hsukaria

On a slightly different subject, I finally got to fly my plane with the Fox 74 Eagle IV today. I did as advised and took out the cowl, and switched to 5% fuel with an extra 10% approximately of added castor oil to a 12% synthetic and 6% castor blend fuel. I had to lean out the idle needle a bit to allow it to idle, but the high speed needle I kept the same setting as it was when I ran 15% nitro. It was already on the rich side and now even richer. I also went from a 13x6 prop to a 12x7.

The good news is that it ran well with no stalls in flight as it did before. Throttle transition was very good considering how rich it was set. I ran 5 flights of approximately 9 minutes each, mostly cruising at half throttle.

2 notable things I noticed: Once, I heard a "pop" in the engine, I took out the glow plug and the coil had expanded out quite a bit (it still glowed). I replaced it with an RC long plug (with idle bar). I also noticed a lot black and grey slime all around the engine, is that burned castor oil?

Thanks for all the help I got from here. Next week, I will fly it with the cowl back on and hopefully it won't overheat.

Another question, I have 1/4 of a gallon of this fuel left and will need to make a decision. Should I still replace the head button to the newer higher nitro design? If not, what would happen to the engine behavior if I switched to 0% nitro fuel? The fuel I see at the LHS is oil blend though, not 20% castor like I would expect for FAI.

earlwb

If it is working for you, you can procrastinate on replacing the head button. But it may be needed after you get the engine broken in good and can lean it out more. Anyway, I am glad you re successful with the engine today.

The black like oil residue is typical, it is mostly the synthetic oil in the fuel turning color, not so much the castor oil, but it could be picking up crud from the synthetic oil in the fuel.

Cougar429

My Feedback: (3)

If it is a new engine you will likely get that black exhaust residue also from microscopic wear particles during the initial break in.

As mentioned before, never expect a new plug to last long during initial break in as those microscopic particles bond to the glow wire, seriously degrading performance. I always use an old plug for the first few tanks, then install new for best performance.

earlwb

I have a small pile of used glow plugs I keep in a little box inside my field flight box. I always use the used plugs first and save the new plugs for after those initial engine runs as the engine is getting broken in. Some of those used plugs are perfectly good, as sometimes I have a recalcitrant engine at the flying field and when in doubt put in a new glow plug. I have had glow plugs go bad and they still light up and look good, but they don't ignite the fuel anymore.

hsukaria

I am very happy to get this engine running properly finally. I think I have put a gallon of fuel through it since I bought it used and replaced the bearings and piston ring. The piston ring is Fox brand and I wonder if that is why it has been taking so long to break in.

The next time I will fly it, I will have the engine cowl installed. If it does not overheat and stall, I will continue to use 0-5% nitro fuel with extra castor for a while. If it does overheat, I will order the new head button and retrofit it and run with 5-15%% nitro fuel.

Thanks again for all the help and encouragement. I really like this engine a lot.

Cougar429

My Feedback: (3)

If it overheats with the cowl installed then you likely have an airflow problem, not fuel related. If fuel was the issue then that would show up uncowled, as well. I just maidened my Harvard this afternoon with a fully cowled OS 91S and as with my other cowled setups the cooling work done to direct air only over the cylinder and head worked flawlessly. I use the same concept as in our real aircraft where the key is to have an adequate exit area, (general rule is exit is 3X the entry area to allow for the heated and expanded air to escape). One other little trick is to have that entry slightly smaller than the cylinder and the dams open towards the cylinder, but fit tightly to it. This ensures all the cooling air goes over the head and barrel, rather than bypass in the lower drag area below the case. Remember it will search the easiest path and has to be directed to where you want it.

EarlWB, back in the 80's when we used to meet Duke at the Toledo Show I always made it a point to pick up a dozen or more Fox plugs every time. I tended to burn through all but the last very quickly, yet that one remaining plug would run trouble free for the rest of the season. Go figure, but that happened many times.

hsukaria

I bought a couple of Fox glow plug sheets at the Toledo show 2 years ago. They were selling them dirt cheap. I have a whole sheet of Miracle plugs for my 4-strokes and a sheet of the #8 for my 2-strokes. My plugs usually last a long time and I won't be having to buy more for quite some time.

