Conference vmszoo::rc

Add to that the skill factor.  If you fly like me you
will never wear an engine out.  Break it into pieces
maybe but I should be so lucky to wear one out.

However I do tend to stay on the rich side because
my engines don't have enough hours on them and I don't
have enough experience and expertise to keep them
alive and lean both.  

Now the flight line is different.  I may wear out
that guys corn field with all my crashes in it.

              _!_      
Bye        ----O----   
Kay R. Fisher / \     

================================================================================

    
    I have two examples for you.  The first is my Enya .46 4-stroke,
    which I was usually very careful with but made the mistake of
    running too lean for ONE FLIGHT.  Result?  Seized crankcase bearing.
    Replaced the bearing and ran rich from then on, which resulted in
    no more problems.
    
    Ok, so maybe 4-strokes are different.  Well, my second example is
    of a friend who needed every ounce of power out of his 2-stroke
    OS .40 (FSR, I think).  He ran with it tweaked to top RPMs and got
    maybe a season out of it before he had to replace the piston -
    the hole for the wrist pin had turned from round to oval.
    
    Personally I am on a tight RC budget and need my engines to last
    as long as possible, and am convinced that the way to do that is
    to run 'em rich.  I have heard many experts say the same thing.
    I'll opt for a larger engine and run it rich before I'll try to
    squeeze every ounce of power out of a smaller engine.  By rich
    I don't mean spewing raw fuel out of the exhaust, I mean a few
    clicks on the rich side of top RPMs (occasional 4-stroking which
    usually is gone by the time you're in the air).  Maybe part of
    the disagreement is with the terminology?
    
    Bill
    

    I have a strong tendency to agree that rich/lean makes little or
    no difference in the life of the motor.  And, like everyone else,
    I have lots of stories to support my opinion. I think that other
    things we do to them are more harmful than running them at the top
    rpm,which is what most manufacturers recommend. Most instruction
    booklets will mention "bring motor to max rpm then open needle one
    or two cliks" more to compensate for the different conditions after
    the plane takes off than to ensure a richer mixture.
    
    The motors have a way of telling  us when they are running too lean:
    they slow down or even stop in flight.If you adjusted a motor and
    it managed to run for 12 or 15 minutes at peak rpm, land and still
    taxi and idle all the way to your tool box, I'll say it is not running
    lean.
    Refering to one of the replies, I've never seen a motor come down
    and be just warm to the touch, but that may be just my own experience.
    They've always been hot enough to boil methanol, which boils ( I
    believe ) at close to 90 degrees c.
    
    But, like everything else in life, there are compromises. You may
    have bought a motor for a plane that turned out to be slightly 
    underpowered. If you bring it to 3/4 throttle, it looks like it's
    flying through Jello. Well, if you can afford it, you buy a bigger
    motor. If you can't, just let it have it. In most cases, the plane
    is more enjoyable to fly at the proper speed.
    
    Fern
                                                         
    
    

Tom in note 238.0 has the right idea, if an engine is run lean you are running
at very reduced power, with modern day engines they are capable of running
at much less oil content and leaner than the engines of yesteryear. 

Fern in note 238.4 does have a valid point in that running slightly rich at
take off will help compensate for changing conditions during the flight. My
preference is not to have to compensate for changing conditions, rather to
build the model and install the engine so any change is an acceptable minimal.
The biggest cause for changing conditions is the tank position. Many schools of
thought exist on the correct position, my own belief is the top of the tank
should be level with the needle assembly; provided, you don't have a deep tank
which gives a great change in fuel head height and run with muffler or pipe
pressure to the tank pressure you should not have a problem. If you are unable
to position the tank as above use one of the Micro Oscillating pumps to provide
pressure to the venturie. 

An engine properly set up should have a wide needle margin; at least 2-3 clicks
with out any perceivable change in engine performance. This condition is
effected by the plug condition, plug type, plug temperature, fuel, prop
size,compression ratio, and head profile. The latter two items are out of the
control of the average modeller. Using a too large prop will overheat the
engine creating a high probability of engine failure. 

