Little Bugger!

Ron, how could you do that to your Fox? I'm quite fond of the .15. They can be a fun engine and good weight. Many choose to hurl them. I'm not a fan of the hurl club. They're a good choice for the Akromaster and Jr Ring. Let them sing, don't bog them down with 8" props. Use a thin bladed 7x6 and have fun. Oh yeah, you really should have a adequate engine stand. We were running a Mccoy .60 and had that happen. So much for the nice anodized head as it has a big ding in it now. Hope your ankle is good . Ken

Haha, I mean ow. That's gonna be sore.

“To be is to do”—Socrates.
“To do is to be”—Jean-Paul Sartre.
“Do be do be do”—Frank Sinatra.
 
"Do run Ron"- Ron Cribbs
 
I have heard that Foxes bite!
 

I posted this a couple of weeks ago.

"Hello folks.
A lazy holiday weekend here............. Next was a McCoy .35 Red Head.  Just couldn't get it to play ball until I flooded the heck out of it and off she went.  Man those engines are loud.    All these engines were firmly clamped in my (well) home made wooden test stand, until something we all fear happened.  Gents, beware of complacency.  The final test was a McCoy .29 Red Head.  Fired up really well and peaked out beautifully prior to me adjusting it back to a comfortable breaking 4 stroke.  I thought I tightened the wing-nuts down firmly, but I noticed them vibrating loose.  Do I tighten them? Do I throw a rag in the prop? (Don't do that).  I know, I'll pull the fuel line off.  By the time I made that decision it was too late.  I was looking at the engine one second, and then it just vanished.  Man, did it rev up well as it took off.  Only about 6 feet to the wall of my shed and bang. followed by the tinkle tinkle of bits of prop landing around me.  Fortunately no damage to me or the surroundings that I've noticed.  I retrieve the engine from behind the bench to find that it only had a small scar on the front of one head fin and just the stub of a prop left.  
So the moral of the story is, check everything's tight, then check again.  It could have been far worse.

Rod."


All sounds too familiar.  Fortunately I didn't get hurt, but Ron, that's a nasty place to get an injury.  Lucky my McCoy .29 didn't get me there (or anywhere).  It has the potential to remove quite a bit of skin with a 9" nylon prop.  Complacent it the word.  I knew it had the potential to happen but went ahead anyway.  Mistakes seem to be the only way some of us learn.

Happy Independance day to all our friends in the U.S.A.    

Aussie Rod.

You all are too funny!   

To be honest I wasn't expecting the little guy to be all that powerful. I was using a 7x4. I also think the .15 hurl is idiotic Ken. My little .15 is still in good shape as I think my ankle broke it's fall. It's going on a Jr. Ring

Anyway, my ankle is fine and I am a little wiser. Happy 4th Everyone.  

Ron: Apparently you didn't read my post about having a SAFE 4th. Sorry about your injury. Hope you heal quickly.

   

happydad

  

Ron, what needle valve is in that engine? Not to change the subject, but I believe it was George that posted a week ago in regards to the Midwest p-40. I had one of those kits. The p-40 in my opinion wasn't all that common, you just didn't see them. In the larger warbird series I feel the Skyraider was in the same category. Most bought the Mustangs and Messcherschmitt 109. The P-63 was also a big favorite due to the trike gear. I always liked trike gear, unfortunately it's more weight and drag. It allows for great touch and goes especially coming out of the wingover until you blow the wing through the top. Reason I mention this is that the Fox .15 was a good choice for these. Still made the plane nose heavy, but not like the OS or Enya. I had one with a Medallion .15 which balanced spot on but the power was certainly lacking. Those kits were not the lightest of the bunch. Why no one ever improved on the airfoils of these .15's is a mystery to me. Maybe they felt it would impede the semi-scale look.

I feel with some minor work to these engines, they can really run quite well. Many times the screws on the head can't be adequately tightened due to them stripping out or being caked with castor goo. Replacing them with socket head screws is a good idea. I also lap the top of the cylinder liner on a piece of glass to insure that all is flat. New head gasket and this usually insures good compression. While the modern designs work well and are powerful, they just can't beat the weight of the Fox. Ken

I guess when these kits were designed back in the 1950's, it was a different world then. I imagine the thinner airfoils allowed the planes to fly with sufficient speed on the earlier 15's, which weren't all that powerful.

