AP .061 Hornet

1 size larger than yours, but may still be an interesting read:

https://www.sceptreflight.com/Model%20Engine%20Tests/AP%20Hornet%2009.html

I have two of the .061's - few efforts with them using all castor in the fuel mix.
15 to 25% nitro is all you really need to enjoy them.

I was using them for 1/2A combat when Norvel's were essentially defunct. These engines appearance wise look like a Norvel but by design they're different.. Wrist pin is retained by circlips which is a plus over the Norvel. The AME Norvel has issues when the staked areas of the wrist pin wears. The wrist pin then slide forward and jam in the port of the cylinder ruining it. The case is not the same as the AP utilizes a round intake opening opposed to Norvel's oval bathtub shape. This is a plus actually if one is to machine their own venturi as I have. I made a adapter for the AP to utilize a Cox TD needle valve assembly.

           The bearing material in the AP is a real POS. It fails rapidly. It was noted that case wear would be far substantial over the Norvel due to being a bushing and not riding in the case. I found this not to be true but the complete opposite and I'm not the only one to experience this. Larry Renger from COX made mention of this equally as he was gloating about this engine for quite some time. In addition, he specified the engine and designed his Skysport around this engine.

      I never found the AP performance to exceed or even match a Norvel .061 in a Big Mig configuration. I used every available head to increase performance in search of doing so. I ran 10% nitro to 35% nitro. Essentially I took out more plugs than the engine was worth in doing so. To reduce plug blowing, I was using 10% nitro and regardless of how many gaskets I was using, it was taking out plugs ferrociously.  When this engine was available , NO PARTS were available. I contributed the plug blowing to the crank wobble in the case so I had a new bearing installed in the case. I was fortunate that one of my friends who owns a vintage Ferrari rebuilt the heads and gave me the valve guides. My fellow club members and I made case bushings from the old valve guides.

         The shaft diameter is slightly larger than a Cox 5-40 screw. This was a bit problematic for me. I don't care to have specified props for a particular engine especially when using for combat. I didn't understand why they made the diameter larger. This now required me to ream out my props to accommodate. The stock head button is very short lived. I liked the way it performed however. I switched to a Nelson head and never looked back. They last longer. The AP stock head shim is aluminum and looks like it was made in a cave. Throw it out immediately. It will cause nothing but a headache.

       The piston sleeve fit is very good in this engine. I've since revisited the engine and currently have a diesel head on it. It's been working real well. The price for me was less than $30 when Hobby People was having sales on them and I purchased 3 of them. I liked the engine for it's price. I was really hoping it would of fulfilled my needs. However, it works terrific for stunt / sport use. I don't do r/c so I can't comment on that use.

944_Jim wrote:Love mine. Feed it like I feed a Cox engine. I would not go high nitro unless I had a pile of them and nothing better to do with them.

Oh, and I do have a pile of them...but I intend to use them (so yeah, something better to do).

Hello Jim
I must say that your Scientific P-40 looks real nice. I liked the transparent canopy and the venturi on your engine,did it come with it?
Juan

balogh wrote:1 size larger than yours, but may still be an interesting read:

https://www.sceptreflight.com/Model%20Engine%20Tests/AP%20Hornet%2009.html

Hello Balogh
Thanks, I went to the sceptre flight site and read the test.
Juan

[quote="1/2A Nut"]I have two of the .061's - few efforts with them using all castor in the fuel mix.
15 to 25% nitro is all you really need to enjoy them.

Hello 1/2A
I watched your interesting videos,you must have a lot of fun playing with your engines.
Juan

Hello Ken
                   Thanks for your very detailed information. Do the AP Hornet .061 crankcase bushing wears fast when using high nitro content? I can always try to improve lubrication to the crankshaft. I took my engine apart to check it out and noticed that the fit of the piston and cylinder is loose. I will be replacing the head gasket as you advice.  I`m modding the engine and could not find information on what the weak points were. I made a pressure fitting,replaced screws with allen heads,made a venturi and installed a cox NV assembly.Thanks again.
                                                                                    Juan

Juan, I see you replaced the screws that retain the cylinder. I didn't mention that part. The stock screws are very soft and are prone to getting buggered. As far as high nitro was concerned. One thing that I've always found is that Norvel Big Mig engines don't require more than 10% nitro at my elevation. The AP shares the same porting as the Norvel. I came across my old post on here in regards to the AP. Most of what I stated was from memory and almost word for word. One thing that I saw which still puzzles me is that the piston doesn't come to the top of my engine and it was below the top of the cylinder .020". I also had nearly .020" of head shims and was still taking out plugs. My engine took out a plug after the bushing was replaced and I said I had enough with it.  A thirty dollar engine that ate $50 worth of glow plugs.

