A "hurlable" Fox .15?

Why would one hurl that? A little cleaning and it would look like a nice little engine.

It makes me want to hurl just looking at it.

The one you show is the Rocket .15 steelfin. The Fox .15 that's hurled would be the .15X. However, I would say those whom participate would certainly not be objected to hurling it. I'm a big fan of Fox .15's and I never had an issue with getting them run. I truly enjoy them and they're great little engines. The steelfins need to be treated with a little extra caution. The wrist pin ends tend to cut grooves in the liner. I would also say that the backplate is on backwards.

lol, my first 'big bore' engine, something larger than a .049 was a Fox .15X, purchase it with paper route money in 6th grade, bolted it to a Ringmaster Jr.

Looks like there is gasket there on the exterior of the backwards backplate. Probably/maybe the PO installed it that way, because if installed properly it would rub on the crank and connecting rod.

Bob, your example is certainly in need of some care. In one of your posts recently you expressed a Babe Bee which you also had some additional parts. I commented on the gasket as it was for a Fox Stunt .35. You also pictured a needle valve which was needle only. That needle is the needle for this .15. Certain parts do interchange from the rocket to the X series such as drive plate, crank. I believe the backplate gasket as well so if yours is damaged, these should be relatively easy to find. These engines do like nitro. I run them on 10%-15%. The oil content needs to be high, 25%-29% oil. It's typical Fox with slop everywhere and that heavy oil just takes up the tolerances. I keep the prop sizes in the 7x4-7x6 range. The .15X turns up higher than the steelfin but the steelfin makes for a great sport .15.

I have two Fox .15 steel-fins, although they are not Rockets. I think that Ken might have mentioned the wrist-pin problem a while back when I posted about mine. If he mentioned a fix for that problem.. I didn't save it to a text-file as I often do with his recommendations. If there "is" a fix.. I'd certainly want to try to apply it.

This one would be my "runner".. It was my Grandfather's.




My other one was stuck/siezed.. and had its' backplate center-drilled for a crank-pressure tap. It was my Uncles'



I tapped the backplate and installed a screw to seal it off.



The latter (seized one) became the victim of a then inexperienced-Roddie. In an effort to "un-stick" it.. I pulled the head, set the case in a fixture (vise.....) and proceeded to tap the top of the piston with a hardwood dowel and hammer.. resulting in denting-in the top of the piston.. as well as freeing it up. Knowing what I know now; I probably could have freed-it with some heat.

On a more positive note; I do have the runner and a parts-engine (less piston)

When my Grandfather gave me his; he included an expansion-chamber. It's an obscure item.. in that there are no markings.. other than my Grandfather's etched name. It's just a bit too sophisticated to be home-made.. and I never thought to ask him where he got it. It fits snugly over the exhaust-port.. and probably is held by a tension-spring around the back of the cylinder.






I've never run it... with or without the muffler. I need to source proper fuel for one thing. Gramps' engine is pretty clean.. and may not have ever been run. When I run it.. I'll treat it to a few break-in cycles; open-face.. and see how it runs.

Here are images of the original operating manual.









I hope that you can get your engine running Bob! I have a Jr. Ringmaster waiting..  with its engine-bearers drilled for mine!

My understanding of the "fox 15 hurl" is for the ball bearing schnurle ported engine that was written out of the rules for some particular event. (combat I think)

That is NOT a hurling engine.

Phil

pkrankow wrote:My understanding of the "fox 15 hurl" is for the ball bearing schnurle ported engine that was written out of the rules for some particular event.  (combat I think)

That is NOT a hurling engine.

Phil

Amen.. and if you're an American.... you naturally have a love for anything well-designed and built here.

I have never known the BB .15 to be the engine to hurl. The Fox .15 BB is a very good engine. Aside from their weight, they offer a lot of power. The slant plug .15X is the hurled Fox. The running joke is that this is the only way to get it airborne.

Roddie, the steelfins use a fiber base gasket. I would only take these apart if absolutely necessary. If you take the head off and start to see signs of the wrist pin marking wear paths in the sides of the cylinder, I would take it apart. Grinding the end of the wrist pin and applying a radius around the perimeter followed by a good polishing is how you buy some more time. I use drill rod if the wrist pin is too loose, I then drill into the end of it and make Delrin end pads. This type of construction was typical with K&B and a few other manufacturers.

Folks have been recommending the Fox .15X for planes of class 200 square inch wing area. Comparing Sceptre Flight Engine Tests, it and my Enya .09-III are in the same ball park HP wise.
Regarding Bob's engine, I'd say go for it, give a good clean up and match it up with a suitable airframe.

