3D Printed Pulsejet Uses Tesla Valve

For most people, a jet is a jet. But there are several different kinds of jet engines, depending on how they operate. You frequently hear about ramjets, scramjets, and even turbojets. But there is another kind — a very old kind — called a pulsejet. [Integza] shows how he made one using 3D printed parts and also has a lot of entertaining background information. You can see the video below. (Beware, there is a very little bit of off-color language and humor in the video, so you might not want to watch this one at work.)

They are not ideal from a performance standpoint, but they are easy to make. How easy? A form of pulsejet was accidentally discovered by a young Swiss boy playing with alcohol in the early 1900s. Because of their simplicity, they’ve been built by lots of different people, including rocket pioneer Robert Goddard, who mounted one to a bicycle.

Tesla — the inventor, not the car — invented a lot of things, including a one-way valve design with no moving parts. A pulsejet expels exhaust and intakes air through the same hole, so good ones use a one-way valve. Tesla’s is interesting because it is nothing more than a shaped channel that has low resistance to flow in one direction and higher resistance in the other direction. The trick is in a teardrop shape that is thin on the inlet side and fat on the outlet side. It isn’t perfect, but it does provide a basic and mechanically reliable one way action.

The biggest problem, of course, with a 3D printed jet engine is that the engine gets hot and plastic likes to melt. [Integza] used lost PVA casting with plaster which worked well. There were still plastic parts melting, though. He used a high tech PLA, but we wondered if PETg or nylon would have been better choices for heat resistance.

It took several iterations, but he finally got some pretty impressive results. Well, impressive when you consider what he’s working with. We aren’t sure you’d ever want to use a 3D printed pulsejet in an actual project, but if models like this help you understand the principles, it might lead to a more practical engine somewhere down the road.

If you think Goddard’s bicycle idea was cool, here’s a more recent attempt. If a bicycle isn’t your thing, a jet sled is a possibility. We’ve seen other attempts to make jets with at least some 3D printed parts.

18 thoughts on “3D Printed Pulsejet Uses Tesla Valve

  1. Very humorous video. Over a half a century ago, a company by the name of Minnesota Engine Works (also known by their acronym, MEW, actually manufactured a machined metal (NOT 3D printed) pulse jet, which they called the Dynajet Redhead. The name came from the red color of the ignition bulb on the front, that contained a sparkplug. It used white gas for the fuel. When it was operating, it was very loud (one of the magazine articles about it recommended wearing ear plugs). It was marketed mainly to the model airplane hobbyists. It was very powerful, and some hobbyists used it for other applications, including Goddard-like bicycles. Anyone for a jet propelled skateboard?

    1. The adage “a pulse jet is a machine for converting fuel to noise with a slight side effect of thrust” has been attributed to a whole bunch of early jet engine and pulse jet designers.

  2. Great graphics and educational background segment!!!
    I don’t know how to say this and I’m sure my terminology will be wrong, but here goes.
    Depending on your fuel and air mixture the ignition wave front speed will vary. My thought is that the loops in the Tesla valve need to be changed to take into account the speed of the ignition wavefront. Faster the ignition wave, smaller the loops. That would need to be matched to be able to maintain a flow of the pulse jet.

  3. PETG might be less prone to melt but my experience is that if it does burn inadvertently inhaling the fumes can cause some weird issues like blood pressure changes and dizziness that last about a half hour. Nylon probably would be OK?

  4. wonder if he printed it with a metal loaded filament if he could get it to self sinter…LOL okay I know the heating wouldnt be even and it would fail hard…but its a funny thought.

  5. Using a non Moving part valve solve only one part of the non efficiency and complexity of a pulse jet. There is still a part of the cycle where the incoming air has to stop then reaccelerate. I think that this issue could be solved with multiple chambers desynchronised. Maybe a rotating air entry should be used to garanty this desynchronisation.

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