While on the subject. Have you read the September Model Builder, particularly
the article on breaking in model engines by Berkley McCollum. Don't know the
guy myself but I suspect he must be close to his 100 birthday after reading his
outdated and inaccurate words. (must send him a birthday card!!!). He suggests
to use a minimum of 25% castor oil in the fuel used for breaking in the engine;
this much oil will glaze the engine, definitely not beneficial, he also says
"don't use fuel containing Synthetic oil". Where has this fool been for the
last ten years, the Amazon Jungle. Secondly he states that wood props vibrate
less than palastic props. What crap. No wood prop is as rigid as a carbon or
glass prop, even a Master air screw is as rigid as most wood props. 

John 

    I think one of the most destructive thing I've seen modelers do
    to an engine is over prop an engine. Try running your car up a hill
    in fourth at low rpm and see how it likes it.  You have to not only
    prop an engine for RPM but also for the plane your flying. Classic
    example is my COMO 51 ABC. Running upright in a 4.5 lbs plane to
    will pull a 10/7 hard. When I installed it into my Skyleader at
    just over 5 lbs side mounted I couldn't get over 12k on the ground.
    The engine wouldn't pull. Tank locations on both planes were optimal.
    I'm not running a 10/6 and the plane pulls like you won't beleave.
    DON"T OVER PROP.
    
    						Tom

    re .-2 Castor Oil vs synthetics: 
    
    John, Duke Fox published something in his colunm/advert in the Sept
    87 issue of RCM (and AMA pub). He suggest this test: Heat castor
    oil to about 500 deg F. Note how it becomes pasty..  Repeat same
    with a Synthetic oil. Note how it dries out. 
    
    Message here is that Castor Oil pick up oxygen as it heats up (say
    when running lean) and still provides some lube. With a synthetic,
    this is not the case... Old wives tale or ???? 
    
    re .-2: Would the profile of the plane also affect the RPM ??
    
    md 

      WHILE AT THE FIELD YESTERDAY A FELLOW MEMBER POINTED OUT THAT
    HE MIXES 1 OZ CASTOR OIL (GOTTEN FROM LOCAL PHARMACY) TO 1 GAL OF
    FUEL. HE USES THE TOWER PREMIUM WHICH HAS SYNTHETIC OILS. CAN THERE
    BE JUST TOO MUCH OIL IN A FUEL? IS IT A GOOD PRACTICE TO ADD CASTOR
    TO A SYNTHETIC OIL.
    
    BOB G.
    

Re: 474.0

>      WHILE AT THE FIELD YESTERDAY A FELLOW MEMBER POINTED OUT THAT
>    HE MIXES 1 OZ CASTOR OIL (GOTTEN FROM LOCAL PHARMACY) TO 1 GAL OF
>    FUEL. HE USES THE TOWER PREMIUM WHICH HAS SYNTHETIC OILS. CAN THERE
>    BE JUST TOO MUCH OIL IN A FUEL? IS IT A GOOD PRACTICE TO ADD CASTOR
>    TO A SYNTHETIC OIL.
    
Bob,

Previous notes have discussed fuels in some detail, it could be worth while 
re-reading them. You will note that some people believe the addition of castor 
to synthetic fuel is desirable and others including myself are opposed to the 
practice and believe highly undesirable.. You have to make your own choice 
based on the facts presented.

Refer to the following notes:-
				156.*
				238.*
				289

As far as using Pharmacy castor that is not a good idea. Pharmacy castor is 
very pure and refined, a lot of the lubricating properties have been removed in 
the purification process. The best Castor is a first pressing raw castor. In Oz 
the best readily available is a product called "Castrol M", Shell make a 
product called "Shell M100" which is a second grade castor with additives that 
can stain some model finishes.

Make your own choice but I say NO castor if you use a good synthetic oil.

John.