As far as the cowl, it is huge and buries the engine cylinder head completely inside it. I have a huge opening in the bottom to let out the air and it runs the whole length of the cowl bottom. The cooling air may end up bypassing the cylinder/head. If that happens, I will have to learn how to do baffling. Is there information around here for designing/building cowl baffles?

By the way, that MVVS Quiet Muffler I have installed is really quiet. The most quiet muffler I have, including the OS AX and Super Tigre monster mufflers.

Cougar429

My Feedback: (3)

As I mentioned the key is to ONLY allow the air to go where you intend. Like holding water in your hands it will always look for the easiest path to escape.

Here are a few of my projects. The first was the Saito 91 powered Skybolt. As this was my first 4-stroke I had perhaps a dozen flights on it to check and "Tweak" before the cowl was installed. On the first flight the motor overheated. I went back and fit the baffles and as of yesterday afternoon I believe I hit flight number 300 on this airframe/motor combi. I think this one requires the crock pot technique. I just never want to take it out of service as it is so much fun to fly.

The second Harvard installation got this treatment during the build process and I "Remaidened" it yesterday afternoon. Absolutely flawless cooling.

Third example is the soon to fly Rare Bear. Same process. This was earlier in construction with a test prop and landing legs.

All these examples came from the fact that none of my 2-strokes required this to date, (i.e. anything with a large enough cowl) and 4-strokes do run hotter under normal circumstance. The cooling requirements should be identical regardless of the make or model of engine.

hsukaria

That's nice work. Unfortunately, I am too lazy to do that kind of work. I will have to devise something easier to fit my plane due to "low motivation".

Tarasdad

Earl, I'm planning to put my .25 in one of he two Super Sportster 20 airframes a nice gent here on RCU just gave me. I also have a .19 BBRC Schneurle from the same source. Do you think it would be a good hit for the other one?

earlwb

Yes it would work good too. Those planes a great flyers and fun too.

Tarasdad

What prop sizes are appropriate for the .19? Looked it over and it seems to be in good shape. Gummed up with old castor but nothing a bit of scrubbing won't fix. Bearings are stiff but have no bumping or other indication of deterioration. I'll know more once I get them clean.

Cougar, my .50 sat for 15+ years after I had to leave the hobby. I put it to use again last fall when I assembled my first kit in 20 years, a Carl Goldberg Tiger 60. A new glow plug was all it needed to fire up and start singing. I did tear it down about 3 years ago and replace the piston ring (broke the dang thing trying to reassemble it after cleaning it) so I'm treating it as a brand new engine and breaking it in as such.

Tiger 60 with Fox .50 BBRC

earlwb

A 8x6, 9x4, 9x5 would work on the .19 engine.
We used to run 8x6 props mostly on them years ago, but they tend to turn larger props Ok too.

Fox test runs all the engines, using fuel with castor oil in it. So the new engines tend to stiffen up on a long layover. But usually a little judicious heat and some oil loosens them up quite well.

I am running a circa 1967 Fox Blue Head .60 RC engine on my Tiger .60 plane. A old Davis Diesel Development Soundmaster muffler on it too.

Tarasdad

Nice looking Tiger, Earl!

The muffler on my .50 is a J'Tec Snuffler. Had to go to that when the AMA was pushing the "90 @ 9" thing. All my other engines were fine but that .50 just screamed with the stock muffler. I'd gladly go back to a stock muffler if they didn't cost so dang much.

