# 1/6 scale 9 cylinder radial build



## ninefinger (Nov 27, 2011)

OK, this is going to be a really slow build so I thought it more appropriate to make a thread here as a work in progress. I'll go back and add info to my thread in "engines from castings" when I'm all done in a couple of years...

OK, for this months progress report I had a go at the crankcase (I won't say how many tries I've had at it so far but its getting up there...lots of stupid, dumb, noob mistakes...)

Anyways this one is a keeper (so far!) and I'm learning as I go so that is worth something.

Here is the part on the rotary table, I've just skimmed the 9 flats where the cylinders mount. I had machined this before using CNC to cut the flats but I decided to double check the CNC and also square it up just a fraction as the cutting from the "front" is not ideal and I had a longish tool stick out.

You can see in the 2nd picture the uncut area - only on this one face. Its probably only 1-2 thou down so I'm going to leave it as is and deal with any consequences later.....

Next up is to open up the faces for the cylinders and drill & tap for the attaching screws.


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## ozzie46 (Nov 27, 2011)

I have my chair pulled up and waiting further posts. woohoo1 woohoo1 woohoo1 woohoo1


  Ron


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## ninefinger (Nov 29, 2011)

Well, just a little bit more progress. I managed to put in the holes for the cylinders. Almost botched the whole thing again - I should have had a plate to clamp it to the rotary table and chuck as it almost came off. Also, this part has a mistake that I'm going to accept for now as I don't see it having a huge effect on the part. The round flange is supposed to be 5mm wide but somehow it has ended up at 4mm with the flats gaining the extra mm. It just means that the back cover screws may protrude instead of being concealed. 

I plan on drilling the cylinder attaching screw holes using a jig as indicated in the drawings - seems reasonable, plus I haven't figured out feeds / speeds yet on the CNC for the tiny drills (#50) needed - I need a higher speed spindle I think.....


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## petertha (Dec 1, 2011)

Nice! I'm interested to know a bit about the design itself. Modeled after a particular engine? Your own plans? Cad? Ignition/fuel type?


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## ninefinger (Dec 1, 2011)

Hi,

No, not my own design - I posted up in the "Engines from castings" a bit of info on this engine but it won't hurt to repeat it here early on in the build documentation.

The drawings are by Robert Roach of Australia [ bobroach1 (at) bigpond.com ], and the castings are by Vernal Engineering in Utah, USA. 

Vernal Engineering has a page on Model Engineering and Model IC Engine Projects website (an excellent site BTW) http://www.modelenginenews.org/
Bruce Satra is the guy behind vernal Engineering and is a pleasure to deal with. http://modelenginenews.org/vernal/index.html

The drawings are not CAD. I have drawn up most of the parts in CAD over the course of the last 2 years or so while I was building up my machine shop / converting my mill to CNC. I did that as an exercise to become familiar with the parts and in some cases, to give me a head start when it came time to machine them.

The engine itself is designed for spark ignition - though I'm sure it would be fine on glow plugs. There are 2 options for induction -both carburated. Either a 1:1 impeller drive for even fuel / air distribution or a more to "scale" in principle 1:5 blower for "supercharging", though at that speed it won't likely add too much pressure and the designer mentions it is a bit problematic, especially if building with the intention of flying it.

It has pressurized lubrication with dry sump (scavenge pump).

Oh yeah - forgot to mention that it is a 1/6 scale version of the Pratt and Whitney Wasp Jr. R-985 found in many pre WW2 aircraft - my favorite being the Beech D17S Staggerwing - I was going to post a picture but I can't find it right now. 

Anyways, here are a few pics of the castings.

Mike


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## Letsflyj3 (Jan 25, 2013)

Thanks for all your pictures.  I have the plans from Bob Roach and am gust getting ready to get started in building this R-985.  Its is my favoriate aircraft engine as I have over 3000 hourd behind 2 real ones.

Letsfly
Dave


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## oblong (May 12, 2013)

What are your thoughts on the plans regarding details needed tools etc.?

Thanks


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## Letsflyj3 (May 13, 2013)

I am just getting things together to start.  The plans are a little hard to read in places and could be clearer in some things. The main concerns I have is the cylinder to barrel threading, so I have ordered the head castings  threaded, from Bruce but have not been able to getting touch with Chris Lauridsen.  I talked to him once and he indicated he had or could supply the barrels threaded so I ordered them but that has been several months and he has not responded to my email about them.  I will keep you informed as to the progress and tools as time goes on.

Dave


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## Letsflyj3 (May 13, 2013)

I would love to have a set of the plans in CAD.


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## oblong (May 14, 2013)

have you seen the 1/6th 9 cylinder R-985 run?


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