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Thread: Club FOX!


  1. #2651
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    RE: Club FOX!

    Cougar429, I think Fujiman is really referring to Glow-Gas fuel. They mix methanol with the gasoline and oil to make glow-gas. You can figure out how much methanol is needed to keep the glow plug heated up when the engine is running, then the engine runs off the mix quite well.
    Granted it isn't perfect but it works. If you find a source for methanol you can get it for like $3 a gallon from some race car specialty places (usually a 5 gallon minimum).
    It is similar to some of those denatured alcohol brands that have a fair amount of methanol added to the ethanol and thus it works as a glow fuel then.


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    RE: Club FOX!


    ORIGINAL: carddfann

    Sounds familiar. As you probably know, Fox tried designing their engines for no or very low nitro back in the early 80's (if I remember) with the idea that they're doing modelers a favor to help save money with rising cost of glow fuel. But, it didn't catch on that well because people still used nitro that was a bit too much because it was what the imports were designed for or they thought they had to use. Also, most people used what ever fuel the local hobby shop carried. When there was a problem due to wrong fuel (no castor or too much nitro), Fox got the blame. Its risky to design a engine to use a fuel that's outside of what everybody typically uses because people refuse to read and follow instructions so its the manufacturer's fault.


    Back around 79 or 80, I called the Fox factory one day. I was unhappy that Fox engines were designed to burn their Missile Mist fuel. Missile Mist had 25% nitro content and was not the cheapest of glow fuels.

    Duke and I talked for a couple of hours about this very subject. At the time, I was flying pattern (competition aerobatics) and I practiced a lot, burning copious amounts of fuel. Duke asked me which engines I used and I told him that they were not Fox engines. He asked me why and I told him because his engines didn't run that well on no or low nitro fuel, as did the European designed/made engines such as OPS and Rossi, just to name two. I told Duke that I would rather invest in a more expensive engine that would burn inexpensive fuel, versus having a cheaper engine (Fox) that burned expensive fuel. He asked me why. I said that the fuel goes through the engine and is lost forever, along with its expensive price. The more expensive engines retained their resale value and burned much less expensive fuel, in those days. They were better bargains. Shortly after that, Fox began emphasizing that their latest engines were set up to burn low or no nitromethane fuels. I like to think that I had something to do with that change.


    Ed Cregger
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    RE: Club FOX!

    Well done Ed, you were ahead of the times. I hope people turn this thing around before glow fuel and engines become extinct.

    I think most of my 2-stroke engines can run on low nitro except the OS that I have. I tried 5% nitro fuel on it last year and it puked. It is great on 15% nitro, but no lower.
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    RE: Club FOX!

    I'm as bit curious about Fox engines, but I can't tell from the website what the features of the RC glow engines are. What are th differences beween the "Fox 40 RC Sport Model Engine", the "Fox 40BB RC Delux Model Engine" and the "Fox 40BB RC STD Model Engine"?

    Is Fox still intending to market and develop glow engines, or are they really more interested in competing in the gas engines and specialized CL stunt engines?

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    RE: Club FOX!

    Fox has been rather weak in the marketing department in recent years. They have a nice website but terribly underutilized. They could do so much more to make it better for customers by providing better pictures and information. Any way, here's the differences.
    * 40 Sport is a basic lapped iron piston engine with bronze bushing and its a schnuerle ported.
    * 40 Standard is the same as Sport, except it is ball bearing
    * 40 Delux is like the Standard, except its ABC. I have no idea why they call it a non-descriptive name like delux. Sounds like something you'd call a cheeseburger - just say ABC so people know what it is.

    Anyway, the 40 has been around a long time and is a good little engine. I have one in an old Sig Kadet and another in a CL Nobler.
    They are still into developing glow, but its at a snails pace since they don't have the resources and its not their main business. They recently came out with a new 60 CL, a ceramic 35, a much improved carb for their larger glow engines, and a gas version of their 50. They were working on a ceramic 46 and 25 but I don't know their status. They also have a very nice line of large gas engines but its hard to compete price wise with the Chinese imports.

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    RE: Club FOX!

    carddfann, thanks for that explanation. I always wondered what that bewildering list of engine choices was.
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    RE: Club FOX!

    That little Fox .40 Sport will swing a 10 x 6 @ 13000 on 10% nitro fuel and is one of the lightest .40's out there.

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    RE: Club FOX!

    Both of my Fox 40's are their sport version. One is RC and the other is CL.

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    RE: Club FOX!

