Conference vmszoo::rc

    
    	Shawn,
    
    		For a .15 I think that a 8/6,8/4 should be a correct
    prop size.  Fuel, well I use a 10% nitro mix of 50% castor 50% 
    synthetic oil. You'll find that fuel is usually broken down to
    ( ? )% nitro, 20% oil and the remaining part of the gallon is
    alcohol.  The object of break in is to allow the engine time to
    loosen up before it see's excessive heat. I typically run 8 - 16
    oz. of fuel thru an engine on a stand and the install it into a
    plane. Subsequent flights are rich and then slowly leaned out.
    You can install the engine in a plane and just tie down the plane
    for one or two runs. This is just a little messier than a stand
    but is cheaper when getting started.  When an engine is running
    and is rich it makes a four cycling sound. There is a distinct
    increase in frequency when an engine goes to two cycling. Your
    first engine runs should be as rich as you can get them yet still
    keep the engine running. Some times I have to readjust the needle
    valve to start the engine and then richen it.  Have you hooked
    up with a club or flight instructor?  Don't attempt to fly by 
    yourself.
    
    						Tom

    I'll most likely be hooking up with CMRCM.  I authored note 166
    but was goofing around the other day and accidently deleted the
    initial note.  I'll be going out to the field sometime in the next
    week or two to meet some of the members, see some flying and make
    arrangements for flight lessons.  I WAS thinking (as I'm sure most
    beginning RCers do) about teaching myself but after reading note
    100 and numerous other warnings about the horrible nasties involved
    I changed my mind.  This notes file has been a great help.  I think
    that without it I probably would have turned my plane into scrap
    the first time out.
    
    
    						Shawn

    Even though it has probably been covered, I will enter this because
    I feel that in a helicopter, break-in is not necessary.  I have
    built three, and the last two I broke in in the chopper.  The reason
    I feel that it is not necessary to have a separate break-in is that
    in a helicopter, the mixture is set rich enough to keep the engine
    running cool.  Also, if you only hover it for about 30 - 45 seconds
    and set it down, and keep doing this (while trimming out the chopper)
    you will be changing the speed just as you would during break-in.
    Ernie Huber talked me out of a separate break-in and I have had
    no problems.  Good luck.

		________
	 /	  __|__  
	=========[_____\>
	/	__|___|__/  BREAK A BLADE,
			    Ken    	

    I have followed some of the best expert advice available. This advice
    was easily understood, (it was written down for me), and came from
    a source that understood the particular engine that I had bought.
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    The Manufacturer.... In my case OS engines.
    
    
    I'll be quite biased here on this point. Sure everybody has their
    own thoughts (and folklore) of what is the "proper" way to break-in
    an engine, and I have heard of lots of ways, which include everything
    from auto engines, auto racing engines, motorcycle engines, etc.
    
    Precision machined engines such as OS require less break-in than
    say a sloppy machined K&B. Why?, simply because OS engines are built
    to much better tolerances than K&B, and final fit and finish of
    mating parts are more carefully controlled thoughout the entire
    engine building process. Unless you know about how a particular
    engine reacts to different break-in procedures then why fool with
    it. You can be sure that OS, K&B, PICO, etc. are NOT going to tell
    you to break-in their engines in an abusive manner. They are not
    interested in turning off customers, nor handling warrenty claims.
    
    Despite all the advice you may get, you must remember that much
    of this advice may come from information that's been around for
    a while. The advice may be be applicable to engines of yester-years.
    Things change, such as materials, machining, and assembly.
    
    
    Now for my soapbox stand on break-in............
    
    I've played with auto, and motorcycle engines for years. One of
    the folklore tails that surfaced was: " After a real short break-in
    period" (far less than manufactures recommended period) " run'em
    like your going to use them"  For Example:
    
    Three of us back in 1975 bought three new Suzuki GT750 watercooled
    2 cycle motorcycles. I pretty much babyed my bike following what
    Suzuki said for the entire 1000 miles. My 2 other friends after
    several hundred miles, would take them out for a "beat run" You
    know wide open throttle, up to the red line, hit 100-120 MPH or
    so, enjoy the adrenalin rush, and back to normal cruis'in.
    
