2-stroke or 4-stroke - better for beginner pattern flying?

Not sure that Webra would cut it today. Not sure you could make it meet the noise requirement and still have enough power. The trend now is low revs and a high torque engine. But muffler's are better these days, perhaps with a silenced pipe and a three blade prop?

It's no myth. Any time you called them with tuning problems they would send you the rest of the instructions for your engine. Both my Q500 Special and Eagle IV .74 came with the modification instructions. This was in the mid '80s.

Ahh. You are right, here is the instructions for a small case .40 and smaller with that recommendation.

I don't see that fileing the tip is that difficult. The threads on my Fox engines do not seem any looser than other wire sized threaded needles. Not as refined as OS and others with a O ring seal, but mine do not seem to leak excessive fuel. Nor any excessive air leakage problems, mine will sometimes stop when the throttle is closed and other times it will be stubborn reqireing me to goose the throttle to stop it. I assume this is because of air leaking past the needles at idle.

Hmm, when I read the user comments about the ST .51 on RC Universe, the comments seemed to indicate that the ST .51 idled smoothly at low rpms, but the midrange performance wasn't so good. Everyone seemed to agree it was a great motor at full throttle though.

I'm getting lots of differant RPM readings also. Comments that it is a low RPM engine, performance figures that seem to verify that, and others that are clearly above that. Comments that it performs poorly with muffler, great with other mufflers. That the older ABC version was a high revver. That the C/L version is ported for lower revs and more torque. And the possibilty that ST has played around with the porting, etc. I am not sure what you would get from the present Chinese version.

No, it isn't a myth. I had an early .45 schneurle engine with a wart on the bypass port that had needle shaping recommendations in the instruction material. Not a myth at all. That was in 1978 or 79, IIRC.

Ed Cregger

I was under the impression that he wanted the model for learning the maneuvers, not actually competing with it.

If folks want to see pattern come back in popularity again, drop the idiotic noise regulations and let the Europeans cope the best that they can. To me, that was one of the things that ruined pattern. I liked it the way it was. No scale-like models, no giving four-strokes twice the displacement because they thought they were quieter, etc.

Bill Bennett truly screwed pattern flying up.

Ed Cregger

Actually I think the AMA noise rule shoud be bumped down. Maybe not as low as the pattern folks though.

He said at the Sportsman level, which tells me he wants to compete. Though maybe he meant the pattern difiiculty. That is why I pointed out the older .60 sized ships, because they are larger and are thus judged better. Should do the current Sportsman pattern fine, though I am not up to date on the exact pattern manuvers. Then again if not a big event they may not be strict about the noise requirement.

The Supertiger carbs are set up to with a rich midrange. When you tune it you can shift the spray bar to one side to lean out the midrange. My G.91 seemed fine without adjusting it, but may have been adjusted by the previous owner. I haven't flown it just ran it on the bench, so it may have a rich midrange in the air.

Well, I can't believe that it is a low rpm engine. People advertise the hell out of that behavior and then charge you more if they have been designed to run that way. Look at the OS SF and RF .61. Even today they go for a premium price.

In pattern flying, you do not need the kind of throttle response that is required for 3D flying, so that is not a factor in choosing a two-stroke for a pattern trainer. As long as it doesn't quit when you throttle back or throttle up, you are okay.

If you are super concerned about not buying a one trick pony, the YS.45 is still for sale at Sheldon's Hobbies. It does have excellent throttling characteristics through out the rpm range, but it is really designed to run with a pipe and will still be peaky. Peaky engines are okay in learning pattern maneuvers.

One of my favorite engines in this size class is the Enya .45CX AAC engine. Unfortunately, it is no longer being manufactured. The .50CX is a different kind of creature and is not in the same league.

When other engines are breathing hard during a climb and are sagging out, the AAC piston and liner of the .45CX just accommodates the extra heat and lets the engine pull like a freight train. The secret to running this engine is to run it leaner than you would an ABC engine. It thrives on it. I just picked up two samples of the .45CX via eBay. I be smilin'. These engines run great with the stock muffler.

The YS.45 will out turn it on the ground, but in the F3A Hour Glass maneuver (vertical 8 with a half roll), the little YS sags out and the Enya .45CX just storms right on past the YS. Peak rpm doesn't mean a thing if you can't bear down and do the work when it is needed.

Besides, the difference at peak rpm is only a couple of hundred rpm. Not of much significance when both engines are turning at 14k rpm plus.

If you tune these AAC engines the same as you would an ABC or ringed engine, you'll be trying to sell it to me on eBay because you won't have stumbled onto the extra power that is built into these engines. I wouldn't know about it either if a modeling friend named Shorty hadn't told me about it in 85. May your soul rest in heaven, old friend.

