New radial engine project concept

[Swede]

For those who have subscribed to the defunct Strictly IC, you may remember one of their cover photos being a 7-cylinder radial which was created using Saito 4-stroke model engine heads. It was gorgeous! For a miniature radial, it was also a bit on the largish side.

Saito 4-stroke model engines, aesthetically, are the best, IMO. They have angled, separate rocker boxes, unlike the O.S. series which have a single rocker-box cover and perpendicular valves. For quite a while, I have been toying with the idea of creating a similar radial engine except on a smaller scale. Horizon hobbies sells and maintains spares for the Saito line. I was thinking of using either the .30 or .40-sized cylinders and heads. Saito produces these as one-piece. Here's a link to the .40:

http://www.horizonhobby.com/Shop/ByC...rodID=SAIE040A

Picture 9 of these in a classic radial! I'd convert it to spark, gasoline, using forced-oil lubrication. About the only change to the head I'd make would be to replace the rocker covers (chromed plastic, I believe) with CNC-machined aluminum.

One way to produce this engine would be to scale the Hodgson-9 crankcase down a bit. What do you guys think? It would take some $$ to buy the necessary jugs, but ultimately it would save probably a year of work, and it would still be quite original.

One other IC engine concept would be 2 or 4 of these cylinders (or O.S. cylinders) in a flat twin or 4-cylinder opposed aircraft engine. I like the concept of using an available head/cylinder combo for experimentation. Anyone who has produced 18 or 36 tiny, stainless-steel valves would probably agree with me that $13 for a pair of precision Saito valves is a bargain, not to mention the rocker arms and other tiny fiddly parts.

[ESjaavik]

Look at this: http://hem.bredband.net/b207653/9-cyl.html
If it's small size you're after, it is too big at 124ccm, but if it's the looks, it is superb.

His head castings comes with rocker boxes and covers and are superb die cast aluminum. I have no connection with them other than being a satisfied customer. And, no, he does not sell finished valves. But you have finished your CNC mill, are there not enough leftovers to convert your lathe? Valves are meant for being CNC-produced with 9*2=18 pieces made after making just 1 program.

The only thing I don't like with the construction is that the pushers are hemispheres and thus only have point contact with the cams.

P.S. I can show some pic's of jigs for machining these heads if there are interest.

[Swede]

Hi Einar, Wow it's the Wright Whirlwind from SIC! I didn't know that the castings were still available. I've always admired that engine. Did you produce one? I'd love to see some pictures if you have, or whatever progress pics you can find.

Hemispherical tappets - true, not optimum, but my Hodgson uses them. The cam is 4340 steel Rc 46 or so, while the tappets are A2. After many, many hours, I can detect no wear on either the cam or the tappets. Perhaps roller tappets/followers could be fitted.

Thanks very much for the link. There is one other radial that I am interested in, the P&W Wasp Jr in 1/6th scale as designed by Bob Roach and head castings by Bruce Satra. I have the prints for the Pratt, but no castings yet, and Satra has zero presence on the www.

I have no problems machining valves, etc. My overall desire is to use the Saito jug as a foundation for a number of engine projects which might ultimately be marketable as a "kit", whereby the user need machine only a crankcase, crankshaft, and of course any other "lower" engine parts.

Again, photos would be very appreciated!! And a word of advice to anyone interested in IC engines that require castings... when they are available, I recommend that one buy them and store them. A lot of great engine designs out there use castings and were designed by older fellows who may not want to support or continue to create castings for years and years. I think I am going to go for this Whirlwind while the castings are available. I really missed out on some other designs from the 80's and 90's in which castings are no longer available... Zimmermans deHavilland designs, for example.

[ESjaavik]

If you go to the site mentioned, then at the bottom there's a link to a Norwegian site. You can find close up photos of some parts there. I'll see if I can place some pictures of the jigs there too this weekend.

And as to buying and storing: I bought 2 sets of 10 heads.

