More Fun with Foxes !

Hi Kim, I thought you would appreciate this particular bird. This is my F-82 Twin Mustang. My plane is in a correct paint scheme as well. You have to love the sound of a Fox and you really have to love the sound of two of them in synch. Initial fuse design was taken from a Midwest P-51 with the fuse extended another 2". Wingspan is 65" and weighs in at 81.5 ounces. I'm using stock mufflers in which both have been modified by filing the inlet as wide as possible and cutting off the casting at the rear to expose a much larger outlet.

For some crazy reasoning, I'm still using the Fox needles which are a chore to set on the ground. This plane is just an awesome sight when both Fox's are on. Smoke is pouring out of both of them and when you put this up into the wingover, you can only imagine the sound when both are breaking lean. One thing the Fox loves is a load on it and this plane certainly does that for them. I'm using 4 oz. tanks on muffler pressure. Towards the end of the flight as things start leaning out you start flying two handed. Headed out to Brodak's until the end of the week so I hope to get some flights in. My friend Dan has successfully joined to Fox.35's together and calls it the Fox.70. That engine is totally amazing. The pic isn't a close up but you certainly get the idea. Plane is a .60 size Bearcat from M.A.N. plans in the 80's. This particular Bearcat was built in 1983 now donning the Fox inline twin on the nose. Ken

[quote="shawn cook"] Hi Kim, I thought you would appreciate this particular bird.


Definitely! Four Ounce Tanks ?! Do you take a lunch with you when you head out to the circle?! Wayne's Chip has a 4 ouncer,, and IT was getting pretty heavy toward the end of it's flight last Sunday !! Figure longer lines might help the Chip...what length do you use on the '82?

Also definitely cool is the inline twin Fox...though I can only imagine your friend's technique for setting up the mixture.

Yes...this IS the cool stuff!

Kim, my lines are center of handle to center of plane 70'. This applies to basically most contests.Technically your not supposed to exceed that length. My son Shawn flew it last year for a 1st place in fun scale. Burning 8 oz's of fuel a flight, fuel goes fast. After Shawn completes the entire pattern, he has about 8-10 level laps before the last engine quits. I'll admit, I can fly a fair pattern but Shawn is pretty tough to beat. He has the no fear and is totally relaxed.

The twin Fox Bearcat is burning 8 oz's as well. The Fox is swinging a 13" prop with some serious authority. It was quite funny actually. We both saw the Fox twin at Brodak's fly in in 2009. He asked the individual if he ever flew it and he said no. Well this got the gears turning and Dan set off to build it. Dan's first attempt worked well until it arrived at Brodak's in 2010. The day of arrival and flight testing it broke the crank. After a careful redesign and help from another friend of ours, the crank was professionally heat treated. The crank has been balanced and I have to tell you it has a great sound to it. The plane was entered in profile yesterday at Brodak's so I'm not sure how he scored. I will hopefully get a close up picture. Nice machine work on the outside. Basically the rear cylinder runs a tad richer than the front due to lack of airflow. You know your on though when that ear piercing shriek sounds in unison. Ken

Absolutely great deal on the Twin Fox...you is some serious people !!

Maybe next year I'll be able to hit the Brodak Fly-In...keep intending to...but also keep loading up my schedule with other stuff!em

At present, the Chip is flying on 52' lines to make it fit in Wayne's back yard. We're gonna stick it on some 60 footers as soon as we get a good place to use them.

Still MORE Fox running ! Taking great personal risk at seeming redundant, may I present my Uncle's Fox .29 Stunt as it gurgles along in the mid-9's on Glowplugboy's 10% with a M.A. 10-6.

AND at great risk of garnering more negative points, may I state that NO attempt was made to restore the engine before starting it (other than a squirt of Xena Lube in the venturi and exhaust)! Same glowplug that lit it up back in '69, four to five turns on the N.V. from closed, and off we went!

My point being in conjunction with someone's earlier statement that these old engines, no matter how long stored, will happily come to life with the least provocation.

This is the engine that is slated to power Wayne's Goldberg Buster Restoration.

