AP .061 - a quick note

I got my hands on one, for evaluation. Fits the Norvel mount, even has a hole in the lug for a spring starter (though this might've been put there by the people who had it before me). One problem I immediately ran into is that the prop shaft is considerably bigger than that of the Norvel or of Coxes (5-40). Reamed the prop out to 3.5mm, a tight fit. Maybe 4 would have been better. The prop is held on with a spinner nut rather than the Norvel arrangement of a screw and spinner-shaped washer. The propnut seems to have malformed threads, it only screws in halfway. Come Monday I'll go to the nut and bolt shop and get an appropriate nut. Meanwhile, I put a #6 washer under the spinner nut.

I'll actually get to run this tomorrow. I'll take some pics beforehand of it mounted on a Platter.

Oh.. forgot to mention. This thing comes with a head wrench. Whoop de doo, you say. Well, it's the best fitting one I've ever had yet. Fits Norvel heads and is PERFECTO for the Galbreath head. I took a pair of popsicle sticks and used duct tape to sandwich the handle between them, and using this, was able to remove one particularly stubborn Galbreath head from a Norvel. Feels VERY secure, unlike other head wrenches I've used.

Well, did some actual running. Like Norvels, this thing was TIGHT in the beginning. Took a lot of working at it with the spring starter before it would burp, and then quite a bit more before it would run. Gave it maybe 3-4 tanks on the ground.

This thing is absolutely GUTLESS. It's the Fox .35 Stunt of .061s. The Norvel puts out huge amounts of power in comparison, with a 5x3 prop - several thousand RPM more. I'll try different props and see what I can do - maybe it likes more pitch, or more diameter. Or maybe it needs more of a break-in. Not a bad engine for an ab initio trainer, though..

Thanks for testing this engine. The AP .061 is readily available at our local Hobby People chain and I've wondered how they run.

Some questions:
1. Even if it's not up to Norvel performance, do you think it would be a good entry level engine?

2. Does it use the Cox glow head thread like the Norvel? Would the standard Galbreath head/Nelson plug combo work?

3. Does it have a decent needle you could use with a bladder?

- Norm

>Thanks for testing this engine. The AP .061 is readily
>available at our local Hobby People chain and I've wondered
>how they run.

Not that they're expensive - might as well get one to see how it runs... it's possible I might have a bad example.

>Some questions:
>1. Even if it's not up to Norvel performance, do you think it
>would be a good entry level engine?

Once broken in, yes, it starts easily (but I used a Norvel spring starter - if you have an electric starter, no problem at all). You can always go to shorter lines (I was flying on 42s).

>2. Does it use the Cox glow head thread like the Norvel? Would
>the standard Galbreath head/Nelson plug combo work?

Yes. I've heard people suggest using the head/plug in Norvels, if they couldn't get the Norvel heads. Can't vouch for that combination, though.

>3. Does it have a decent needle you could use with a bladder?

Haven't tried it with a bladder as yet. They don't make a CL version, mine is the RC version with the throttle jammed wide open. It runs on suction about 3 1/2 turns from all the way shut.

I just ran one for the first time yesterday, and mine is a screamer. It was running steadily over 21K on a 6x2 APC and peaked briefly over 22K! So far it only has about 14 minutes of the recommended 40 minute break in, so I will be interested in where it ends up.

Also, I don't yet know how well it will pull fuel in maneuvers. It is mounted on my Sky Sport, so as soon as I feel it is running steady, I can fly it.

One thing to check is that the venturi hole should be as far as possible toward the needle valve. Otherwise, the fuel nipple partly obstructs the airflow. You can loosen the retainer nut under the needle and back the drum out to change its position in the carb housing (it is screwed onto the fuel nipple on the inside).

Hmmm.. maybe I have a bad one after all, or I need to try the APC. I was using a Grish 5x3, I doubt it broke 15,000. I'll have a look at the carb later tonight to see if I can slide the barrel over. The intake is centered fore-and-aft as well as left/right at this time.

Isky, and all,

I picked up a pair - Mike K's October thing in mind - and note that the AP glow head and clamp don't fit into NorVel or Cox cylinders, but Cox, Nelson and NorVel parts fit into the AP sleeve. The thread is the same, IOW, but the AP glow head button is about 0.001" larger diameter.

Rinsed both in gasoline (Coleman fuel, actually) before running. No swarf or crumbs...

Mine had a little reluctance for first starts, in 35°-45° F temperatures, and wept a bit of grey/black metal in the exhaust oil for the first minute or so of running. Clean oil ever since. Hand starts on 10/11/11 fuel worked fine. 3 to 5 flips after two choked turns seems about all it needs. Contact to the plug is the only nuisance. I tilt a McDaniel-type so the skirt of the plug element and the centerpost both get good contact. Starts should go even quicker with an electric starter, of course...

Four-cycling wide open at ~14,000, crackling just out of solid clean 2- at ~15k. Haven't really wound either one out yet - only about 20 minutes on each, but they wash through 18k plus when shutting down, and haven't really got hot-hot yet.

The throttle is too simple to work, but it does. Both hold a smooth 5k and respond cleanly to opening throttle. 5.7-3 APC prop, as instructions say. (5k sounds fast, but on a 1/2A prop it doesn't push hardly at all.) Sounds like it can turn a bunch of RPM on that prop and fuel, which should be a safe, dependable combo for useful life.

Btw, these observations were at my home altitude of around 5,000' above sea level. Not too bad, IMHO.
edit:typo

...a further thought...

The APC 5.7-3 prop has a very thin hub - the cross drilled spinner nut bottomed out before it secured the prop.