    The small case Fox .40 engines are sort of the first of the big bore .25 size engines that came out many years ago, when a .25 engine was considered big. The Fox .40 is only slightly more wide, if even that much, than a OS 35AX or a Thunder Tiger pro 36 engine for example. So it makes for a good hop up for a .25 size engine powered airplane. Plus the prices are good too, you can almost buy two of the Fox .40 sport engines for the price of a OS 35AX engine. the BBRC version is still less expensive than the OS engine. At this moment Tower wants $155 for a OS .35AX engine where Fox wants $100 for the standard engine, $112 for the deluxe BBRC engine and $85 for the standard RC engine. The Thunder Tiger Pro 36 is selling for $95 at Tower. of course with a trade in clunker engine the Fox engine prices are even lower.

    The Fox .40 Sport engine weighs 9.5 ounces and the OS 35AX weighs 12.8 oz. The Fox Deluxe .40BB engine weighs slightly more than the standard sport engine due to the bearings being added to it. of course mufflers add more weight too. The Thunder Tiger pro 36 weighs 11.6 ounces with muffler though.

    The Fox .40 small case engine traces its ancestry to the .29X and .36X control line engines used in combat, etc, before Fox bored it out and made it into the .40 we see today.


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    RE: Club FOX!

    When I first began messing with competition fun fly models many years ago, I remember coming across engine reviews of the Fox bushing .40 and the standard ball bearing .40. I found it interesting that the power difference between these two was barely discernible on the dynamometer.

    It turned out that my OS .32F-H was marginally more powerful than my friend's equally new and broken-in Fox .40 Deluxe. I was surprised and somewhat disappointed.


    Ed Cregger
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    RE: Club FOX!

    The OS 32F is a pretty good and strong running engine. I think the old OS FSR series of engines was their best. But the 32F engine usually was run with a 9x6 prop and with a 10x6 prop it tended to turn about 1,000 rpms less than the Fox.40 as it was getting out of its powerband with that size prop. A 10x6 prop was probably the max size prop for the OS 32F engine. A Fox usually turned a 10x6 at about 13,000 RPMs and the OS 32F was down a little in the RPMs with that prop. I never tried running a Fox .40 with a 9x6 prop though as it turned a 10x6 prop really well and for my purposes that was good enough.

    Mr Duke Fox stated before that the bushing engines don't lose a lot power at normal RPMs and that bearings are pretty much a waste unless you are in a competition and need the higher RPMs and every RPM you can get. He had found that the bushing engine loses about 500 rpms at full throttle over a ball bearing version, if everything else like port timing, etc stays the same. A tight bushing would lose more as it has more drag though. A lose or worn out bushing actually approaches the low drag of a ball bearing engine too. But for us to measure that 500 rpm difference with our tachometers becomes a bit tricky to do.

    But you know people, a ball bearing supported crankshaft engine sounds more sexy than a bushed crankshaft engine, so you know which one most people would buy then. Duke Fox felt that the regular sport flyers really didn't need ball bearing engines, etc. But some engine companies started a big marketing campaign pushing the merits of ball bearings in the engines and made it the thing to have of course.

    But if most of us were all flying bushed crank engines then the ever common ball bearing failures or bearings wearing out would be a more rare thing to happen.

    Fox used to offer bushed crank .40 and ,45 engines in the large frame size too. But they never became all that popular though. Eventually they quit making them. But the bushed large frame .40 and .45 engines had some subtle port timing changes and the crankshaft and connecting rod were different too. The crank had a shorter crankpin for the rod, and the rod was more thin on the big end and used a very thin slot cut into it for lubrication. I used to fly the bushed .45 engines for many many years. my last bushed .45 engine got traded in for a .60 Eagle IV a couple of years ago. I had run that old bushed .45 for many years and one day the rod partially failed on it and the little pieces shot peened the insides real good. But in its defense, I really should not have been running a tuned pipe on the bushed engine.



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    RE: Club FOX!

    i believe when it comes time to rebuild a glow eng. ball brgs. makes it a bunch easier than bushing engs. bushing eng. if ran with hi oil content fuels will last a long time but for me i just prefer brgs. the down side is the eng. MUST be ran dry (just as bushing engs.) of residual fuel and well oiled after each day of flying to prevent rust and corrosion from nitro fuels. i know that many fuel comps. say that NO after run oil is needed with their fuels, but i oil to be sure!!!!!!

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    RE: Club FOX!

    Good points fujiman.

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    RE: Club FOX!

    so when the bushings wear out, can you just buy a new crankase with the new bushings installed?
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    RE: Club FOX!