        I was using 10% nitro and switched now and then to higher. The whole purpose of me using this engine was strictly for practice. I didn't want to invest a lot of money and I didn't want to use high nitro. High nitro was in the early stages of just becoming real expensive so I was trying to curb that. In addition, speed limit combat was 10% fuel and I didn't want to bring different fuels with me. For the same reason I switched to Nelson plugs. I use one type of plug and one wrench for all.

        I have no idea why the engine was eating plugs and why the bushing failed so quickly. My guess the Chinesium metal used was probably the issue.  Typically, lean runs will taxi plugs as well as out of balance props. Too much compression and not enough deck height is the other. I covered all those bases.  Larry Renger also mentioned 1-2 failures of the bushing he experienced equally. But even after all this, I like the way it runs now in my current diesel configuration. I do enjoy the engine.

      Eventually, reality set back in and I just realized that I invested quite a bit of time and effort into this $30 engine whereas I could've just paid $120 and bought the proper engine. This is a true case of a reality check. I was able to purchase Fora .049's for the above price and they start, run fast, they only require 10% nitro, and they're already setup for bladder use. A true plug and play. My Fora's have only ever required a bearing replacement now and again and have offered me over 10 years of service free use other than a bearing. So you ask yourself, do I want to fiddle fart around as a mechanic or do I really want to fly the plane and get better?

Hello Ken
                 I have saved your comments for it`s valuable information. I see this engine as a challenge and I enjoy working on two stroke model engines be they big or small. I take them apart to make sure there are no problems that are detectable. Small engines can be improved. As you mentioned the head gasket from the factory was leaking when I checked. The threaded backplate is very thin and it was not possible to drill and cut threads for a pressure fitting so I turned a pressure fitting in my lathe and JB welded it in place. I have been in contact with the friend that gave me the engine and he wants to be around when I fire it up. We have been friends in modeling for many years. I will be taking the engine apart to see what I can do to the crankcase to get better lubrication to the crankshaft. The case has a very light plating of what it looks like copper. Thanks again for your insight on this engine.

                                                                                  Juan

There are plenty of write-ups on these engines on RCU from the time that were made, just search for AP Wasp (and not Hornet).
Here are some of my findings (under the username Mr_Cox): https://www.rcuniverse.com/forum/1-2-1-8-airplanes-70/9607673-ap-engines-wasp-061-a.html

Mine were never as powerful as the Norvel that they copied, and it also lasted shorter...

Some cylinder pealing showing after a few seasons on all castor oil:

Thanks, Kris. I read most of the thread, seems longevity of the engine is not good, quality assurance problems, etc. Regarding possibilities of swarf (excess material left from machining process), back in the mid 1980's on two Fuji .099S-II R/C engines (of the few that were ABC but still cross scavenge with fence on top of the piston), bought them on closeout from now defunct Hobby Shack store in Lakewood, California.

Opened the back, both were filled with swarf. Disassembled both, washed clean in solvent, relubricated and assembled. And these were engines manufactured in Japan. I gather that Fuji was on its way out with Hobby Shack (Global Hobby Distributors) discontinuing engine contracts in favor of the Magnum (made in China) engine series that replaced them. Fuji must have been short staffed and simply slapped the last of the engines together.

Never had any of these problems with the Cox reedies (pre-Estes engines). As long as I kept the engine reasonably clean (wash dirt off with a shot of fuel ), like a Timex watch, takes a licking and keeps on ticking.

I own 6 OS FX.25's. 4 of them have similar peeling problems as Kris shows. I suppose it's the nickel plating used. I also have a LA .25 doing the same at the very top of the liner. I still run them in this condition and surprisingly they run quite well. It really doesn't make sense as to why. I'm sure longevity however is going to be way down.I figured what's the difference now, just run them till they die. FX piston cylinders are fairly pricey opposed to the LA.

The AP .061 even though it somewhat let me down, I really wanted it to succeed for all of us. I can only assume the reasoning behind the discounted cost when I purchased them is that they were on their way out. It wasn't long afterwards that AP rebadged again as Sanye were being once again discounted to the point of unavailable.