Then to, although some were interested in competitive stunt and combat flying, most are like our modern RC'ers, basically sport flyers. They were interested in doing some basic stunts, loops, wingovers, may be inverted flight, not not interested in flying the complete stunt pattern accurately. It was a method of socializing with friends. May be even give a shot at combat with a friend. Ease of construction was important. Many of the Scientific 1/2-A kits designed by Walt Musicano were easy to build, affordable, but didn't stunt well. Ditto with others.

However, nothing prevents us from altering the airfoils to thicken them to increase stuntability, nor adding flaps, revising construction to modern standards, upsizing to match today's (or earlier) heavier engines, etc.

   Ron that just made my morning as my neck was really hurting ,,Been there when that fox36x was tring to get off the stand. Glad YOU AND ENGINE are ok. I have a OS15FP on the stand now one of the hold downs broke at the wing nut and I am making some new ones for it    Yea that safe thing without hindsight.....Eric

Ken,

Here is the NV. Nothing special

Cribbs74 wrote:You all are too funny!   

To be honest I wasn't expecting the little guy to be all that powerful. I was using a 7x4. I also think the .15 hurl is idiotic Ken. My little .15 is still in good shape as I think my ankle broke it's fall. It's going on a Jr. Ring

Anyway, my ankle is fine and I am a little wiser. Happy 4th Everyone.  

Ron, my Fox .15 has the original box, instructions etc... and I remember chuckling with my Uncle when we read this note about mounting the engine. I'm glad nothing worse happened to you. Imagine...Headline; "Man's 4th of July holiday gets cut-short.. when his Achilles tendon was severed by an angry Fox that he was playing with in his shed.     

 funny Roddie.

You have an earlier steel fin .15, I don't have one of those, but I hear it's a little more desirable than the .15X.

The .15X is rumored to be more powerful. Supposedly Fox offered a lighter piston and a stronger rod that allowed it to turn up to 30K. I'll believe that when I see it...

Cribbs74 wrote:You all are too funny!   

To be honest I wasn't expecting the little guy to be all that powerful. I was using a 7x4. I also think the .15 hurl is idiotic Ken. My little .15 is still in good shape as I think my ankle broke it's fall. It's going on a Jr. Ring

Anyway, my ankle is fine and I am a little wiser. Happy 4th Everyone.  

I have a couple of those. I bought one when they first appeared (1958, I think). I have never used that small a prop, I use an 8x4 or a 7x6. If it works for you though...good luck with it.

A Ringmaster Jr. should be a good match. Enjoy!

George

Reading this thread I realize that I've owned my Fox 15 for 50 years!

An entire summer's allowance to pay for it; removed from a Jim Walker kit so no engine box per se.

Not a whole lot of compression especially when hot.

I know this is an older post, but I hope your ankle has healed well.
I never had an engine come out of a test stand but I have gotten bit by a wide open .40 with a razor sharp Master Airscrew 10x6! I had my first .40 size R/C trainer and like a Dummy, I decided to break-in my shiny new O.S. .40FP without restraining the airplane which was my First mistake. The Second mistake is in 2 parts, (1) I neglected to shave those sharp edges that M.A. props are famously known for! (2) I forgot to adjust the exhaust tip downward and left it pointing upwards towards the wing. Third mistake, I was holding the plane by the wing where all of the unburnt fuel and oil was being blown making for a very slippery and unsafe grip, Fourth mistake, instead of laying my TX down flat, I stood it up on the bottom end and when I went to grab the TX, it fell over face first pushing the throttle stick wide open which caused the plane to slip from my oily hand and go right into my upper leg! At the time, we were having some pretty bad Winter weather so I was wearing a pair of thick jeans over a pair of Long Johns and the plane hit so hard, it went through both layers of clothing and stopped the engine. Being that it was so cold out, made the pain even worse! Needless to say, after a few painful hours and a few stitches later, I learned some very valuable lessons!

The " DUH I'll never do that again" Shawn

706jim wrote:Reading this thread I realize that I've owned my Fox 15 for 50 years!

An entire summer's allowance to pay for it; removed from a Jim Walker kit so no engine box per se.

Not a whole lot of compression especially when hot.

Years ago, I did some trading and I got an old FOX .15 that had a 2 piece crankcase. That engine ran like a top!
I had it on a Jr. Flite Streak and it was ball to fly!

Shawn

sdjjadk wrote:I
I never had an engine come out of a test stand but I have gotten bit by a wide open .40 with a razor sharp Master Airscrew 10x6!

   Sorry, that would have been funny except for the injury. Like most aircraft disasters, a combination of failures.

Ken asked about the needle valve. I have two Fox .15's that look to be identical. One should be a "runner".. the other has some issues.