Cougar429

My Feedback: (3)

Another to add to the complaint department on noise. That 50BB was a powerhouse, but seemed twice as loud as anything else I have. That was the reason for the adapter. I recently yanked the OS 40 muffler and bolted on the Powerbox from one of my 55AX's, (same bolt pattern) as both those have Macs mounted. Have yet to fire it up, but expect it to be a nice match.

earlwb

I have some of the J'Tec Snufflers too. Although I expect that I could go to the local lawnmower repair shop and get some used ones to stick on the back of a Fox muffler too. I do have a old Fox muffler for my .45's that I stuck on a short lawn mower muffler with and I ran it like that for a long time. A couple of years ago I switched it out to a bridge adapter and a Performance Specialites muffler, but then switched it back to a stock OEM muffler. it is on my Combat Airmadillo plane that I fly when the flying field is busy and there is a good risk of mid-airs occurring. The Airmadillo comes through mid-airs quite well with little damage.



and to think that many many years ago we flew our model airplanes with engines sans mufflers. I remember guys complaining about the weight, power loss, blah blah blah about having to put a muffler on their engines way back then when the clubs were required to have people use mufflers too.
But then you haven't lived if you haven't run a .60 engine without a muffler though. Way back then no engine came with a muffler, and we all used and flew them like that. The engines weren't even designed for putting a muffler on them either. No one thought anything of it then.






My poor old Fox .60 Blue Head languished for many years as at first I couldn't find a muffler to fit it.
Then one day I found that a large Davis DieselDevelopment Soundmaster muffler would fit it OK. But I needed to removed the exhaust baffle and plug the holes and then clamp the muffler on. So I made a couple of aluminum plugs for the holes. Since the exhaust inlet and outlets didn't quite match, I also machined out the muffler to match the engine better.

















Yes the old engines are quite messy, they tend to ooze oil from everywhere on them. But the bearings get plenty of oil and don't go bad on you like some engines do.

Tarasdad

Yup, gotta love open bearings on the front.

Elwood

My Feedback: (2)

Hi all,

Just a couple of questions. I am interested in a Fox .45 BB for a Sig Somthin Extra. Plan on using a 12.5 X 3.75 Prop. I want to keep it light and agile, and need a prop that can slow the plane down at idle - there is a hill at the end of the runway in one direction and a lake at the other!

Does it have a sealed front bearing?
Will the included muffler pass noise limits?
Is it as powerful as a TT .46 Pro, or an OS .46 FX? Messier then them?

Any other thoughts on this combo? Any thoughts on going with a K&B Twister .61? It looks to be quite light...

Thanks!

earlwb

Yes the muffler does just pass the noise limits that the AMA suggests for clubs. But a MVVS or Rossi muffler or muffler made to fit those engines also works too. A lot of guys like using DIY mousse can mufflers on their 3D planes too.
Fox has been considering sealed front bearings but I don't know if they have found a bearing that is suitable for it. The sealed bearings that one can get really don't work well or last all that long, so Fox has had trouble in that area. They may or may not be sealed now. But honestly I much prefer some oil oozing out of the front bearing myself as then I know it is getting lubed and cleaned too.
Yes the engine will idle extremely well after it is run in good. So it should slow down for you OK. You might put a little bit of drag on the wheels, if you can keep it even enough to take off and land, that way you have both helping you to slow down. Many years ago, we used to rig up a simple brake on the wheel or wheels too. I would use the idle stop on the carb with a flex cable so it could flex and not stall the servo. Then a thin cable ran to the brake or brakes on the wheels. The brake was a simple piece of flat brass hinged in the middle and a small brass tube is soldered as the hinge on it. I would then solder a right angle piece of piano wire that fits inside the hinge tube and a solder on a small washer to keep the brake from slipping off. Then when the throttle servo closes the throttle it goes a little farther pulling up on thewire causing the pad to dip down and press against the tire on the wheel.

Try a google search for "RC Airplane Wheel brakes" as there are a number of ways one can do it too.

One could possibly use the K&Btwister engine on the plane but it is fairly big plus it would need to turn a larger diameter prop and you could wind up with some serious torque roll effects on that size of a plane. It might make it more tricky to balance as well.

