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Engines Plugs Mufflers Fuel > heehee hee YOU better do something OS !!!
 
 
mmc205
Senior Heliman
Location: PA - USA

I'm a mechanical engineer, and deal with designing bearing fits and applications quite often. From my experience, especially seeing that data that somone provided about where the "flaking" was happening on the bottom of the rear bearing, i think that it is most likely a overloading situation having to do with heavy loads at the ignition point. Being as this is a one cylinder engine, there is not another opposed cylinder (optimum configuration) to balance out the shock loading. I believe the reason some people see this effect and some don't is due to how lean/hard different people run their helis. I personally run relatively rich, and 85% throttle max right now (mostly sport flying) I've run about 6 gallons and everything is kosher. A little poll might help us figure this issue out. Respond with "hard flying-bearing failure" if you run relatively high headspeeds and on the lean end, or "easy flying-no bearing failure" if you run richer and mostly sport fly. When i say bearing failure, i mean premature, like 10 gallons or less. Depending on the responses, we might be able to see a corelation between headspeed/running lean and failure. I know its been talked about but this might make things clear

My blade mCX can outfly your Aurora!! (in a 1' x 1' x 1' box) :)
05-12-2008 03:58 PM
 
 
mmc205
Senior Heliman
Location: PA - USA

"EASY FLYING-NO BEARING FAILURE" 6 GALLONS/SCEADU 50/1700 RPM HEADSPEED

My blade mCX can outfly your Aurora!! (in a 1' x 1' x 1' box) :)
05-12-2008 03:59 PM
 
 
Dilbeck
Key Veteran
Location: Springdale Arkansas

Sport flying, 1750 head speed max, 22% nitro. 4 gallons. No bearing failure.

If it doesn't fly sell it!
05-12-2008 04:28 PM
 
 
tchavei
rrProfessor
Location: Portugal

Moderate 3D, 20% nitro, 20% kl-198 oil, 17850rpm (sometimes up to 19890 during unload), 200 flights average per engine, no bearing failure ever.

Tony


--------------------
"Perfection and patience usually walk side by side..."
05-12-2008 04:40 PM
HOMEPAGE  
 
 
HelividD
Senior Heliman
Location: Auburn Hills, MI, USA

Trex600N: Mild 3D(rolls,tumbles,inverted forward and backward, vertical tic tocs), 1890 headspeed(on governor and tached), 3.5 gallons so far, richer settings(abt 1.25 turns on needle), 30% nitro, Hatori pipe, no bearing failure thus far.

600N(2nd model): Breaking in and sport flying, not sure of the head speed, but softer controls so I would figure between 1600-1700, 1/2 gallon through it, richer settings(about four clicks below 1.5 turns), 30% nitro, MP5 pipe, no bearing problems whatsoever.

Both motors of course OS50 Hypers. One thing I did notice and a few other guys I fly with have noticed is that when new, the compression and tightness is much higher on the newer engines. My older one that I purchased last year(October) was much easier to break in and start than the new one.

I try not to push any engine as I also had extremely bad experiences with TT car engines and learned to run engines richer because of this and have done so ever since then. But the Hyper has been a solid performer for me thus far. I probably need to change my glowplug on the first machine as this plug has been in there since probably the fourth flight on this machine(and the plug the last time I looked at it, still looked good), but no problems whatsoever. I am hoping my second will run as well.

Man.... I had no idea what an addiction this was going to be.....
05-12-2008 05:04 PM
 
 
the Wasp
rrProfessor
Location: Vt

OS 50 Hyper, baring failed at 2.6 gallons, sport flying,

tuned rather rich,

engine speed 1600 and 1625,

added 3 oz of extra oil to the first gallon,

2 oz to the 2nd gallon,

1 oz to the 3rd gallon..

Jim
Buzz Buzz Buzz
05-12-2008 05:31 PM
 
 
nivlek
rrProfessor
Location: Norfolk England

OS50 SXH , Hyperhead , 60K carb , Weston UK pipe , 10% nitro/16% synthetic/4%castor , Raptor 50V2 , HT cooling fan , 17,000 RPM ,mild 3D , 300 degrees F and no bearing problems .

EDIT . Headshim removed .

At the end of the day , it gets dark .
05-12-2008 05:49 PM
 
 
mmc205
Senior Heliman
Location: PA - USA

I think i'm seeing a pattern here, anyone who runs the poor bugger a little harder want to weigh in?

My blade mCX can outfly your Aurora!! (in a 1' x 1' x 1' box) :)
05-12-2008 06:28 PM
 
 
Dilbeck
Key Veteran
Location: Springdale Arkansas

nivlek, 300 deg F? Is that on the head or back plate?

