fox is (or is gearing up) to re-release the FOX 50, nice, made in the USA no OEM parts China or wherever from
Hobbsy was talking to Sharon at Fox and just found this out martin
sweet engine have one with a Davis diesel head

I may get one again. My last one would pull a barn full of livestock.

Woops Martin, I need to apologise to you and others, this came from Broken Wings, I did not intend to take credit for stumbling across it, I'm just glad to hear it. I'll re-phrase in the Diesel forum.

Hobbsy thanks for giving him credit but the important thing ITS BACK martin

I got it from someone else.....

I'm just glad we can purchase the 50 again.

i have two fox .50's , i was thinking of trying one in a 68 inch 9 pound plane, you think it would pull it good enough?

In a word, Yes. This engine has the power of a .60 in my opinion. As long as you don't expect to do 3D flight with this plane. This engine will except a wide range of props anywhere from Sport performance right up to exterme fast aircraft. One word of advice though, The company fits the ringed aluminum piston tighter than most other companies dare to, so use castor oil in your fuel to prevent piston galling. I forgot to add this, my Fox .50 pulled over my test stand during running in and fine tuning the carb. Aslo I have used 0% nitro fuel in this engine and it still made bags of thrust[X(]

How fast will they turn a 10-6 APC?

MJD

Actually the .50 isn't designed to turn small props fast. It is designed to turn larger props faster than the smaller displacement engines can.
The .50 being a bored out .45 tends to be flow restricted due to the shallower inlet ports, so it doesn't breathe as well at higher rpms.
But it'll turn a larger prop better than the smaller engines can. The additional displacement helps there.
But as I remember it right, the .50 could turn a 10x6 at about 500 rpms more than a 45 could.
Where it winds up being good is like for a large 40 size scale plane where you want some extra oomph. Or a 40 size 3D plane where you want more vertical performance out of it.
The .50 is able to turn a 11x7 prop pretty well. The 11x7 prop used to be what we used on all the big .60's years ago.
The .40's back then used 10x6 props or maybe a 11x5 or 11x6 sometimes.

If you go to the diesel site FOX 50 (these are new posts) you can see the rpm numbers on the Fox 50 remember as a diesel it will turn a larger prop than on
glow so I guess you have to knock off a inch in prop diameter to get close on these numbers

martin

I think both the Fox .50 and the .47 would turn a 10-6 at 14,700 RPM, but the .50 probably does a bit better on larger props.

The owner's manual quotes 14,500 RPM on a 10X6. The engine is better suited as a stump puller (it's just timed that way)

The .50 has the same .905 bore as the Eagle .60 but the Eagle has a .937 stroke.

Just out of curiosity, how would it compare to an OS 50 SX????

It is hard to say, OS is known to over inflate their engine's actual RPM figures and BHP rating. I believe the Fox will outlast the OS and parts are way cheaper. If Fox puts this engine out with an AAO piston and liner, It will be a Barn Burner.

The 50SX was a pretty good engine. The Evolution 52NX was even better as far as power. I've flown both engines on the same model.