Hi Kim, I think that's awesome. I have several engines my father gave me and one thing for certain is that it really is cool to see one start right up after 40 years. Cleaning some of these old engines actually can do more harm than good. All that baked on castor especially on the piston cylinder fit helps the old Fox. I never seem to come across many .29's. I actually bought a piston sleeve for a .35 only to discover it was a .29.

I wish the engine bolts didn't chew up the cowlings on the Buster and the Shoestring when they exit on that side. The .29 should be a good runner for the plane. I always liked the Buster as I always felt the wing had a bit more squares than the others. I've also noted that the Fox doesn't seem to shake as much on the Buster design. I've had two Shoestring's now that I had to hang up due to bad vibes. After closer inspection, I noticed that the problem may lie within the wing itself as only 2 1/16th ribs are spaced 1/2" apart and are directly under the fuse. Ken

Hey Shawn!

Thanks...I probably will do a bit of cosmetic touch-up on this old dog before it goes in the Buster. Yes, the Buster's wing DOES seem a bit more "squarish". Wayne's Buster was a replacement of the his Shoestring which met it's fate at the end of a failed cable.

Gonna put the Fox Combat .35 on the stand next chance I get...maybe tomorrow morning if I don't throw the alarm clock across the room !

Another note about the .29: While I'd NEVER advocate using less than the best stuff you can get your hands on, this old engine is a veteran from the days when "Fuel-is-Fuel" ruled our thinking. It's probably had every good-cheap-junk-old leftover-dirty syrup possible run down it's gullet. And...it STILL runs...no Triple Crown Winner to be sure...but it runs. A tribute to Mr. Fox's design and quality control !!!

The more I read of this thread the more I want a big Fox!

Ivanhoe wrote:The more I read of this thread the more I want a big Fox!

They're lurking around out there. While the Swap Meets here have mostly dried up for the summer, I WILL keep an eye out for a good deal, and shoot you a note if snag one.

Kim wrote:

Ivanhoe wrote:The more I read of this thread the more I want a big Fox!

They're lurking around out there. While the Swap Meets here have mostly dried up for the summer, I WILL keep an eye out for a good deal, and shoot you a note if snag one.

Thanks, Kim

One prop I found to be extremely good for the Fox and works like no other is the Master Airscrew 9.5 x 6. This prop is extremely effective on planes like the Ringmaster, all the Goldberg planes and Flite Streak as well. When I break them in, I use a thin bladed Master Airscrew 9 x 6. I generally see rpm's from the mid 11's to high 12's using no mufflers. When the Fox decides it doesn't want to be so cantankerous after a few runs, I switch to the 9.5 x 6. Mind you that the newer 50th and 60th versions break in far quicker than the older versions.

I've seen these engines bolted on and flown out of the box. I don't recommend that as you have no way to control the run if it goes lean. The 40th anniversary engines are claimed to have some really good fits and are desired by some for their quick restarts due to the better fit. They also take a bit longer to run in as well. A good needle for the Fox that works quite well is the Enya needle http://www.ebay.com/itm/ENYA-NV-ASSY-C-L-NIP-PART-29420-29-35-/290718712483?pt=LH_DefaultDomain_0&hash=item43b02f82a3 Ken

Can someone explain the thinking behind this modern idea of running-in a new engine on a small prop?
In my day you ran an engine in on a larger prop to keep the revs down until it loosened up enough to avoid any danger of a seizure, surely if you are letting a brand new engine scream on an undersized prop you are not only risking a siezure, but causing excessive and uneven wear, and certainly overheating?

There is no way I would run a new .29 or .35 on a 9 x 6 prop, and I would hesitate to do it with a properly run-in engine! Maybe this explains all the horror stories I read about McCoy 29 & 35 Redheads wearing out after one flight!

I can't speak for Ken, but it might be that since the break-in involves running it back and forth from rich to peak (which for me is taking it to its two-stroke break), you might have some lower temps due to the fuel that's passing through and taking the heat with it. Not sure though. I'm sure he'll be back will his thoughts.

