Poppin - Another Flamesucker Engine

[cfellows]

Here is my rendition of Poppin, a flamesucker featured in Live Steam magazine back in November 1980. I built this engine a number of years ago and have never really gotten it to run well. I kept tinkering with it and finally tried using Coleman lantern fuel instead of alcohol. That seemed to make the difference and now it will run until it runs out of fuel. Doesn't run very fast and it's really finicky about the placement of the burner, but it does run!

[ame=http://www.youtube.com/watch?v=0TI-scZGthc]http://www.youtube.com/watch?v=0TI-scZGthc[/ame]

Chuck

 

[mklotz]

Very nicely done. Sounds just like mine.

Do you have any theories about why the change in fuel helped?

 

[cfellows]

Thanks, Marv. The only thing I can figure is that the Coleman fuel has a higher BTU output than alcohol. Or maybe the alcohol I was using was high enough percent.

Chuck

 

[jack404]

this may be way wrong but,

with differenet forms of propellants they have smaller or higher expansion rates and what i call super fast propellents have a greater expansion rate so there by a higher contraction rate again after its been fired

with a suger based propellant for BP rifles its possible to get a secondary "pop" ( its very soft compared to the BANG) this is the air rushing back into the barrel so fast and when it hits the primer hole it makes a small pop type noise and you can see the soot blow out the hole

maybe these have a similar issue higher expansion rate which is matched with a greater contraction rate which is what drives flame eater style engines

jacks 2 bobs worth ( my 2 cents in US speak)

cheers

 

[rake60]

That's beautiful Chuck!

I need to try the Coleman fuel on my Poppin.
Methyl alcohol actually burns hotter than Coleman fuel.
When I run my Poppin on alcohol it will overheat and stop after about 2 minutes.

Thanks for the new tips to try!

Rick

 

[steamboatmodel]

I have never done any work with this type of engine and was wondering has anyone used water cooling on the cylinder, or would that stop the engine from working?
Regards,
Gerald

 

[cfellows]

I have never done any work with this type of engine and was wondering has anyone used water cooling on the cylinder, or would that stop the engine from working?
Regards,
Gerald

I've never personally tried water cooling, but lots of people have and they seem to be successful.

These engines run better when they get somewhat warmed up. I'm guessing this is because the engine runs with less friction when it's warm. Intuitively, you would think the the colder the cylinder, the better it would run, but that's apparently not the case.

On the other hand, when the cylinder get's too hot, the engine stops working because the gases from the hot flame aren't able to cool enough or fast enough to create the partial vacuum which makes the engine run.

So, I think the short answer is that a water cooled flamesucker probably would run more consistently for longer.

Chuck

 

[mklotz]

If the cylinder is overly cool, it will 'quench' the hot gas (i.e., absorb the heat from it) before the valve can close fully, thus making it impossible for the vacuum to 'form'* once the valve does close fully. This explains the fact that most of these engines will start more reliably if the cylinder is preheated with the alcohol lamp before attempting to start it.

My version of Poppin, with an aluminum cylinder, will run for long periods of time (tens of minutes). I suspect this is due to the fact that aluminum has good thermal conductivity and can quickly shed the heat it acquires from the hot gas. With a cylinder of less conductive material, some external cooling (fan or water jacket) may extend the running time.

I've tried dripping a few drops of water on the cylinder while it's running and discovered, to my confusion, that the engine then runs a bit faster. I'm at a complete loss to explain why that should happen.

 

[kustomkb]

What a treat!

nice video, a relaxing moment of contemplation.

Thanks, and well done.

 

[ghart3]

Couple of observations made on engine. A Philip Duclos "Little Blazer" that I had made.

Cylinder needs to be warmed enough so water from the flame don't condense on outside surface where valve slides. Think Philip Duclos, mentioned that.

Engine will run long time if bolted to large brass heat sink. No heat sink and will only run short period, guessing something like 5 or 10 minutes.

Used to have metal piston, don't recall but think was steel. If had dirty flame some soot would build up on outside piston wall. When was shut down and cooled off it would be froze up solid. The aluminum cylinder had shrunk on the piston. Heating cylinder with torch would free it up enough to take apart and clean. Then would work good again.

Had to replace piston and made new one from graphite and haven't had any problems since.

Flame position is critical and any slight breeze will be enough to make quit.

gary