As many of you know, I have become totally addicted to this sport in very
short order. If a blood sample were drawn on me right now, mass spectrometry
would show an unusual high titer (level) of nitro and castor oil flowing in
my veins :-)

About two weeks ago, my OS .46 wasn't running as well as it had been.
Another fella at the field has the same Stik I do with a Thunder Tiger .46
on it. We 'race' every chance we get. He was waxing my butt, something I did
not particularly like. :-) I'd cut the corners on him, gain altitude, and
dive to catch up, but he was pulling me despite my devious efforts.

Another pilot offered to tune my engine. "Sure! Brad's waxing me, and that
is unacceptable", I said.

So this pilot, a very experienced and long time flier tweaked my OS. Brad
and I met at 100 feet, and I not only waxed him, I bitch-slapped him on
every lap. He even started copying my devious moves and I still pulled him.

Then my engine quit.......... "Dead stick" I hollered, nothing new to the
others who fly around me regularly. "Hey, pr, do you EVER land with power?"
I was usually noted for trying to get every foot of air time out of every
single milliliter of fuel, and having several hours of "private" (read that
all alone) flying to practice dead stick landings from every possible
quadrant and orientation, I know when my bird calls it quits, I can bring
her home, most often to a greased landing, from anywhere within my eyesight.

But this was different. I had never had my plane slow to 50% of its speed
before dying. Something was wrong.

As most of you have guessed already, my engine 'tuner' leaned me out too
much. As my plane got lighter, and flying at higher altitudes, the engine
went lean, got hot, and stopped.

As I walked the 100 or so yards to my plane, I was trying to conjure up
what I have learned here in the newsgroup. When I got to my plane, several
minutes later, the engine was still hot to the touch.

"Damn!--a lean run, for sure" I thought.

On my next attempt to start the plane, all went well until I removed the
glow igniter. The engine died immediately. I repeated this twice before
making the diagnosis of a blown glow plug.

I replaced the plug, richened her up a tad, and all was well.

I have flown maybe 20 or so flights since that day, but today, in cooler
temps, things went awry.

My first flight this morning, through light fog with beautiful blue skies
above, was superb. I tached the motor about 800-900 rpm's below max
revolutions, ran the entire 480 foot runway, pulled straight up and shot to
the moon. 4 minutes into the flight, the engine went dead. Another,
'routine' dead stick landing, the Stik stopping about 2 feet away with
light applause coming from the background. I doffed my ballcap to the
adoring masses.

Another blown plug.

I inserted another, started it, and when I removed the igniter, it died
immediately. Hmmmm......

After a consult with a few others, I installed another plug, and the motor
would barely turn.

I knew something bad was wrong. I hated the thought of it, but my flying
was over for this day.

We tore the engine down, and in less than 10 minutes, I knew my fears were
well founded. An OS .46, with about 25 gallons run through her, was toast.
Kaput. Finis. Dead-a- rooskie. Paperweight city.

What happened??????

 

Here is what I, and a few others, surmised. Newbies, take heed:

1) On the initial lean run, the plug blew out, and the idle bar commenced to
bounce around inside the cylinder.

2) She flew well for awhile, but today, the damage caught up with me.
Although I never flew her without a lot of visible smoke pouring out or
having a wing that took 4 paper towels to clean off, I cannot convince
myself that I ever ran her lean after the initial cock-up. My OS was doomed
from that one flight.

3) I blew 3 plugs today, a dire warning that the engine is running hot, very
hot; hot enough to cause the glow elements to get hot enough that the engine
compression blew the elements down to the bottom of the glow plugs. Although
I was running her rich, the damage to the engine had already been done and
was slowly, but surely, catching up with the lean run of weeks ago.

4) Autopsy showed a piston top that looked like it had been sandblasted. The
sides of the piston were heavily scored, obviously by metal fragments of the
blown plugs.

5) A small piece of what appeared to be a glow plug element was founds
inside the hole on either side of the piston where the circ-clip holds the
piston onto the connecting rod. Uh, oh.

I called my hobbyshop. It was 1:00 PM. He closes at two.

"I'll wait for you. No problem. Stop and get a pack of Greenies on your
way".

I left the field like Armageddon was imminent, making the 40 mile drive in
less than 50 minutes.

After a few hours of commiserating over whether to get a four stroke engine
(OS vs. Saito), Mark, the owner, took down a cherry LT 40 that was hanging
from the ceiling, got his screwdriver, and removed a very slightly used OS
46 out of the trainer.

"Pat, I hate seeing you tear yourself up about which engine to buy. Here,
I'll give you a ball slamming deal on this one. No break in required, I know
the owner only flew this a half dozen times. No break in, and I think the
OS 70 or Saito 68 may be a tad heavy for the Stik. Plus, you can this one
for less than half of a new motor. I'll back it up--she'll fly great!"

"Well get you into a bigger four stroke on your next plane", he said.

"Sold!", I answered. :-)

His arm twisting didn't last long. My 'new' 46 awaits installation as soon
as I send this message off.

