Noob question - would these parts work?

Discussion on Stirling or "hot air" engines (all types)
Ian S C
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Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: Noob question - would these parts work?

Post by Ian S C » Thu Mar 08, 2018 2:35 am

I think most of the power comes from being an ALPHA motor, my second built motor is a BETA with a 1 3/4" bore, its a wee bit tired now, but it was the one the hacksaw was built for, and it can still run it. Either of those motors can run a radio, or charge a battery.
Ian S C

Blaf
Posts: 32
Joined: Fri Mar 02, 2018 2:50 am

Re: Noob question - would these parts work?

Post by Blaf » Mon Apr 09, 2018 3:46 am

Oh dear, i thought my order for ventilation pipes (which i planned to use for cylinders), i made weeks ago, got ignored since i didn't get any response from manufacturer. Now i've received an email saying the order is being delivered.

It seems i'll have to try to build it anyway...

Ian S C
Posts: 2154
Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: Noob question - would these parts work?

Post by Ian S C » Mon Apr 09, 2018 5:09 am

Blaf, That motor gets its power from being an ALPHA motor, it has no fancy regenerator. With a generator in place it will easily run a radio, or charge a battery. Here it is now with it's air cooling, and I'v removed the side arm on the yoke and fitted a roller that slides up and down in a slot, I also increased the stroke by 4 mm, had to raise the cylinders to clear the pistons, and the big end of the con rods only clear the bottom of the crankcase by a bit over 1 mm. Next job on that motor is to test its power out put.
Ian S C
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Blaf
Posts: 32
Joined: Fri Mar 02, 2018 2:50 am

Re: Noob question - would these parts work?

Post by Blaf » Mon Apr 09, 2018 5:54 am

Ian S C wrote:Blaf, That motor gets its power from being an ALPHA motor, it has no fancy regenerator. With a generator in place it will easily run a radio, or charge a battery. Here it is now with it's air cooling, and I'v removed the side arm on the yoke and fitted a roller that slides up and down in a slot, I also increased the stroke by 4 mm, had to raise the cylinders to clear the pistons, and the big end of the con rods only clear the bottom of the crankcase by a bit over 1 mm. Next job on that motor is to test its power out put.
Ian S C
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You seem to be very productive :) Have you ever thought about making smaller series of some of your designs for sale?

Ian S C
Posts: 2154
Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: Noob question - would these parts work?

Post by Ian S C » Tue Apr 10, 2018 4:14 am

NO, call me lazy, well not really, I just like developing the motors I build, I seem to have slowed up a bit over the couple of years. I make very few drawings when I build a motor, only if I can't visualize a part I then put it on paper.
Ian S C

cbstirling2
Posts: 146
Joined: Sat Dec 17, 2016 9:35 pm

Re: some alpha engines have displacers

Post by cbstirling2 » Wed Apr 11, 2018 5:36 am

Blaf wrote:
Alfista wrote:Blaf,
some alphas have displacers and since you have not started building yet, I would encourage you to consider the possibility in your design. Usually, this has the result of moving the rings of the the hot piston a good distance from the heat. Directly heating the cylinder and piston is rather problematic as it increases both the prospects of friction as well as leakage and complicates the problem of lubrication. If these issues are not addressed, then, if the engine runs at all, it may either run when it is quite hot or when it is warming up but not under both conditions. In any case, the issues of the coefficient of friction and the thermal expansion coefficients are especially important in a heated cylinder. Rider (1905) dealt with this in two ways, he moved the sealing ring as far from the heat as possible and he also used a rather long displacer attached to one cylinder. I am not saying that things must be done this way. I am saying that these are important issues to resolve in order to build a successful alpha engine.

Stainless steel is relatively sticky compared to cast iron but it still could work. In any case, as long as the issues of thermal expansion and friction are addressed with regard to the cylinder and piston combination, then it can certainly work. Keep in mind that the hotter the cylinder and piston, the more difficult the job of lubrication.

Alfista
....
I have to apologize, since it seems my poor english caused a misunderstanding - i was refering to separate displacer in my previous post, as i was under impression its called a "Heylandt crown" in alpha configurations, being attached to piston.
I am aware proposed teflon tape sealing is far from perfect, therefore i already plan to use pretty long 60-90cm) hot cap with displacer/heylandt crown in it. Separation of hot cap and hot cylinder is planned, using flanges with thermal insulation in between.

I should probably attach a picture of some sort, i understand my initial description is not thorough enough.

Regarding the stainless steel stickiness - do you think maybe some additional dry lubricant would help? Graphite powder comes to mind, i found out its quite cheap.
It is called a Heylandt crown in alpha engines. In my book, the word displacer has no business being used with alpha designs...
CBStirling2

Ian S C
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Location: New Zealand

Re: Noob question - would these parts work?

Post by Ian S C » Thu Apr 12, 2018 2:09 am

The Heylandt Crown in an ALPHA motor does have some similarity to a displacer in that it does to a degree work as a regenerator. A honed stainless cylinder with a well made cast iron piston will have similar friction to an ordinary steel cylinder, and not too far off a cast iron cylinder. Metals other than cast iron for pistons will need lubrication, and with both parts in mild steel you could have problems with galling.
Ian S C

Blaf
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Re: Noob question - would these parts work?

Post by Blaf » Thu Apr 12, 2018 1:00 pm

Well, technically it still is a displacer (it displaces medium), and it even does the same job in alpha as in other configurations, the only difference is it is attached to a piston instead of a rod.
Ian S C wrote:A honed stainless cylinder with a well made cast iron piston will have similar friction to an ordinary steel cylinder, and not too far off a cast iron cylinder. Metals other than cast iron for pistons will need lubrication, and with both parts in mild steel you could have problems with galling.
Ian S C
Ian, you are probably responding to the month old post, which Cbstirling2 quoted. Since you already reopened the topic, i already got PTFE tape, so the contact is planned to be between PTFE and stainless steel coated with dry MoS2.

Btw, ive just received these 300mm diameter stainless tubes. This gonna be huge!

Blaf
Posts: 32
Joined: Fri Mar 02, 2018 2:50 am

Re: Noob question - would these parts work?

Post by Blaf » Fri Jun 01, 2018 1:39 am

Soo... i'm now in process of fitting pistons into cylinders, unfortunately the tube i got has some pretty rough dimensional tolerances. Or to be more specific, it's crooked as a bygeorge. Therefore i might need to get some better quality tubes before going on with the construction.

However i at least made a simple animation of this engine in the meantime :)
[youtube][/youtube]

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