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Gallery, Projects and General => Gallery => Topic started by: vtsteam on February 26, 2013, 04:40:17 PM

Title: No 83, a Hot Air Engine
Post by: vtsteam on February 26, 2013, 04:40:17 PM

This is a hot air engine I built for my father for his 83rd birthday several years ago.

Made from mostly stuff in the scrap bin, a piece of channel, a piece of square tube, a sink tailpiece, skate bearings, molten scrap aluminum, and some bits of brass.

But possibly more exotic is the graphite piston, and more unusual is the nearly zero connecting dead space between displacer chamber and power cylinder.

This last was achieved by offsetting the two cylinders until they were nearly tangent, with only a small overlap. Holes to fit the cylinders were stop drilled and bored into the massive aluminum rectangular heat sink. these two holes meet and stop in the middle of the sink. so the two cylinders bear against each other, and their axial overlap becomes the connecting passage of zero axial dimension.

There is still a little headspace at the top of the power piston and some around the displacer so I can't claim true zero dead space overall, but but there is none in passages.

Fun to work that out, anyway.

Ran really powerfully when I tried it out the night before I visited him down in Connecticut. And performed wonderfully at the birthday, party but I haven't run it since. So I can't give more performance details. He's not capable of running it himself any more. I also didn't take construction photos -- was in a rush to complete it in two weeks, working from early mornings into the wee hours every night.

Anyway, these are the photos I have.



(http://i786.photobucket.com/albums/yy150/vtsr/vtsr/No83/No83sm3.jpg)

Title: Re: No 83, a Hot Air Engine
Post by: vtsteam on February 26, 2013, 04:42:12 PM

View from above.



(http://i786.photobucket.com/albums/yy150/vtsr/vtsr/No83/No83sm2.jpg)

Title: Re: No 83, a Hot Air Engine
Post by: vtsteam on February 26, 2013, 04:43:46 PM

The graphite piston and displacer gland.



(http://i786.photobucket.com/albums/yy150/vtsr/vtsr/No83/No83sm4.jpg)

Title: Re: No 83, a Hot Air Engine
Post by: vtsteam on February 26, 2013, 04:45:32 PM

Cantilevered shaft and double skate bearings in the big frame boss.



(http://i786.photobucket.com/albums/yy150/vtsr/vtsr/No83/No83sm5.jpg)

Title: Re: No 83, a Hot Air Engine
Post by: vtsteam on February 26, 2013, 04:51:51 PM

Overview of the mechanism. Actually I'm remembering better looking at this one -- I didn't have the two cylinders meet inside the aluminum heat sink, they met whre the brass flange meets the heat sink. That makes more sense -- easier to do. Anyway same effect.

The massive aluminum arms also serve to cool this engine, and stiffen it -- something needed in an unbalanced hot air engine like this one to allow it to rev up higher. Probably balancing would allow even better performance but there wasn't time.

Anyway, that's it for this project.


(http://i786.photobucket.com/albums/yy150/vtsr/vtsr/No83/No83sm1.jpg)

Title: Re: No 83, a Hot Air Engine
Post by: Ronkh on March 16, 2013, 04:56:17 PM

I would love to see more of this please!

Any chance that you could show an up-date?

Kind regards,

Ron.

Title: Re: No 83, a Hot Air Engine
Post by: Stilldrillin on March 18, 2013, 04:43:28 AM

Sorry..... Only just found this  post!  :palm:

I love hot air engines, and that one is a beauty. Bet Dad was pleased!  :clap: :clap:

Thanks for showing!  :thumbup:

David D

Title: Re: No 83, a Hot Air Engine
Post by: vtsteam on March 18, 2013, 09:29:22 AM

Thanks guys, sorry I missed both of your replies earlier.

I don't have any more info about the hot air engine I built -- my father was very happy with it when I gave it to him. I was raised by my stepfather, but my father and I had a connection for a few years late in life. He was an engineer, and I'm glad I built it for him. He was surprised that I had built a lathe, myself and  taught myself to work in metal.   

Since then he had medical reverses after a bad fall, and his cognitive abilities have been reduced. I spent a month with him to get him through the hospital stay and physical rehabilitation. I welded up and installed railings throughout his house, and got him live-in nursing care so that he didn't have to enter a home. But  several months later my brother forcibly took charge of his life and resources, and I'm not welcome there any more.

I don't think the engine will be run by my father again, but I am really glad that I was able to make it for him. And I hope he remembers me some time when he sees it.

If you have any technical questions about the construction, I'll do the best I can to answer. But I don't have it any more and I didn't make drawings of it when I built it. I do have the wooden patterns I made for the side arms, and the other parts can be guessed at -- I still have the graphite piston stock, and the bearings were standard roller skate bearings.

Title: Re: No 83, a Hot Air Engine
Post by: Brass_Machine on March 25, 2013, 12:18:01 AM

I am sorry to hear of the family strife.  That is never fun (been living it for years)

It is nice to see what you made for your father. Gifts like that are amazing... Can become lifelong and heirloom. 

Nice job

Eric

Title: Re: No 83, a Hot Air Engine
Post by: vtsteam on March 25, 2013, 06:16:43 PM

Thanks Eric.

 :mmr: