How To Make A Pulse Jet
Pulsejets are pretty simple to make compared to most engines. A valveless engine can be made with no moving parts and a minimum of tools, you can even build one from pipe fittings without any welding or machining if you really want to, but I really wouldn’t recommend it!
This page will serve as a general guideline of what is needed in order to build and run a typical pulse jet engine, and we will be adding links to the appropriate media and in depth pages
For most of you out there that want to go the route of making your first pulsejet out of sheet metal and tubing, rather than heavy & expensive pipe fittings, you’ll need a few basic tools and materials. These engines are a little harder to build, but perform much better due to their design not being limited by what pipe fittings exist, and are cheaper to make if you already have the tools.
To make and run a Pulse Jet Engine you will need:
Plans with the dimensions you need to make the engine.
Fortunately we got you covered here. Check out our Plans & Kits section for several different valveless pulse jet engine designs, in several styles and sizes. These engines don’t require any machining like valved engines, and are vary in skill level required to successfully make them from beginner to advanced.
Don’t bite off more than you can chew, starting off with something quick and simple will be more rewarding than jumping right to the tough build and not being able to complete it. If you have a little bit of shop experience and all the tools you need, you could build your very own Pulse Jet Engine in just a few hours!
Metal that can withstand high temperatures
Mild steel or Stainless steel are the only practical types of metal that can realistically be used for the beginners pulsejet. Other rare and expensive high temp alloys like Inconel, and Titanium could also be used but few have the budget or tools to make them from such metals.
Mild steel is cheap, and will last more than long enough for your first engine. Stainless is more expensive, harder to cut, form, and weld.
Small quantities of these metals can be found online, and chances are you can pick some up from an automotive body work shop, or local welding shop.
Once you have your design picked out, you can determine what materials you need. Using steel tubing instead of rolling tubes from sheet metal can be a good shortcut where possible. Make sure to keep the INSIDE DIAMETER of the tubes as close to the dimensions listed in the plans as possible.
Cut the metal to the size and shape you need. A good pair of hand shears, or electric nibblers will do the job. A hack saw can be useful for cutting tubing.
Avoid using plasma cutters if you have access to one, the time you might save cutting the pieces out, will be negated when you have to spend ten times as long prepping the part for welding, and trying to weld plasma cut sheet metal.
Form the metal to the final shape. This can be as simple as some heavy steel pipe and a rubber mallet and some pliers. Some other miscellaneous tools such as hand files, sand paper, and a drill can be useful.
Weld the metal pieces together with few to no leaks. This is typically the most difficult part of the build process. Welding is not necessarily difficult, but it does take some knowledge and practice. If you’ve never welded before, consider taking the ready to weld pieces to a local welding shop and see how much they’d want to weld your project up.
Stick arc welders are useless for making pulse jet engines unless you are making a monstrous sized engine out of rolled steel plate.
Keep in mind that most MIG welders cant weld any thinner than 20 gauge steel, if this is all you have access to, maybe plan on making a larger size engine so you can form it from heavier metal.
TIG welders are more expensive, but can make cleaner welds in thinner material.
To start and run the pulse jet engine:
The most common way to fuel a valveless pulsejet is with a propane tank. Propane is a clean burning fuel, and is easy to start an engine with.
Pulsejets require a lot of fuel flow, most people use a modified hose from a propane weed burning torch, since these are not flow-regulated and will give the engine the fuel it needs to run. You can however buy the fittings & hoses you need to assemble your own high quality propane hose.
Its important to note, that propane tank regulators, reduce the flow rate and pressure to the levels needed by a BBQ GRILL. They do not stop “flashbacks”. A properly maintained commercially filled propane tank contains no oxygen, and propane is chemically stable in storage, there is no way for fire to travel up the fuel injector, through the fuel hose, and into the propane tank causing an explosion.
What you need to make sure of, is that all connections are totally leak free. While the tank cant detonate like an acetylene tank, if you have leaky hoses and connections, you will have a fire. If the tank is exposed to fire the gas pressure can build until the point where the safety valve on the tank vents pressure, at which point you will have a huge 20′ long flame shooting out at great speed.
People think propane is dangerous because of Acetylene tanks. Acetylene is chemically unstable, and when not in a dissolved state in the tank, can easily DETONATE in a powerful decomposition reaction that travels at thousands of feet per second, and that does not require any oxygen. If you have an Acetylene tank with no flash back arrestor, the reaction can travel back into the tank, causing a massive explosion.
You’ll need some kind of system to ignite the engine. Some people stick holiday sparkler fireworks up the tailpipe, or have an open flame at the tip of the engines tail. You can also heat a spot on the combustion chamber up to red hot with a torch in order to ignite the fuel. These are all very “rigged” solutions, and while they might work, there really is no comparison to even a simple battery operated BBQ grill igniter.
If you decide to use a spark plug, consider using a AA battery powered electronic grill ignition unit. These are small, cheap, and reliable. You can pick them up from most home improvement stores such as Home Depot, Lowes, and others for around $20 to $30. It is by far the cheapest, simplest, and safest route, and small enough to fit in your pocket!
Another alternative is Model T Ford ignition buzz coils, unfortunately there is only one person that manufacturers them anymore, and they are not cheap, or small, or light… You could also wind an electromagnet, and wire it in with a reed switch & car ignition coil, and power it from 4 C or D batteries.
⇒ Dont use high voltage transformers such as TV, Microwave, or Neon sign transformers, they are extremely lethal and will kill you instantly if you get shocked. If you think you’re smart enough to use them safely, then you are not. You’re asking for trouble when you forget the ignition is still on because of your attention being focused on the ridiculously loud jet engine shooting flames and shaking the ground. You can start a pulsejet with static electricity, you don’t need a HV transformer.
Forced Air Source
Most engine designs will require a quick puff of air to get the engine started, an air compressor, shop vac, hair blow dryer, or leaf blower can do the job. Leaf blowers are unwieldy and you should have an assistant to help control all the other things. For air compressors, the pistol grip air blow guns work best, as they give you control over how much air you provide.
Safety Goggles, Ear Protection, Work Gloves & Fire extinguisher
Pulsejets are incredibly loud, reading about how loud they are online does not prepare you for reality. The big ones actually shake the very ground beneath them! Ear protection is an absolute must or you will get instant permanent hearing damage at close range. For big engines you should use foam ear plugs, AND hard shell ear muffs.
Pulsejets spit out fire, occasionally little sparks and chunks of red hot metal, and can kick up dust and sand. Always wear eye protection.
Pulsejets do get orange hot, so work gloves and some way to put out a fire is always a good idea.