    The three of us many times would go out and drag-race I always lost.
    The person who would usually win was then one that litterally
    used to constantly "beat" his bike in the early break-in period.
    
    Suprizingly enough though, mine was the smoothest running of the
    three, and it delivered several MPG better.
    
    
    How's that for folklore.............
    
    
    							Dave
    

    I always break in my motors on a bench prior to installing them
    in an airplane (no chopper experience) for several reasons:
    
    A new motor needs to go through several heat and cool cycles to
    stabilize the metals.A new motor, even though precisely machined, 
    does not have perfectly mated surfaces.  If you run it rich enough 
    to keep it cool, you also run the risk of having it quit.  Same with 
    running it too lean and having it quit with damage from scuffing, 
    galling etc.  During breakin its not uncommon for a small piece
    of metal to nail the glo plug for an abrupt stop.
    
    Most important, if it quits with your machine in the air you'll
    be lucky if you have the altitude to autorotate or dead stick in,
    why risk it??
    
    All of my O.S. motors were broken in on a bench for about an hour
    as follows:
    
    Start with the needle valve about 2 to 2 and 1/2 turns out.  Once
    it starts, see how rich you can make it run without dying.  
    
    Run it rich for five minutes then slowly turn the needle valve in
    to just below peak RPM's, run it there for about 20 seconds.  
    Back it out again and run it rich for another five minutes. Every
    20 minutes stop the motor and let lt cool completely.
    
    Repeat this cycle for an hour.  At the end of the run let it peak
    for a minute or two to clear it out.  After your done, pull the
    back plate off and flush the crankcase with fuel or light oil to
    remove any stray metal particles.
    
    Do your bench running right, secure the motor properly to a regular
    motor mount, bolt the motor mount to a piece of wood and firmly
    secure the wood to a bench (my favorite is a fence post out at our
    flying field).  Rubber band the fuel tank to the piece of wood.
    Use a fuel filter between the tank and the motor.  Run a prop at 
    one inch of pitch less that the smallest recommended by the 
    manufacturer.
    
    Your reward will be a smooth reliable motor that starts easily when
    others are having fits.  Its definitely worth the trouble.  Mine
    all start with one flip after a prime and run reliably tank after
    tank.
    
    Happy landings.
    
    Will

Will, you obviously have broken in a few engines in your time,
and I don't question your success...but the advice to lean the
engine out periodically and to use a small prop doesn't seem
right to me.  Aren't you risking hot spots -- places where the
wear is a little slower?  Seems that I read Clarence Lee
somewhere saying that you shouldn't use a small prop or lean out
the engine during breakin.

I do agree with this: it takes more than an hour of bench running
to properly break in an engine.  My K&B sportster .20 is a
pussycat now, but there was a lot of hot running and other
problems for the first hour and a half, at least.   That squeak
at TDC from cylinder taper is very unnerving if you don't know
why.   Also, a Thunder Tiger .15 that I have is approaching an
hour and a half, and its just beginning to be nice; it takes lots
of running to get them good.

The conventional wisdom at the field is to bolt 'em up and let
them break in while flying.  The reasoning being that if you take
it easy and run a little rich the unloading effect and the better
cooling from flying give a better breakin.  I still like to bolt
them up to the bench and do it the old way.  

    I go with one inch less pitch, but same diameter to avoid unnecessary
    loading during static run up.  I lean to just below peak RPM and would 
    agree that overleaning the motor is not good during breakin.  The
    idea is to go from a cool well lubed state to a five second burst
    of near full power then back to a cooler well lubed sate.  Myy
    understanding is that the most important part of getting uniform
    results in break in comes from letting the motor fully cool off
    so that the metals go through complete heat cool cycles.  I guess
    the bottom line is I am always amazed with the poor devils who come
    out to the field and have fits getting their motors to start/run
    when just a little TLC at break in would have saved them all that
    grief.
    
    Happy landings.
    
    Will
    
    

    I agree with some of what has been written.
    
