Which four stoke
 

Hello,

I'm in the uk and found this site, very helpful with all the reviews etc. I've just passed my BMFA "A" and looking to take my "B". I'll be sticking to 40 size planes too due to space and the size of our flying clubs flying area.

I'm currently running a OS46LA in my World Models Super frontier 40 and Black Horse Super air models. I've also got a World models cap232r with an OS55AX in it which I like so won't change that.

However, more people seem to be going for a four stroke. I'd like stlightly more power and longer running times, and reliability as I've heard four stroke can be hard work and I like plug and play. My budget is approx £100 give or take a few £.

I've looked at SC52FS and ASP 61FS but still don't know. Will a four stroke do what I want, I like basic aerobatic flying. Any personal reviews of props, flight time on what size tank etc would be great. I've asked some people who give me various flight times but not given a tank size so not very helpful.

Thank you.

RE: Which four stoke
 

Take the 4stroke displacement and convert it with this formula. Divide by 3 and multiply the result by 2. Example: the 61FS would be 60/3=20 and 20x2=40

So you want more power and figure to use a 61FS. That 61 is going to give you the power of a 40 two-cycle. More power? Not that way.

You want performance? Power isn't the only way. Lighter weight helps performance. Consider engine design and weight. Look at a 4stroke and all it's parts. See all that stuff on a 2stroke? All that stuff weighs something. And isn't on the 2stroke. So not only is the 4 less powerful for a displacement, but it's also going to be carrying stuff that makes it weigh more. OK....... what's left on your list...........

Plug and Play......... chuckle...........
The valves on a 2cycle are holes in the cylinder walls. Do they ever need to be adjusted...... nah. Do they ever get out of adjustment......... nah. Do they add to the cost of the engine..... oops, wrong topic. But no, they don't.

How easy are 4strokes for beginners...... We got two in the last few months who tried 4s on their 2nd airplanes. Both have ruined those 4s with bad needle settings. Why did they set the needles wrong........ They didn't want to buy a tach because the 4s cost them so much more than 2s would have cost. And 4s are harder to set by ear. And their ears hadn't learned to hear what almost can't be heard, the change in pitch that 4s don't do but 2s do. Heck, we got a couple of flyers who've flown for years who've ruined 4s just in the last year. They wanted to try them and did.

Reliability was a criteria.......... whadda you think after reading about the complexity deal. Which is going to be more reliable..... a simple device or a complicated one.

Can all these things be overcome...... you betcha.
Would it be possible for a newbie...... you betcha.
Sensible to expect success doing it.......... hmmmmmmmmmmmmmmm

Actually, you can't overcome the weight penalty. Or the power loss per cubic inch. Or the added complexity.

Why was it you wanted to pay more, get less power, have to fly more weight, have a harder to handle engine??????????

RE: Which four stoke
 

Oh yeah, I forgot that 4strokes do give slightly longer run time.

Beginners need to have both sides of the issue to judge. Time for the other side.

RE: Which four stoke
 

The ASP61 is a nice motor, you can run it with 5% nitro and it will turn an 11x7. It is also very economical. On something like the Super Air it will be enough to enjoy sports flying but do not think it will give you unlimited vertical.

RE: Which four stoke
 

da rock, you are scaring me!!! Also making me feel back for the two new pilots at our field, one has a new OS70FS and one has a SC52FS.

I was just considering that fuel costs £18 gallon here in the uk[:o] But if its going to be that difficult and expensive then maybe I should just pay the extra and fit a biger tank for the 2s?

any other opinions?

RE: Which four stoke
 

Don't let Da Rock scare you, Get a 4-stroke.

The ASP 61 will have as much or more power than your 46LA (The LA series is not known for their overwhelming strength) and it will burn less fuel.

The ASP 61 is 6 oz heavier than the 46LA. This usually means shifting your battery back, or NOT adding the nose weight many planes need if you're using a 2-stroke. At the absolute MOST, you'll have to add 2oz of tail weight to compensate (Probably more like 1 1/2) for the 6oz difference.

If you're flying 3-D, weight is a major concern. If you're not - it's not - period. Contrary to popular belief, lighter planes do NOT fly better - heavier planes (Within reason of course) slice through the air and are less effected by winds.

Now I will admit that there are some planes that I prefer to use a 2-stroke on, but they are few and far between. And when I do use a 2-stroke, I'm usually left cursing out the slimy, oily mess they spit all over the airplane. With a 4-stroke, there are many days when, after flying, I put my airplane back in the car without having to clean it.

Beginners are often swayed away from 4-strokes mainly due to the expense. They are no more difficult to operate than a 2-stroke. True, they do like a little more nitro content than a 2-stroke, but they burn much less fuel, so the extra cost is a non-issue.

Ok, so the weight, and the cost of fuel is not an issue, but the initial price is. Is it worth it to have a more efficient engine, that gives you better, smoother throttle response?

