JollyPopper

My Feedback: (6)

I have decided to run all OS engines from here on out. I am currently looking for an engine for a yet unbuilt Great Planes RV-4. How are the AX engines compared to other OS engines? Would a .46 AX handle this airplane or should I go bigger? And do you folks think a 4 stroker is the way to go? I love the sound of the 4 strokers and they are a must on bipes and some other types of planes, but what is the best way to go with the RV-4? I have no interest in speed for its own sake. Much more interested in sport type flying. Anyone have any thoughts on the subject? Thanks in advance for any suggestions.

RVman

A 46 on an RV-4 is perfect, the plane will fly great with that engine. A bisson or other pitts muffler will keep the exhaust in the cowling. A fourstroke would also be ok, probably a 70, they won't fit in the cowl near as nice though.

NikolayTT

Try OS.91FX; I have sold all smaller ones - here I have power as much as need, it is simply another
style of real RC-life and it is pitty to miss that unique experience; surely some minor changes in the
fuselage are needed.

RVman

in a 40 size sport plane?

DarZeelon

JollyPopper,


Are you sure about this choice?

Please read post #23 in [link=http://www.rcuniverse.com/forum/m_3402107/tm.htm]this thread[/link] (Dr Nitro).


Are you a part of the 'instant gratification' crowd that this particular brand serves best?

NikolayTT

Yes, more than couple of times with following cases and modifications:
A)In .25-.40 plane best seems to fit .50FX without any airplane modifications.
B)In .40-.60 plane, I removed all coverings, cover it with one thin layer of fibergals and epoxy
without usinng any molds and applied on it monocote; then placed .91FX. The differences are
many in the behaviour: - Power and Speed as much as you could handle and still +20% more
maybe are availble; I usually fly it in most aerobatics with only on half trotle, vertical is
really amazing - it accelerates like there is no Gravity for the plane, and most important for
the windy-land where I live is that such plane doesn't care about wind much. Couple more
numbers: Wing-load is 120g/sq.dm, propeller is 13x7 at 12800 rpm and 10% nitro with 20% castor;
max.speed - the guys say it looks at least 150km/h, and no landing gear = starts from hand and
lands on the grass and the Balsa with the fiberglass and epoxy seems to be about 3-5 times stronger
with only 20-30% weight increase. Well, those things I re-"discovered" while reading the Reno-races
big aiplanes - it seems the Aviation has been always going for more power in almost the same
weight, isn't it ? [] It is just a different life, but of course not as safe as to fly a slow 3D with a
wing-load of 25g/sq.dm; that makes me fall a sleep and wait for next non-windy day, usually one
like that per month ...

asmund

He he, that sounds exciting The most important is to have fun and it sure sounds like you do that, so why not a heavy fast plane? I might just need one of those myself as we have pretty much the same windy conditions here in the western Norway, but nowadays I`m mostly into 3-d flying but as you say, not many days a month to do that

blw

My Feedback: (3)

The .46AX will fly the RV-4 kit okay. The 50SX would be a better choice for faster sport flying. I've seen another kit fly with either the .40LA or .46LA, I don't remember which now. It was underpowered most of the time.

JollyPopper

My Feedback: (6)

blw, do you suppose the .50SX will give me more "instant gratification" (see post #5 in this thread) than the .46AX? If so, it's for me. That is, I assume, as opposed to endless frustration.

Sport_Pilot

The instant gratification is that the OS engines break in quicker, but also wear out real fast. If you don't want frustration and don't want a long break in time, I suggest the TT Pro line of engines. More power, tunes just as easy (or the same), and lasts longer. Since the SX is a ringed engine with a longer break in then it is not as instant a gratification as the AX. If you don't mind breaking in an engine and plan on flying a lot then most any brand would be better than OS. It is the longer break in that seems to get to many casual R/Cers. They just won't run a half gallon or sometimes much more on the ground to break in an engine. Some very good engines have long break in times. Saito for example take about a gallon of fuel for a .90 sized engine. And by break in I mean that it has almost reached its peak HP, not simply getting reliable service.

blw

My Feedback: (3)

I'm not sure what your instant gratification is, or where you are being frustrated. Are you wanting a reliable engine without hassles of being finicky? Or, are you not wanting a longer break in period with time spent on the test stand before flying? I am guessing that you are looking at only 2 stroke engines.

