How Do I scratchbuild a radial engine?

I make the crankcases out of basswood.  I am working on one for a 1:16 SBD but have the opposite problem- I am working on the cylinder, which I will duplicate with resin casting.

I have the crankcase already done. I have a table saw, which I used to cut the flats.  I made the actual crankcase  a flat polygon with the nose separate. I made a jig, laying out the angles so I could move the block to a new angle, cut that "flat", move the block to the next angle, cut that flat, etc.

I drill a hole in the crankcase blank on the prop axis, that fits over a dowel sticking up from the jig.  The jig slides along the rip fence. The blank starts out as a disk (circular).  The facets where the cylinders mount overhangs the jig and get cut off as you slide the jig along the fence past the blade.

I have a small metal lathe that I use to make the nose (accessory/gear) case. But I think you could just chuck up a block in an electric drill.

Basswood has a tight grain, so finishing it is pretty easy, a few coats of a full-bodied primer like Krylon or auto body primer.

Hello Don,

thanks for the info.

A question if I may, how are you dealing with the cylinders?

I realize you engine is a 1/16, much bigger than my 1/32 scale.

What are you kaing your cylinders out of?

Are they round?

I wish I could get a hold of a Jacobs cylinder but as on tonight, I have no idea of its geometry.

HG

Try googling "jacobs r-755" and "stearman restoration" many Stearmans had the "Shaky Jake" I found plenty of photos from about every angle that way. You may also be able to find a 1/48 scale one, brand: Engines and Things (Roll Models had them just a while back.) and use it as a reference for the upscaled 1/32. 

HGarcia1

Hello Don,

thanks for the info.

A question if I may, how are you dealing with the cylinders?

I realize you engine is a 1/16, much bigger than my 1/32 scale.

What are you kaing your cylinders out of?

Are they round?

I wish I could get a hold of a Jacobs cylinder but as on tonight, I have no idea of its geometry.

 

HG

I am making fins out of cardboard and paper, laid out by CAD, cutting them out with scissors, and gluing them together.  Actually, cylinder pattern is done. I primed and painted it, then intend to make silicon mold of it.

This is fine for 1/16, it would be really tough in 1:32.

Ironically, recently finished the Czech Models "Songbird kit.  They provide two sets of cylinders, for building either military or civil version. I built the civil version, the military version uses Jacobs.  But, that kit is 1:48 not 1:32.

Oh I've done that many times.

Sadly the only images I find are from the front or a 45 degree angle, no side or rear views.

As for Roll Models, nope, not anymore (I got the last two they had ) and the detail is horrible!

I just learned that a Museum close to me has a Waco biplane (still active) and I think that one used a Jake.

I also recently discovered an airdrome close to me where they house a number of vintage aircraft including 2 or 3 Stearmans (I'm on the prowl).  I'm going to hit them up for some technical diagrams.

Yes I have that kit as well. But as you said, it's a 1/48 and it would be too small.

Oh I only with I knew how to use CAD.  That and a 3D printer would solve my problems!

Hello again, both the Waco and the Stearman COULD have the Jacobs. They could have one of several different 7 or 9 cylinder, Jacobs, Lycoming, P & W, Wright etc.

Hello HGarcia1,

You might try the Williams Brothers site they have a few 1/32 engine kits in their RC section, I bought the Wasp a while back and was pleasantly surprise at the detail and at a very reasonable price.

http://www.williamsbrothersmodelproducts.com/rc.html

Cheers,

Thom

Yes they are.

Already have them.

Thanks

DON STAUFFER gave some sound advice.I too have the "SONGBIRD/BAMBOO BOMBER by czech models.The engines are small.You can if you want put one together and then place it under a magnifier. This will enable you to recreate your engine in the size you need. I believe it will work for you. Good luck!! Tankerbuilder

that sounds great don. i've fancied a combat models tigercat in 1/32 but have been put off by the prospect of the engines and props.

I will tell you how I did one,if you promise NOT to laugh!!  I don,t build that many planes and I wanted to display the engine next to the complete aircraft. I was cogitating this problem when my son started playing with his LEGOS on the table next to mine.( I always made a place for him to watch in the shop area) I noticed these little round ones with a flange on them. I call them "buttons) LEGOS calls them something else. I bought 8 from my son,and I told him the reason I paid for them was I might make them so he couldn,t use them anymore. I did the crankcase out out of a piece of LEXAN. When I sanded them down to the height I needed ,I glued them together.I had to buy 8 more! This then is the way I built my FIRST aircraft radial engine. It didn,t look to bad either.Of course over the years I,ve gotten better and now use brass tubing for the cylinder walls and stiff brass sheet for the fins.I still use LEXAN for the crankcases though. I still have that LEGO twelve cylinder radial in storage somewhere. I will look at it once in a while to remind me how I started scratch-building stuff for planes. I still build more things that float though. Good luck and send us some pics to the gallery so,s we can see how you are doing.    tankerbuilder

Here's some pictures, a few months late, and probably a different engine.
This Stearman is based about 10 miles from my house. Didn't know it was there
until a fly-in a month or so ago.

My first ride in an open cockpit.

---Kevin

Hi, although I,ve commented twice ,I have to share another way I,ve done it. When I was aboard my tanker we didn,t have a lot to do after hours so we read , watched movies or built models. Several of the crew were into paper models and that,s where this comes from. I wanted to do a radial engine for a SPAD that I was building and after looking at the instructions I did this. I got some shirt cardboards (My steward never forgave me) and using three kinds of paper punch I got the cylinder parts. I made the crankcase and front dome from lotsa paper glued into a block liberaly soaked in glue and then carved it to shape. I even used spare wire the radio crew had for the pushrods and other visible gear. Doing it this way you can build ANY scale as long as you have good pictures. I do say DON has given good solid advice , but , if you don,t have a fully equipped shop as you can see ,there are other ways. Again , good luck.  commodore4