Ken Cook wrote:
Roddie, the steelfins use a fiber base gasket. I would only take these apart if absolutely necessary. If you take the head off and start to see signs of the wrist pin marking wear paths in the sides of the cylinder, I would take it apart. Grinding the end of the wrist pin and applying a  radius around the perimeter followed by a good polishing is how you buy some more time. I use drill rod if the wrist pin is too loose, I then drill into the end of it and make Delrin end pads. This type of construction was typical with K&B and a few other manufacturers.

Thanks Ken. A save of this advice revealed a previous saved document of your's from an older thread or PM that I overlooked. I'll summarize between the two, before running my engines. Thanks "again"!

Ken Cook wrote:I have never known the BB .15 to be the engine to hurl. The Fox .15 BB is a very good engine. Aside from their weight, they offer a lot of power. The slant plug .15X is the hurled Fox. The running joke is that this is the only way to get it airborne.

Ah. OK. That makes sense.

I have a Fox 15 BB with extra parts I likely will never use. I felt it was "strong" when bench running, but I had a bad carb and it was a nightmare so I never flew it. Fox took care of me before closing their engine service.

Phil

On the Fox .15 Steel-fin you might find that when adjusting the needle the needle will move slightly after you let go. It is caused by the spring. I found that adding a washer or filing the end of the spring will correct this.

The Fox .15X (slant plug) hurl was created buy some guys in CA. Someone couldn't get his .15X started so others offered to help. The owner got so frustrated he pulled the engine and hurled it. Other guys laughed, then thought about it and the Fox hurl was born. I believe that only the Fox .15X is eligible. Perhaps one of the California guys will add more info.

The Fox .15 steel-fin does not like to be over propped. An 8x4 or a 7x6 should be max.

George

I particularly like Roddie's stamped steel muffler. that must be something from the 1940's or 50's. It was amazing what they could do with stamp steel machines then. I remember seeing a WW2 "grease gun" in an arms room at a National Guard armory in the 1990's. It had a .45 caliber pistol round clip, except for barrel was all made of very heavy gauge stamped steel. I heard that tank crews carried them, because it could be easily carried entering and exiting a tank. IMO, Roddie's muffler is a rare one, indeed.

The steelfin 15 and the 15xs had press fit wristpins.  The pin was free in the front hole (towards the venturi) and press in the rear hole.  The pin is pressed forward to remove and slipped in the front and pressed home to install.  Of course with Fox tolerances, you might expect it to slide forward.


The Steel fin and the .09 were never marked as Rockets.  When the Rocket 35 came out (that was marked as a Rocket) Fox had an ad saying that that his new low priced line would hereafter be known as Rockets and included his 35, 15, and .09.  There was no difference between a steelfin and a Rocket.

Also, Fox used the Rocket crankcase casting (2 version with lugs on front) for his Series 3 needle bearing Combat Special.  He cut the front crank journal off and machined the case to accept the needle bearing front end.  Thus the needle bearing engine with the removable front end is often called a Rocket, but it is a COMBAT SPECIAL.

Ken, nice to meet you and your son at GSCB swap meet Ken.  See you at Lebanon.

I admire everyone's loyalty to your American made, particularly Fox, products, and I know that there are many here who love to fly their Foxs, but from all the negative stuff about them that I glean from the things written here, I really don't see why you would persist when you have engines of such exceptional build quality available out of Japan, being Enya & O.S.
Of your home-grown products, it would even appear to me that K&B engines are far superior in their function & finish than the Foxs. Sure, there are exceptions in everything, but to me, the Fox engines in my collection are a curiosity only, apart from maybe the .049, that would never be considered for use.

Sure, there are those who will think this Aussie doesn't know what he's talking about, but you don't need to look very far in these pages to find a lot of criticism of Fox engines. I can only go by what I read here and clearly there were many "duds" among them. For those who fly them and get enjoyment from them, that's great. I'm glad to have a few in my collection, but I really fail to understand why they are held in such high esteem.

Oldenginerod wrote:... but I really fail to understand why they are held in such high esteem.

I grew up flying Cox and Fox engines. I doubt I am the only one.

My Dad favored McCoy in 19 and 29. Mom flew the same engine choices.

We always wanted OS and Enya but Dad as a mechanic and Mom teaching school there wasn't budget for pricier engines. We stopped flying as a family when my older brothers were in high school.

Phil