    ORIGINAL: earlwb

    The OS 32F is a pretty good and strong running engine. I think the old OS FSR series of engines was their best. But the 32F engine usually was run with a 9x6 prop and with a 10x6 prop it tended to turn about 1,000 rpms less than the Fox.40 as it was getting out of its powerband with that size prop. A 10x6 prop was probably the max size prop for the OS 32F engine. A Fox usually turned a 10x6 at about 13,000 RPMs and the OS 32F was down a little in the RPMs with that prop.* I never tried running a Fox .40 with a 9x6 prop though as it turned a 10x6 prop really well and for my purposes that was good enough.

    Mr Duke Fox stated before that the bushing engines don't lose a lot power at normal RPMs and that bearings are pretty much a waste unless you are in a competition and need the higher RPMs and every RPM you can get. He had found that the bushing engine loses about 500 rpms at full throttle over a ball bearing version, if everything else like port timing, etc stays the same. A tight bushing would lose more as it has more drag though. A lose or worn out bushing actually approaches the low drag of a ball bearing engine too. But for us to measure that 500 rpm difference with our tachometers becomes a bit tricky to do.*

    But you know people, a ball bearing supported crankshaft engine sounds more sexy than a bushed crankshaft engine, so you know which one most people would buy then. Duke Fox felt that the regular sport flyers really didn't need ball bearing engines, etc. But some engine companies started a big marketing campaign pushing the merits of ball bearings in the engines and made it the thing to have of course.

    But if most of us were all flying bushed crank engines then the ever common ball bearing failures or bearings wearing out would be a more rare thing to happen.

    Fox used to offer bushed crank .40 and ,45 engines in the large frame size too. But they never became all that popular though. Eventually they quit making them. But the bushed large frame .40 and .45 engines had some subtle port timing changes and the crankshaft and connecting rod were different too. The crank had a shorter crankpin for the rod, and the rod was more thin on the big end and used a very thin slot cut into it for lubrication. I used to fly the bushed .45 engines for many many years. my last bushed .45 engine got traded in for a .60 Eagle IV a couple of years ago. I had run that old bushed .45 for many years and one day the rod partially failed on it and the little pieces shot peened the insides real good. But in its defense, I really should not have been running a tuned pipe on the bushed engine.





    Not to be contrary, but my OS .32F-H would out turn a Rev-Up 11x4 by four or five hundred rpm over the Fox .40 BB ABC pulling the same make and model prop. Of course, we are talking about only one sample of each engine, so all my claims do is prove that the two engines were really close in performance. My friends engine was certainly much less expensive than my OS.

    I'm trying to remember what we were using at that point for mufflers. I think mine was stock exhaust, but I'm not sure of my friend's engine.


    Ed Cregger


    Ah-ha. Now I see the discrepancy. The ringed heli OS engine did not come with a muffler, but, when I bought the heli engine, I also bought an OS .32F ABN engine, which DID come with a muffler. That is the muffler that I used on my heli engine when on my fun fly models.


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    RE: Club FOX!

    The mufflers can make or break the engine performance as the stock Fox muffler does take a chunk off the performance or the engine. A better muffler can really liven them up nicely too. I hadn't tried the Fox .40 small frame in a 3D or fun fly plane, so the 11x4 wasn't a prop I would have run on the engine at the time. I am thinking about a new plane for thst purpose though. But your test with the 11x4 prop must have put the OS engine it its best powerband for horsepower and torque then, so yeah you are likely correct in that it outperformed the Fox .40 in that situation.

