rt4957

I have a Midwest Aerostar that is nearing completion,and I was contemplating getting it a 4 stroke engine.

I have NEVER flown a R/C plane before,and am looking for something docile,but powerful enough to have fun once I get better at it,,if it doesn`t crash first.

What do you recommend?

Is a 4 stroke better than a 2 stroke,,as I have a couple 25s from other builds I`ve done

Thanks Phil/Rt4957

davidgeorge212

If its a .40 size plane, I would say something like a minimum .56 four stroke and probably no bigger than a .72 four stroke which would give you plenty of power. Some where inbetween would be good though.

As far as diffrences between two strokes and four strokes, I would say the major diffrences are 1. the price (four strokes are way more expensive), 2. four strokes sound a lot better, 3. four strokes supposedly get slightly better gas mileage.

David

davidgeorge212

of course now that I think of it, the one I had flew with a .32 two stroke so I would rethink what I said above and go a lot smaller. I looked it up online and tower hobbies reccomends a .40 to .50 four stroke. Some of it depends on how big a space you have where the motor mounts are.

FILE IFR

An O.S. .40 4 cycl. will pull that plane around nicely at half power once it's flying. You can fly for nearly 3/4 of an hour with a 12 OZ. tank.

FWIW, You'll get some people to recommend you stuff the biggest engine you can in it, so you can "Get Out Of Trouble" if need be. I laugh every time I hear this.

tunes079

I would recomend a O.S. 46AX two stroke for a trainer due to its power, ease of use, and most importantly, the price. Now if you have your heart set on a fourstroke, I would go with a saito .56. It has good power
and should be very similar in weight as your average 40 size twostroke.

ChuckW

Any good .52-.56 4-stroke will work well in a .40 size trainer.

I've flown a trainer with a Magnum .52 4-stroke and it was a great combination. OS used to make a great .52 that was recently replaced with a .56. Saito also has a .56 and I believe Thunder Tiger has a .54.

All will work great for your airplane.

If it were more of an aerobatic plane, I'd say go with a .70 but it isn't necessary for a trainer.

I've heard people recommend staying away from 4-strokes on a first plane because a 4-stroke is more "complicated". I don't get that logic at all. They have the same two mixture screws as a 2-stroke and I've always found them to be extremely reliable and easy to operate. Of course 4-strokes do cost more and they often don't survive crashes as well. The torque and sweet sound is well worth the trade off though in my opinion.

Whatever you decide on, if this is your first plane, be sure to hook up with a local club and have someone there help you out. It will shorten the learning curve and make for a more enjoyable experience.

Here's an old trainer I had with the Magnum .52:

cooperd

I'll second that advice. The 46AX is a VERY strong engine. Easy to tune and affordable. I have a Saito .56 on a low wing sport plane designed for a 40 to 46 two stroke. It flys it very well with plenty of power, sweet idle, and that wonderful 4 stroke sound. And it didn't mess up the weight and balance .

Jetdesign

My Feedback: (8)

Personally I am thankful I learned this season on a two stroke - it allowed me to spend less time tuning or learning how to tune and more time flying.

That being said, if I were going to buy a four stroke for a trainer, would opt for one on the larger side so that I could take it out of the trainer and put it in my next plane where I would be more likely to appreciate the low end power and scale-like sound of a four stroke, and then buy a cheap two stroke to throw in the trainer for the few days I'd actually fly it once I moved past flying a trainer.

dignlivn

FWIW,

A Saito 82 and Throttle management.


Bob

ChuckW

As I said in my earlier post, I do not understand this logic. I own both 2-strokes and 4-strokes. They both have a low speed and high speed needle and they adjust in exactly the same way. 4-strokes start easy and idle very well. In fact, my 4-strokes actually seem a little easier to tune correctly for some odd reason. That's probably more my perception than reality though.

My point is that there is no "voodoo" required to make a 4-stroke run right as some people seem to think. Other than the sound, torque curve and maybe checking the valve lash once a year, they are no different than a 2-stroke. Once you have actually owned and operated a 4-stroke you will see what I mean.

As for using a larger engine so it can be put into another, more advanced plane I do get that philosophy. I say, however, keep the small 4-stroke in the trainer and keep that plane around long after moving past it if you can. There may be days when you want a relaxing flyer or perhaps you want to introduce someone to the hobby. A flyable trainer-type plane is nice to have around. In fact, I was trying to think of a kit to build on the upcoming rainy, foggy days and I think a trainer with a nice little .56-FS might be a good idea. I doubt I will personally fly it much but if I can use it to get people into flying, it will be worth it.