The first gen Brodak CS crap was possibly one of the worst engines I ever purchased. I couldn't get rid of that fast enough. The Brodak MK II has been doing quite well for me. One needs to realize this is a entry level engine and no real performance to be had with it. I do think it's one of those engines with hidden potential. The AP had some nice features to it and I really feel that it would terrific to see these again. Unfortunately, I don't think that will ever happen.

Surfer_kris wrote:There are plenty of write-ups on these engines on RCU from the time that were made, just search for AP Wasp (and not Hornet).
Here are some of my findings (under the username Mr_Cox): https://www.rcuniverse.com/forum/1-2-1-8-airplanes-70/9607673-ap-engines-wasp-061-a.html

Mine were never as powerful as the Norvel that they copied, and it also lasted shorter...

Some cylinder pealing showing after a few seasons on all castor oil:

Hello Kris
                  Thanks for the information. I have seen peeling nickel since I bought my first OS.40 VF and used it in a scratchbuilt Quickee 500. I used to race it using K&B 1000 fuel and had a tuned pipe. If I missed the NV setting and it went lean it meant a new cylinder and piston. The plating would flake badly from the exhaust up all the way around. The good old days.
            I made a tool to make a groove on the front bushing of the .061 hornet engine to improve lubrication in hope that it will slow down bushing wear as I plan to see how well it do on high nitro fuel all castor. I practiced the operation in an old .049 Norvel crankcase. here is a pic.  
                                                                                   Juan

Ken Cook wrote:                I own 6 OS FX.25's. 4 of them have similar peeling problems as Kris shows. I suppose it's the nickel plating used. I also have a LA .25 doing the same at the very top of the liner. I still run them in this condition and surprisingly they run quite well. It really doesn't make sense as to why. I'm sure longevity however is going to be way down.I figured what's the difference now, just run them till they die. FX piston cylinders are fairly pricey opposed to the LA.  

       The AP .061 even though it somewhat let me down, I really wanted it to succeed for all of us. I can only assume the reasoning behind the discounted cost when I purchased them is that they were on their way out. It wasn't long afterwards that AP rebadged again as Sanye were being once again discounted to the point of unavailable.

The first gen Brodak CS crap was possibly one of the worst engines I ever purchased. I couldn't get rid of that fast enough. The Brodak MK II has been doing quite well for me. One needs to realize this is a entry level engine and no real performance to be had with it. I do think it's one of those engines with hidden potential. The AP had some nice features to it and I really feel that it would terrific to see these again. Unfortunately, I don't think that will ever happen.

Hello Ken
                I also like the looks of the AP Hornet.061 and the way they decided to make the round intake for the carb that allowed me to make a venturi for it. The Norvel bathtub intake hole I don`t like. I guess they were using them with no venturi like the stels.049 combat. I just bought a couple of Norvel big mig sport .049 what I learn from this I will apply to them.
                                                                                        Juan

Juan, I own a few of the Stels engines. I owned a .15 as well which served me well for quite some time. A fellow from one of the other forums noticed I owned it and really wanted it.  I parted with it and I hope he's equally enjoying it. The .049 twin horn as I refer to it was available in a few different crankcases virtually all the same. They even made a .061 which is very rare and I almost acquired one. Stels did make a insert for these to run on suction. They're equally as rare because everyone lost them. I see in the picture you posted the stock cylinder screws are still on that engine. Those stock screws usually fail and the cylinder blows off.  I never had good success using the Stels needle with bladders and I opt for my own. One surprising detail about the Stels twin horn, you quickly know how many cuss words you forgot when you burn your hand off trying to adjust the needle. It hurts real bad.
         I run my Norvel's without the venturi just like the Stels for combat. Unfortunately, fuel economy is poor. I contribute that with burbling over the side of the case. What I'm doing now is having a venturi 3D printed which will fit the bathtub opening properly with a shoulder. I'm interested to see how this is going to work. Norvel made a heli version of the .061 which used a tall venturi stack which is what I'm replicating but not as long.