Yes, I was also surprised to hear of the McCoy quality problems, as all of ours seemed to run fine. We were, however, just Boondock Flyers, and our engine had pretty easy lives.

Got this Fox .35 Combat Engine on the stand this morning, and as Ken had suggested, it's a much different animal from the Stunt Engines I'd previously run.

Right off the bat, it tested the effectiveness of my leather starter glove with vicious kick-backs and hard thumps to the back-side of my finger!

However, it didn't turn up like I thought it might, settling in the mid 9's or so. Could be that the M.A. 10-6 prop and 10% fuel doesn't suit it's tastes, so it may get some different accessories the next time I run it.

At any rate, regardless of the numbers, I'm having a big time just running these old engines and filling the shop full of castor aroma!

Also...anyone got a clue as to the purpose of that hole in the back-side of the engine? You can see the sleeve through it, and it doesn't vent gas that I can tell....

Let me just explain my thoughts on the prop choice. The 9x6 is a recommended prop by Fox. When we flew slow combat using Fox.35's you used wide blade (Taipan) 8x6's. I own about 30 Fox.35's currently and have owned at least twice that many. We would buy 10 at a time between friends and run all of them checking the rpm's of each one. Choosing the best one out of the bunch usually went to full bodied stunters. Other engines that didn't make it up to par saw action in various other models that didn't require the performance. I basically run them in a brief two stroke and cycle them. The lighter the load on the engine the easier it is on the engine. The other factor is the more rpm's it's running the more cooling in turn it's getting. So what you have here is lesser load and more cooling.

I don't run Fox.35's right out of the box, I take them completely apart polishing the crank immediately and dressing the crank bushing inside. The conrod is removed and oil holes drilled top and bottom. I lap the piston to sleeve fit immediately out of the box. My Fox .35 break in is somewhat done right at this stage. If you have experience with the Fox, you have to realize that at no point through the piston travel can you feel a bind. You can take a brand new engine and right out of the box feel the piston hang up on the exhaust cutout in the sleeve. Breaking in an engine traditionally using a large prop here is going to do nothing more than ruin the conrod. The Fox conrod is not bushed and it eggs out on the large end attaching to the crankpin.

In addition running a new one slobbery rich which is how Fox originally recommend break in usually resulted in not only a egged out conrod, but the wrist pin also egged the hole in the piston. I run a Fox during break in a wet 2 stroke, pinching the fuel line repeatedly for 5-10 seconds running the engine at about 3-5 min a run. Everyone is different when it comes to running engines and in no way am I saying to do what I do. This is what works for me and I have been quite successful at doing so. Most Fox .35's that you see have vertical scratches on the piston. The majority of my engines you can't even see a scratch on the piston. The reason why two identical engines run differently is due to the parts being fit better on one vs the other. Lapping in a piston doesn't take the place of running the engine as they both go hand in hand. If I don't see the rpm's I like during break in I take the engine apart and lap a little more. I've seen differences of 3k just in 10 min worth of piston lapping. Most of your overheating is caused by the initial fits. I'm just doing what Fox should've done in the first place. Ken

Kim,the hole on the back of your Blackhead was for wristpin removal. When you look through it now, your seeing the liner. They have a tendency to get stuck. Your 10 x6 is probably a bit large as a 9x6 would show better results. The old plug could be robbing you a few rpm's as well. Many Fox plugs leak around the insulator and many times the post usually shoots out the top of the plug. The combat special uses brass end pads on the end of the wrist pin. Keeping good oil content is a must due to the brass cutting two distinctive grooves into the liner. OS used the same brass end pads on their Max-S engines. These really did more harm than good. When they finally switched to the Teflon this was a big plus. I also believe that you may have a removable restrictor in the venturi on that engine. The Fox Rocket which is essentially the same case had a removable restrictor. Ken

Man !! You are one serious Dude !!! This stuff gets the 'cut and paste treatment' and will be used if I come across a new Fox !!! I guess this commitment is what makes the difference, even if it wears me out just THINKING about it!

OK..the Fox gets a 9-6...maybe even one of those (gasp!) APC razors (extra glove UNDR the glove!), and a fresh plug!.