Things learned:

1) However well intentioned, no one will screw with my engine anymore. I
think I now know enough from what I have learned from fellow fliers here how
to get my engine to its best output yet still fly 'richer than leaner'.

2) If you blow a plug, and the engine is hot to the touch when you land, you
just flew lean. Look DEEP inside the plug, and if the element is missing,
assume the worst and figure it is within your combustion chamber somewhere.

3) Perform appropriate surgery to remove or to prove your gut instincts. It
only takes a few minutes to tear down an engine.

4) Read #1 again. :-)
 

I have never taken on a sport such as this that required the learning of so
many things all at once. Engine anatomy and physiology. Aeronautical
engineering. Electrical and computer engineering. Airframe and powerplant
maintenance/rebuilding/reconstruction. Fuel technology. Arboristics
(knowledge of wood). [I just made that word up, I think :-) ] Adhesive
characteristics and applications. Radio frequencies and
anomalies/interference scientology. Battery maintenance 101 (Thanks, Red!).
Charging.discharging/cycling of nickel cadmium electrical storage devices,
meteorological phenomena...the list goes on.

You can bet when I arrive at the field tomorrow morning, (I am always the
first one there, to watch the sun come up over the Chattahoochee River,
casting long shadows over the swamp that awaken the egrets, the herons, and
yes, the buzzards); I'll do a thorough engine check, using my auditory
senses and my tachometer and everything I have gleaned from the gurus here
to do my best to avoid another lean run. I never had one until I let
someone else tinker with my engine. That is not to say it will never happen
again, because as you know, saying never will almost always explode in your
face somehow, now or later down the road...... :-)))

,
Could you please answer some bullet questions with some bullet (short)
answers?
1. What prop are you using?
2. What glow plug are you using?
3. How did you break-in your OS46FX?
4. How are you using the tach information?
5. What is your general opinion of the OS46FX?

P.S. Thanks for your great insights into the world of RC!!!

You might want to add one more thing to your list.
5) Try to stay away from idle bars.
I have heard stories of idle bars coming off glow plugs and killing engines.
I idle bars don't combust very well.
A lot of the scoring to your pistion was done when the oil broke down and
you had metal to metal contact. It will kill and engine every time. The
scoring seems to form on the piston first. Running a little castor will give
some protection from a lean run. It will also gum the motor up.
Harlan

Great posting Pat but one more suggestion. Lose the idle bar plugs for
your 46FX. The good old OS #8 is generally considered the plug of
choice for that engine. There are others that work well with that
engine but you don't need an idle bar plug.

,
Another thing to think about.... Today, very few (I'll leave room for
doubt) engines need a plug with an idle bar. If the engine is set up
and running properly then the idle bar is likely not needed.

Great post. I think your lesson #1 was the very hardest for me to accept
when I first took up this sport/hobby about 3-1/2 years ago. It took a
while but I finally figured out that there's no shortage of experts at most
flying fields, and one or two of them actually know what they're talking
about! Nothing is more confusing and frustrating to a beginner than for
"Expert #1" to make some adjust to your plane, then another "Expert #2"
comes over and says something like, "No, no, that's all wrong! Here, set it
up like THIS!".

After a number of experiences very similar to yours, I finally decided as
you did that no one else screws with my engines or planes. I'll listen to
advice when I figure the person really does know what he's talking about,
but as often as not, it's just hot air which I can safely ignore. At one
club I used to belong to, there was an older guy (my age, actually - 50-ish)
who'd spend hours going up and down the tables in the pits, offering his
fatherly advice to everyone who was there with a plane. No one ever saw
this guy actually fly, although he'd set up a plane on one of the tables.
Finally, one day I asked him how long he'd been flying. He replied that he
expected to solo "any day now..." True story. Anyway, I figured --
correctly as it turned out -- that I can't do much worse by myself by
listening, reading, observing, then applying what I've learned.

Good luck to you. Sounds like you're well on your way to becoming your own
expert.

I think you are blaming the wrong engine component. Eventually
most engines see an unintentional lean run due to a tank problem or air
leak in the fuel system. As for glow plugs, idle bars are not meant for
Schnurle ported engines but rather domed piston engines. It is highly
unlikely you damaged the engine significantly if you continued to beat
the other plane for several laps without your engine sagging. If the
engine is an FX, I would suspect the damage is from the ball bearing
races coming up thru the engine. I sold all eight of my 46FX engines due
to similar problems and replaced them with Rossi engines. The Rossis
have true chrome (not nickel) on the cylinder liners and high speed
bearings. I run the Rossi's much harder than the FXs with no problems
and only $15 more per engine. I would send the FX to Hobby Services and
try to get it fixed under warranty, then sell it when you get it back.
The only other engines I would like in this class would be Enya 50 or
Webra 50 (Webra has good nickel plating and holds up). Good luck and
deep six the FX aka the glorified LA.

I ave a post on the TT pro for tuning.
The same would apply to the OS engine
except the amount of opening the valves.
OS generally takes 2 full turns for starters
then lean.. But the rules are the same.
Perhaps it may help.