Author Topic: 3 Cylinder Radial Compressed Air Engine  (Read 17223 times)

Offline cfellows

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3 Cylinder Radial Compressed Air Engine
« on: May 29, 2013, 09:11:10 PM »
I saw Nick Muller's 3 cylinder radial engine several weeks ago and asked him if he would be willing to sell me one of the castings.  He graciously agreed to and yesterday the casting arrived via US Mail.  There was no glaring evidence that the package had been opened by customs and, so far at least, no invoice from the Post Office or Customs Office for any fees or duties.

The casting was nicely done although it did require some cleanup with a file to remove flashing and smooth some of the edges.  Here is a photo of the casting mounted over the 3" 3-jaw chuck on my 7" minilathe. 



Not the best work-holding method, but by taking light cuts and slow feeds, I was able to face off and turn down the outer end.  I also drilled out the center hole for the crankshaft, starting with 1/8", followed by 5/32", and finishing up with 3/16". 

I plan to mostly follow Nick's plans but want to incorporate my slave exhaust valve in the head, so the top end will be quite different.  My head design won't be quite as nice looking as Nick's, but I can't use my slave valve with his design... bummer.

Chuck
So many projects, so little time...

Offline vcutajar

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #1 on: May 29, 2013, 09:37:47 PM »
Will be following Chuck.

Vince

Offline b.lindsey

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #2 on: May 29, 2013, 10:22:09 PM »
Wow Chuck....i hope you at leasr stopped long enough after the fairbanks to take a breath :) Will look forward to following along on this one too!!

Bill

Offline MuellerNick

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #3 on: May 29, 2013, 10:26:24 PM »
I, for sure, will be following too!


I don't remove flash, because I know everyone has his own opinions how things have to look afterwards.
Chuck, what you did was the most critical machining, but you mastered it! I have ruined a few castings at that step. :)


Nick

Offline cfellows

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #4 on: May 29, 2013, 11:11:37 PM »
Thanks, folks, gotta keep making some chips while I'm fussing with the paint job on the Fairbanks. 

I made a prototype of the cylinder.  I also made the head as an integral just because I could and it simplifies things (if it works).









The piece was made from a 1 1/8" length of 3/4" diameter brass round.  The bore is 7/16".  The cuts for the fins are .060" deep and the diameter of the bottom which will slide into the casting is 9/16" diameter. The side with the small hole will face the front of the engine where the compressed air will be admitted with a tube, much like Nick's design.  The large hole, then, will face the rear.  The slave exhaust ball bearing and spring will be inserted from this end and will serve as the exhaust port.  This obviates the need for an exhaust port in the crankshaft, simplifying construction and reducing the air leakage (hopefully).

Chuck
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Offline b.lindsey

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #5 on: May 29, 2013, 11:30:19 PM »
Chuck, is that cylinder sitting on a pink granite surface plate or the wifes countertop. If the former i am jealous :)

Bill

Offline cfellows

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #6 on: May 29, 2013, 11:54:05 PM »
Chuck, is that cylinder sitting on a pink granite surface plate or the wifes countertop. If the former i am jealous :)

Bill

It's the wife's kitchen counter top, but now that you mention it, I don't see why I couldn't use it as a surface plate...  as long as she didn't catch me!  :hammerbash:
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Offline Tennessee Whiskey

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #7 on: May 30, 2013, 12:13:06 AM »
Just don't wipe it down with WD40 when you finish, it's a dead give away :lolb: :old:

Eric

Offline Don1966

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #8 on: May 30, 2013, 12:38:22 AM »
Chuck are you going to take a breather bud, you burning the candles at both ends here.  :lolb:
Well you are certainly off to a good start anyway.

Don

Offline Swifty

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #9 on: May 30, 2013, 04:51:06 AM »
Chuck, you get more done in a day than I get done in a month. My wife is happy that I have a hobby, but within reasonable limits, your wife must be very supportive or just wants you out from underfoot.

Paul.

Offline cfellows

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #10 on: May 30, 2013, 05:17:17 AM »
Well, I am retired and we have the house pretty much set up the way we want it.  We don't travel or entertain and my wife has her social groups and the grandkids that keep her busy.  So, other than chores like yard work, taking out the trash, etc., I'm pretty much free to do what I want.  Actually, lack of energy keeps me out of the shop more than anything.  I could have been out in the garage making the other two cylinders for this engine but instead I spent the afternoon and evening putzing around on the computer and watching TV.  Sitting in my Lazyboy with my laptop cruising the internet consumes at least 3 or 4 hours every day.  But, in fairness, it is usually educational and hobby related stuff.

Chuck
So many projects, so little time...

Offline MuellerNick

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #11 on: May 30, 2013, 07:42:53 AM »
I just thought, that it might be a nice addition to my plans, if I include your slave valve system as an alternative.
If you allow, Chuck!


So that would be a modified crankshaft and a new cylinder head with the valves.