[ESjaavik]

OOps! Just realized I put pictures of some of the jigs there already.
The link is at the top "Videre til avsnitt 2", or just klick here:
http://www.metallhobby.net/KEO9b.htm

[Swede]

I love seeing the jigs and fixtures guys design to work on oddly-shaped castings. Sometimes the fixtures take as much time as the product, but there's no other way to do it. Einar, are you going to produce a Wright Whirlwind, or did you buy the heads for your own projects? I think when I buy my own, I'm going to buy one complete kit, and another set of heads. 10 heads assumes that you will either trash one by mistake, leaving nine, or it assumes that if all go well, you'll have *one* spare. I think 11 or 12 heads at the start, for me at least, would be prudent. With 20 heads, you'd definitely have some spares, or you can take the extras and create singles, twins, or flat-4's. The head is attractive and can create any number of engine styles.

[ESjaavik]

Yes, I want to make the Whirlwind. The extra sets of heads, I bought just for the reasons you mention. (Already trashed one while trying to press home the valve bushings). They come with the possibility of having both ports at the rear, or one at the rear and one at the side. Also when I bought them, it looked like KEO himself was not going to continue making them (he's over 80). But now it seems his nephew will continue offering them.

We are 4 in our club that bought the castings, all of us with too many projects already. So the noise will not be deafening for some time yet. One of the guys have a wire EDM in his basement, so if there are chances of selling some rockers, rods and maybe gear wheels, that may reshuffle his priorities.
The gear wheels are available commercially, but quite expensive at around $3-400 for all of them.

[balsaman]

I owned a Saito 120 and the rocker covers were chrome plated aluminum. Not sure about the smaller Saito's....

[Swede]

Guys, here are some photos of the little Saito "jug". After tearing down this brand-new engine, I am more convinced than ever that this project is very possible, and will result in a dynamite radial. Small model radials are basically unavailable... commercial model radials tend to be pretty big. I'd estimate that a finished 7 or 9 cyl engine using these heads would measure roughly 7-8" in diameter. EVERYTHING from the skirt upwards is very nice.

Note the ringed piston. Good quality. The only part I would replace would be the rod, which has no bronze bearing and seems a bit cheaper than the remainder of the engine. The exhaust port is threaded; the intake port may require work as it is NOT threaded.

Balsaman, you were right, the covers are chromed aluminum. I'd replace these too with some CNC's covers with plain aluminum finish, and perhaps some more elaborate exterior styling.

[Swede]

Thanks to Einar, a set of Wright J5 Whirlwind castings are crossing the pond to Texas! I am going to incorporate as much CNC as I can with this project... it'll do me good (as in learning CNC work) to actually draft the parts with Rhino, run the CAM, and start generating some of these pesky repetitive components with a button-push.

I'm going to primarily post the project to my website, but I'll also get some pictures up here on the Zone, if guys are interested. I'll try to make it a point to post CNC aspects of the construction here.

This is gonna be fun!

[Ken_Shea]

Dang you Swede, I would love to do something like you are doing but do not think it is in me in regards to ability or the patience.

What are the castings you are getting ?

Will you be cad drawing and making all the rest ?

Thanks
Ken

[Swede]

Originally Posted by ESjaavik Look at this: http://hem.bredband.net/b207653/9-cyl.html

Here's the engine. Einar brought it to my attention. What CAD I will do will will be CAM oriented. I'm not going to model the engine in 3D. I don't have that ability... maybe some day!

For example, pocketing of the underside of the heads. With manual machines, one would use a lathe and faceplate to bore the head internals, or perhaps a boring and facing head in the mill. With CNC, I'll be able to park a head below the mill spindle and do a pocketing with ease. Same thing for the connecting rods, which can be done manually, but the shape is complex. A decent CNC setup can create strong, beautiful rods with correct filleting all day long.

This project will force me to get deeper into CAD/CAM than I have so far.