First test run of a new engine

[Gary Dowler]

It didn't get into the air, I had forgotten about fitting the hand me down Ringmaster with a fitting for my remote launch, but I got a test run on the Fox 25 I had fitted it with. Lacking a more modern engine, and having actually read good things about the Fox 25, I opted to give it a try.
It was pretty cold out, around 52deg and trying to rain, so I used some 35% nitro 1/2A fuel (30% castor).   APC 9-4 prop.   After getting it running (used engine) I gave it a tweak and ended up seeing 13,300 on the tach!!!  I was amazed.   It may be too much for this Ringmaster.

Gary

[Target]

I'd guess it would slow down on 10% nitro, unless you're planning on running it on the high-test all the time?

[Dave_Trible]

I'd not be doing that any more or you will melt that thing down!  NOT made to run that way!  10% nitro, plenty of oil, UNDER 10,000 rpm. , 9-5, 9-6 prop.  This is the Fox .35's little brother..........

Dave

[Gary Dowler]

Used the fuel I did because it was the only stuff on hand with "Fox quantity" oil levels.   

[frank mccune]

        I ran one for awhile.  According to old engine tests, it had more power than the Fox .35 Stunt and was lighter.   Some sort of better timing and porting made the difference.  I am talking about the one with 3 rear cover screws circa 1954 I think. 

                                                                                                                                                  Enjoy the Fox,

                                                                                                                                                  Frank McCune

[Steve Helmick]

While I wouldn't run 30% Nitro in any of the Fox .25's...there's quite a variety of Fox .25's, from the most desirable 3-bolt backplate version, to the more common 4-bolt backplate version (has a bolt-on venturi/throttle), and the Schneurle ported one with the switchable exhaust position.

The 3-bolt is the nicest one for a 4-2-4 run, if that's your thing. The 4-bolt is a 2-2-2 engine, but that doesn't make it bad, if you understand that and run it that way, with a low pitch propeller. Same for the Schneurle engine, but even lower pitch and smaller venturi bore. So, which one is it?    Steve

[Gary Dowler]

Steve, I looked. 4 bolt back plate, bolt on venturi.

Gary

[phil c]

The newer bolt-on venturi model should hold up OK to 25-30% nitro if you break it in carefully.  It's the same metallurgy, construction and, I believe, half inch crankshaft similar to vintage Fox engines.  It was primarily a free flight/sport RC engine, so don't expect an easy 4-2 run.  You can get that with higher nitro levels.  The nitro lets you use richer mixtures and helps cool the engine.

For sport flying support the top of the venturi with a pressed on washer or a glob of epoxy putty to prevent it from breaking off on a nose in crash.