Small air inlet tubes long enough to be below the water inlet incorporates air in flowing/falling water at the bottom of the floor the air is allowed to fill a chamber that contains the pressurized air and then the water is forced to flow upwards before exiting the system. The second upwards flow controls the amount of pressure generated.

  2. I think I’m missing a lot here. He built a compressed air powered motor. The energy source is a mass (water) flowing down via gravity. That’s how hydroelectric power generation works, a very, very solved problem. Only they create electricity directly. And if someone is worried about water in the attic having enough energy to cause and explosion… I’m at a loss. This is neat and all but I don’t… get it. I freely admit I didn’t watch the entire video maybe that was addressed.

    1. Reminds me of a home-brew winemaker, trying to filter his carboy of red wine. It wasn’t going through the filter fast enough, so he got the brilliant idea to put the carboy on a balcony a couple of stories up, to generate the pressure head.

      Yep — the filter exploded. Made a huge mess, lost 20L of passable wine, but he earned his lesson in hydraulics.

    2. It is using water pressure to make air pressure to drive a compressed air powered motor to spin a propeller. There’s no electricity involved.

      The weight of the water over just a few meters of height can compress the air so much that you have to be careful that it doesn’t cause the air container to burst – that’s the explosion mentioned in the text.

      Yes, air pressure can cause a container to burst.

      1. That makes no sense. 10m of sea water is one atmosphere of pressure. I also regularly carbonate beer to 15, 17 or more PSI (roughly an additional atmosphere. ) And that is regular beer not even the Belgian type stuff in heavy bottles, or even soda water from the grocery store that is more highly carbonated. So unless this dude lives in the Eiffel Tower the chance of an “explosion” is about zero. Maybe a leak or a pffffff. A soccer ball is about 15PSI and no one worries about those exploding.
        Also, as many commenters elaborated, I know there is no electricity involved in this dude’s set up. That is the *problem. Using energy to raise a mass that is then used to… fall down then is used to compress air that is then used to do work is probably massively less efficient than using water to directly generate useable electricity. As has been done for a century.

        1. But when you are Tom, who has been developing ever more revisions of his compressed air engine efficient is quite likely not all that important, its controlled, cheap and convenient compressed air (that helpfully also doesn’t require a noisy compressor to ruin his audio).

          Your regular plastic drinks bottle is good for over 50psi, folks in the compressed air water bottle rocket world even cut and join bottles together and still get that sort of pressure despite the seam, but that doesn’t mean your brittle? clear plastic tube with lots of drilled holes held together only by epoxy can take the pressure – until you actually test it or can source the materials with good consistent mechanical specs to know beforehand it might go pop and all that energy even a paltry 10psi let out badly could be a pretty nasty burst.

  3. Seems like a lot of trouble to get a bit of air pressure. Could do the same without climbing the ladder by just making the cylinder with a piston or a bladder and sitting on it.

    The total stored energy is 300J (5L of water x 6m head x 10m/s/s, or 60 kPa x 5L — ain’t metric convenient?), about 1 percent of that stored in a single 18650 lithium cell.

    That water-damage-in-waiting contraption ran that prop for less than 5 minutes. A single 18650 would run it for 8 hours.

    But I get it. Do it for the clicks. Pays the bills, I suppose. And lets you write off a neato CNC router as a business expense.

      1. Don’t be naive. Tom Stanton is not learning about water head or power generation here. He’s producing entertainment.
        If he’s ‘learning’ anything, it is about what generates Youtube views. He’s modestly successful at it, getting a few thousand dollars a month, able to write off new toys as a business expense, and likely having some fun doing it. Not a terrible side hustle.

        1. Those air engines of his are definitely a learning exercise, mostly in design for manufacture but also in core operating principle – been through so many revisions. That it is also entertainment (at least to those that choose to watch) and earns him some money doesn’t negate that there is learning being done…

          Same as something like Mythbusters (at least those myths that actually required real testing), despite the clowning around and clear entertainment focus there is a huge amount of learning in those, some of it quite possibly new to everyone – like shooting into a swimming pool – what bullet do on impact with bodies of water is bound to have been studied for common military rounds as it might be important operationally, but they shot all sorts of things that probably wouldn’t have been done before. And all their crash test dummy routines in uncommon situations, something you might be able to simulate accurately enough now but back then that test was quite possible the only somewhat scientific setup to study of that type of event.

  4. It’s ca;;ed learning. Not everything is intended to be an instant comercial product. Success, or failure, we learn something that can be applied to future ideas. It’s just a starting point, no telling where the path wil lead you.

  5. I think you’re really onto something here. Crankshaft in a piston are really inefficient because it has to switch Direction on every cycle maybe some way to incorporate a Wankel engine design?

    Also you can increase your pressure using a ram pump instead of just using gravity. I have a ram pump that uses 1 inch pipe going in and three quarters going out was about 3 ft of head. I can get over 50 psi out of that thing. As a matter of fact my first Ram pump design kept blowing the pressure tank up in the air like 40 ft.

    The concept is right on and I think it’s just it’s going to take a lot of trial-and-error. I’m going to work on something like this myself now. Using neodymium magnets as frictionless bearings would the efficiency exponentially.

    There are some Amish people that have workshops that are run on compressed air and we are talkin big workshops running all different types of machines.

  6. +1. I read and reread the comments policy and can’t see any “infractions”. Also have been coming to this site for a looonnng time and had my first comment deleted a couple weeks ago and now this. So something is different. Best.

    1. And so they did. So how does this work? Does a comment get auto-hidden after three grumpy people click on “Report comment”, only to be reinstated after a cooler-headed moderator reviews it? (If so: My apologies to Matthew)

      1. That I don’t know, must be something like that – I do know folks click report meaning reply a fair few times from reading the comment afterwards too though so it might just be grumpy people…

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