    
    
    For the engine at hand I'd bench run it is possible outside of the
    chopper. Not because there is andthing wrong with running it in
    the chopper as Ken has suggested but rather with this being your
    first chopper it would be good to have the engine somewhat broke
    in and the needle valves set up so that it limits the fiddleing
    you'll need to do once the engine is in the chopper. Whew!!!
    
    When I break an engine in I run it rich the first tank full to the
    point where I can hold onto the cylinder as the engine is running
    and not burn myself. It;s run for the entire tank this way. The
    secong take is run with leaning periods. The third tank is run with
    more lean than rich settings. This is then followed with a final
    tank run at power and moving the crab to go from idle to top rpm.
    After all this I've run about one gallon threw the engine I then
    start to adjust the lowend and the high end of the engine to get
    a consistand running engine.  The only three engines in recent history
    that I have not done this to were the webra in my Xcell (run rich
    in the chopper as is doing good) and two magnums that have been
    giving me problems with inconsistant runs.
    
    
    Tom

    Today I decided to break-in a new OS .40 FP on a test stand rather than
    wait until the plane is finished.  I had no trouble getting it started
    and ran thru the first tank at low speed with no problems.  I loaded up
    another tank of fuel and started it up again. About a minute into the
    second run, the engine spits the prop, andi  it went into a high speed
    whine.  Luckly, I wasn't in the way of the prop, and it flew off
    harmlessly into the ground about 15 feet away.  Realizing that the
    engine was in a run away condition, I quickly pinched off the fuel line
    to shut it down.  It stopped about 15 seconds after throwing the prop,
    but by this time the cylinder head was smokeing.  After letting it cool
    down, I was unable to get it started at the same setting as before. 
    Finally, after opening it up to a richer setting, it did start and run
    thru another tank.
    
    Question:  I have never had an engine throw a prop, and I know the prop
    nut was tight when I started it the first time.  What happened to cause
    this?
    
    Second Question:  Did the engine suffer any damage during the 15 sec
    period when it was running flat out without a prop?  The fact that I
    was able to get it started again leads me to believe that if there was
    any damage it might be slight, but I don't know.  Is there any way to
    check this out?
    
    Any help and advice is welcome.
    
    Thanks,
    Joe  

        Re:                      <<< Note 178.10 by WAV13::MARRONE >>>

        Joe,
        
                If the  prop  nut  really  was  tight  I  would  think it
        loosened because of  detonation.    This is caused by running too
        lean and too hot.
        
                The basic problem with  over revving is that the oil film
        breaks down when the cylinder velocity exceeds a certain maximum.
        In effect, the oil film starts behaving like a solid instead of a
        viscous liquid.  A godd example of  this effect is putty.  If you
        qhueeze it gently it will flow, but move  it  fast  enough and it
        breaks.  Once this happens you have metal to  metal  contact  and
        heavy  wear.   I suggest you pull the cylinder and  look  at  the
        piston.    If it has heavy gouging you have an engine  that  will
        always be a poor performer.  The rest of the surfaces move  at  a
        much slower velocity  than  the  cylinder,  so  its  unlikely you
        damaged them unless aluminum  and steel filings from the cylinder
        and sleeve got into them.    The  smoke  was  caused  by the heat
        generated from metal to metal friction.
        
        Anker

Pinching the fuel line made it lean and die... putting a finger over the venturi 
makes it richen and die. If you're lucky, you might have done nothing more than 
accellerate the break-in process with the excessive wear...

Jim the_eternal_optimist

I "abused" my OS 35FP a couple years ago by running it too lean. It
would die after a few minutes of flight, and actually seize up. After
cooling down it would turn freely again.

There was no obvious damage or deterioration in the motor, and I ran it
many times afterward with no problems. They are rugged engines. Thermal
seizing due to overheating shouldn't cause any serious damage unless it
siezes so suddenly you bend the crank or pushrod or something.

If it runs now with no apparent problems, don't worry about it.

Dave

    Re .11
    
    What's involved in pulling the cylinder?  I've never done this.  Does
    it require any special tools, or do you have to torque the bolts when
    reassembling?  How do you make sure the clyinder goes back in the same
    way it came out?
    
