JThuntsalot

Hey guys, New here but not new to R/C Starting flying when I was 13 until I was 17 when my mom and step dad got divorced. Got back into it when I was 24 then sold everything when I was 28. Starting to get back into it know.

Now to my question. I used to have a Uproar 40 with a O.s .46FX on it. It was a flying demon with this motor on it. I am fixing to start building another one here in a few weeks and was looking for another .46FX looks like O.S doesn't make this motor anymore. I was wondering if anyone knew why and maybe where I could find one. I had 2 planes with this motor, the other being a Super Sportster and like the way the motor pushed these planes around thanks for any info.

Ed Smith

It is now called the "AX"

Ed S

JThuntsalot

Thanks for the Info.

mclina

The AX engines are great. OS also came out with the .55AX, which is designed to fit the same mount as the .46 - if you really want a flying demon, check it out. The .46AX is great, though.

Gray Beard

My Feedback: (-1)

The .55 is a great choice. Not only is it a good choice for any plane that will take a .46 but it has the beans to fly most any of the ARF 60 size planes as long as you aren't into 3-D. Welcome back, I was also an Up-Roar fan. I built two of the kits but made templates for all the parts and started to scratch out my own kits. I think I built 8 of them. I kept three for myself and gave away the others to friends in my clubs fun fly days.

w8ye

My Feedback: (16)

The AX line is more user friendly than the FX line was

Gray Beard

My Feedback: (-1)

8, how so?? I have heard this before but I haven't seen it. It may be a memory thing but I can't remember any OS engine being a problem and the FX was great except for that little chrome problem some years back. What is the difference?? Serious question, not yanking your chain. An inquiring mind wants to know!!

w8ye

My Feedback: (16)

I used to have three 46FX engines and they were never any trouble as you are probably thinking to yourself. But we've built model airplanes and run engines for years. For me it has been over 55 yrs.

I've never owned a AX but watching the newbies come to the field with their 46AX engines, the engine is a little milder at idle and easier going on the needles with a better tuning spread. The new guys seem to have little trouble with them.

I have old timer friends with 75AX and 120AX engines and I notice these engines are easy going also at the starting bench yet they run very well in the air. One is on a Delta Vortec and the other on a GP UCD 60.

da Rock

How are the AX engines more user friendly? It starts with their breakin. The metalurgy and assembly tolerances make for an engine that starts the very first time you fuel it up, and that basically breaks in fault-free on the 1st run. And seems to do all that if you don't follow the suggested break-in proceedure. If you do, it's a slam dunk from a step ladder and will be pulling like a bull on the 1st flight.

Having worked on timing, compression, internal flows and whatnot of these little engines for years, my opinion of why the AX is so good is metalurgy. I think they've finally found the best combination of piston metal and liner metal. Add in an excellent fit and finish and an amount of metal that works for temperature control, and you got synergy of all components.

I too have over 55 years using these little jewels we have for engines. The experience goes back to the OS35-S that basically got OS it's toehold here in the US, back when the Fox35 was one of the most popular sellers. I've lost count of the 46AXs I've been asked to break-in at the field by new owners. Every one of them started 1st flip. They all have settled in on the 1st run to hold a decent idle. They all responded within reason to the throttle at the end of that 1st run. A couple showed a touch of rich on the low speed adjustment, but would have flown safely on the next tank of fuel (and possibly settled in more from the additional "break in" if tightness had been the cause). About half of them benefitted from a slight amount of low speed leaning after they'd been flown some. Which shows that when the plant erred on their initial setting on the low speed, they are doing so on the safe side.

Yesterday and the day before, I flew the 1st one I bought back in... 2005? 2006? It is a bull and way overpowers the WM Ultimate46 it's been on since I put them together back then. I flew the sucker around at 2/3 throttle most of the flight.

The 46AXs I've got and messed with have all been plug-and-play which is what today's modelers seem to want and need.

da Rock

BTW, the 46AX led me to try the 55AX and I've been running a 75AX since they came out. The 46AX is everything I mentioned above. The other two.......

hhhhmmmmmmmmmm.......

I'm not sure where the 55AX's extra cost is worth it. Granted, I've only got a couple of them. I put both on heavy 46sized models. And truth is, the difference in performance wasn't worth it. Heavy airplanes are heavy airplanes. More power just gives you a heavy airplane with more power. Wing loading never changes. So that part of the envelope isn't affected. And flying on the wing is actually more fun than challenge. I don't fly 3D much at all, so do not need the 55 for that, however. The 55s ought to be worth the extra price for 3D.

