davidbegg

Well after months of trying to get this SC 46 engine to run properly I have decided to retire it. GIVE UP ON IT!! Any one want a paper weight???Cheap!!

It has been very difficult to tune the engine to keep it running, and once that is achieved, at next flying day the tuning is not right again and you have to start over again. Instead of learning to fly my instructor and I spent hours at the flying field tuning the engine.

We have tried different brand fuels, nitro and non nitro, different brands and heat range glow plugs, plugs with idle bars , plugs without idle bars, checked and rechecked and checked again the fuel tank and fuel setup, engine experts from my Model airplane club have looked at the engine, the plane and the setup of the engine, tuned the engine. After this it will go OK and everyone thinks the problem has been fixed, until the next flying day when it is back to the same, not transitionng between full power and idle, or just stops for no obvious reason. The engine has been checked for airleaks, the carb has been replaced with a carb from another engine that runs fine. All to no avail. The engine will still just stop without warning, my instructor has never has as much practice with dead stick landings!!!! When the engine is running and you try to tune it, one click of the needle valve will send the tuning from lean to overly rich. The high and low sped needle valves have adjust so many times and using so many different methods I have lost count. The carb has been cleaned checked and reassembled many times. Care was taken to only change one thing at a time to correct the tuning to avoid not learning what the problem was. The SC 46 has always been very easy to start using an electric starter. The engine runs an 11 x 5 prop @ 11000 rpm and will idle quite happily at 3100rpm.

My belief is there is some manufacturing fault in this engine which has put the timing or something out, and this engine will never be any good, it is a LEMON, just like you used to get with cars in the days before computer machining and assembly were used.

I have replaced it with an OS40 LA, which I have read is not the most powerful engine around, but the plane (Explorer 40 trainer)is faster than with the SC46 engine. This suggests to me that the SC46 may be down on power as I would have expected the plane with the OS40 LA to have inferior performance. There has been no difficulty with tuning the OS, some flying days it just requires starting and no tuning at all.

My flying instruction is now coming along well, however I am frustrated having wasted months of training time fiddling around with this useless SC 40 engine trying to get it to run properly.

Cheers

David

Flyboy Dave

My Feedback: (21)

....it has an air leak....either at the carb, or most likely the front bearing.

When a two stroke engine has an air leak, you can forget about it holding a setting. []

FBD.

Jezmo

I second what FBD said.

davidbegg

Thanks guys, I presume the front bearing will need to be replaced to eliminate any air leak there, as it is definitely not the carb as it has been sealed with the additional of silicon sealer as well as the O ring. However as it is nearly impossible to get parts for the engine in NZ, it will have to be put into the perhaps get around to it someday box. Honestly I am sick of fiddling around with it. I guess it is the old adage, you get what you pay for. It is still now a paper weight as far as I am concerned.

Cheers

David

asmund

Bearings?? Here you go[)] http://www.rc-bearings.com/catalog/p...8fa5c4c427f08e

If you give it up I`ll be more than willing to give it a go

I find it incredible that an "instructor" wastes months on tuning an engine that clearly has some sort of defect that needs to be repaired, most likely an airleak in the front bearing.
The SC, ASP, Magnum 46 is a sweet running engine, not even a YS will run great with an airleak[)]

Flyboy Dave

My Feedback: (21)

....yep. I use rubber sealed bearings in all my engines these days. If you
want, you can just install the bearing with both side seals intact, and let
it run on the grease inside. It will run forever like that without worry about
air leaks or lubrication. [)]

FBD. [sm=teeth_smile.gif]

davidbegg

Yes, agreed, might be worth a go, a bearing is cheap. I will strip it down and go from there. I do like the sealed bearing idea.

Cheers

David

davidbegg

There is a little bit more in the instructor / pupil relationship than what there looks on the surface. We are both on stress leave from high powered jobs in the education sector, and on medication from the doctors. I used to be a Principal of a large primary school until I crashed and burnt about a year ago. Some days are better than others for both us, unfortunately not always the same day! As part of the stress condition you can get fixations on things, one of the instructors was getting this engine to go. Last year when I was not to good, my large electric drill blew up, I got a fixation on drills and ended up buying 4 through the email auction! I still do really dumb stuff at times., but are slowly getting better

However we are now moving ahead although it still annoys me that I can only concentrate on flying the plane for about 10 mins and then I feel my concentration rapidly slipping away. However my concentration is slowly getting longer. I will learn to fly!!!

Cheers

David

davidbegg

Where would I get suitable rubber sealed bearings from?

Cheers

David

XJet

Or (to save postage)... [link=http://www.uavaerospace.com/parts.shtml]UAV Aerospace[/link] sells Paul's bearings in Australasia.

They may have the sealed front bearings in stock or can get them (usually in around a week or so).

davidbegg

Excellent, they are actually located in NZ. I have emailed my request, we will see what happens.

Thank you.

Cheers

David

rcdude7

My Feedback: (264)

As you have found, the OS .40la is a great engine for a begining pilot, use it until you learn to fly, and beyond. If the SC gives you fits, get rid of it, In your stressed condition it is probably not worth the hassle. I will say that OS engines in general are pretty easy to live with day after day, so go with what works for you.

Good luck on your flight training

davidbegg

I intend to stick to the OS 40LA in the trainer. I am finding it hard enough to concentrate on flying the plane without worrying whether the engine will behave or is going to stop again. 10 minutes flying sees me 'done' at the present time

However it appears I can get bearings for the SC40 in NZ, so if the price is OK I will get a set and see if that will cure the problem. Just something to do, might score a good engine, might have a paper weight with new bearings!!!!

Thank you for your support.
Cheers

David

nguyencuongaa

It's important to understand that there is a reputation for glow-engines to be difficult to tune. This is a common error in thinking. With a little bit of know-how, tuning a glow engine can really be a simple, pain-free process. People that don't properly understand the basics can easily become frustrated by what should be a simple, straightforward process. Here's how you do it:

Glow Engine Tuning

DarZeelon

Quote:

ORIGINAL: nguyencuongaa

It's important to understand that there is a reputation for glow-engines to be difficult to tune. This is a common error in thinking. With a little bit of know-how, tuning a glow engine can really be a simple, pain-free process. People that don't properly understand the basics can easily become frustrated by what should be a simple, straightforward process. Here's how you do it:

Glow Engine Tuning

Nguyen,


You have revived a thread that's been dead for over a year... I see you are pretty new here, so take notice.

Also; the link you have sent us to, discusses ground vehicles that require totally different methods of tuning...

For example, the technique says the low-speed needle must be adjusted first, which is not correct in aero-engines...
Also, methods of adjusting the low-speed circuit and the high-speed needle differ immensely...

This link is a disservice, because could just confuse those that need help with their aero engines and this forum discusses aero engines almost exclusively...
Questions regarding car engines are moved by the moderation team, almost exclusively to the car fora...

downunder

Dar,
I suspect Nguyen is the author or owner of that blog on glow engines or at the very least is promoting it. He's got 3 similar posts here in RCU and has hit RCG with a similar posts in the last couple of days. If you look at the bottom of any of his links you'll see they seem to originate in Vietnam. However I've found the exact same information (and wording) on a British hobby shop web site so there's a possibility it's been lifted. If I'm wrong then my apologies.