Hello ken
                     I don`t know anything about the stels Engine series. Didn`t know there was a .15 engine. I bought a new Stels .049 and a Stels .35 Combat Engines without any information because I liked their looks and I was adding to my engine collection. I had to look thru my boxes of engines to find them luckily I always place a list inside which made it easier to find them. I searched the internet for information on this engines and Sceptre flight engine test and had no luck. I saved your comment on the stels also for future reference. here are some pics of the Stels 5.8cc .35 ci engine.
                                                                                  Juan

Juan, the Stels .36 is a rare engine . Is that a new example? I've run the Fora .36's and all I can say is hang on. I had the Fora on a combat plane and it was running 122 mph and it's just all out nasty, scary and cool all at the same time.   I have 3 different variants possibly 4 of the Stels .049's. My favorite is the side exhaust version. I have to say, this was a very powerful .049. AME was a manufacturer prior to AME being the reference of cylinder porting. These engines came in a small styrofoam container. Larry Driskill former owner of Kittingitogether  gave me one some years back. The engine is brand new and I've never run it. It seems as if Stels used the same crankcase of the AME and ground off the A3RO which was in the casting on the side of the case. I'm not familiar with the Cyrillic alphabet so I can't say for certain as to what that means. I think the Stels were true chrome vs the nickel used on some of the other manufacturers. Regardless, the Stels turn up and they offer considerable rpm differences over the others such as Norvel, AME.

I didn't know that Stels made a .35.  Bet it goes well.  I have a Stels .049 that a friend sold me for a deal.  It ran fast but could not hold a setting because of too much slop in the crank that was leaking air.  I made a new bushing and that stopped the problem.  I ran it up to test but never flew it.  Also have a few TTiger .07s that leak at the crank.  My swap meet example of the AP .06 does not run well at all.  Maybe worn out when I got it, IDK.  The crankcase looks so much better than the Norvels, but it is a disappointment. I am pretty happy with the AP .09 and .15 if run without the muffler. Someone told me that after blowing plugs, there is a coating of the element that stays on the top of the piston which will make the problem worse. You can see the particles that bond on the top of the piston and head almost like plating. I imagine it can be removed and then it would be OK.

Ken Cook wrote:               Juan, the Stels .36 is a rare engine . Is that a new example? I've run the Fora .36's and all I can say is hang on. I had the Fora on a combat plane and it was running 122 mph and it's just all out nasty, scary and cool all at the same time.   I have 3 different variants possibly 4 of the Stels .049's. My favorite is the side exhaust version. I have to say, this was a very powerful .049. AME was a manufacturer prior to AME being the reference of cylinder porting. These engines came in a small styrofoam container. Larry Driskill former owner of Kittingitogether  gave me one some years back. The engine is brand new and I've never run it. It seems as if Stels used the same crankcase of the AME and ground off the A3RO which was in the casting on the side of the case. I'm not familiar with the Cyrillic alphabet so I can't say for certain as to what that means. The Stels cylinders were usually not plated and I can't be certain but I think they're true chrome vs the nickel used on some of the other manufacturers. Regardless, the Stels turn up and they offer considerable rpm differences over the others such as Norvel, AME.

Hello Ken
I`m doing some more search to find information on the Stels.36 . The engine is New.
Juan

aspeed wrote:I didn't know that Stels made a .35.  Bet it goes well.  I have a Stels .049 that a friend sold me for a deal.  It ran fast but could not hold a setting because of too much slop in the crank that was leaking air.  I made a new bushing and that stopped the problem.  I ran it up to test but never flew it.  Also have a few TTiger .07s that leak at the crank.  My swap meet example of the AP .06 does not run well at all.  Maybe worn out when I got it, IDK.  The crankcase looks so much better than the Norvels, but it is a disappointment.  I am pretty happy with the AP .09 and .15 if run without the muffler.  Someone told me that after blowing plugs, there is a coating of the element that stays on the top of the piston which will make the problem worse.  You can see the particles that bond on the top of the piston and head almost like plating.  I imagine it can be removed and then it would be OK.

Hello aspeed
I think that I might have to make a bushing for the AP hornet, the bushing that it has is thin and not well made. Thanks for the information.

Today I got together with my friend and made a few runs on the AP Hornet.061. We started using a 5.7 x 3 apc propeller and 15%/22 oil  Half Blendzall castor half Klotz synthetic oil. On the first run we noticed some soot in the oil coming out of the open exhaust but by the third run it was coming out clear. Then since the engine felt real loose we went to a 4.5 x 4 Apc using the same fuel I started adjusting the needle valve to fine tune and was able to get 22K RPM. We only did 6 runs in total as my friend had to leave. we will do some more runs soon hopefully to see if we can extract a few more Rpm`s. I will be taking the engine apart to inspect all the parts. here are a few pics.
                                                                                                Juan

Bravo! I miss my P-40...sigh.