A trip to a local ACE Hardware found that a 4x0.7 metric nut(I think that was the size) fits, and takes up just enough length to get the prop secure, and lock-nutted with the spinner nut. In any event, it is an available size easily found.

I don't think the OEM spinner nut threads enter the cross-drilled hole. I've used some other engines where that was the situation, and the cross-bar, used to tighten down on the prop, got trapped by the shaft...

If you remove the stop screw on the left side of the carb body (don't lose the spring!) and then the needle valve and finally the nut that holds on the clip and control lever, you then can screw the barrel out a turn or so to move the venturi away from the obstructing fuel nipple. This will give you more venturi area. Screw it in for more fuel draw. Then you can reassemble the thing.

Larry,

...That's odd. On the ones I have, the thread on the choke end of the fuel nipple is the restraint on the barrel. Maybe I read your post wrong...

Yes, it is possible to locate the barrel off center toward the fuel nipple, possibly also toward the NV - but why? It's a fairly coarse pitch thread at the nipple end of the barrel, and a half-turn to align the choke hole properly is a significant distance.

BTW, I'm sure you've noticed that the eccentric"stop screw" operates merely on the throttle arm outside the 'works.' It doesn't bear on a flat on the barrel.

Also BTW, the throttle barrel 'advances' the tapered NV into the fuel nozzle as throttle is reduced, partially leaning the mix for the reduced RPM high 'suction' conditions. Something like the ST MAG carbs, but much less travel. Moving the choke bore off-center may complicate that leaning function.

Brutally, crudely simple - or is it actually a refined elegance? It works, and pretty well, anyway.

I would probably leave the venturi centered for RC use, but for maximum power on a CL model, I backed it out to the edge of the carb body opening. The way it is designed, you can use half turns to get where you want to be, close enough, anyway.

BTW, I am running 15%/11%/11% fuel. Fuel consumption is high, I get 3-1/4 minutes on 22ccs. That is at a slightly rich setting, when it is broken in and can run flat out, it should be better. Also, switching to the 5.7x3 will improve the economy too.

Larry,

Good info, thanks.

I'm still just about halfway through the recommended/suggested run-in time on a pair I hope to use for Mike Keville's multi-/profile-/1/2A Scale thing this October. (Throttles optional, but...)

I'm delighted with how well they run on 10-11-11 fuel*, on a 5.7-3, the recommended break-in prop. Economy seems quite good, and I'm still around 14-15k, with engine just out of 4-cycling and below sweet 2-cycling, i.e., bare hint of crackle in the exhaust note. Running out the last bubbles from the tank, it flashes past 18k...

Instructions call for all- or mostly-castor fuel for at least break-in. Sounds inappropriate for plated sleeve/aluminum piston layout, so I split the difference.

Idle is already quite steady around 5k, may 'improve' down to around 4k or so, but if not there's negligible thrust at 5k anyway.

* - It can be a nuisance toting Fox-type, AB?-type glow fuel AND plain bearing AND BB diesel fuel. Simplifying even one of those helps.

Larry,

I spent a little time finishing the 'mandatory' minutes on one AP .061 yesterday, after my previous post.

Now I see what you described. The reason I hadn't visualized it was that when I looked over the seemingly crude carb, I chose to disassemble it from fuel nipple end instead of the throttle arm end.

That way I didn't have to fiddle with the eccentric-head idle travel stop screw alignment to the throttle arm. I'll check to see if the assembly threads allow a complete 360° of the barrel away from the nipple - which does occupy quite a bit of the choke opening.

Throttling and mixture compensation should not be affected, as the NV pretty much controls that. It may just mean a different initial setting than the mfr recommendation. With muffler pressure, the area gained doesn't compromise fuel delivery.

Thanks for this thought!

I will back up what Larry said about the AP being a screamer. Saturday he brought it out to the flying field and his plane literaly jumped into the air with the AP .061. It is the hottest stock out of the box 1/2A I have ever seen. It may not be a Cyclon, but then again what is? But where I was standing it sure seemed faster that the Norvel he had on the very same plane.

I have one on an old litehawk. Delrin venturi, needle from a small MP Jet. Running on a bladder. Cox rubber ducky prop.

It runs OK, Like a good TD but not a Norvel. Not competitive, but a fun practice plane.


Dave

Well, I flew the engine on my Sky Sport today. It pulls through maneuvers beautifully! The plug burned out after the 6th run (from new), so I put on a Galbreath/Nelson combo.

New peak rpm was over 23K!!! Steady in the mid 22s. When cranked, the plane is too fast for comfort - with a 2" pitch prop!

Folks, this one, at least, is a winner! I have a 2nd one to start breaking in tomorrow. =)

>Well, I flew the engine on my Sky Sport today. It pulls
>through maneuvers beautifully! The plug burned out after the
>6th run (from new), so I put on a Galbreath/Nelson combo.
>
>New peak rpm was over 23K!!! Steady in the mid 22s. When
>cranked, the plane is too fast for comfort - with a 2"
>pitch prop!
>
>Folks, this one, at least, is a winner! I have a 2nd one to
>start breaking in tomorrow. =)

Hi Larry, it must be turning way over 23K. Using a 2" pitch prop,
your airspeed works out to roughly 43.56mph. It's not really going
that slow is it? I would think that it is turning closer to 26K with
that 2" pitch prop. All my 1/2A Combat TD's turned better than 24.5K
on 4.6-4.8"x3" Tornado black props. At any rate I'm glad you discovered
another suitable engine for forum members. It would seem that it needs
to be played with a bit to suit a particular use, but that's common for
many small displacment engines.
Tony