If it doesn't fly sell it!
05-12-2008 08:06 PM
 
 
nivlek
rrProfessor
Location: Norfolk England

Top of cylinder / bottom fin of the head at the rear of the engine , measured with an onboard MIP temp gauge.
I ran it with a standard OS50SXH Carb and standard muffler for one season , it peaked at around 270F with both the standard head and with the Hyper head (Bellwood head ran a few degrees hotter) . I then fitted the 60K carb . This gave me more power but the maximum temp went up to around 285F , I ran it like that for another season . Then I fitted the Weston Genesis pipe and now get more power again but the head usually gets upto 300F , I have seen 317F a couple of times , but it's run like that for another season so far .
After landing I can hold my finger on the backplate for around five seconds no problem .

At the end of the day , it gets dark .
05-12-2008 08:20 PM
 
 
DS 8717
rrProfessor
Location: Here wishing i was somewhere else

I had one get to 330 degrees on my Venom temp guage.It gauled the piston at the exhaust port,i dont know why it just leaned out,since i went to a 60K carb with the OMI mod and crankcase pressure i haven't had a lean run.I am strictly YS now on all my 50's and 90's.
05-12-2008 08:26 PM
 
 
mmc205
Senior Heliman
Location: PA - USA

Hlding hand against backplate, thats a pretty good metric. The way i run (and i'm guessing the way a lot of people run that don't have bearing problems) is so that if i land quick i can hold my finger on it for as long as i want. Its not cool, but i'm guessing 140ish on the backplate as most people cant hold onto much more than 150 for any length of time.

My blade mCX can outfly your Aurora!! (in a 1' x 1' x 1' box) :)
05-12-2008 08:27 PM
 
 
RAK402
Veteran
Location: Alhambra, CA

"I beleive most failures from rear bearings are from people who are trying to squeeze everything they can out of an engine and not really understanding what lean is and/or they do not inspect thier engines from time to time to see how it is running."

I suspect that there is a great deal of truth in this comment.

I continue to see people posting about how they want to brake the motor in then "lean it out" as soon as possible. I have seen several of my local brethren, new to glow motors from electric) cook their motors because of this philosophy.

I was always taught to run it rich enough to where you could hear the periodic tick of four-cycling. This has served me well for 32 years of model helicopter flying.

I have had a few comment regarding how rich I run my engines (if you can still see the helicopter through the smoke, it is too lean), but have yet to have to replace a bearing.

Of three OS .50 Hypers, I have probably 7-9 gallons through one, and 5-6 through each of the other two.

So far, no bearings requiring changing yet.
05-12-2008 10:26 PM
 
 
Dilbeck
Key Veteran
Location: Springdale Arkansas

Somebody needs to start a new post on the pole of the OS 50 Hyper with what they run exc so we can get to the bottom of this subject once and for all!! This problem with the os 50 has been a subject of so many of discussions but we are still in the dark of the rut cause of the problem.

If it doesn't fly sell it!
05-13-2008 01:05 AM
 
 
DS 8717
rrProfessor
Location: Here wishing i was somewhere else

It's normal wear and tear,if you run it too lean they go out faster. Replacing bearings is normal maintanice.
05-13-2008 01:14 AM
 
 
Dilbeck
Key Veteran
Location: Springdale Arkansas

Bull Sh!t, Need a better answer!!

If it doesn't fly sell it!
05-13-2008 01:22 AM
 
 
Joe90
Senior Heliman
Location: Quebec, Canada

BIGGER bearing

The solution is extremely simple:

BIGGER bearing
or/and
Better materials
or/and
Less load
or/and
two bearings

have fun !!
05-13-2008 03:31 AM
 
 
Divot
Veteran
Location: Mesa, AZ

Let me sing a song for ya'all

preload, preload, preload, preload, preload, preload,


Fuel, bearing type, too much power, its all crap.

preload, preload, preload, preload, preload,
05-13-2008 03:37 AM
 
 
StillTryin
Senior Heliman
Location: Perth, Western Australia

So Divot, that would mean that everyone who has done the "Coke Can Mod" has subsequently lived happily everafter - never a bearing problem and hundreds of gallons through every engine.
After all this time the answer was so simple!

I suspect you have been reading too much Lewis Carroll
05-13-2008 04:11 AM
 
 
Divot
Veteran
Location: Mesa, AZ

Quote 
So Divot, that would mean that everyone who has done the "Coke Can Mod" has subsequently lived happily everafter - never a bearing problem and hundreds of gallons through every engine.
After all this time the answer was so simple!

Good stuff 'Still'

I have never said anything about the 'coke can mod'

I am saying that preload (clearance) is the solution.

I know there is a lot of problem with bearings, but it is not
the bearing, fuel, power(this is really crap)
or 'hard 3D'(the most retarded term of all time)

The lateral travel of the bearing is the cause and effect.

Edit: Yes it is that simple.
05-13-2008 04:33 AM
 
 
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Engines Plugs Mufflers Fuel > heehee hee YOU better do something OS !!!
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