The OS engines probably break in easier since they don't use chrome plating for the cylinder liners. It seems that they are okay as far as ease of tuning. I have my own opinions about them and did have a problematic .46FX at one time that I traded. Same for an older model Thunder Tiger Pro .46. The two .50SX engines that I've seen run didn't take time to break in past a couple of tanks of fuel while in the air. Those are discontinued now and there is the new .55AX.

A general consensus is that there are equal if not better 2 strokes out there, and most have better prices with a higher quality of manufacture. This is only my opinion though. You are probably going to be bombarded with advice on other engines. (g) My straight advice on OS engines would be to look for a ringed engine like the .50SX if you can find one new.

DarZeelon

Hardly, JP.

That is opposed to a more prolonged 'teething period' (not two tanks like an OS) and more time invested in initial adjustment (not 'it will run as it is').

But at the benefits of more power, greater reliability, lower operating costs and a 400+ hour life-span...
In a previous thread someone wrote the piston-ring in his .50SX lasted just 13 hours (calculated from the number of gallons it consumed - I remember the hours). That, in addition to what Dr Nitro wrote.

If you regard ~6 hours of running a slight-bit rich and being careful with the throttle, so as not to risk an occasional stumble; 'endless frustration' and the value of 400 hours of engine-life is marginal to you (i.e. you don't mind buying a new engine every season, or two), you have made a good decision...

AMB

About a month or so ago I got a AX46 from bob davis it was new and used to make his diesel head conversion never got the glow head back he just sent me the engine with the head installed. It started on 5 flips as a diesel no glow break in no real tight pinch at top, I am not suggesting everyone run a diesel head on their AX However being it runs cooler than glow the extra lube in the fuel Kero does help its not likely the ABN thing will be an issue. I expect it to last a long time. It is one of the best running engines I have . its going into my Pulse XT 40 which is really a great plane , cannot wait to get up in the air martin
Pix and numbers are on the diesel site

JollyPopper

My Feedback: (6)

OK guys, let me clarify something. I am not especially a lover of OS engines. I have just recently made the decision to run (buy) them exclusively because of $$$$$$$. I am retired, on a fixed income, and the way prices are escalating, I can't afford to buy RC engines that won't work for me. I realize that they cost more than most others, but when I buy one and nail it to the front of a plane, it starts and runs--forever. I have never worn one out. Never wore any other brand out either as far as that is concerned. If there are other brands out there that start, run reliably, don't dead stick, don't break fingers when back flipping, etc., etc., and cost less money, I would certainly be open to the idea. What I want is instant and CONTINUED gratification. I really dislike the idea of going to the field with one that is difficult to start, dead sticks after five minutes in the air, and then requires re-tuning after each flight. And that is after it has been properly broken in. Among my engines, I have an old Super Tiger .60 (Italian version) that required probably a gallon and a half of fuel to break in, but it is a sweetheart now. I don't mind taking the time to do that--I simply want it reliable and remain so after break in. Sport_Pilot thinks TT Pro engines do that. If so, then TT it is. I really don't give a damn what name is on the side of the engine so long as it does what works for me. It doesn't need to be the fastest or most powerful engine at the field, but it better be among the most reliable and easiest to use. Fiddling with an engine at home is acceptable--fiddling with one at the field is not.

So, with all that said, let me pose another question to you folks. Another kit I have waiting to be built is a Great Planes Super Skybolt. I had pretty much decided to buy an OS FS .91 II Surpass for the front of it. I would buy Saito, but I understand from RCU postings that they are a pain in the butt to keep tuned. I have heard good things about Enya. Magnum is almost a clone of the OS engines. What do I put on the front of this puppy that does what I need it to do? Remember: INSTANT and CONTINUED gratification. Remember also that on the front of this puppy, only a four stroke will work for me.

Sport_Pilot

You must be talking about another engine, not OS. MVVS? TT? Not Magnum. Two stroke so not Saito. Maybe Tower? Forever just doesn't fit for OS. Easy to tune, good for beginners, reliable for twins, maybe. But not lasting forever. That is in the realm of Fox, and Enya cast iron piston engines. I haven't worn out many engines so I can see where this may not be a big factor, but don't think that OS is among the longest lasting, it isn't.

Lots of them TT, MVVS, even a Fox (well the ones with good carbs). Except maybe for the break fingers part. You see if it is not breaking fingers when flooded and backfliping then it doesn't have good compression.[sm=lol.gif] Some of the problem is that some brands need to be tuned differantly, others need lots of break in, etc.

