STAS'S and ZEUS

[Robert Zambelli]

I found these two engines in a box of Russian engines that was in storage for around twenty five years.

Both are RC, .42 CID, brand new, ABC, test run on 5% nitro, 23% castor/synthetic. Appear to be very well made.

First photo - STAS'S: Plain bearing, 11.2 ounces, 1.6 ounce factory muffler. Ran it for a few tanks but it's not yet loose enough for a lean setting. Around 9,000 RPM on an 11-5 wood prop. Hemi head, small squish band. The carb ID seems very small.

Second photo - ZEUS: Ball bearing, 12.8 ounces, 2.1 ounce factory muffler. Ran it for a few tanks, turned up to just over 11,000 RPM on an 11-6 wood prop. Very smooth throttling from idle to wide open. Very easy starting.
As presented, neither of these engines seem appropriate for stunt.

I did put two extra head shims in the STAS'S and I'll run it again.
Same for the ZEUS.

I'll learn more as I experiment a bit more.
Anyone heard of or had any experience with these engines?

Bob Z.

[Brian Hampton]

Probably the easiest way for me to answer is to refer you this article by Adrian Duncan.
https://www.adriansmodelaeroengines.com/catalog/main.php?cat_id=254
To sum up, the Stas's were all experimental engines to figure out what surface finishes/machinings would be used on the final production engines which were the Zeus 42 and 61. There were a couple of hundred SE Stas's 42 made but only 50 of the RE version. I should add that the Stas's all had iron piston/liners while the Zeus are ABC.

[Robert Zambelli]

Hi, Brian - you are correct. The STAS'S has an iron liner.

The ZEUS - I made a statement that it is ball bearing but now I'm not sure. I thought the 1.6 ounce weight increase indicated ball bearings.
In any case, the serial number is 0 11.
It appears to be very well made.
The bore appears to be quite small. I used head shims (2) from a Fox 35 - perfect fit.
I can't mount the muffler - the hex head bolts don't clear.

More to come - I'll make venturis for both engines and run them this weekend.

Bob Z

[Jeremy Chinn]

I have some Zeus .049’s. I’ve seen pics of the larger Zeus’, but never held one in hand.

[Robert Zambelli]

Jeremy: How about some photos of the Zeus .049.

Bob Z.

[Dave_Trible]

I have a new Zeus .61.   It was a convert from RC.   It wants to draw a lot of fuel.   I need to fit it with a larger venturi and have put in a larger Enya NVA to allow enough fuel passage.   It just screams full out on the bench even with the previous aftermarket needle about to fall out.   Nicely built though.   I have a number of sort of unique 'onesies".   Hard to justify risking airplane builds on the unknown to test a new engine that won't fit anything else.   Still might on this one.

Dave

[Brian Hampton]

The ZEUS - I made a statement that it is ball bearing but now I'm not sure.
Bob Z

You were right the first time . Here's a look inside my 42.

[Robert Zambelli]

I forgot to thank you - the article was great!  Very informative.

I ran the STAS'S with the two extra head shims - much closer to a stunt run but we're not there yet.
Today I will narrow the squish band, angle it upward and break the edge.
See the attached diagram.

Bob Z.

[Robert Zambelli]

Brian - I did the head mod on the STAS'S as shown in the photos and the PDF file.

Still two head shims but the squish band narrowed from .075 to .044 and angled upward approximately 7 degrees.

Definitely made a difference.

Now, let's see what it does in the air.

Bob Z.