As for the 75AX, I'm not really impressed at all. It does break in great like the other two. But that's where it ends for me. Bottom line on it's attractions is just that.... bottom line. I'd rather spend $10 more and have the .91FX if I want power. And for that $10, DO I GOT POWER OR WHAT....... And if I don't need the bit more power the 75AX gives over the 61FX, I save far more than $10 when I buy the 61. Like save about $40. Moreover, I've flown a 75AX on my Tiger60 eversince the engine came out. And at least my one example is less than a dependable starter. It's the worst OS I've got when it comes to starting the sucker. It ate a couple of plugs the first couple of months so I tried a couple of different heat range plugs and adjusted the compression. It's ok on plugs now but even after adjusting the low speed a couple of times (and finding it was basically ok each time), I tried it with lean low speed and with rich low speed. It didn't care at all. It simply doesn't want to start easily. I won't be buying another as I don't see it's niche, and have no need to discover if the next one picks back up the family tradition or instead proves that one engine type is a smudge on the OS name. Here too, the 75s ought to be worth the extra price for 3D. I just don't do that stuff enough that I'd need another one.

LuvBipes

My Feedback: (4)

I love my 120 AX,

Gray Beard

My Feedback: (-1)

Thanks 8, I have broken in a couple of the .55s and was very impressed with them but have only gotten a couple of the .46s tuned for people out at the field. I didn't see any difference between the old and new. I thought maybe the changed the port timming or something? They really run very well.
Gene

w8ye

My Feedback: (16)

Due to the 46AX's good beside manners some people think it is not as powerful as the old 46FX.

I don't think that is the case

millertym2000

My Feedback: (4)

hey JT I have the uproar also with a 46ax on mine. I maidened it with an old 46fx that I had before getting the new ax. This is a great fit for the plane, plenty of power, unlimited vertical, will hover and pull out of it like a rocket. I love mine its a fun little plane.

Gray Beard

My Feedback: (-1)

8, I didn't think the AX was putting out as high RPMs but I can't remember what they were with the .46FX, kind of an old ear thing?? I put together one of the 60 size H-9 Pulse planes for a friend and we used the .55 on it. Other then the lack of 3-D pull the plane fly's perfect with it. Nothing in the IMAC book it can't do. I'm very impressed with the tug I get out of the .55.

w8ye

My Feedback: (16)

It is highly likely that with a 11-6 or greater prop the AX is better but you drop down to a 10-6 or less diameter and the FX will do the shining.

I get that feeling because of how nice the AX is at the bench.

victorzamora

8, that's a good point. AX's really don't seem to like turning up those really high rpm numbers. Well, the 55 and 75 don't. I'm sure the 35 and 120 don't either. I've seen someone running a 46AX (I've owned like 4 of them) on a tuned pipe with a 9x9 or 10x8. It SCREAMED. If you pull the baffle out of the stock muffler, it also helps. OR the tower hobbies muffler. BOY does that muffler help!

Regardless, my 46AX's have been the BEST engines I've ever seen run. They're the most durable little suckers out there, reliable as all else, and powerful to boot!

jet60

excellent thread. you guys really educated this newbie. many thx from me[8D]

Jetdesign

My Feedback: (8)

My 46AX runs happily at 12,000rpm, my 120AX runs happily at 9,000.

The 46 was my first ever engine, and I tried starting and tuning it completely alone with no experience. I'm pretty sure I leaned it out to the point of it dying out, a few times. It forgave me, and is still screaming with a 12x5 prop at 12,000+rpm. I liked it so much I got the 120, and unfortunately for the little guy he spends a lot of time hanging on the shelf jealous of all the play time his big brother gets =)

w8ye

My Feedback: (16)

Hang on to the 46. There'll be a day when it will come in handy

hugger-4641

My Feedback: (6)

Hey W8ye, I was just given a .60 sized Sierra Trainer with no motor and I happen to have a spare .46ax laying on the bench, do you think it would pull it?

w8ye

My Feedback: (16)

I've seen 46 engines on original 60 planes

What I notice

a longer take off run

The pilot flies them at higher power

There's sometimes a balance problem

Otherwise fine

hugger-4641

My Feedback: (6)

Ok thanks, I might just try it while I'm waiting to find a .60 sized engine. Do you think the 11X6 apc thats on it would do fine also or should I try something else?

w8ye

My Feedback: (16)

With that situation, I'd stick with a 11-6

hugger-4641

My Feedback: (6)

Thanks, I'm game to try it and maybe have the skills to fly it , I'll post the results when I get it in the air![8D]