    I had a couple of shy folks PM me and state that their Fox .40 deluxe engines outran the stock OS 32F-H engine by a considerable margin in the 16,000 rpm band with 10% glow fuel. But if you used 25% nitro and a special tuned muffler the OS engine would start running much better. The OS 32F-H engine being a heli engine was tuned to run around the 15K rpm range at a fixed RPM and hold that RPM as the load changed, it also tended to be extra rich through the mid range as they had setup the carb for heli's of course.
    If it helps any, this guy had the most to say about it.
    Earl,
    I think I ran the same test as Ed.
    The Fox Deluxe I had was the early first production run one ( double taper cylinder bore).
    The OS FSR 32-H came out of a Hirobo Shuttle heli.
    I ran these tests on a test bench on the same day.
    I ran then open faced because the OS heli muffler couldn't in the engine stand.
    I used 15% nitro and synthetic fuel.
    I was at 6K feet altitude in Denver.
    What I wanted was a sport engine that would out run the COMO 40 PDP. I needed the Como for our Quickie 500 races.
    I wanted an engine that would turn a 9x6 rev up prop at over 16K rpm.
    The OSFSR was the ringed engine and had the large heat sink head
    The Fox had a true chrome ABC P&L and that cast spinner that came with the early Deluxe engine.
    I will say that the Fox Deluxe out ran the stock OS in the 16k rpm band. It wasn't even a contest.
    Some notes; the carb on the OS was rich in the mid rand with airplane props. (remember that heli engines are set up to run at close to one rpm [around 15k -16k rpm] no mater the load [collective, pitch])
    This test was done at high altitude where the low compression ratio of the OS is at a disadvantage.
    The stock OS 32 -h started to run well in the Shuttle after I started to use 25% plus nitro and a Magic Muffle pipe. (at hi altitude it need this to get descent cylinder pressure and not over heat)
    Sorry I don't have any note from that day. I doubt I even took any as this was for a my sport ship a Great Planes, Super Sportster 40.
    The SS 40 flew great with the Deluxe 40 on a rev up 9x7 for many years.
    I did use an OS FSR 32 ABN in an Andrew's minMaster (a 20 size ship that didn't look like a Hershey bar on top of a cigar box).
    I thought the OS FSR 32 ABN was a great little engine. I had to use a K&B 4011 on pipe on my Midwest Little Stick to equal the performance of the miniMaster
    Now the next OS 32 ( I think it was the OS 32SX-h) could run close to the Fox deluxe (I never ran the OS 32SX side by side).
    As for the best power to weight in the 5cc to 6cc class engine I found that the early Webra 28 and 32 (true ABC) could out run engines in the 16k to 17k power band. what I didn't like about them was the hose clamping on of the pipe. I often had problem sealing the header to the engine.
    So the short of it the Fox Deluxe was more powerful than the OS 32. This isn't too surprising as the little OS gave away 1.5cc in displacement and had a head that was to large in volume for rational levels of nitro.

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    RE: Club FOX!

    Well, on a slightly different subject, I had an interesting day flying my Fox 74. I bought it used about 2 years ago but only recently installed it on a plane. Previously, while bench testing it, it seized up. After teardown, I discovered that the front bearing had rusted badly and was dragging. So I replaced both bearings and the piston ring. Then, I replaced the carb to the new TN, just for kicks. The engine would run great on the ground but would stall in the air. Based on good advice I got here, I temporarily removed the engine cowl, reduced the size of the prop from 13x6 to 12x6 and switched from 15% nitro to 5% nitro. I tested that last week with complete success, no engine stalls.
    Today, I flew the plane with the cowl back on with some cowl baffling that I built up yeaterday. I also installed the 13x6 prop. I still had the engine tuned fairly rich and it would rev up to 10K rpms. I flew it 4 times with no stalling or problems, the throttle was slightly slow, but manageable. The engine never felt hot, it was very cool, like I never seen before when I had trouble. Then, the final flight (always the final flight), the engine stalled. I landed the plane safely and restarted the engine. I could not get to rev up above 8500 rpms. Then I thought maybe something was wrong with the glow plug. I waited for the engine to cool down and began to remove the plug. I then realized that the threads were stripped. I thought it must be just the glow plug, so I tried another plug, but it is the engine threads that are stripped.
    I had been debating whether to replace the head button to the newer lower compression one or not. So, today I was startng to think that I could keep it as is since everything was working so well, with excellent power I might add. But now, I will have to change the head button regardless. The question is, do I send it in to Fox to let them have a good look at it to see what happened, or just order a new head button? I am inclined to send it in just for some peace of mind.
    The glow plug that was in it was installed 3 weeks ago, so I had several successful flights with it. The stipped threads just "happened".
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    RE: Club FOX!

    I am glad it was working good for you now. Bummer on the glow plug stripping out on you.  Well I suspect the threads were already damaged before you got the engine unless you were a bit hamfisted with it earlier. You just happened to be the one to find them stripped out when the threads finally let go. You could send in the head button, but Fox has seen that failure a thousand times already. It is one reason Fox started using the replaceable head button on their bigger engines. it is easier to replace the head button than the entire head as a unit. I suppose one could send the head button to Clarence Lee and have him put in a insert to repair it too. But it probably costs more than just getting  a new head button. if you have the tools you could put in your own insert to repair it too.  I would keep the old one so I could compare it to the new head button to finally ascertain what I have the old high compression one or a newer low compression one. If you send it in you won't be getting it back. I think Ajholic once posted some pics of the different head buttons on the .60 engines somewhere in this thread way back too. So one could see what some different combustion chamber shapes were like.  So it is up to you.


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    RE: Club FOX!

    I am not going to bother with heli-coiling the head button. I can get a new head button for less than $20 and it will be the new style head button.

