compressed air engine

6 Articles

Stretching The Flight Time On A Compressed Air Plane

October 15, 2023 by 23 Comments

[Tom Stanton] has been experimenting with compressed air motors on model aircraft for a good few years, but keeping them aloft (and intact) for more than a few seconds has proven a tough nut to crack. His latest design represents a breakthrough — pulling off an impressive 1 minute and 26 seconds flight on 4 liters of compressed air.

The model incorporates an enhanced engine design featuring an expanding seal on the piston, a concept inspired by the old Air Hogs toy plane. For the airframe, he constructed lightweight wings using 3D printed ABS ribs on a carbon spar and reinforcing rods, all of which were wrapped in heat shrink film. Additionally, [Tom] incorporated a thin balsa former along the leading edge of the wing to help maintain its shape. The fuselage is also composed of a carbon fiber tube, and is outfitted with printed fittings to install the wings, V-tail, RC electronics, and soda/air bottles. A hollow nylon bolt holds the two bottles together end-to-end while allowing the motor to be screwed directly onto the front bottle. To conserve weight, each of the two V-tail control surfaces are actuated by single cables linked to servos, with piano wire torsion springs in the hinges to maintain tension

Despite successful flights, [Tom]’s trials were not without challenges. One crash threatened severe damage to his airframe, but thanks to a central 3D printed bracket that absorbed most of the impact, total destruction was avoided. Similarly, a printed shaft saved his expensive carbon fiber propeller from being damaged during multiple landings, an outcome that led [Tom] to devise a readily replaceable consumable connector.

A second video after the break offers a behind-the-scenes insights into this project including some fascinating technical details. For more on this project’s history, take a look at the initial diaphragm engines and his attempts to make them fly.

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the water gravity air powered engine running

Gravity-Water-Air Powered Engine

March 28, 2022 by 19 Comments

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.

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3D Printer Air Compressor Is A Wankel

March 11, 2021 by 31 Comments

We wonder if mechanics are as annoyed when we say “engine” as we get when someone talks about a “computer” or a “radio.” Sure, you know what all three of those words mean, but there are many different kinds of radios, computers, and engines. In [3DprintedLife’s] case, he made a compressed air engine of the Wankel style.

The Wankel — a rotary engine — is most famous for its use in some Mazda cars. If you’ve done a lot of 3D printing, you know that creating an air-tight piston on a 3D printer is no mean feat. Of course, he didn’t do it right off the bat. It took what looks like a number of iterations to get it going, and he shares some of what he learned doing this project.

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Pelton Turbine Development For An Air Powered Model Helicopter

February 23, 2021 by 18 Comments

[Tom Stanton] has been messing around with compressed air power for a few years now, and most of his work focused on piston engines. He likes using 2-liter soda bottles as lightweight tanks but their capacity is limited, so the nozzle can be a maximum of 1 mm in diameter if he wants to produce thrust for 30 seconds or longer using a turbine. Pelton turbines have been in use for a long time, especially for hydroelectric systems, and they use small diameter nozzles, so he decided to experiment with a pneumatic Pelton turbine. (Video, embedded below.)

Pelton wheels are water wheels with specially designed buckets to efficiently extract energy from a high-velocity jet of water. [Tom] 3D printed several geared Pelton turbines and started doing bench tests with a propeller and a load cell to gather empirical data. With the help of high-speed video of the tests, he quickly realized that the turbine efficiency is highly dependent on the load. If the load is too small or too large, the moving air will not come to a complete standstill, and energy will be wasted. [Tom] also suspected that some moving air was escaping from the bucket, so he created a version that enclosed the buckets with a ring on the outer perimeter, which increased the peak thrust output by 65%. Compared to his diaphragm air engine design, the peak thrust is higher, but the overall efficiency is less. [Tom] believes there is still room for improvement, so he plans to continue working on the Pelton turbine concept, with the hopes of building an air-powered model helicopter that can lift off. Continue reading “Pelton Turbine Development For An Air Powered Model Helicopter” →

Steampunk Motorcycle Runs On Compressed Air, Is Pure Hacking Art

January 6, 2020 by 27 Comments

Sometimes it’s ok to sacrifice some practicality for aesthetics, especially for passion projects. Falling solidly in this category is [Peter Forsberg]’s beautiful, barely functional steam punk motorcycle. If this isn’t hacker art, then we don’t know what is.

The most eye-catching part of the motorcycle is the engine and drive train, with most of the mechanical components visible. The cylinders are clear glass tubes with custom pistons, seals, valves and push rods. The crank mechanism is from an old Harley and is mounted inside a piece of stainless steel pipe. Because it runs on compressed air it cools down instead of heating up, so an oil system is not needed.

For steering, the entire front of the bike swings side to side on hinges in the middle of the frame, which is quite tricky to ride with a top speed that’s just above walking speed. It can run for about 3-5 minutes on a tank, so the [Peter] mounted a big three-minute hour glass in the frame. The engine is fed from an external air tank, which he wears on his back; he admits it’s borderline torture to carry the thing for any length of time. He plans to build a side-car to house a much larger tank to extend range and improve riding comfort.

[Peter] admits that it isn’t very good as a motorcycle, but the amount of creativity and resourcefulness required to make it functional at all is the mark of a true mechanical hacker. We look forward to seeing it in its final form.

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Converting A Lawnmower Engine To Run On Compressed Air

July 8, 2016 by 31 Comments

Our most likely exposure to a steam engine these days will probably come courtesy of a railway locomotive. A machine capable of immense power and probably with significant complexity and engineering  in its construction, something the majority of us will only ever be able to see at second-hand. But there was a period when steam engines were much more accessible, before internal combustion engines and electric motors took on the task of automating hard work you would have found small stationary steam engines in all corners of industry.

These engines are on a scale much more easily embraced by hackers and makers, and though vintage stationary engines are thin on the ground these days there are a significant number of people pursuing their construction by converting modern petrol and diesel engines to a more old-fashioned medium.

[Lindsay Wilson] has a lawnmower engine which a few years ago he converted with the addition of a sleeve valve to run on compressed air. It’s not a steam engine because creating a safe and legal steam boiler is an expensive process, but despite this it amounts to the same thing. The engine in question is a small sidevalve single cylinder Suffolk Punch lawnmower engine from which he has removed and blocked the valve gear, and added a sleeve valve powered by a linkage from the crankshaft and using the spark plug hole as an inlet and outlet. He provides a lot of detail on the sleeve valve’s construction, and it really is a surprisingly simple arrangement. We might look for a harder metal than copper pipe for the guide in which it runs though.

The video below the break shows the engine being run up after a period of storage. It’s an effective device, easily capable of taking more air than his compressor can supply.

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