Now my Fox .45 powered 3D plane lands so darn slow at a high alpha angle that it really doesn't matter much about speed. and it is pretty heavy too. But I forget as to how fast or slow the Sig plane flies at.

carddfann

I don't know how the 45 compares with the 46 imports on power. I've never compared them. I have two 45's and they are my workhorse engines of my 40 size fleet. After break in, they are very reliable and easy to start. After using them for 3 years, I still haven't had a dead stick and they are very tuff. I put one in the ground at full speed (nose first) and thought it was toast. All it did was break off a small piece of my exhaust stack and break the muffler. A little JB Weld and a new muffler and I was back in the air (after cleaning out the dirt). Noise wise, the stock muffler is louder than most other mufflers but hasn't caused a problem at our urban field in Dayton. An engine that is more powerful than the 45 and probably at least as powerful as any import is the Fox 46 ABC. I think its the same physical size as the 45. That sucker is a stump puller. Its a shame Fox quit making it because they are trying to get away from chroming operations. When I was at the big Toledo show, I stopped by the Fox booth and that's what I was told. To me, seems like they could just contract out the chrome plating like everybody else. You can check Ebay and other such sites to find a 46 ABC. I see them from time to time.
Regarding the K&B 61 twister, I have two and they seem quite lite and I'm very satisfied with them. If the specs on the K&B/Mecoa website don't give the weight, I can weigh mine for you. Power seems very good but I don't have any comparison numbers. The K&B/Mecoa site has (or used to have) a forum for their engines so it might help to check them out.

earlwb

I forgot to mention that Fox now sells their Fox .50 once again, and it'll outpower the K&B Twister 61, plus the Fox 50 weighs slightly less than the 45 does. Fox hasn't updated their website, so it doesn't show the Fox 50RC and CL engines yet. I have several 45's as well as several in use. I have three 45s in planes ready to fly at any time. I have several .50's too but at the moment they aren't in use. Two of my .45's are 20 years old or older and they still run just as good as after they were broken in new. So it is hard to wear out a Fox engine.

The Fox engines compare favorably with the other brand engines. They all wind up about equal when using realistic props on them.
Not like some of the engine reviews looking to see what the peak HP is.

Elwood

My Feedback: (2)

The MECOA site had the weights listed, but thanks anyway!

I guess I will have to call Fox to see about the .50, it is not on the site right now.

NM2K

My Feedback: (14)

I have been using Fox engines ever since I received my first one as a gift in the late Fifties or early Sixties. The engine was the Fox .09. It ran well and it powered my models well. I never did have to replace the glow head, which was pretty expensive in those days.

My next Fox was a then new model, the .15X in 1962. I still have it, although there is no compression to speak of, but it will still run if you can fling the prop fast enough for it to get going.

The next Fox engine that I had was the Fox .36X, which, I flew while in the USAF without it missing a beat.

Next was a Fox .25 Bushing R/C engine that powered a Goldberg Falcon 56 for a couple of years before being sold, plane & engine together.

Let's shorten this process up a bit.

I then bought/owned/flew:

Fox Eagle .60 (baffle piston)
Fox .19 Bushing R/C
Fox .45 BB Schneurle R/C
Fox .74 BB Schneurle R/C
Fox .19 BB Schneurle ABC R/C (my favorite of all)

Do I qualify for being a member of the Fox engine club?


Ed Cregger

earlwb

NM2K
Yes it does, welcome aboard.



ELwood, yes Fox has the Fox .50 engines, but they hadn't updated their website yet.

Sport_Pilot

I have a TT Pro .46 and it doesn't have a sealed bearing either. And I don't believe it does now.

http://www3.towerhobbies.com/cgi-bin...?&I=LXAPGZ&P=Z

Just because it does not have a sealed bearing does not mean it will through oil out. It may drip a drop or two when stopped, but most will suck a very small amount of air back through the bearing preventing fuel from being thrown out the front. In fact the most common problem today is poor idle from too much air leakage.

I don't recall the older Fox engine dripping oil all over the place either, the most common problem is oil from the fuel standoff from the carb spraying mist from the carb. And the fact that it was 100% castor oil. Modern engine have longer carb throats which reduce the fuel standoff.