FILE IFR

+1

Steve Collins

My Feedback: (8)

I have a Y.S. .63 4 stroker in my Midwest Aerostar. It makes a great combination! I have also used this engine in a Great Planes Corsair. People have a hard time believing it is just a .63.

da Rock

Very few modelers, even very experienced ones can set a safe needle valve on a 4stroke. Their rpm response to the needle is quite a bit less obvious. Beginners have a difficult enough time learning to set 2strokes by sound, and 2strokes have pretty obviously different sounds from rich to lean. The advice is often meant to save the newbies money replacing engines they've ruined. 4strokes are more complicated. Noone has to set the valves on 2strokes. And 4strokes with downdraft carbs can drive experienced modelers nuts when inverted. Upright or inverted, lots of them take a bit more attention to detail to either keep 'em from flooding or getting them primed. Pick one of those problems and there's a chance it'll be there depending on up/down draft and upright/inverted mounting. So there are more complications.

A year or so ago, one of our newbies to 4strokes showed up with one nobody at the field could get running worth spit. The list of things he was told you probably had to do was long. Need higher nitro fuel. Shouldn't mount some of them inverted. Have to use a 4stroke glowplug (very much more expensive). Shouldn't choke that specific 4stroke but only start with a mechanical starter. Shouldn't use a mechanical starter with that one inverted. Have to use larger diameter props to get flywheel effect for starting the smaller 4strokes...... and on and on. It was amazing to hear all the things the experienced 4strokers felt were normal for those engines. I doubt half were really true, but those guys thought they were. And it showed what 4stroke fanboys think is covered by, "just like 2strokes".

4strokes are kewl. But if you're thinking of putting one on your first plane, find an experienced 4stroker and talk to him from day one.... before you buy the engine would be day 3 or 4. And get him to explain how he sets his engines and be absolutely certain you fully understand all of it. And get a tach and learn to use it. It'll teach you what the sounds you'll need to learn sound like. Later you might not need it, but you won't learn the sounds cheaply otherwise unless you're very lucky and have a great ear.

ChuckW

You know... other than cost and potential crash damage, I really see no reason not to start out with a 4-stroke. A nice little .52 upright in a trainer is really no big deal I think. Maybe the throttle linkage issue could be problematic but not unsolvable.

As for the sound difference from rich to lean, it's pretty evident when a 4-stroke is lean. Use a $19 tach and tuning gets really easy. Your right on about so many people not getting needles set right but I think that also applies to 2-strokes from what I have observed.

Maybe I'm just not seeing the difficulty. I've been workign on small engines since I was a kid, then transitioned into cars, forklifts as I got older. Maybe it comes easier for me because of that, who knows. Still I don't think a 4-stroke is this big mysterious thing like some newcomers seem to think.

mscic-RCU

My Feedback: (6)

i have both 2 strokes and 4 strokes. i don't find either one more or less difficult than the other. i will say though, if you break in saito's like the direction say to, they purr like a very satisfied kitten. i would go for the four stroke. by the way, they do use less fuel. they intake fuel 1/2 as often as a 2 stroke, thus the name 2 stroke and 4 stroke.

dignlivn

Now That ought to be a Sticky !!

Well Put !

Bob

speedair

if you want a four stroke for a 40 trainer i would go for a 52

T.L.A.R. eng

The Midwesr Aerostar is a great trainer plane. My second plane was an Aerostar with a Saito GK .50 and it flew very well.
It lasted all through my flight learning curve and didn't meet it's demise until I was learning aerobatics. [Inverted flight 1-1/2 feet off the tops of the beans, down is up and up is........]

First plane was a PT-40 with a 2-cycle Royal .45 Climbed like a rocket, way over powered for a beginner!

The Aerostar with a .50-.52 4-stroke is definately a winner! Learning the 4-stroke as a beginner wasn't that big of a deal. just set it and forget it! Very reliable for a beginner to use!

Jetdesign

My Feedback: (8)

I was thinking in terms of rocker arm adjustment, knowing if that was needed, improperly adjusting, etc. Especially after a crash. There is obviously more going on in a four stroke engine that could potentially be problematic for someone who's never flown an RC plane before. Personally, I ended up in a situation that needed a tear-down and complete cleaning of my engine. Had it been a four stroke, I feel it may have been very, very difficult to get the engine set up correctly had it been a four stroke.

And of course it always depends on who's around to show you stuff. I feel there is a lack of deep understanding of engines at my club so the two stroke has been fantastic for me - lots and lots of flying time, very little down time.

Delta3

Magnum / Asp 52 FS are a tidy little engine that are reliable (well mine have been) have a couple of Thunder Tiger 54 FS which go well upright or at 90 degrees, they don't like working inverted. Also have a couple of Saito 72 FS. With this hobby as with just about everything in life you get what you pay for and you can do a whole lot more with a Saito 72 down the track than you can with a 52 of 54 size FS motor. It is all personal preference but my PC9 flew with the 52 and the 54 four strokes (that is about all it did) but with a 72FS in the nose it flies with authority and will do all of the moves. For my money pay a little extra and have a much more versatile engine. You can fly a trainer with a 72FS in the nose you just don't need as much throttle to do it.