www.pulse-jets.com

Nick wrote: On this run it pulled 550ml of water, unaugmented and against the friction and inertia of the device itself, i have yet to find out how much 550ml of water is im sure someone can tell me.

550 ml weighs 1.21 lb.

Could you tell us what "adjustments" you made, to get it running?

Bill H.
Acoustic Propulsion Concepts

".......some day soon we'll be flying airplanes powered by pulsejets."

What a nice thing to wake up to! Very nice! What's the over-all length on this one, and the total length of the intake on the latest video? I want to compare the frequency to after you alter the intake length.

232 Hz, nice and high.

Dear Bill.
Just balanced the massflow over the period of pressure rise. My initial thought was that the model was reporting a low massflow in the tailpipe but as it happened the model was spot on.

Dear Mike.
I'll send you the information in an email. As you know this model is the soft one of the two Flavours that this design can produce. I think we can get a lot more from it.

It would have been nice to run this motor at your meeting at the end of this month but money is a bit tight at the moment and I will not be able to come along. Hope this makes up for it.

Best Regards
Graham.

Morning Mike!.

right, adjustments, incremental reduction of the intake tract, starting at 114mm plus the 6mm bell mouth down to 91 plus 6mm bell mouth.

The overall length now is only 750mm

the length in the first video is the original 773mm.

hope this answers your questions.

:)
Nick

Great-looking machine. Looks pokey, given he size. Why aren't you wearing hearing protection? Do you want to become the Beethoven of pulsejets?.

Thanks, Nick, so that's 97mm intake including the bell mouth. The frequency, 232 Hz, is right on the distribution curve.

I have a straight piper of the similar length, 784mm, that ran at 240 Hz. It's intake settled in at 98mm. The obvious conclusion is that the straight pipe allows the duct to run a bit hotter at the expense of thrust, which makes sense.

Nick, it works well to throw a block 4-6" in front of the intake to determine it's thrust contribution by subtraction. I've verified that there is no augmentation or "sticky breath" effect.

Well done Nick. Just some thoughts, your jet being somewhat "symmetrical", it would be interesting to see how the intake/snorkel would work from the other end. Probably it would not be as good but something similar might run, having a mirror image look if cut in half in the middle.
I can relate to your first video, that's all I have ever done with propane, pop, pop, bang, bang. And my neighbor gently reminds me of how loud it is. Glad to see you back and your recent success and enjoyable movies.
Foa comes to mind, he said something about two engines, one having good aspiration, the other good mixing or something, my memory is off. I think there is a sketch of two engines in his book illustrating a kind of trade-off. Does anyone remember that reference in Foa's, "Elements of Flight Propulsion." ?
Mark

Hi All,

thank you for your kind words.

you are right Bruno i should have worn ear plugs, its not too bad though once its going, its the pops and bangs which are really loud.

Just tracked down my wifes kitchen scales the "bucket" wieghs in at 23grams so that translates to an overall thrust of 1.26lbs with no recooperation. Noted Mike ref the block, I wont get a chance to test this again for a while so i might make a recooperator in the mean time anyway.
Cheers :D

Nick

1.26 lb. net. Nice! That's exactly the same as my shorty Kazooenstein (1.036m long), only your engine is 27% shorter! Well done, guys! (not that k'enstein is any real benchmark, but it's up there for it's CC dia.)

I mentioned the deflector because making a non-augmenting recouperator is not worth attempting, and you need to know the raw unaugmented contribution of the intake end for Graham. I got 2x augmentation out of a 180 of 2" copper pipe fittings, FYI.

Nick wrote:Hi All,

thank you for your kind words.

you are right Bruno i should have worn ear plugs, its not too bad though once its going, its the pops and bangs which are really loud.

Just tracked down my wifes kitchen scales the "bucket" wieghs in at 23grams so that translates to an overall thrust of 1.26lbs with no recooperation. Noted Mike ref the block, I wont get a chance to test this again for a while so i might make a recooperator in the mean time anyway.
Cheers :D

Nick

I guess now would be a good time to take a thrust measurement of my linear FWE and see how the straight tailpipe compares to your flared one

Have you considered building a linear FWE with a lockwood style tailpipe begining right at the end of the CC? I wonder if that would hurt or improve thrust?

Nick, I was thinking your jet looked shorter than others of that ilk and since Mike has mentioned it too, I remembered something I read about attempts at shortening a pulsejet. It was that fellow, Gore Hagiwara, who also has the same sort of slight bulge conjuction in the middle of his pulsejet. If you look at this attachment, there is that shape that is akin to your pulsejet. I wonder if it aids in mixing the air/fuel somewhat before it can be ejected prematurely? In your jet is seems very slight, perhaps I am imagining too much.
Mark

This other page was from the same article and mildly interesting from a historical aspect. Sorry for going off on another tangent. One idea leads to twelve sometimes. Moderators feel free to refile this under tidbits or something.
Mark

Mark wrote:Well done Nick. Just some thoughts, your jet being somewhat "symmetrical", it would be interesting to see how the intake/snorkel would work from the other end. Probably it would not be as good but something similar might run, having a mirror image look if cut in half in the middle.
I can relate to your first video, that's all I have ever done with propane, pop, pop, bang, bang. And my neighbor gently reminds me of how loud it is. Glad to see you back and your recent success and enjoyable movies.
Foa comes to mind, he said something about two engines, one having good aspiration, the other good mixing or something, my memory is off. I think there is a sketch of two engines in his book illustrating a kind of trade-off. Does anyone remember that reference in Foa's, "Elements of Flight Propulsion." ?
Mark

Hi Mark,

i expect Graham could do this on U Flow and get some idea of what would happen?, its not actually symetrical but i know it looks it, ther are some quite subtle things going on in the design of this as Graham spent a while in fine tuning it on U flow.
Hope fully we have learned even more about using U Flow now we can feed the data back into the model. Particulary about intakes and boundry layers.


Nick

Ben wrote:What did types 02 through 06 look like?

They lived only on the drawing board or in U Flow, unless the original FWE i did was an 06 but i dont think so, Graham ?

Nick

I guess now would be a good time to take a thrust measurement of my linear FWE and see how the straight tailpipe compares to your flared one

Have you considered building a linear FWE with a lockwood style tailpipe begining right at the end of the CC? I wonder if that would hurt or improve thrust?

Likewise i need to test the Original FWE i made for thrust, interesting times!.

Nick