Fox 15 1975+

Ian,

Not sure what year that 15X is. It's at least '75 due to the muffler mounting. I think '76 was the first year for the .15BB (My fave Fox .15)

Not sure when the 15X was discontinued and there was not much variation since it's intro in the early 60's.

I imagine the .15BB wiped it out.

The Fox .15's were not always offered with the silencer. That particular silencer like many Fox provides are very restrictive. This same silencer was offered for many of the Fox engines. from the stunt .35 to the Eagle .60. The best way to ruin a engine is to use the over and under holes in the exhaust side of the engine. On the stunt .35 these are 2-56 screws which can hit the liner and distort it if used. NEVER use these screws as that's the worst way to support a large muffler. Use the side screws or adapt a radiator hose clamp to the side mounts. Best thing is take the guts out and pop rivet the end cap back on. Drill the hole out as large as possible and it will still be quiet. The silencer pictured made it's debut around 1974. The Fox .15 is a very light engine for it's size. It suits many of the models of the times. I have a few that run quite well. I've seen these on ARF Flite Streaks with very impressive results. Fox however with their POS needle valve assembly and this one is no different really can test your patience. Austin Craft made a far superior needle for these. There's no comparison in a new Fox .15 BB other than the same piston liner material. Performance skyrockets with the BB .15 over the .15X. What most don't realize though is that the coffin back Schneurle ported .15 was made with a bronze bearing vs the ball raced engine currently available. While these did run well, I had many Fox .15 X slant plugs that could out run them . The Fox .15's do quite well on smaller props. Many try to over prop them with 8" props. While they will turn a 8" the engine is much happier on 7". Ken

Ken, I've got a Fox .15-X, was planning it for a Midwest 33" (838mm) span profile Curtiss P-40 Warhawk combat/stunt CL plane. I ought to use a 7" prop on it? May be a 7x6 wood?

Ken Cook wrote:  What most don't realize though is that the coffin back Schneurle ported .15 was made with a bronze bearing vs the ball raced engine currently available. While these did run well, I had many Fox .15 X slant plugs that could out run them . The Fox .15's do quite well on smaller props. Many try to over prop them with 8" props. While they will turn a 8" the engine is much happier on 7". Ken

Ken,

I believe the bronze bushed schnuerles came with a lower compression head on the CL version and a higher compression head on the RC version. The BB versions came with only high compression heads for both.

For my purposes the Fox .15's work best with either a 7x6 or an 8x4 ... ALL over the counter versions. The newer ones just spin them faster. Of course your needs may dictate a different size.

My first steel-fin (~1958) was a dog when I tried to run it on an 8x6 nylon. It came alive when I went to a 7x6 or an 8x4.  

George

 

George my problem with the steelfin is that the wrist pin cuts grooves in the liner. I like the looks of the steelfin. I believe they did the same thing as K&B did with the Stallion which was just radius and polish the ends of the wrist pin. Fox engines have soft liners. When the .15's including the BB versions are run hard, they wear out. I run them hard so I've gone back to the 7x5's -7x6's. Most of my .15's were using 7x4's and 35% nitro. I pretty much cut that in half and run them on 10-15% nitro. I just lost an engine last weekend when the wrist pin clip dropped out of it's retention groove. This just instantly ruins the engine. The Fox .15's are just smaller versions of the Mark series engines which also suffered from wrist pin clip problems. Ken

In regards to the Midwest kits, the p-40 is somewhat of a rarity. You just don't see those often. I had one as well as the P-63, and the ME-109. Just like most .15 size planes from that era, they build nose heavy.My current ME -109 has a Cox Medallion on the nose which in fact still required 1/2 oz of tail weight.  I personally would not use the flaps when offered and went with fixed flaps as I feel this just reduced too much wing area and the plane would fall out of the air. While the .15x is a lightweight engine, it's still heavy for this plane. Where I feel the problem is with these is that the stab and elevator are small to give it the scale appearance. I feel they should be wider which may just contribute to better flying. I also try to use woodie props on most of my engines like the .15x. I just think it assists in helping the rpm's come up and is easier on the shaft and especially the rod. I use many of the APC's due to availability but I was fortunate to buy a lot of props for these when younger and I still have a good supply. While may don't care for the Fox .15X, I like that engine. It's what I grew up with and it's what I figured out without help. Ken