Oh yea, and don't forget that cool 4-stroke sound! How many full-scale Extra 300s have that anemic 2-stroke sound?

How many Harleys or Triumphs use a 2-stroke?

You wanna fly an airplane, or fly a dirt bike? :D

RE: Which four stoke
 

I agree with da Rock - learning to adjust and operate a 2-stroke is easier than a 4-stroke. As a beginner you'll have your hands full and plenty of confusion added by nerves to worry about the additional effort of making sure your 4-stroke is set up properly. Also with the difference in fuel burn between a 2-stroke and 4-stroke, it'll take a lot of fuel to make up the initial purchase cost.

I recommend going with the 2-stroke also.

Hogflyer

RE: Which four stoke
 

A O.S 46 AX weighs 17.2 oz with muffler , a Saito .72 weighs 16.6 and the Saito .82 weighs 17.6 both with mufflers. I have all three engines. Have had both the O.S .46 and the Saito .72 in a the same plane , a Twist. The Saito is the stronger of the 2.
The O.S .46 is a great engine , for someone who is not to mechanically inclined . but on the other hand, I`ve never had a problem with my 4 strokes either.
da Rock is right on the money about getting a tach for adjusting the 4 strokes HS needle till you get familiar with them.
I like both 2 and 4 stroke engines , and let the airframe dictate which one to use.

RE: Which four stoke
 

But he has gone passed the Beginner stage, and he owns two 2-strokes already.

An engine has two methods of tuning - a high and low end needle valve.

A 2-stroke has them and a 4-stroke has them. So why would one be more difficult than the other???

The only maintanance difference is that sometimes (But rarely) a 4-stroke needs to have the rocker arms adjusted. This is a simple matter of removing 2 screws, checking to see if it even NEEDS to be done (I have only had to do it once in over 20 years of running 4-strokes), and turning a screw.

He WANTS to get a 4-stroke, don't talk him out of it because YOU guys prefer 2-strokes.

boos boy, get a 4-stroke. I can't recommend one over the other (Of the 2 you mentioned) because I have no experience with either. But in general, I'll give up my 4-strokes when they pry my cold, dead hand from around it.

RE: Which four stoke
 

Minn,
It isn't that he WANTS a four stroke, he asked if a four stroke would do what he wants.
He will not get more power or (noticably) long run times. So the answer to his question is no.

RE: Which four stoke
 

My second engine was a OS FS-70.. if I can run these things, anyone can..

RE: Which four stoke
 

Not true, In my experience, a 61 4-stroke will run considerably longer on the same amount of fuel as a 46 2-stroke.

A 46 LA will be lucky to turn a prop at 10,000 RPM. A 4-stroke would turn a bigger prop just a little slower, let's say 9500RPM

So in one minute, a 46 2-stroke sucks in (10,000 x .46ci) of air, or 4600 cubic inches of fuel mixture. A 61 4-stroke (Which only pops once for two revolutions) will suck in (9500/2 x.61) 2897.5 cubic inches of fuel mixture. That's about 2/3 of what the two stroke is using, and that doesn't take into account all of the unburned fuel that a two stroke spits out on every single stroke.

At 2/3 fuel consumption, a 10 minute flight with a 2-stroke becomes a 15 minute flight with a 4-stroke.

Another way of putting it is, If you burn 4 gallons of fuel per month, that's 12 gallons in 3 months. A 4 stroke will burn only 8 Gallons. If you buy fuel at $15/gallon, that's a $60 savings in 3 months.

But don't let the facts stand in your way.

RE: Which four stoke
 

WOW!!!! Minnflyer what a lesson. I need to print that out and take it to my math class. Thanks

RE: Which four stoke
 

I am also going to print that out for my wife's math classes. She teaches and is always on the lookout for answers to the dreaded
" when will I use this stuff?":D THANKS

BTW I like 2 cyclers for ease of operation and care. an extra gallon of fuel each summer is OK with me.
Also the power to wieght ratio is better for 2 cycle. 4 cycle engines have done a lot of catching up in that dept. though.

I have to admit 4 cycle engines do sound cool, they aren't actually a lot quieter but the tone is more acceptable.

RE: Which four stoke
 

Ok I've give this a bit more thought and I MAY be wrong (I know... there's a first time for everything). It's all in the details I guess. I was thinking of my own experience where I replaced a 46FX with an ASP .70. Flight times and flight performance were very similar.
Now with a direct comparison of the anemic 46LA to ANY engine with a displacement larger than .40, yes, one would expect more power. :D

RE: Which four stoke
 

Four Vs two stroke is a pointless debate as their are rarely any clear cut winners.

However there is the simple fact that four strokes rarely survive crashes as well as two strokes. This one factor alone makes the use of a four stroke for someone brand new an exceedingly poor investment.

