Is it a steady burner or a pulse jet?

[Viv]

Is it a steady burner or a pulse jet?

I would just like to try and settle that question if I may.

In the old forum there was a marvelous spat over this issue, did the pressure jet behave as a steady burner or in effect a pressure fed ram jet as some argued or was it in fact just another version of a valveless pulse-jet.

The picture below is from the output of a load-cell, the load cell has a bandwidth sufficient to resolve the individual thrust pulses of an engine under test, the mass of the rig is low enough not to distort the reading too badly all though some hysteris will be a feature.

If the engine under test was a steady burner then the display would be a steady line, if it was a pulse jet with discrete combustion events leading to thrust being produced in pulses then the line would resemble a sine wave.

The engine under test is a 130R you may draw your own conclusions from the display now that you know what you are looking for:-)

So enough of all that mystical marketing mumbo jumbo, I have a sound recording that says it pulsates and a thrust recording that says it pulsates.

Any other data you want? and how do you want it!

Viv

[Stuart]

Interesting Viv. I am building my own variation of a pressure jet. My design is pretty different than a Glueharath. I don't have it proportioned correctly yet (modify, learn, modify, learn), so it isn't putting out a lot of thrust, but it does work. I'll start listening for evidence of pulsation now that I know.

[Bruno Ogorelec]

So, Viv, what the hell is it? A Logan with a bit of boost from the ejector intake? The sine wave looks convincing. What's the frequency?

[Viv]

So, Viv, what the hell is it? A Logan with a bit of boost from the ejector intake? The sine wave looks convincing. What's the frequency?

Yes Bruno a Logan or a Chinese would be good analogy, the frequency is the same as the engines running frequency, in this case that was about 138Hz.

If you remember the thread it was quite lively at times but short of any actuel test data to prove things one way or another.

Viv

[Bruno Ogorelec]

Damn! Now I'll have to include it in my valveless review (the next update) and add to the controversy.