I HAVE wondered about the vertical lines in the pistons, but they are so common, I got to figuring this was just the deal.

Once again, thanks for your continued input and support with these engines, and this thread !

A few comments:

A small prop for initial break-in allows the engine to turn up while running rich and cool. Sleeve bearings like on the crankshaft and the conrod wear in during the first few minutes. By turning up, the bearing is supported by a film of oil, thus fast smoothing with less wear. This is true for all engines.

The piston/sleeve bearing requires heat cycles to allow the fit to smooth in without causing excessive wear. This is true for all iron/steel setups. Many get by with running right out of the box but a proper break-in allows your engine to be all that it can be. Your choice.

An interesting note is that back when almost all engines were iron/steel there was always a debate as to whether an engine needed break-in. Most FF folks said no, most CL guys said yes. As it turned out, both were correct. The way FF guys run their engines, that is, start it and run it hard for short runs is an acceptable way to break in an engine.

The thing about some McCoy .35's being bad is because during that time engine companies were in tough competition and McCoy's got down to ~$5.99. You can't (even back then) produce a high quality engine for that price. I understand that many were assembled in someone's garage...not sure if that is true. Someone posted that they would run one for a weekend and chuck it. I have a couple of early ones, made apparently before they cheapened them, that seem to be fine.

One additional comment...both Fox .35's and McCoy .35's need more than average oil with half of it being castor. Many recommend 25%-28% lube.

George

The Mccoy as questioned above to it's longevity was mainly quality control. I own and still run some that are over 40 years old. I've run some ONE TIME right out of the box and they were destroyed and worn out on one run. Twice I had this problem both being the Mccoy.19. This happened using Powermaster 10% 29% oil content all castor. This is due to the sintered piston. This was a powdered metal placed under extreme heat and pressure formed into a piston. They just didn't last. Quality was better on others not to mention they didn't even use a crank bushing until the very late 60's early 70's when the Lightning bolt case came onto the scene.

It's a real shame because for those that have used them, they were light and they ran a great stunt run in my opinion. The Mccoy and the Fox were my first big engines so they have sentimental value. Like George stated, they need a good quality oil all being castor. There are several things to do to fix a Mccoy redhead. The best solution is to find the gated cylinder liner. This is the one that has the webs across the exhaust port. You can purchase a Testor's 21 series ("The brick engine") piston and piston ring. The Series #21 used a Dykes ring on the top of the piston. I'm told this will direct fit into a Mccoy redhead sleeve with the gates.

My method was to put the case in the lathe and bore for the entire piston sleeve of the Series#21 liner which is of larger diameter. I purchased a entire sleeve piston and ring from Mecoa. You now have a ringed Mccoy that isn't going to wear out. There was a fellow on Ebay making these hybrid Mccoy's and selling them. Ken

I have a McCoy .35 Redhead, a .19 Redhead, and a "Brick" 19, both the Redheads were virtually new when bought, and the "Brick" looked to have had reasonable use. I've run both the Redheads several times on no-nitro fuel, bog-standard out of the can, no idea what the oil percentage was. This was before I heard all the horror stories, so I took no special care, as far as I can ascertain they have suffered no ill effects from this, perhaps I have earlier models as you say.
The "Brick" runs extremely well, but weighs a ton! it is certainly far more "professionally" built, compared to the Redheads, but I get the impression that McCoy resorted to a little "overkill" perhaps as a reaction to criticisms of the Redhead quality?
The only one of these I have any real plans for is the .35, I want to build a big stunter, possibly a Nobler or similar, as my first serious stunter in 40 years! However, if I ever get hold of a Fox .35 this is the engine I'll use.
I may put the McCoy in a profile stunter first, 1 - to see if the engine does wear, and 2 - to see if I can still fly a big stunter after all these years!

Wilf

Here's what you need, Kim, to add that authentic touch!

Here are some of the engines being discussed:

McCoy .19 Series 21


McCoy .35 Redheads


George

George, you left out the best part of the Mccoy...........The springy needle valves. Ken