Nick

Offline cfellows

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #12 on: May 30, 2013, 03:10:33 PM »
I just thought, that it might be a nice addition to my plans, if I include your slave valve system as an alternative.
If you allow, Chuck!

So that would be a modified crankshaft and a new cylinder head with the valves.

Nick

Sure, Nick.  Feel free to include it in your plans.  I made the head and cylinder as one piece, but it should be easy enough to make the head separate from the cylinder. Attached is a rough drawing with the dimensions I used on my version.

Chuck

« Last Edit: May 30, 2013, 03:15:18 PM by cfellows »
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Offline cfellows

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #13 on: May 31, 2013, 12:31:56 AM »
I completed the heads and began work on the body casting today.  My fixture isn't very fancy, but it's all I had and worked find.





I bored the opening for the cylinder with 1/4", then 3/8", then 1/2" end mills going very slowly.  I finished the bore diameter to 9/16 using a boring head.  Nick's castings are pretty accurate so no special fixtures were needed.  The cylinder clamping ring seems kind of fragile, so I was slow and cautious drilling, splitting, and tapping it.





I drilled the crankshaft bore out to 7/32" and Loctited in a 7/32" OD x 3/16" ID brass tube.  I figured that would make better bearing material for the crankshaft.

Next, I'll start the crankshaft...

Chuck
« Last Edit: May 31, 2013, 12:44:16 AM by cfellows »
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Offline Don1966

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #14 on: May 31, 2013, 02:10:30 AM »
You go chuck, Looking good bud. Dang your making headway.  :ThumbsUp:

Don

Offline cfellows

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #15 on: June 02, 2013, 05:19:36 AM »
Thanks, Don.  Today I finished the connecting rods and the pistons.



I made the rods out of 1/4" x 3/16" aluminum, the milled the crankshaft ends to overlap each other.

Chuck
So many projects, so little time...

Offline ths

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3 Cylinder Radial Compressed Air Engine
« Reply #16 on: June 02, 2013, 06:34:34 AM »
Looking good Chuck. How did you go about indexing the casting for milling on that fixture? Is It a bit of angle iron?

Hugh.

Offline cfellows

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #17 on: June 02, 2013, 03:46:47 PM »
Thanks, Hugh.  The casting is mounted on a piece of 4" x 4" x 1/2" aluminum angle.  I picked up 3 pieces of this angle at a scrap yard a number of years ago and kept them for fixturing after squaring them up.  For indexing, I just laid a flat piece of metal across he top and eyeballed it against the top of the aluminum angle.  There's also a thin line scribed on the aluminum angle that is directly in line with the threaded rod holding the casting to the fixture.  Side to side positioning of the cylinders on a radial engine doesn't need to be terribly accurate as long as it looks straight.

Thx...
Chuck
So many projects, so little time...

Offline b.lindsey

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #18 on: June 02, 2013, 04:21:22 PM »
Its looking great Chuck!  Did you take any pics of how you split the three legs to clamp the cylinders?

Bill

Offline cfellows

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #19 on: June 02, 2013, 07:02:34 PM »
Thanks, Bill.  Here is a photo of the setup I used to cut the clamping rings for the cylinders.



I used the same setup to drill and tap the holes for the clamping screws.  I may have already stated this, but the casting was pretty uniform and accurate so it didn't require any extraordinary fixturing setups.

Chuck
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Offline b.lindsey

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #20 on: June 02, 2013, 07:45:37 PM »
Uniformity does help....thanks for the setup pic.

Bill

Offline cfellows

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #21 on: June 03, 2013, 04:19:34 AM »
I think tomorrow will see this thing running. 







All I have left to do is mill the air valve flat on the crankshaft and make the air inlet tubes.  The cylinders are complete with the exhaust pipes, the slave ball valve, and springs installed.  The rods and pistons are also complete.  The engine turns over freely so if I can get the flat on the crankshaft in the right position, it should run.  Oh, yeah, I also have to make a mount for it.

Chuck
So many projects, so little time...

Offline vcutajar

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #22 on: June 03, 2013, 06:17:31 AM »
Chuck

You are killing me.  In less than a week you are going to have another runner.

Looking forward to see it.

Vince

Offline ths

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3 Cylinder Radial Compressed Air Engine
« Reply #23 on: June 03, 2013, 06:46:43 AM »
Smart work Chuck, thanks for showing us. The dremel set up is also instructive. And as Vince said, another week, another engine.

Hugh.

Offline b.lindsey

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #24 on: June 03, 2013, 02:20:26 PM »
Chuck, are you planning on running it with a prop or flywheel?

Bill

Offline cfellows

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #25 on: June 03, 2013, 10:54:29 PM »
Thanks, guys.  Bill, I got the engine running today.  I have a small flywheel mounted on it for the time being.  However, I'm planning to make a prop out of thin steel since I think it needs a prop and the weight makes the engine run smoother.

I want to make a stand for it before I do a video of it.