    A few pointers would be appreciated before I attempt surgury.
    
    -Joe

What we are talking about here is a shaft run. These are not uncommon with 
racing engines, a nose over on take off is the most common reason for it to 
happen. The common way to stop a shaft run in those instances is to push the 
spinner into the ground before the engine breaks, dramatic but effective.

The big risk with a shaft run is the stress of the very high rpm the engine 
reaches (ie. > 30,000rpm) which stresses the whole engine beyond design limits 
but mode particularly the piston, rod, and bearings.

I have not heard Ankers explanation before, I can't say it's wrong but have my 
doubts on it's validity. I think the effect would be for the oil to produce a 
solid barrier between the two components. Using the analogy of the putty I 
think the course of least resistance would be to glide over the surface rather 
than push the putty out of the way.

Re: Joe's question on dismantling the engine.

It would be a good idea to check everything for damage but if as you indicate
you are apprehensive I would suggest you ask somebody in your club familiar with
engines to do it with you. The advantage of this approach is the eye of
experience would probably pick up a problem that you may miss, as well as
supervising and instructing you on the task. 

Model Engines are nothing magical, a logical, careful approach to disassembly
and reassemble is all that is needed. However after saying that some people
have the ability to wreck screws and nuts, burreing the heads or cross
threading, those people should leave small machinery well alone and give it to 
somebody else to do for them. You must have seen those people who use a pair of 
pliers to tighten the prop nut or an instrument screwdriver to tighten wing 
bolts.

Some simple rules to engine maintenance are:-

	1. Find a clean, CLEAR, light work space
	2. Have good tools on hand (ie: no rounded corners on allen keys or
	   screw drivers). Ensure you have a selection of sizes to suit the job
	3. Have a container of solvent for washing parts and clean cloth
	4. Containers for putting piece parts in
	5. A note pad and pencil
	6. A small scriber for marking parts
	7. Some light machine oil
	8. Chose a time to do your first few rebuilds where you can complete 
	   the work without interruption

Many notes have been written in this conference on engines. Try at the Notes> 
prompt DOOR /TITLE=ENGINE *.* 

It really is not difficult to work with engines, it is very satisfying.

John

    John Chadd's advice (at the end of his note) is good.  The following
    is better and 60 times faster:
    
    	Notes> sho k/f *engine*
    	Notes> 11.(whatever is appropriate)
    
    The reason is that DIR *.* has to check a zillion entries; SHO KEY
    takes seconds for "engine*" and not much longer for "*engine*".
    This is described in 2.4; another technique involving a file containing
    the results of "DIR *.*" is in 2.2(?).
    
    After all this, I hope your info is in here.
    
    p.s.  John meant "DIR", not DOOR, unless Aussies really _have_
    perverted the spelling of the language.    :-)   "shaft run" ?

Joe Marrone an I dropped by his house over lunch yesterday (he lives just down
the road here in Merrimack) to see if we could get his 40FP to run any better.
Well, it actually ran pretty good for a new engine that is still a bit tight.
Didn't throw any props either. After we talked for a bit, I think that the
thing that was causing the props to be thrown could be that he is using a
"chicken stick". Huh? you say... I'll bet that what was happening was that the
engine was starting backwards and the reverse rotation was causing the prop
nut to loosen at full throttle and eventually throw the prop. Whenever I'm 
starting with a stick I always wind up starting backwards a few times because 
I don't always flip the prop with enough authority. This would also expalain 
the "shaft run" since the prop would separate cleanly leaving the engine to 
rev up still running in the same direction. In any event, the engine seems to
be OK.

Glenn Schrader

Glenn,

You may recall my 40 FP did the same thing quite often last year.  This
has never seem to be a problem with my 40 SF.

BTW, my wife flet bad I didn't have an engine for my Eagle since I moved
it to my new Skytiger.  She bought me a new 40 SF ABC (on sale at Bill's
Hobby Barn for $109).  Hard to believe I now have two fully functional
birds.

Loren