I realize the original poster is somewhere above that level However how far? I,ve no idea and only he can answer that question. So if you are comfortable with the fact that in many crashes your financial potential for loss is even greater then great go ahead and start the required new learning curve.

John

RE: Which four stoke
 

I agree. For a beginner, a 2-stroke makes way more sense than a 4-stroke.

RE: Which four stoke
 

I would like to see the information that makes this a simple fact. Or is this just another opinion ?

RE: Which four stoke
 

It's true, but the key phrase is "as well"

a 4-stroke has the two pushrod tubes right in front which are susceptible to damage in a crash. In the old days, they used to put them behind the cylinder, but that put the glow plug too close to the prop for most people's liking.

So it's true, a 4-stroke IS more likely to sustain damage in a BAD crash.

Simple remedy, don't crash :D

RE: Which four stoke
 

Mmmm, easier said than done.

Even the most experienced pilots may crash at some point.

So are you saying I should just get a OS46AX and a bigger tank and pay more for fuel just in case I crash? Sounds like sound advice as I can't guarantee I'll never crash.

RE: Which four stoke
 

Of course it is just "just another opinion" and it is my opinion based upon simple observation as well as my own personal use with both four and two strokes from long before there were any commonly avaliable four strokes.

I,am sure you have your own personal opinion also that is of course "just another opinion" and that is exactly what any forum is, a simple collection of individual opinion.

John

RE: Which four stoke
 

Boosboy,

Only you can make the final decision on which type of engine to purchase, but let me give you some of my experiences:

I don't believe four-strokes are more difficult to set if you have a tachometer.

A .61 four-stroke will give comparable power to your two-stroke engine.

Four-strokes hold a tuning better through density changes and use less fuel.

They "feel" better at lower than full throttle settings. Two strokes seem to be happiest going full bore while four-strokes give the same response through the full throttle range.

I would personally go with a four-stroke.

RE: Which four stoke
 

Welll lol. Most 2 strokes have their carbs mounted on the front, knock that off and you more than likley bust the crankcase. A set of pushrod tubes are $14.00 . Pretty cheap fix. But I admit it ,I`m bias and think 2 stroke belong in weed eaters. Just my opinion, not a fact.
No worries

RE: Which four stoke
 

Personally, I could never understand why anyone would NEED a tach to tune an engine. Or for that matter, even USE a tach to tune an engine.

An engine is going to run its best owing to many different factors. Engine size, fuel type and quality, Prop size, ambient temperature and humidity, etc.

So why is looking at what RPM you engine is spinning going to do?

Just listen to it. When you lean it out, it will increase RPM, then you will get 3 or 4 clicks where the RPM stop increasing, then it starts to go sick as it gets too lean. Just back it off to where it first stopped increasing RPM. Now, at Wide Open Throttle (WOT) point the nose straight up. If the RPM drop, hold it level again and open the needle 2 or 3 clicks and point it up again.

(Note, anytime you do this, if the engine is at idle, bring it to WOT and let it come to full RPM for a few seconds before pointing it up - I have seen people pointing the plane up before the engine ever gets to full-bore and this is not the proper way to do it)

A tach is one of those tools that are great when you know what you're doing, but bad in the hands of someone who doesn't.

I once saw a kid burn up an engine because he was only getting 10,800 RPM and someone told him to "tach it" to 11,000 RPM.

Boos boy, getting a 4-stroke doesn't mean it will break if you crash. If the guys at your field are using them, I suggest you ask them how many of them have ruined a 4-stroke in a crash

RE: Which four stoke
 

John, let me tell you that I've crashed my four stroke driven planes, a lot. I have destroyed, beyond repair four planes. I have had many crashes requireing major repairs. In only two of them did I cause any damage to the engine other than having to replace the spinner. On was when I went in nose first in my trainer and pushed the firewall back (ARF Quality). The needle valve extended through the fuselage side and it cracked the carb mount on the back plate. The second, wel, I did do some major damage to the engine. First contact with the ground was on the head and the engine came apart.

I see the guys at the field havine similuar crashes and bashing up the carb the intake port on their 2 strokes. Lets face it, a crash that is going to damage an engine doesn't care if it is a two stroke or a four stroke. The biggest difference in my mind is replacement cost if you do destroy an engine. The four stroke is going to cost you a bit more.

The first photo is the first time I damaged and engnie. The was the broken back plate. I had the plane repaired by the time the replacement back plate arrived. The next to are photos of the trainer after hitting a 2x6 board fence and the last is of my four star 60 after a full throttle nose first crash. In both of those totals, a quick cleanup of the engine and it was ready to go in the replacement plane.

I am biased to the four strokes. When I get it tuned, I fuel and fly, for days before I need to touch the needles again. I watch the 2 stroke guys and it every flight ritual to tweek and tune. Dead sticks are rare. I do have a couple planes with two strokes and they do have a place. Mainly flat out speed. Four strokes are what I like to fly though.

Don