www.pulse-jets.com

Ok I got some steel tubes for my new lockwood.
I have 2.5" tube, 2 x 2.5" 90 deg bends, 3" tube and for combustion chamber, inner diam. is 170mm / 6.7 inch.

So I was thinking to use that 3" for intake and 2.5" for first part of exhaust, rest of it will be conical anyway, after U-bend.

But I have a problem, I have no idea about optimal lengths for those tubes. Combustion chamber should be ok if making it 2:1 length to diam. ratio?

My goal is to achieve 50-70lbs of thrust.
Any info is welcome

first version is now ready and we made some test runs.
It is not easy to start, requires lots of gas to get it started. Not running smoothly..it is a bit erratic and unstable. Throttle range is quite narrow..dont know why? bad construction mistakes I think..
Fuel supply is 11kg propane bottle. I turned it upside down and it gives nice amount of extra power but it easily stops running after 10sec.

Without intake cone, it didnt start at all..after adding small cone it started but not easily tho..

running on liquid prop:
http://www.youtube.com/watch?v=VqvMQcwJ ... e=youtu.be

The noise from the engine is low so i think you need to make some changes to get it going good.

ganuganu wrote:The noise from the engine is low so i think you need to make some changes to get it going good.

Yes, indeed. This is first version. I need to tweak propane injector etc, flared exhaust.

Edit: here is my spark generator


it is simple NE555 based oscillator, driving flyback transformer from TV through a power mosfet.
Gives nice and hot arc of 25kV..

Oh shit, be carefull with that. One mistake and you're dead with a flyback. You may want to consider a safer alternative

metiz wrote:Oh shit, be carefull with that. One mistake and you're dead with a flyback. You may want to consider a safer alternative

It wont kill, puts out only 1 milliamp current (lethal current is around 15-20mA).
Btw, I'm very experienced about high voltage technology anyway..

Thats what I call lethal:
http://www.youtube.com/watch?feature=pl ... VL8Y#t=76s
Just one of our experiments with high voltages...

Back in topic, I wonder what kind of fuel injector to use.. rosscojector or long tube through the CC having multiple 0.5-1mm diam. holes.
Currently, it is just a brake pipe of about 2.5mm inner diameter. Pipe is about 50mm inside CC, close to intake. Absolutely not the best option but at least we made it running with this.
How loud it was? Not sure how loud it should be at full power, but it was hard to stand near the exhaust because of heavy body vibration it made. No way without ear protection.

use the long tube through CC with multiple holes. That will supply enough fuel to the engine.

ganuganu wrote:use the long tube through CC with multiple holes. That will supply enough fuel to the engine.

Ok I'll do that next. I also need different valve for my propane tank as it has now regulator type.. It cannot feed enough gas to this engine.

get a fitting straight off the bottle with no reg. i struggle in the uk to buy the part but whilst looking at the caravan section of the local gas supplier i stumbled upon a pipe with the correct fitting either end, its used for joining bottles together. cost 12gbp