twin opposed air engine.

[MCRIPPPer]

here is a 2 cylinder engine i designed. it is almost complete. i just need to build the valve system and a flywheel.

it started out as a 3 inch long piece of 3/4 inch square aluminum block. the cylinders and crankcase are all one piece. the bore is .375 inch and the stroke is 0.500. the valve will be a rotary tube type driven by the gear.

i started it 2 days ago and hopefully it will get its first run in a day or two.

it measures 3.9 inches across the whole engine.



















and the tiny crankshaft.

 

[dreeves]

Man what a cute little engine. I look forward to seeing it run.

Dave

 

[gus]

Very good workmanship. First class finishing.

 

[cfellows]

As Dave said, really cute little engine. Nice design. I look forward to more details as you go along.

Chuck

 

[Shopguy]

Very very nice. I like not only your concept but also the execution.
Keep us posted.
Ernie J

 

[MCRIPPPer]

thanks guys. this is my second model engine. the first one, i just built as i went along and made each part to fit the last. this is my first engine that i did some designing on. although i mostly made the parts fit. i just planned where to drill the cylinder, how far to mill the crankcase, where to tap the head bolts, and thats pretty much it. i figured out how big of a stroke i could fit in the 3/4 inch block, and figured out a conrod length. everything else is "freeform"

 

[AussieJimG]

Good design, good execution. Congratulations

Jim

 

[jwcnc1911]

This is looking nice. I'm looking forward to seeing your valve design.

 

[MCRIPPPer]

i figured out the valve. will post pics a little later. tomorrow i will make some little plugs to fill holes i had to make in order to manufacture the assembly. then i will air it up!

 

[MCRIPPPer]

here are some pictures of the progress so far. the valve works by picking up air from a hole in the middle of the block, then the air goes through the drilled out tube to another hole that distributes air to each cylinder every 180*. the exhaust works the same way. the exhaust goes through a hole into the rotating valve and out the back of the tube.

today i will make plugs to fill the holes i had to make.

 

[MCRIPPPer]

well! it runs! i stole the flywheel off my other engine for the first run. it idles quite nice on around 5psi.

here is a rather poor video of it running for the second time! i will make a flywheel for it and a nice stand and take a better video.

http://www.youtube.com/watch?v=ebu891aLKsY&feature=youtu.be

 

[MCRIPPPer]

here is a slightly better video of it running. i made a little stand so it can be held in the vise. i will make the stand better later.

its also got its own flywheel made now. i will do another "photo shoot" later when i take it apart to clean it out from break in.

im also going to replace the brass bushing with a bearing.

here is the vid.

http://www.youtube.com/watch?v=rQAV3u94X3w&feature=youtu.be

 

[MCRIPPPer]

here is another video of the little motor running.

http://www.youtube.com/watch?v=LrQxbX9ghuA&feature=youtu.be

the little engine runs much better with the addition of another ball bearing replacing the bushing on the main shaft.

 

[cfellows]

I think it needs a propeller... looks like an aircraft engine.

Chuck

 

[MCRIPPPer]

i thought the same thing. i might make one. first i need to get it to go to higher rpm so a prop will actually make a little noise.

cfellows, your aircraft engines are very inspiring. i might have to build one of your designs sometime.

 

[MCRIPPPer]

i made a prop for it and like it alot. it lets you see the engine more then the flywheel allowed. i will have to build another engine to use the flywheel on lol.

here is how to make a nice little prop for small engines. i use a jewelers precision saw to cut this kid of thing out. one of my favorite tools.

first get a piece of heavy paper. draw a line with a ruler and draw half of the prop, like this.



once you are happy, cut it out.

get a piece of metal. i used 20 gauge brass. scribe a straight line and drill a pilot hole in the line. i used sharpie all over the brass so i could see the lines easier. poke a hole in the template and use the drill bit as a pivot. line up the line on the brass and the line on the template and scribe around the template. swing the template to the other side and do the same.



start cutting. if your good you wont need to do much filing.



almost there.







i will get pics of the prop on its spindle and on the engine. i need to make a nice mount for the engine. i noticed that the engine has enough torque to "roll" when i hold it in my hand. i will have to make a loose rubber mount so it torque rolls when i throttle it, which is pretty cool.