Ed Cregger

Except for the Hanno version the RF was a high revver. The Hanno went to extra measures to get max torque at lower revs than I was thinking of, like 9,000 RPM VS 11,000. The SF was a long stroker and they really didn't charge that much more, more inflation than anything. The G91 is a torqer, they don't charge anymore for that one, VS OS who makes you pay a premium for the FSR 1.08.

A friend of mine and an active pattern competitor at the time the RF was popular, George Asteris, was flying the RF with 11-11 props in the 10k rpm range, as were many other folks. Very low revving and extremely quiet. George's plane was "The Omen". He wrote the newsletter for the NSRCA (I hope I have this right) for a few years some years ago. I "think" he was also president for a while, but I wouldn't bet money on that one.

Yes, you can get it to rev up pretty high with an 11x7 and a shortened pipe, but that was not its design goal. Same with the YS61AR, which is what I owned. It would rev, but that was not its forte'.

George switched to the Hanno engine and was not happy with it. For his model and his style of flying, the RF was perfect and it helped him pass the sound checks with ease.

Your recollections are equally valid, my friend. No argument from me.

Ed, NM2K

I am primarily interested in learning how to fly pattern, with an eye on possibly competing at the Sportsman level down the road. I guess what I'm really after is an engine for the Imagine 50 that would be capable of competing well if I ever get that far down the road with it. I don't see a point to learning to fly pattern with a power system that won't be able to compete if I should choose to do so down the road. I don't know how to fly pattern yet, but I want to learn on a "typical" setup.

I appreciate all of the feedback so far. I'm concerned that a .60 sized two-stroke will be too heavy and require extra weight for the tail. I'm also confident that a .46 ball-bearing two stroke or .54 four stroke engine would be adequate for general flying but a bit underpowered.

I'm going to buy a new engine here in the U.S., so my choices seem limited to the following:

Magnum XL .70 four stroke (long shot, but possibly a good value) O.S. FS-70 Surpass II (front runner, not cheap but worth it) Saito .72 (expensive, no experience adjusting valve clearance) Super Tiger .51 ringed (bargain priced, adequate power) O.S. .50 SX (expensive, priced too close to four stroke) Webra Speed .61 GT (expensive but much lighter than other .60 2-strokes)

The availability of the new YS .63 supercharged 4-stroke is nil for the next couple of months, so I've taken it off my list. Most of the other brands like Enya or Fox I just can't seem to find available either at my local hobby stores or from a mail-order reseller that I'm familiar with.

Please feel free to talk me into, or out of, any of the above engines on my list!

Ed

Putting a 11-11 on an RF may have worked, but not sure it was designed for that. The Hanno was typically used with a 12-12 and turned about

9,000.

Since you have the Webra .60 on your list you might want to consider the K&B .61 twist head. Not as strong as the Webra, but lighter. Cost $100 from Mecoa. You know myself and Ed are basing our suggestions on past experiances and I can't speak for Ed but I am really not up on the latest in pattern. You might want to check the pattern forum's on RCU and RC Groups.

ok, I gotta ask....

Just how many engines do you have Ed? Seems you're picking up a 'new' one every few days...

Another thought. If you don't want to go the four stroke route and noise is a consideration. Chose one of the two strokes that will do well at lower revs and a pipe. You could learn without the pipe but proped for higher revs. Later when competing buy the pipe with a bigger prop.

The Webra .50 GT will eat any of the choices in that size class alive. Pattern is not a hovering event, so the peakiness and brute power of the Webra .50GT is perfect.

The only real problem will be getting any high revving two-stroke to pass the noise qualifications, whether OS, Webra or whatever.

I haven't looked at the Sportsman pattern lately, but I'll bet you don't need a full blown pattern ship/engine combo to be competitive.

Of the four-strokes you listed, you DO NOT want to consider the Magnum .70. IIRC, it is built in the .91 casting and is even heavier than the .91.

The Saito .82 would be my choice. The .72 is actually heavier than the .82. The .82 only costs a few dollars more, is lighter and is more powerful. Drop in prop diameter and up the pitch to compensate. That will give you prop clearance.

Check the model and its fuel tank location. If you can't get the fuel tank centerline even with or slightly below the carb spray bar, you will need a YS.63 or another engine with a Cline or Iron Bay fuel regulator. There is no work around other than what I have mentioned. I had a Phoenix 8 that would drown any atmospherically aspirated engine without a regulator.

A truly competitive model will set you back about $3,500 complete. Fortunately, you do not need the latest and greatest to win in the lower classes - but it doesn't hurt.

Ed Cregger