Author Topic: Senft "Poppin" engine  (Read 24505 times)

Offline Brian Rupnow

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Senft "Poppin" engine
« on: March 12, 2018, 12:42:44 AM »
I just finished building the latest flame-licker engine designed by Jan Ridder, and my results were not what I hoped for. I did get it to run--long enough to get a video of it running.--But barely. I found it to be an easy build but a very temperamental and difficult engine to run. I don't think this was a result of my workmanship, as I have 25 other self built engines which all run quite well. It may have been my choice of 316 stainless steel for the cylinder. I tried it with a cast iron piston and valve and with a machinable graphite piston and valve, but the performance was no better with either material. I still want a flame licker engine which starts and runs repeatably, and after doing a fair bit of research have decided to build a "Poppin" engine from plans by Dr. J.R. Senft. I will attempt to post my progress and pictures of this engine as it is built.

Offline 10KPete

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Re: Senft "Poppin" engine
« Reply #1 on: March 12, 2018, 01:36:00 AM »
  :ThumbsUp::popcorn: :popcorn: :popcorn: :ThumbsUp:

Pete
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Offline Chester

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Re: Senft "Poppin" engine
« Reply #2 on: March 12, 2018, 02:05:29 AM »
I’m also along for the journey. Popcorn and frosty beverage in hand!

Offline crueby

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Re: Senft "Poppin" engine
« Reply #3 on: March 12, 2018, 02:31:28 AM »
Me too!


 :popcornsmall:

Offline JULIUS

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Re: Senft "Poppin" engine
« Reply #4 on: March 12, 2018, 06:05:51 AM »
Brian

I drew this engine up a few years ago.
Are you working in imperial or metric?
May be my metric drawings might help.

Julius

Offline Brian Rupnow

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Re: Senft "Poppin" engine
« Reply #5 on: March 12, 2018, 02:17:13 PM »
If you really squint hard, and use your imagination, you can see the frame of this engine layed out on a piece of 2" x 1" aluminum bar.--Everything has to start somewhere.

Offline Brian Rupnow

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Re: Senft "Poppin" engine
« Reply #6 on: March 12, 2018, 02:18:54 PM »
Julius--thank you, but I work in Imperial. I generally make a few changes along the way to suit what is available to me.---Brian

Online mklotz

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Re: Senft "Poppin" engine
« Reply #7 on: March 12, 2018, 02:19:46 PM »
I built Poppin many years ago...

<a href="https://www.youtube.com/watch?v=eCssHXWVYm0" target="_blank">http://www.youtube.com/watch?v=eCssHXWVYm0</a>

My version has an aluminum cylinder with a stainless steel piston, all non-corroding materials.

The first time I tried to run it, I sat there manually spinning it over for what seemed like hours before it finally ran on its own.  Fiddling with lube, valve material and positioning, etc. did little to solve the hard-starting problem. 

Then it occurred to me that the cold start-up cylinder might be prematurely quenching the hot gas so that, once the valve closed, there simply wasn't enough hot gas left in the cylinder to form the vacuum needed to allow the atmospheric pressure to power the engine.

So I tried heating the cylinder by holding the alcohol lamp under the cylinder sides for a bit before attempting the first start.  It took off slowly on its own almost immediately and gradually, as the cylinder warmed, increased its speed.

Since then I always pre-heat the cylinder before starting and it's become a very reliable runner.

I can't prove that my theory about why this works is correct but I can testify that it does work.  Keep the idea in mind and, if you have starting problems once the engine is built, give it a try; it won't cost you much time.
Regards, Marv
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Offline Steve F

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Re: Senft "Poppin" engine
« Reply #8 on: March 12, 2018, 04:53:18 PM »
Hi

I built the Poppin a couple of years ago. I enlarged it by 20%. The cylinder went from 5/8 to 3/4. It came out great and was and still is a good runner.



regards

Steve

Offline b.lindsey

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Re: Senft "Poppin" engine
« Reply #9 on: March 12, 2018, 05:03:13 PM »
I documented a build here a few years back and it also was and is a good runner. I will say though, that the valve mechanism is rather delicate so it is important to keep the wick far enough away so as not to get in the path of the valve as it opens and closes.

Bill

Offline Brian Rupnow

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Re: Senft "Poppin" engine
« Reply #10 on: March 12, 2018, 06:11:42 PM »
Marv, Steve, and Bill--Thank you for stopping by and saying Hi. All suggestions carefully considered.---Brian

Offline Brian Rupnow

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Re: Senft "Poppin" engine
« Reply #11 on: March 12, 2018, 06:49:05 PM »
Well jeez, Louise--How many set-ups did you think there were going to be?



Offline bent

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Re: Senft "Poppin" engine
« Reply #12 on: March 12, 2018, 06:51:17 PM »
I'm sure your build will be successful or at least informative, Brian! :popcorn:

Does this engine use ball bearings or plain?

Offline Brian Rupnow

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Re: Senft "Poppin" engine
« Reply #13 on: March 12, 2018, 06:51:44 PM »
And some more---


Offline Brian Rupnow

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Re: Senft "Poppin" engine
« Reply #14 on: March 12, 2018, 06:52:10 PM »
I'm sure your build will be successful or at least informative, Brian! :popcorn:

Does this engine use ball bearings or plain?
Ball bearings

 

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