Chuck
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Offline cfellows

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #26 on: June 04, 2013, 11:25:59 PM »
Here's the finished engine.  Runs great, scary fast!

<a href="https://www.youtube.com/watch?v=RrL0M3OkADY" target="_blank">http://www.youtube.com/watch?v=RrL0M3OkADY</a>

Chuck
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Offline b.lindsey

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #27 on: June 05, 2013, 12:35:38 AM »
That runs great Chuck.  I see it is running clockwise when viewed from the front. Given the valv set up will it run either direction?  Nice job btw!!!  :praise2: :praise2:

Bilk

Offline Don1966

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #28 on: June 05, 2013, 12:44:00 AM »
Chuck you're just to much, another engine and great runner. Your making us look bad man!  :lolb:
Great work as usual.   :praise2: :praise2:

Don

Offline MuellerNick

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #29 on: June 05, 2013, 06:47:07 AM »
Hey Chuck!


Your's clearly sounds better than mine, I have to admit!
I'll add your valve design to my plans as an alternative in the near future.


 :cheers:
Nick

Offline Thayer

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #30 on: June 05, 2013, 06:54:56 AM »
Chuck,

That is a great runner indeed! Congratulations. I couldn't help but be reminded of the old Whirlwind by Bert Pond from years ago. My guess is you could turn a much larger prop if you wanted to.

Thayer

Online sco

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #31 on: June 05, 2013, 08:01:31 AM »
Yeah good stuff Chuck!

Looks great as a three but could it be extended to six?
Ars longa, vita brevis.

Offline MuellerNick

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #32 on: June 05, 2013, 08:07:10 AM »
Quote
but could it be extended to six?


An even number of cylinders looks odd. :)
Radials always (?) had an odd number of cylinders. Yes, more would be possible. But the diameter of the hub has to increase as the number of cylinders increases.


Nick

Online sco

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #33 on: June 05, 2013, 08:37:51 AM »
How about a five then?

I've been thinking about making the central 'hub' from a chunk of Ally rather than a casting so would have free choice on the number of cylinders.

Simon.
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Offline MuellerNick

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #34 on: June 05, 2013, 08:57:30 AM »
Quote
How about a five then?


You can make any number, as you want. You won't have any problems coming from the oddness or evenness of the cylinders as this design works like a two-stroke.
It is just that even cylinders look strange. At least to me.


Nick

Online Jo

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #35 on: June 05, 2013, 09:05:37 AM »
If you are building a radial four stroke you have to have an odd number of cylinders because it operates on a "skip and fire cycle". If you had an even number of cylinders half of the cylinders would never fire  :facepalm:.

Jo
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Offline b.lindsey

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #36 on: June 05, 2013, 12:21:28 PM »
SCO....you could think about doing two rows of three to get the total of six cylinders, then offset the rows by 60 degrees if my early morning math is correct for an even appearance.

Bill

Online sco

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #37 on: June 05, 2013, 12:39:59 PM »
Bill,

Yes I wondered about that - searching on the internet there is a Bristol 18 cylinder radial aero engine - an even number of cylinders but it's two rows of 9 so complies with Nick's requirements I think!

Simon.
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Offline MuellerNick

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #38 on: June 05, 2013, 12:56:02 PM »
Yep! Two rows is a new game.
The even number of cylinders comes from the way the camdrum (they had no camshaft) was and that they were all 4-strokes with pushrods.
If they had had OHC, they could have had andy number. But OHC was not common at that time for radials. At least to my knowledge (that doesn't mean too much).


But I think, we are drifting off way too much from Chucks work.




Nick

Online sco

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #39 on: June 05, 2013, 01:00:56 PM »
Yeah but Chuck knocked it out way too quick - we need to persuade him to attempt a multi-row version  ;D
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Offline cfellows

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Re: 3 Cylinder Radial Compressed Air Engine
« Reply #40 on: June 05, 2013, 01:17:43 PM »
Thanks, folks, for the comments and support.  A five cylinder version may be in my future sometime.  I've thought about building Rudy Kouhoupt's 5 cylinder radial using my slave valve arrangement and may do that at some point.

I just wanted to add a few notes for those who are interested.

The crankshaft on my model has a diameter of .1875" of an inch.  I think Nick's crankshaft was closer to .27" so larger crankshafts are certainly not a problem.

Another thing to consider is the air pressure it takes to run my engine.  While the spring loaded ball exhaust valve engine is somewhat simpler to make it does require from 15 - 20 PSI to run.  And, it won't idle as slowly Nick's design.

Finally, the parameters of the spring and ball bearing are somewhat critical.  The ball bearing must move freely in the bore and a clearance of several thousands of an inch is desirable.  The spring must also fit loosely and have a very small compression force.  The springs on my engine are about .008" wire size, 1/8" OD, and just barely long enough to hold the ball bearing in position between power strokes.  The stiffer the spring, the more air pressure it takes to run the engine and the faster it will run, but won't idle as slow.

Chuck
So many projects, so little time...

 

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