Ken Cook wrote:In regards to the Midwest kits, the p-40 is somewhat of a rarity. You just don't see those often. I had one as well as the P-63, and the ME-109. Just like most .15 size planes from that era, they build nose heavy.My current ME -109 has a Cox Medallion on the nose which in fact still required 1/2 oz of tail weight.  I personally would not use the flaps when offered and went with fixed flaps as I feel this just reduced too much wing area and the plane would fall out of the air. While the .15x is a lightweight engine, it's still heavy for this plane. Where I feel the problem is with these is that the stab and elevator are small to give it the scale appearance. I feel they should be wider which may just contribute to better flying.

This P-40 that I have was advertisted as a slow combat model.


Regarding its rarity, occasionally I see them appear on E-Bay, although overall it is harder to find Midwest CL kits there.

I'm wondering if it may be the choice of woods used for the prototype consisting of lighter weight contest grade wood, which the balances would work out with, instead of the hard pine consistency balsa that shipped in the kits. If one were to reconstruct the kit using choice woods, perhaps the balance would then work out? It may be worth my while to replace the 3/8" thick fuselage with contest grade wood.

I also try to use woodie props on most of my engines like the .15x. I just think it assists in helping the rpm's come up and is easier on the shaft and especially the rod. I use many of the APC's due to availability but I was fortunate to buy a lot of props for these when younger and I still have a good supply. While may don't care for the Fox .15X, I like that engine. It's what I grew up with and it's what I figured out without help. Ken

Thanks for the advice, Ken on props I should look out for when trying them out. BTW, I'm using plastic 10x6 and 10x5 props on my Testors .35 Red Head mounted to my Ringmaster S-1. Engine has plenty of pep, but the head turned black. Those I've talked to, figured it must be repainted with an incompatible paint. I think they are right, but thought it might be worth my while to try a 9x6 prop on her, to see if that causes her to run cooler.

I haven't tried wood props on her yet, as I have none in 10 inch size. I found the wood to be the trick to get my Enya .09-III TV to run properly. Needle valve setting for hand start up using the plastic APC's and Masters' was very fickle until I went to wood props. It made a world of difference. That engine runs really well on old Top Flite 7x6 wood props from the 1960's I bought from Penn Valley Hobby on E-Bay.

May be if one uses an electric starter then the inertia issue goes away. I'm a little reluctant to use electric starters, as these older engines aren't designed for them. One can destroy the nylon crank throw spacer that fits in the hollow end of the McCoy's crankshaft connecting rod pin. One .35 RH I bought off E-Bay had the pin destroyed apparenly from using an electric start. Head of the spacer was gone with only the shaft left. Aluminum engine back showed scoring from contact with the hardened steel crank pin.

George, let's just start with the Midwest 48" span. They're really on the heavy side and they have too thin of a wing. The Skyraider and the Mustang was the best flyers. The main problem with the plane is the wing. The smaller sizes suffered from identical problems. The main problem like most of the .15's available is that when scaled down, the nose heaviness just like the larger is even more prevalent. A good reason to use wood props. This is why I fixed my flaps due to operable ones. When the flaps operated, the plane would drop as you just took several squares from it until they returned to neutral. While light is favorable, many other factors are needed to make these better flyers. Midwest wasn't well known for light wood in their kits. Larry Richards provided these kits entirely made from contest grade balsa and they were absolutely gorgeous. I would venture to say that no kit was ever produced made by hand like Larry's kits. His 33" span kits flew superb. While he used the best wood available, he more than likely cut the weight of the stock kit by several ounces. These kits came with a high price tag. Enjoy your plane as I really liked the entire series, I just wished that Midwest modified them to make them in turn fly a little better.

