Opposed 4 Compressed Air

[Maryak]

Yes, a big thanks for the assembly shots. :bow: :bow: Had me beat 6 ways to Sunday on how it went together, thought Houdini had given you some pointers. ???

Best Regards
Bob

 

[putputman]

Thank you Chuck, that cleared up a lot of questions.
I really enjoy following all your builds. You seem to have a unique approach to a lot of these tasks.

 

[kustomkb]

Very nice work chuck!

its coming along great.

 

[Bill Mc]

Hi Chuck - Are you going To Convert This Engine Over To Gas Also ? Hee-Hee Just Kidding - Billmc

 

[cfellows]

Waiting on a new bearing for my Tool & Cutter Grinder mods so I'm back working on my 4 cylinder boxer compressed air engine. I finally settled on and got some work done on the valve assembly. The engine will use a rotary valve located in the center on top of the engine. A 2:1 set of gears will rotate the valve 1/2 turn for each full turn of the crank, giving me a 4 stroke operation. The larger valve gear will go on the left side of the valve assembly. The Compressed Air tube from the compressor will fit on the tube on the right side of the valve assembly which will be the back of the engine. Air will enter the rotating valve tube through the hole in the center, then be directed out radial holes in the side of the tube as they align with the holes drilled in the valve body. 1/8" brass tubing will carry the high pressure air to the top of the cylinders.

Since I will be using my slave valve design in the heads, the air will exhaust out the bottom of the cylinder, opposite the air inlet holes. With this design, there will be no need to worry about a return path for the exhaust air back the way it came in which is typical of most rotary valve engines.

The valve body is made from aluminum with a thin wall brass tube pressed into the hole drilled axially down the center, the rotating valve tube is made from drill rod, and the air inlet piece at the back of the engine is made from cold rolled steel.

Chuck

 

[stevehuckss396]

Holy smokes that is nice Chuck.

 

[Blogwitch]

Chuck,

I really love the way you can come up with these small engines 'simulating' the real thing.

I have just got out of deep storage one that I was working on a couple of years ago, and was the first one I designed and made with your help. I am just in the process of 'putting it right' after the better half lost one of the cams I used on it, during her monthly clean up of my shop, and of course, a little bit of bling.

You really do make extraordinary engines out of ordinary materials. A great credit to you.


Blogs

 

[cfellows]

Holy smokes that is nice Chuck.

Thanks, Steve, nice compliment, especially coming from you.

Chuck,

I really love the way you can come up with these small engines 'simulating' the real thing.

I have just got out of deep storage one that I was working on a couple of years ago, and was the first one I designed and made with your help. I am just in the process of 'putting it right' after the better half lost one of the cams I used on it, during her monthly clean up of my shop, and of course, a little bit of bling.

You really do make extraordinary engines out of ordinary materials. A great credit to you.


Blogs

Thanks, Blogs, I tend to favor the old internal combustin engines of all kinds, from marine, to aviation and industrial. However, getting a model to run, idle, and sound like the full size jobbies is a real struggle. Compressed air gives more control and more realistic scale performance.

I remember the engine you built using my slave valve design and was quite flattered that you found it worth investigating. I look forward to seeing the changes you make to it. There are a number of things that can be changed to alter the sound and the performance. Some include how quickly the inlet valve is opened, the open dwell time, and of course the timing. I also like my engines to make a little noise to sound more like IC engines. To that end, I've found keeping the slave valve pretty loose helps. The sound of air escaping past the slave valve when it "fires" enhances the overal sound. Also, in later engines, I've replaced he sliding piston slave valve with a simple ball bearing.

Thanks for the kind words. I also have a v-twin and a radial engine of similar operation in various stages of completion. So many projects, so little time!

Chuck

 

[Blogwitch]

So many projects, so little time!

I know exactly how you feel Chuck.

I have been working on that engine for a few weeks now, and today I managed to get the flywheels almost sorted. It has only taken me about a two weeks to get them done. Normally, they would have been finished in an evening. When I do eventually get it finished (don't hold your breath), I will take a picture or two.

Blogs

 

[NickG]

Coming along nicely Chuck. I agree, I was mesmorised when I first saw one of your compressed air engines, sounding like the real deal. I think at least one of your engines will make just about everybodies list of projects.

Nick

 

[kcmillin]

Chuck,
Wow, that thing is beautiful. those parts are so well blended. They look really nice together.

kel

 

[Deanofid]

Still looking good, Chuck.
The rotary valve running with timing gears in order to mimic a cam is a neat idea.
Are you going to make your own gears? : )

Dean

 

[cfellows]

Still looking good, Chuck.
The rotary valve running with timing gears in order to mimic a cam is a neat idea.
Are you going to make your own gears? : )

Dean

Yep, I will be making the gears shortly. The will be a 15 tooth & 30 tooth, 24 pitch. I have a pretty complete set of commercial gear cutters for 24 pitch.

Chuck

 

[slick95]

Very Nice Chuck :bow:

Closely following your build...

Jeff

 

[kcmillin]

Chuck,
I find the four stroke design of your compressd air engin verry interesting. you say it help the way it sounds, this may be a dumb question, but how does it affect the sound? I too like the sound to be more "authentic", does this method creat a vacume in the motor and then release with a nice "pop" or is it something els?

kel

 

[cfellows]

Chuck,
I find the four stroke design of your compressd air engin verry interesting. you say it help the way it sounds, this may be a dumb question, but how does it affect the sound? I too like the sound to be more "authentic", does this method creat a vacume in the motor and then release with a nice "pop" or is it something els?

kel

The authenticity comes from several factors. The four stroke design has a minor impact on the sound, but does introduce engine mechanical sounds between power strokes, like most full size engines. The slave valve design, because of the way it works, has a much larger impact on the sound. It forces the engine to run at higher pressures which more closely resembles the sounds of internal combustion. When the inlet valve admits air into the head, it pushes a slave valve to one side, against spring pressure. All this mechanical motion plus the movement and release of the high pressure air creates sounds similar to IC engine operation.

Here's one of my earlier engines that operates on compressed air, in 4 stroke mode, with a slave valve in the head.

[ame=http://www.youtube.com/watch?v=CXH2nNLmBXo&feature=related]http://www.youtube.com/watch?v=CXH2nNLmBXo&feature=related[/ame]

 

[kcmillin]

Wow that really does sound good. I like the time inbetween pops.

Thanks for the vid.

kel

 

[BigBore]

..............You really do make extraordinary engines out of ordinary materials. A great credit to you.

Blogs

Couldn't have said it better. I'm a motivated student of your work as well as the other artisans on this forum. (per wiktionary: Artisan _ A skilled manual worker who uses tools and machinery in a particular craft.)

Thanks, Chuck!

Ed

 

[cfellows]

Thanks Ed, Kel, I do appreciate the kind words.

Today I fabricated and fitted brass manifolds. The brass tubes leading to the cylinder heads will be soldered into the holes showing in the sides of the manifolds. I'm including a few pictures of the everything I've made to date assembled... partly cause I wanted to see how it looks and partly so I can fit the air tubes.

Chuck

 

[Metal Butcher]

Lookin good Chuck!

Are you going to make small 'bolt on' flanges for the tubing to be soldered to on the cylinder heads?

-MB