www.pulse-jets.com

Well I have been building a diesel fueled motor already, because I blew up the engine of my van on the way to the Balkans....
So now you know why I stayed a bit longer than usual

And of course it happened half-way, still 1000 km's to go. Still I got there, stopping every 100 km's for refilling oil because the engine spew it all out.

When opening the engine it appeared that one of the pistons split, no damage to the cylinder though. Also it appeared that many other parts needed replacement. So strange after just 425.000 km's
So I did a limited overhaul.

Fedde

At Ace_fedde's request: here's the latest M40 test with some high speed shot's mixed in
http://www.youtube.com/watch?v=dGpyEKgU2ws

Hi Metiz

Nice run on that engine, very clean and solid

Viv

It looks as though the positive pressure is the greater force at work. I didn't see much if any debris entering the engine, it would almost pause before being pulled into the main exhausting stream.

Makes sense though, the low pressure swing will only see a fraction of 1 atmosphere, yet the positive pressure generation can reach several atmospheres. I wonder if a automotive MAP sensor could be used to monitor a general positive pressure from the CC? Maybe give a rough reading to compare to a baseline of 1.2 lbs./sq.in. of combustor cross section area.

Great work, bet that thing is loud. ha

It's loud alright. I never tried screaming before when running one of these engines so I tried it last sunday. It's a realy strange experience. No matter how loud I screamed, I couldn't hear, nor feel it in my body. Even if you'd be deaf you would atleast feel your vocal cords and chest vibrate, but with this engine there is absolutely nothing. so weird...

PyroJoe wrote:I didn't see much if any debri entering the engine, it would almost pause before being pulled into the main exhausting stream.

We were already planning to put a thin tube on a smoke generator and use it like they do with cars in a windtunnel, and of course film it at 1000fps. Probably it would give clearer indications of the air movement. But where to get a smoke generator

Anyway, more to come (for a couple of months ), like a night run at high speed (to see the flames better).

Fedde

Hey Fedde

Alright, next time will be a nightrun instead of a smoke generator we could also use a couple sticks of incense (at daytime, that is ) and then record at a lower fps to get a bit better resolution

Metiz, where you place the injector, out, middle, far inside the intake, waht are clue?, show picture please!

Why a shorter combustion chamber and convex cap on the current design? Quite a bit different from the original design on page 1.

The original design didn't run, this is the improved version. The convex cap does not have a specific design function. It prevents the endcap from flexing in and out during operation. It also slightly increases the cc volume, giving it another pound or so of thrust.

daab, Injectors should be placed roughly 70mm inside the intakes. Injectors are Rosscojectors ~1mm slit

Metiz, did your second engine use 47 mm intakes or 50mm?

The intakes are cones. They start at 50mm (at the intake elbow) and end in 47mm (at the flare, so NOT including the flare)

This is a very impressive pj!

I have been reading and watching solidly for the past 2 weeks and itching to get started

My plans so far is too build a small, basic, mild steel oh designed by Larry. Then move onto a stainless 12lb Chinese.

Then if Iam successful ill try out this m40 design.

Who knows after that eh. Either monster power valveless or try out a valves design and turbojet design

Hey Metiz,

We currently have the 40 pound chinese pulse jet completed. We are just wondering more details about your fuel system. I know what size tanks you are using and that one is for gas and the other for liquid propane (flipped upside down). I know that they are connected in parallel which splits later into both injectors. It looks like you are using stainless steel tubing. We are considering using copper tubing. Do you think this will still work? Are your injectors "floating" in the middle of the intakes? Should we elevate the fuel tanks and, if we should, how high should we elevate them? Is it for head purposes to prevent possible backflow of the fuel? We know that the fuel requirements for the jet are high enough that you guys don't use regulators on your tanks. Is it possible to place a regulator or a one way valve that would ensure no backflow and still allow enough fuel flow? We greatly appreciate any and all of your assistance.

Thank you

Copper tubes will work just as well. The injectors should indeed be floating in the centre of the intakes. Elevate the liquid propane tank to the point where the gas valve on the tank is above the intakes.

(just a note, this tank is not strictly necessary if you have a big or full tank and it's not cold outside)

There is no chance of a flashback into the tank, flipped or not. The perfect stociometric mixture of propane lies between 2 and 4 procent propane and 96/98% air. There is no air inside the propane tanks and the propane itself is presurised to way above atmospheric.

Do you have any pictures of your build?