    Thanks for all the good advice.
    Content, but not Complacent.

  20. #2670
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    RE: Club FOX!


    ORIGINAL: fujiman

    i believe when it comes time to rebuild a glow eng. ball brgs. makes it a bunch easier than bushing engs. bushing eng. if ran with hi oil content fuels will last a long time but for me i just prefer brgs. the down side is the eng. MUST be ran dry (just as bushing engs.) of residual fuel and well oiled after each day of flying to prevent rust and corrosion from nitro fuels. i know that many fuel comps. say that NO after run oil is needed with their fuels, but i oil to be sure!!!!!!
    I don't think 5-10% castor is enough to get good rust/corrosion protection to not use after run oil. I use at least 50% of the total oil content as castor and never use after run as its not needed. I just run all the fuel out of the engine and set the piston to BDC so all the ports are open and leave it to "air out" on its own. None of my engines have any rust except the light surface rust that they had when new on the crnakshaft counterweight. (most if not all of my engines were 10+year old NIB's and most weren't oiled over their boxed life except what the factory put in)

    Then again, I only use 5% nitro in all of my aero engines so the risk of an overload of nitric acid is minimal.
    GlowHead Brotherhood #3
    Using Dynamite, Enya, Fox, Jett, K&B, SH, Super Tigre, Thunder Tiger, and Traxxas engines.


  21. #2671
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    RE: Club FOX!

    huskaria, way back at post number 1063  ( ref http://www.rcuniverse.com/forum/m_33...m.htm#10011460 )
    Hobbsy posted a pic of some different head button combustion chamber shapes that were used on some of the Fox engines.

    Here is picture of a few Fox .74 head buttons

    Button #1 on the left is an early Fox button up close it has steeper sides than the others and the squish band is tapered inward.
    Button #2 is the AJC button and has less steep sides and the squish band is flat.
    Button #3 is the latest button from Fox has a combustion chamber about the same shape as AJs but the squish band is narrower but still flat indicationg the combustion chamber is a larger diameter possibly to reduce compression. The buttons in the back are identical to the one on the right.

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    RE: Club FOX!

    Thanks Earl. I am going to compare them tonight. I have it in the crockpot with other engine parts getting a bath. I already ordered a new head button from Fox.

    I got a message from Konrad about checking if the crankshaft has shifted back and caused rubbing against the backplate. Is that something I can fix by just making sure that the crankshaft is pushed forward all the way? (this may be considered a dumb question!!)

    I noticed Fox is having a SUPER SALE on their engines, besides the reduced prices, now you get free shipping and 3 free glow plugs included. Was tempted to swap my old .74 for a shiny new one instead of buying the head button. As it is, the propeller hub/collar keep coming off when I remove the propeller.
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    RE: Club FOX!


    ORIGINAL: earlwb

    huskaria, way back at post number 1063* ( ref http://www.rcuniverse.com/forum/m_33...m.htm#10011460 )
    Hobbsy posted a pic of some different head button combustion chamber shapes that were used on some of the Fox engines.

    Here is picture of a few Fox .74 head buttons

    Button #1 on the left is an early Fox button up close it has steeper sides than the others and the squish band is tapered inward.
    Button #2 is the AJC button and has less steep sides and the squish band is flat.
    Button #3 is the latest button from Fox has a combustion chamber about the same shape as AJs but the squish band is narrower but still flat indicationg the combustion chamber is a larger diameter possibly to reduce compression. The buttons in the back are identical to the one on the right.

    You know, it would seem that the head button I have is more like the new one than the old one. I have to check it and verify later tonight. If I had the new type all along, then something else must be wrong with the engine. Time to do some digging.
    Content, but not Complacent.

  24. #2674
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    RE: Club FOX!

    If the drive washer and collet are worn down some, they have a tendency to not stay on when you take the prop off.
    Yes if the crankshaft had been pushed back a little bit, then heating up the crankcase and reseating it works. This sometimes happens when a engine hit on the nose in a hard landing. The engine is hot and expanded and when it hits just right on the nose it can be pushed back slightly up against the back of the drive washer.

    Fox actually had several head button combustion chamber shapes and designs. So you could have something similar or just like what the pics show.

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  25. #2675

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    RE: Club FOX!

    I have not had a crash with this engine (yet) since I replaced the bearings last year. The only possibility is that I did not push the crankshaft all the way forward when I replaced the bearings? I will check that also. This is the first and only engine that I ever replaced bearings on. So, I'm making all my learning mistakes on it. Poor engine!!!
    Content, but not Complacent.


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