IMO Dar and myself are being a little harsh. OS is a fine engine, just that the quality isn't what it was and some of us are not pleased with that.

Dave :^)

Saito a pain in the butt to tune? I'll have a glass of what you're drinking! The only people who have a problem with Saito are those who think they know how to tune and run a four stroke. My Saito's need a tweak to the needle in spring and another in autumn/fall, that is not a pain in the butt. Replacing OS POS liners and pistons on the other hand!
Dave :^)

MinnFlyer

My Feedback: (4)

I don't know who Dr.Nitro is, but these two statements alone tell me something is wrong with his observations.

These are two of the best engines ever made. I had a 46FX that ran flawlessly for years till it was destroyed in a crash, and I have four OS 70's which is probably my favorite engine of all time.

Sport_Pilot

He said that engine lasted through 40 gallons. You should get about 7 hours of flying at part throttle per gallon. I am calculating this on 1 ounce of fuel per minute for a .91 size engine or half an ounce at full throttle and .3 ounces with some part throttle flying. with 128 ounce that is over 7 hours per gallon and for 40 gallons that is 280 hours. So if you fly one hour a week for five months per year or twenty weeks per year that would mean the engine would last for 14 years. So unless you fly a lot more than this even fourty gallons is more than enough for most of us.

asmund

The surpass series have proven to be great. A OS 91 fourstroke will be great and last for a long time. OS only messed up on the Ultimate 70 and I read alot of mixed feedback on the FL 70, but the surpass have been great from all the research I have done and we have several in my club, nice engines[8D]

Super Splatter

Jolly popper , You ROCK !

your decision to use OS is a wise one , stick to your guns !

fly the best , blank the rest !

Enjoy your hobby !

Hobbsy

My Feedback: (102)

Saitos are pretty much set it and forget it engines. I've been trying to wear out a Saito .80 and a 1.50 since 1991, I haven't succeded yet.

DarZeelon

MinnFlyer,


He's an independent fuel tester for a model fuel manufacturer, with absolutely no vested interest in promoting any engine manufacturer. He just runs them continuously, since there are no neighbors to complain about the noise...

He reports these findings, which I have no reason to think of as biased.

I believes he calls them as he sees them.


While I am glad MVVS engines (like TT, Webra and some others) proved to live very long lives, his testing proves some engines, namely OS that are ultra-quick to please their owners, do not do this for very long.


Most of us do get about 20-30 flying hours per year, so nearly any 400 hour engine will be forgotten, before it actually wears out.
But early catastrophic failures, like bearings that disintegrate, crankshafts that break at the intake port, or sleeves that peel... Well, those do take some of the fun away from the hobby...

-------------

Super Splatter,


Please interpret the words 'the best', as you see them.

OS is the best only if there can be something, which is better than the best.

AMB

Dar think one that was forgotten was irvine, have bunch from 15 thru 53 some glow some some dieselsl and some converted to diesel these were made in the UK now made by OS in Japan I would guess the end of ABC and the jet stream carbs are history might be a little edgey about buying the off shore ones yup have my MVVs and Italian STs too martin

think I have enough engines to last a while

Sport_Pilot

Most of may fly 20 to 30 hours per year, I don't really know. But I am sure most of don't get that much time on one engine exept newbies and those who fly very often. However the testing Nitro did was in gallons, not hours so 40 gallons is fairly substantial but I suspect it is way below the life of most engines, at least if not destroyed in a crash first.

DarZeelon

Hugh,


The testing Dr Nitro did was in both hours and gallons.

A .40-.91 engine will typically use between 0.5-1.5 ounces per minute... That is in various throttle settings and various engine displacements...
I.e. a .91 engine going flat-out will run about 10 minutes of flight, until it consumes a 16 oz. tank.
A .40 running in a light 3D plane, at widely varying throttle settings, will get ~20 minutes on a 10 oz. tank.

...That is on 5-15% nitro fuel...

So, it is quite easy to convert from gallons to hours and back, on a given engine.

Let's take the .91 running flat out... 128 oz. will last 1.42 hour, so 100 gallons will last 142 hours...
Are you sure this is below the life expectancy of a typical engine???

Harry Higley, in his engine books, suggested a piston ring will typically 'go south' (not to Georgia...) after ~50 hours...
An ABC (true chromium) setup will typically last 100 hours...

Those numbers are way below Dr Nitro's benchmark figures...


Did you ever own an engine that made it to 2,400 flights and was still good enough to be transferred to your next plane?

I strongly doubt this...