Scaling Up a Flame Licker

[vederstein]

I think my next project will be my first try at a flame licker, the Poppin engine in particular.

I looked at the plans and I really don't like how small this thing is and I want to scale it up about 50% to make the parts more manageable and avoid 2-56 threads.

Therefore the question:

Being that the engine's displacement will increase by 2.25 because volume increases with the square of the diameter, will simply scaling the entire engine 50% work or do I need to have a cylinder displacement scaled 50%?

Thanks in advance for your knowledge and reply.

...Ved.

 

[Cogsy]

I think you want the extra displacement here, so you have extra power to drive the increased mass. The poppin seems to run about the best of all the flamelickers I've seen so I'd be guessing just scaling the whole thing up will work fine. BUT flamelickers can be nasty things to get working so I'm not guaranteeing anything... I'll be watching with crossed fingers for you.

 

[vederstein]

Thanks for the reply. I'll just scale it.

My success with Stirlings has been hit and miss (so to speak), so I may end up with another expensive paperweight. We'll see.

Ved.

 

[vederstein]

Well, here's the main assembly drawing of my plans for a Poppin scaled 150%.

Now here's the question: Even though these plans for the original Poppin are freely available on the Jon Tom website, is it legal for me to post my version of the design? I've made a couple of changes other than just scaling the engine.

...Ved.

 

[Cogsy]

From what I can see (not a lawyer, etc.), unless the designer of the engine actually released the plans into the public domain, then copyright still exists on these for 70 years after his death. It seems he was still alive in 2004 (and may still be alive for all I know) so they would still be under copyright. The magazine scan on the John-Tom site is out of copyright, so the magazine can't pursue a copyright infringement, but the copyright holder of the content itself (the plans) could.

These plans are so common that it appears the author may have waived copyright, or simply decided not to pursue it, but I can't guarantee that. Without a waiver from the copyright holder, if there is one, a derivative work would still be subject to the original copyright. Sorry, I know it's not the response you wanted.

 

[TonyM]

The problem is that it is a derivative work right down to the name. The chances are you would not have a problem as the design is in the public domain but that is no guarantee.
The concept is not copyright just the design within that concept.
The best way to avoid plagiarism is to make the engine parts different in external profile. So different flywheels. Cylinder outline, Base profile. The increased size also helps. You should then call it by a different name.

 

[marvin hedberg]

i am puzzled by the design. wouldn't the spring under the arm rotate the roller away from the cam?

 

[kvom]

The power on flame lickers is very slight. Increasing mass by cube and piston area by square doesn't bode well. Good luck.

 

[sawyer massey]

A friend of min built that engine twice the size opposed twin worked well