I see your quite a fan of the Mccoy. I do like Mccoy's, but I have seen just about every flaw in that engine. A electric starter isn't required to destroy the pin from cutting into the backplate. While yours may have shown signs of this, many of the parts were poorly fit such as the wrist pins crooked through the piston. This causes the rod to snap back and forth on the crankpin wearing into the backplate and reaming out the wrist pin holes. Electric starters shouldn't be used on old engines PERIOD. If the engine isn't starting, put a drop of heavy oil in the cylinder with prime. I'm a fan of the Mccoy redheads but they're really for nostalgia due to them breaking parts or wearing out. I've witnessed first hand when these wear out. It's happened right in front of my eyes as a brand new one directly out of the box wore out. They were very inexpensive engines. Many are infatuated with this engine. The only reasoning I can say is due to the cost of them when they were new. They do run well and in my opinion lend themselves to a terrific run, but they're fragile. Don't fall in love with them. While I have some that are going on 40+ years and running well, I have a HUGE bag of them in pieces. Ken

Ken Cook wrote:George, let's just start with the Midwest 48" span. They're really on the heavy side and they have too thin of a wing. The Skyraider and the Mustang was the best flyers. The main problem with the plane is the wing. The smaller sizes suffered from identical problems. The main problem like most of the .15's available is that when scaled down, the nose heaviness just like the larger is even more prevalent. A good reason to use wood props. This is why I fixed my flaps due to operable ones. When the flaps operated, the plane would drop as you just took several squares from it until they returned to neutral. While light is favorable, many other factors are needed to make these better flyers. Midwest wasn't well known for light wood in their kits. Larry Richards provided these kits entirely made from contest grade balsa and they were absolutely gorgeous. I would venture to say that no kit was ever produced made by hand like Larry's kits. His 33" span kits flew superb. While he used the best wood available, he more than likely cut the weight of the stock kit by several ounces. These kits came with a high price tag. Enjoy your plane as I really liked the entire series, I just wished that Midwest modified them to make them in turn fly a little better.

Thanks, Ken. I look to it more as a sport flier than a contest stunt flier. For beating the air, I imagine it will do fine. Plastic film tends to add weight, but in this case I am more interested in a quick build. Will lighten some by judicious sanding of the fuselage to a tear drop cross section and slight airfoil to the tail feathers.

I see your quite a fan of the Mccoy. I do like Mccoy's, but I have seen just about every flaw in that engine. A electric starter isn't required to destroy the pin from cutting into the backplate. While yours may have shown signs of this, many of the parts were poorly fit such as the wrist pins crooked through the piston. This causes the rod to snap back and forth on the crankpin wearing into the backplate and reaming out the wrist pin holes. Electric starters shouldn't be used on old engines PERIOD. If the engine isn't starting, put a drop of heavy oil in the cylinder with prime. I'm a fan of the Mccoy redheads but they're really for nostalgia due to them breaking parts or wearing out. I've witnessed first hand when these wear out. It's happened right in front of my eyes as a brand new one directly out of the box wore out. They were very inexpensive engines. Many are infatuated with this engine. The only reasoning I can say is due to the cost of them when they were new. They do run well and in my opinion lend themselves to a terrific run, but they're fragile. Don't fall in love with them. While I have some that are going on 40+ years and running well, I have a HUGE bag of them in pieces. Ken

I'm a fan in the sense that I have a couple, and want to try them for my own personal experience. Yes, I hear you, they aren't the greatest engines for longevity. Others say that replacing the lightning bolt red head version piston with one from the Series 21 with Dykes ring provided better wear. Some have chromed the soft iron piston. Ones I have for now have good compression, so it looks like I'm off to a good start. We'll see. I can see the merits of the newer Schneurle engines. A .20 to .25 sport Schneurle properly set up has the power to pull these .35 sized planes. I may gravitate to that route. For now, I'm like a new calf looking through an open gate.

Looks like the .15 I bought the summer of '71, my first big engine!

Nice Jr. Mark,

That's some serious pitch on that prop!

I can't remember what it was (8x6?) whatever Fox recommended. I built the Ringmaster Jr. the summer going into 7th grade, I thought it flew great, later made drop off LG,

