Small.... copper pulsejet, some questions.

[Mark van Werven]

Hi, I'm a total newbie to pulsejets but i have made a jam-jar that worked pretty good, i have also made an pulsejet, which is made of copper conduit.

My first attempt was an aluminium tube, which worked, but melted... :oops:

now i have a micro pulsejet. i always get it to pop, but it never has run.
the dimensions for the combustion chamber are 22mm x 47mm, and i use direct butane (...) injection, from a spotflame sweating device.
The exhaust is 15mm x 70mm, and the inlet is 12mm x 40 mm.

The direct injection is made of an metal valve for aquarium tubing, of which the handle will be attached to a servo, for my rc boat. i hope that i can get a little bit of thrust out of it, and if it does not work for the thrust, i will have a nice gadget on my homemade rc boat. :P

I have some questions i would like to ask, about which size of inlet and exhaust to use, and if it's better to use the chinese design or lockwood design for thrust. I have read that the direct design isn't really powerful:P.

I'm sorry if there is a calculator on this forum, i have manually searched trough the new and the entire old forum, but i still couldn't find it...

i hope you can answer my questions.

Mark van Werven

ps i will be posting some pictures if thats allowed.

[Al Belli]

Hi Mark van Werven ,

Go to the pulsejet section of this site, and download the calculator V1.4

Al Belli

[Al Belli]

Hi Mark van Werven ,

Go to the pulsejet section of this site, and download the calculator V1.4

Eric Beck Lockwood/SNECMA beta version- valveless .


Al Belli

[Mark van Werven]

thanks a lot! i could only find the valved pj- calculator...

(edit) i use butane and now have a lockwood design copper pulsejet, which pops, but does not run, maybe because of the very small stream of fuel the butanetank produces.

[leo]

Mark.
The dimensions you used are not gone give you a working pulsejet.
First of al butane is only good for big pulsejets, how bigger how easier thinks get.
Propane is the best for small valveless pulsejets, if you make them very small, then you have to use acetylene and for even smaller ones hydrogen.
If you read this tread you see a working Lockwood of almost the same ID combustion chamber.

http://www.pulse-jets.com/phpbb2/viewto ... highlight=

here you can find the rest of the dimensions to, just compare them whit your dimensions.
You better build a bigger one it’s a lot easier for first ones.

[Mark van Werven]

Thanks, I think i will be building bigger then. the main problem is that i cannot weld steel, because i have a way too powerful welding machine.
I have seen some plumbing steel at our local hardware dealer, I will search for some dimensions then, i'm probably going to use 2" diameter steel for the combustion chamber.

Mark van Werven

[leo]

2" inc is stil small you need propane for that size combustion chamber to.

[Mark van Werven]

Yes, i know, and i am going to use propane for it...
but first i must find some designs, because the valveless pj calculator is not working for my design, it hasn't got metric sizes, and the lockwood is not my favorite design, so ill probably go for a coaxial type instead of over & under.