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Sunday, May 22, 2011

Fox 60 Eagle II

FOX 60 Eagle II :- This is a second generation Eagle 2 stroke engine produced in United States Mid West in early 80's to mid 80's. The Eagle engines were produced in two  different sizes the 60 and the 74. Both engines are identical except for the larger cylinder on the 74.

The Designer:- One cannot talk about Fox engines without first introducing their famous designerDuke Fox, founder of Fox Manufacturing Company, and a leading model airplane engine designer and manufacturer.

Type 2 Stroke Nitro Glow Ignition;
Displacement Capacity 0.61 ci 10 cc ;

- 1 cylinder;
- Displacement: 0.604 cubic inches;
- Bore: 0.906 (in.);
- Stroke In: 0.937 (in.);
- Shaft: 5/16X24;
- Weight (no muffler): 19.00 oz;
- Max RPM 13,000;
- Propeller size 11X8;
- Power .97hp 7.2 KW

Design Features:- 
 2 Bearing Crankshaft
4 Position Cylinder Assembly and Exhaust Stack
Ringed Piston or optional ABC Design
2 Needle Carburator
Slant Muffler  

Personal Observations:-
I acquired my FOX 60 Eagle II new for powering my SIG Ryan STA. The Ryan requires an inverted fully cowled installation and I was thinking about an OS 61 FSR for the job but was a little put off with the price of this engine. I settled on the FOX on the recommendation of the hobby shop owner.
I was very impressed by the overall quality of the engine as well as its unique design features which included a two bearing supported crankshaft and a symmetrically attached bolt on cylinder assembly. This arrangement allows for up to four different exhaust positions, which is often useful in scale  applications.
The combination was an instant success and the Eagle performed flawlessly without any tendency to overheat until one day I attempted a roll a low altitude and destroyed the STA and sheared off the needle valves on the FOX.
Another carburator from a FOX 74 was installed and the engine installed in the spitfire but I am having trouble finding needle valve settings that give steady performance throughout the throttle range. The best compromise that I have achieved so far is good performance for the low to mid range throttle setting but fuel starving at the high range.  
The engine is not particularly easy to live with after having lost it's factory settings and the dual high and low needle valves is proving to be a big challenge.
Perhaps I can run the engine at a richer setting by running this engine with a glow driver attached. I intend to use an on-board glow driver for my next flight and check out that theory.

View a short video clip featuring the FOX 60 Eagle II engine:-

RC Universe Forum Threads


The history of Fox "60's" goes way back to the late 1940's. The Fox High Speed 59 (for all practical purposes a .60) was, I believe, his first. It was a rear rotary valve type with a very long front shaft bushing. Intake was odd - rectangular across the 'backplate.' This engine was produced for several years, and in several versions. ...Not sure if earliest versions were spark ignited; those I've seen were glow from the word go.

One notable thing about it, which survived as late as the Falcon and some short case Eagles, pics in jj's post, was the 7-bolt head and sideways plug. It sure saved glow plugs! It was odd, but made sense this way: Four short bolts to hold the head to the steel sleeve top flange, plus three long bolts to hold the sleeve (and head) to the lower case. This made for an interesting combustion chamber shape, and may have had something to do with the distinctive bark of all the Fox 59 head/sleeve versions. LOUD! I think I've even seen an early 59 using different length short (head) bolts, as the two straddling the glow plug were on raised 'pads' compared to the other two head bolts.

The current 'ceramic' 60 is a look-alike for the last of the Eagles, but without the seven-bolt upper end. There was a Fox 78, before the later, cubist,bolt front-to-back, Eagle 1 through ...I lost count. I believe there was a Fox 60 of design similar to the 78.

The more recent Eagles bolted together front to back to allow several things. One was a 1.20 cubic inch opposed twin. This is the first time I've seen that rear rotor 'racing' version .60.

Yes, Duke Fox was a tinkerer! For example, his carbs were actually very good, and there've been many, many types of them. They WERE different to set from the ST MAG and Perry types, so they got a lot of adverse comment. Fox factory's reputation for occasionally sloppy QC didn't help there, either. If a Fox carb fit together well, AND YOU FOLLOWED THE INSTRUCTIONS you'd be well pleased.

Fox also developed several engines that pretty much shared major parts. The slant-plug 1970's 29 and 36 differed in stroke -and of course, casting height to suit the displacement. The 4-bolt backplate 19 and 25, had different bore dimensions. The 25 was slightly lighter, as the sleeve wall was thinner, as I recall.

The current 25BB Schneurle was originally paired with a 19BB Schneurle, similarly by stroke length and mid-casting height matched to displacement. The 25BB is 'square' in the sense stroke and bore are equal; the 19BB had the shorter stroke, of course.

Many of his other engines went through various 'developments' over the years, too. Almost all worked well, as intended, and lasted a long time. Even to this day, parts support is likely to be found very quick, if you break something. Even if they didn't have any original-type replacement parts, most often 'developed' parts for that engine type interchanged!


Lou Crane, Sierra Vista, AZ 

There was the FOX 59  that came out in 1943
I was thinking there was something elese 60 related in between here, but Fox made a number of different variations of the 59 in this time frame.
Then the Fox 60 blue head with dual glow plugs circa 1960
Then the Eagle I  circa 1970
The Hawk 60 in 1976 Mr Fox's first schnuerle ported 60 engine
The Eagle II came out and was replaced with the Eagle III in short order this was around 1978 and 1980 or so.

Re: Good News for American Made RC engine.

I'm sorry, but I have the same article, and didn't read it the way you
did. In fact, in the only measure Model Airplane News used for
ranking, the Fox Eagle .61 ranked 4th. They were ranked by "Torque
per Dollar Spent." By that measure, the rankings were as follows:

1. Thunder Tiger GP-61

2. Tower .61

3. Thunder Tiger Pro .61

4. Fox Eagle .61

5. Megatech M-61

6. MDS. 58

7. O.S. .65 LA

8. Magmun XL61A BB FSR

9. O.S. FX-61

10. Irvine .61

They did make comments in the article about build quality, etc, but
they did not give too much of an opinion about which engine they would
actually buy. After all, they hve to keep all those advertisers
happy. If they are ticked off, my guess is that they don't buy as
many of those full color ads.


  1. Amazing, 13000 revolution per minute, really its very high speed 2 stroke petrol engine.

  2. Im glad I found this post. My brother and I used to love to build and fly planes! Great read while using one of my ab machines! Thanks!