George, one problem with the Mccoy is the noise. If this isn't a problem for you it's a non issue. The .19 redhead is louder than the .35. I've muffled these engines. It really isn't good for them and it does rob power. Making tongue mufflers helps or at least I like to think they do and provide less restriction. I've gone through my parts and I have been able to make a few good runners. I've also owned a few of the Dkyes ring Mccoy hybrids.I find myself always turning back towards the Fox .35 The Mccoy's have a place for me due to learning to fly inverted using them. I never found them to be fussy with tank options and generally they were reliable at least until they lost compression. Many of the .19's I own are essentially new but won't start without adding STP oil treatment mixed with my fuel. Once running though they keep going. I have one that just won't die. It's a smooth shiny case .19 with a modified tube muffler utilizing a radiator hose clamp strap that really has a silky smooth snap to it. I guess they got this one right. One Mccoy that doesn't get much play or one that I rarely hear mentioning is the Mccoy .29. This is a fast runner compared to the .35. I have one currently on a Yak-9 with a Rev Up 9x6 that just punches holes in the sky. I always think it's going to hand grenade . I run it hard and it takes the punishment. Ken

getback wrote:Hello! I just got a McCoy 35 red head in the mail , the plug is bent ...what plug do ha recommend for this rascal ? it has good compression and I would like to run it (its my first Red Head ) And the fuel 15-20% extra castor ?? Thanks Eric

Eric, Nice looking engine, looks like they may have repainted the head. I've been told that Duplicolor Ford Red engine spray paint is the closest match to OEM, not fuel proof, but somewhat fuel resistant.

I've been using Swanson Associates Fireball hot long plugs. Hot range seems to be best. Some use an RC idle bar plug to prevent fouling of the plug element due to higher oil content fuel. I was short on plugs and a friend installed a Fox plug, worked fine in the engine.

I'm using standard RC 10% nitro fuel with 18% oil content, Castor 2%, adding 16 oz Klotz BeNol Racing Castor to give 25% oil with roughly 10% of it as Castor. There is a lot of debate on oil content. Some say all Castor with 29% oil, some say at least 25% with half Castor and etc. I've taken a more practical approach because in my neck of the woods, nearest hobby shops are 95 miles away in 3 directions (Amarillo, Lubbock, and Roswell), two hours and $40 in round trip fuel costs. They only carry the RC stuff. Anyway, my 2 cents.

Why not order online? Buy 4 quarts from SIG and pay $10 to ship.

Cribbs74 wrote:Why not order online? Buy 4 quarts from SIG and pay $10 to ship.

Problem is, only Sig Champion comes in quart bottles. Oil package is 10%/10% Castor/Synth for 20%. One still needs to add oil to make 25%. I'm thinking that if one purchased Sig's all Castor (25% oil) and bought a case, even with Hazmat costs would still be cheaper. I've 3 gallons and need to burn those first. There are options.

I've had great success in the past running my old McCoy RH .35 with a Fox idle bar plug.

Shawn

Being quite fond of the Fox .15's, I always keep an eye out for them. I have many new in the box examples that I just like to look at now and then. Last week on Ebay one particular version caught my eye. This would be the Fox .15 MK IV Combat Special. I don't believe many of them were made and 2 appeared on Ebay last week. Quite mysterious I must add or just coincidental.  The Fox .15 BB is virtually a scaled down Mark Series .36 engine. The Fox .15 Combat special is quite easy to identify. This engine has a anodized and quite large drive washer similar to the MK VI engines. This aluminum drive washers extends back over the front of the case. Fox didn't make many of these engines as they were special to the NATS in the 80's. This Fox .15 came equipped with the Fox .36 crankshaft. It was pretty hopped up and this one just sold for $228.00.

             Here's my contender. About the only thing Fox on this engine is the case, ABC piston sleeve, crank timing altered and custom  head.button and cylinder head fins anodized black ( Nelson Head recently finished).  Note that this engine is run on bladder via the backplate as there's no venturi aside from the gaping hole in the case. I wish we could run bladders in clown racing as I feel this would truly dominate. I have many cases with the flanges for the venturi milled off. This is the solution to using them once again due to the case breaking. JB weld will work temporarily. Ken

That's a neat looking engine Ken.  The one thing I love about the forum is I always learn something new and that engine is definitely something new to me. I've never seen one like that.

Shawn

Soooooo.... It breathes air in the front, and fuel in the back, with no valving or timing of any kind to regulate the fuel, apart from the pressure in the bladder & pressure differential in the crankcase, am I right? I would never have thought!!

Rod.

Yes, that is a rather interesting variant of an engine that Ken supplied, thanks Ken. Things folks do in competition to compete are amazing, pushing the state of the art in engines. I'd be curious what size props one would run on this modified Fox, along with type of fuel and RPM expected.