Easy Pulsejet





Introduction: Easy Pulsejet

About: hello everyone iam steam turbine design engineer. My hobbies are making pulsejet engines,stirling engines,animations.
This is the simplest pulsejet you could make and costs only Rs.110 and has got a good throttling range,which you could see in the video..No need to strain much to start this engine it starts in a single attempt..Thanks for watching see you all in the next pulsejet video..



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    i have build this pulsejet according to your design and i have a blower to strat the engine ..... i will upload a video soon...... the engine is totally waste since .... on dipping the 3 mm intake pipe of a LPG gas ..... the gas burns .....<i enter a burning nozzle of LPG> gas .... and the gas just burn in the combustion chamber with some less noise but there is no thrust .... now i am going to make some modification cutting the length of the intake pipe since .... a suty flame<black smoky> flame is coming out that means less combistion of the gas .... and again a argumentr in the exhaust section of the engine ..... ..... but my NON THRUSTABLE engine strat without a blower .... and it really sucks .... since i wanna make a RC car or a plane within two days ..... if u can ..... help me

    4 replies

    Man even I am from Nepal. Can you please tell me where you found those components. I want do this for my science fair.

    From your above explanation i can understand that you got problem starting the engine. First of all check the following things

    1. Did you perform a leak test
    2. Dont use the normal LPG regulator used in house. Try to use high pressure regulator.
    3. Ignition should be inside CC not at the exhaust pipe.
    4. Did you make any changes (dimensions) from the above design.
    5. Do not supply high volume of air to start the engine.

    In my point of view i did not find this engine waste because i performed a thrust test it was able to produce 8 to 9 pounds of thrust. Try to check the above things.

    yup man i got it .... i just checked leak test with water fill in it .... so it pass the test ..... means leak proof and high pressure regulator ok will try to best to find in market .....hope i got it and yaa ... the ignition system is a burning flame from small pipe<inlet> coz my spark plug doesn't run from my ingnition coil ... i try to innovate a idea by dissembling a gas liter .... mm may call u can i have ur number ...... i am from nepal and if i hav ur phone / cell i can call u ... since my project submission is late tommorrow and may be it heklp in eleventh hour

    You can contact me through instructables for any other clarifications.

    Has anyone tried water cooling? I'm building one now and I'm going to attempt to wrap the combustion area with copper pipes filled with cool water and a pump connected to a cool water reserve to help keep the engine cool

    1 reply

    You make a try and share your results here. Many are eager to try this.

    Ok so i have tried starting by the use of a sparkler and a pressurized coke bottle for air. (dont have a compressor)

    I get a few splutters and then it dies out.
    I can deduce that its either i dont have enough air from the coke bottle or the gas feed line is too small to supply sufficient gas essentially starving itself.

    I have attached a pic of both. I cant measure the tube now but my thumb is 20mm wide for a reference.

    Let me know your thoughts

    1 reply

    fuel line should be 0.3cm inner dia which is 3mm. Use blower for starting the engine because you should need 2 to 3 bar of pressure for this engine.

    Hi there

    I recently built this pulse jet and have the following dimensions
    Intake 25mm diameter 130mm long
    Exhaust 50mm diameter 775mm long
    chamber 101.6mm diameter 150 long

    I am having problems starting. i also get the 'candle' effect. I have tried ignition using a click lighter (dissembled) and re wired to extend the spark range. This has proven insufficient. I have tried a blow torch at both exhaust and inlet.
    I am using a aluminium tube inserted about 45mm into the intake and using the valve on the gas cylinder for flow control.

    Any help would be great as want to see this work.


    1 reply

    ignition at the combustion chamber is recommended. What is the diameter of the fuel line(aluminium) is it crimped at the end or not. Do not force too much air through the intake. Provide some pictures and videos if possible.

    Cool engine - the simplest I've seen (I think).

    The closest diameters of steel pipe I could get locally were 40mm, 100mm and 22mm - would they still work (and would it be easier to use slightly longer tubes)? Also, why not arc welding? So long as it doesn't burn through, shouldn't it be ok?

    7 replies

    100mm is ok but 40 is too small you wont get much thrust and becomes difficult to start. 22 is ok to use. Slightly longer- no problem. Yes arc welding is recommended but should hot make holes. Best of luck for your design.

    40 is too narrow? This'll be my first engine so I just want it to run. Would flaring the exhaust improve starting, or is the 40mm pipe no good at all?
    Thanks for your help

    i recommend not to use 40mm dia instead you can get an 46mm dia pipe. Flaring or not flaring is your choice. It does not link about quick starting.

    Sorry about all these questions - this should be the last (thanks for putting up with me)...

    I built your engine with 850mm exhaust length, 150mm intake and 150mm combustion chamber, with diameters 47mm, 22mm and 100mm respectively.

    I can't get it to start. It's arc welded and nearly airtight - I just noticed that when filled with water, one joint becomes a little wet (is that a big problem?). I'm using propane injected with an aluminium pipe crimped at the end so there's a very narrow opening. For air I'm using a leaf blower, and ignition is a blowtorch positioned at the exhaust. Without using the leaf blower and on low gas, it sounds most promising - a few pops, then it goes out. More gas and it burns with a steady blue flame at the exhaust like a bunsen burner; even more gas and it goes out. Same result when air is blown in the intake - steady blue flame, or out completely. It only pops on low gas.

    Any ideas as to what's wrong?

    No problem you can ask as many questions you like.

    It should be leak proof even a single leak will affect the performance try to close the hole. What diameter injector you are using and if possible please post some pictures so that i can find out the mistake. Ah now i got you!! DONT PLACE BLOWTORCH NEAR EXHAUST PIPE, IGNITION SHOULD BE EITHER AT INTAKE PIPE OR IN COMBUSTION CHAMBER. Try to use sparkler for ignition. one more thing dont supply large amount of air at the intake. And what type of regulator you are using can you post some pics and videos.

    Ok, injector has a pretty narrow aperture - there's a pic of the crimped end. It's usually sat just inside the flared part of the intake, but I've moved it about - the wire holding the pipe looks flimsy but is pretty secure - it's tied on in 3 places. The actual inner diameter is a few mm. No regulator on the tank - hose is connected directly to the outlet so it's operating at cylinder pressure. The tap on the tank is what I'm using to vary fuel flow - seems to give good control. I'll try to get some sparklers soon. I don't have video capability at the moment - just a still camera.


    You can open the injector little bit. And place the injector to a depth of 4.4cm through the intake. And remember ignition at combustion chamber gives you best result.