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Lockwood Hiller Pulsejet *almost* running

Posted: Wed Dec 23, 2020 12:25 pm
by buildcomics
Hello all,

I am Tom from And this is the story of my first pulse jet (so far).
I built it from stainless steel 1.5mm thick tubing. These are the dimensions:

Drawing Rev1.png

It's based on the 55lbs Lockwood HIller Valveless Pulsejet design by Bruce Simpson, with the ONLY difference being my combustion chamber is straight instead of slightly smaller at the exhaust end.

This is the actual thing:
This is what the fuel injector (now) looks like. It is a (rather big) 20 or so millimeter tube that sits just a bit into the entry of the combustion chamber. Having about 10 times a 4mm diameter hole into it at various angles, pointing down and inwards to the (rest of) the chamber.

To assure you there's no regulator, this is the attachment to the 10.7 Kg Propane Gas Tank (going into 6mm hose and to the fuel injector)

So I tried starting it with a compressor first, without much luck. Got myself a leafblower (3kw) and got much closer to running the thing:

But not close enough unfortunately. And in the end I had to give up because my leaf blower attachment melted away:

So that's where it's at now. Almost running, but not quite. The question for you here is, looking at all this, any tips to get this thing running? What could I do to run this better? Might it be:
1. My starting technique?
2. Fuel Injector?
3. Not enough fuel going in (try to run it on liquid?)
4. Is the straight chamber really an issue?
5. Something else?

Re: Lockwood Hiller Pulsejet *almost* running

Posted: Wed Dec 23, 2020 11:26 pm
by metiz
Hi Comics, welcome to the forum! Nice build you have there. I don't think the straight pipe will be a problem. Looking at your video, I have one piece of advice, and this is the first time I've said this to anyone on this forum: I think you're using too much gas! Right at the beginning of your video, the engine locks in, and by the sound and looks of it pretty close to full power. It's easier to start with a bit less fuel and then increase when it is running properly. For your leaf blower, try making a steel attachment with two 45 degree sections to get to 90.

Final piece of advice. By the looks of your propane tank and house style, it seems you live in the Netherlands. It's a densely populated country. Running a Lockwood in the back yard for any extended time will make your entire neighborhood hate you. Get your engine running and then find a field somewhere.

Re: Lockwood Hiller Pulsejet *almost* running

Posted: Fri Dec 25, 2020 10:08 pm
by buildcomics
Hi Metiz,

Thank you for the answer. I am gonna try less fuel and see what that brings.

I printed the attachment (the tube is oval shape) again using Poly-carbonate and covered it in aluminum tape:

It worked (didn't get hot, didn't melt), but on my second try haven't been able to start it yet.
I am also going to try a different fuel injector if I get the chance, maybe that help's out the mix.

And yes, I do live in the Netherlands, and I definitely planned to find a field for more testing once I get the hang of starting this thing. Even though the neighbors are used to the odd power tool usage outside, this appears to be something else entirely.

Re: Lockwood Hiller Pulsejet *almost* running

Posted: Sat Jan 09, 2021 8:03 pm
by buildcomics
Allright, I have got it running :-).

Thank you everyone for your tips. I have made a video here:

The pictures when I built it:

And the plans on thingiverse:

Again, thank you very much for allowing me to have so much fun with a running pulse jet. It was a blast :D

Re: Lockwood Hiller Pulsejet *almost* running

Posted: Sun Jan 10, 2021 3:00 pm
by metiz
Good job!