The "runner"..



and a close-up of it's needle..



and here's the other one..



and it's needle (looks identical)


This "issue" engine was "stuck" when I got it.. I freed it up.. but it tightens-up near TDC which concerns me. The backplate was also drilled out for crankcase-pressure. A small .062" bore that I was able to re-drill/tap for a short 2-56 machine screw.


I imagine that this "issue-engine" will need a replacement piston/liner... as well as a gasket set and better 3-48 hex-head cap-screws for the head. I actually have a spare gasket set that was with the "runner-engine" in it's box.

Should I try to start the "issue-engine" on the bench? If so; should I use a certain prop/fuel? Would it make sense to run several tanks through the engine with a "slobbering-rich" needle setting with short intermittent 2-cycle phases? I'm wondering if it may be possible to save the piston/liner by a sort-of "re-break-in"? I'm probably dreaming...

Roddie, have you head the head off of the issue engine? Is there varnish and carbon coked up near top dead center on the baffle side? Taking apart this engine in my opinion is something I wouldn't recommend. Gaskets are a bit hard to find and I never use them anyhow as Permatex products work far superior. The steelfin .15 which is what you have was anemic compared to the .15x. Just about every steelfin I've seen which had some time on them developed grooves in the cylinder walls from the wrist pin cutting into them. The base gasket likes to leak and now due to it's age is quite hard. For now I wouldn't worry about it and just run it. I replace them using Permatex Ultra. Backplates can use Permatex anaerobic gasket maker. Using the Permatex for a base gasket can also increase the compression by lowering the cylinder a few thou.  When using gasket maker, don't assemble the parts immediately, let it skin up for a few minutes  and then assemble as you don't want to fully squish it all out.

Fuel for this engine should be slightly higher in castor. While I've parted ways with castor fuels, I would recommend it for this engine to the tune of 23% minimum and 25% maximum. Sig Champion 25% castor and 10% nitro is a perfect fuel for this engine. Running more oil is just going to make one heck of a mess and your performance is going to suffer. I base my prop choices on what I'm flying. For bench running, 7x6, 8x4, 8x5, 8x6. This engine though is much happier with wooden props like the Top Flite Power props of the 60's-70's. Those props are paddle bladed props that have a bit more blade area than a standard Master Airscrew today. APC props of this size aside from the 7x6 would not be a good choice due to weight and the large hub area. This engine really chugs and doesn't like to wind up too much.

Key thing to keep in mind is that the spraybar is clear, they were brass and really develops the green goo syndrome. Check and recheck that the passage hole is clear as well as the through hole in the center of the bar. A good hot plug is in order here.

Running them slobbery rich beats the rod to death. The rods in a Fox are very poorly made using inexpensive materials. Lower end slop develops rapidly. It's very possible that the cylinder or piston  wasn't ever round to begin with, it's a Fox. A mild lapping with the piston upside down in the cylinder may be in order. Don't lap the top portion of the cylinder.  I would use a very mild compound like Brasso. These engines didn't not have very good tolerances to begin with and you can go too far. I would just lap it a few turns twirling the piston while moving it up and down in the cylinder. Clean and check for binds. Go run it. Ken

roddie wrote:
The "runner"..

That's the same style Fox .15 I used to have. It was a great little engine. When I was a teenager with fairly empty pockets, I did a lot of "Horse Trading" for airplane stuff and after I re-kitted my Jr. F.S. I traded my .15 for a scratch built .10 size Taylor Craft and a Super Tigre .11. At the time it seemed like a good deal but looking back on it, I should have kept the .15
Oh well, Hindsight is always 20/20.

Shawn

Ken, Thank you very much for taking the time to write. The engine with "issues" has had the head and backplate off. The backplate; for plugging that case-pressure hole.. and the head; to try to free-up the piston. I did this a few years ago.. (before CEF attained knowledge..)  I soaked the engine in penetrant for a few days with the plug removed.. which didn't yield any results. So then I removed the head and found a hardwood dowel.. slightly smaller than the bore. Then I think I tried tapping the dowel with a hammer.. and finally resorted to mounting the engine in a block and pressing the dowel in a vise.. which pushed the piston down in it's bore..   

I'll have to procure proper fuel.. but here's the 7-8" props that I have on hand. Most are VERY old.. probably 40+ years.. but most are in good condition.





I have some 3-48 socket head machine-screws for the head.. and will look into the gasket sealer(s) that you mentioned for the head and backplate. Are the backplate screws 3-48 as well?