Conference vmszoo::rc

ABC = Refers to the construction of the piston/liner. Aluminum piston (A),
Brass Liner (B) that is Chromed (C). (ABC simple, Eh!) The idea is that the
piston being made of a silicon aluminum alloy (about 16% silicon) it expands a
little less than the brass hence as the engine heats up the fit gets looser. 
   
BB = This stands for ball bearing or ball race as opposed to plain bearing 
support for the Crank Shaft.

Schneurle porting = This refers to the transfer ports you know those holes that
stuff the fuel into the engine during the transfer timing. A Cross Flow engine
has generally a single port opposite the exhaust port, Schneurle porting has
three one of which closes later on the compression stroke than the others. This
is called the boost port. This port is the one that gives the boost to blast
the burnt gasses (and fuel) down the header pipe that is later forced back into
the combustion chamber before the exhaust closes whel tuned pipes are used,  
this boost can be several PSI. 

OS Jargon.  VF = Front intake rear exhaust. FSR = Front intake side exhaust. 
            VR = Rear intake rear exhaust.  H = Helicopter
            M  = Marine                     P = Pylon
            RC = The old original Cross Flow engine.

Exhaust timing = The time in degrees from exhaust port open to exhaust port
closed. Normal engines are around 150�, performance engines with tuned pipes
are 156-180+�. 

Transfer timing = The timing in degrees that the Transfer ports are open.

Induction timing = The timing the induction port is open. Governed by the Crank 
Shaft in front exhaust engines and by the Drum or Disk valve in rear exhaust 
engines.

Drum Valve = Used by rear exhaust engines to gain induction timing. Looks like
a drum in the backplate. 

Disk Valve = Used by rear exhaust engines to gain induction timing. Would you 
believe it looks like a disk on the back plate.

< Also what is a tuned pipe going to buy me over the standard muffler

Heaps more power when properly set up. eg a OS45 FSR on a muffler gives 16,000
RPM. The same engine on the same prop gives 22,000 RPM on the pipe. (The engine
is modified to take advantage of the pipe, I also use different bearings) Pipes
can be tricky things to use, be prepared to put some work into learning how
they are adjusted. Condor Models sell the Australian Magic Muffler, they are
simple to use and give almost all the power of a properly set up full length
pipe. 

I cant think of any more confusion to bestow upon you at this time, I hope it 
helps.


< (BTW, I'm buying a FOX .19 Schneurle BB RC) (hey, what the hell,
  let's start an argument on engines while at it)

They make nice spinners. 

John.

    
    RE.3
    
    You mentioned glowplugs w/without idle bars, what does this idle
    bar really do for the engines performance, and how do you decide
    which is better?
                    

re .-2 (or so the thing about pipes)




		Hmmmnnnnn,looks like an awful lot of messing about
 	to me....

			I have an ED pipe,which is the type that requires
	the mainfold to be cut..... They make 2 sizes of pipe,one for 
	.40-.60 and onefor smaller engines.... put simply their instructions
	for tuning go as follows :-

	1. Measure the exhaust opening angle.

	2. Run the engine and check the open exhaust revs,on the chosen	
	   prop.


	3. Then consult a chart they provide to get the length from the 
	exhaust port to the end of the pipe.hey presto,easy eh.I guess
	the dimensions they provide should hold true for any make of
	pipe.


		If anybody wants a copy of this chart,let me know 
	and I'll mail them a copy.	
	

		This seems to be straying away from the initial 
	query.Maybe we shoul open a topic on tuned pipes.

    
    The idle bar glow plug was an invention made to combat a problem
    seen in the earlier days if RC. When flwing ment Free Flied and
    or Control Line the engines were set for high speed only. With
    the advent of RC eventually came the throttle. With the throttle
    came problems with idling because the crude carbs. in use.
    The problem was as I remember tha the mixture wasn't precise
    enough through the range to control the amounts of fuel that was
    going into the engine. This caused a problem with excess fuel
    splashing up into the glow plug cooling the plug to the point that
    it would stop functioning and the engine would die. the answer
    was to install a bar of metal across the glow plugs opening to divert
    the splach of fuel away fro the element. With the engines used today
    mixture can be comtrolled to the point that the splash is no longer
    a problem. If your new to the game of setting up engines and RC
    then the glow plug with idle bar is the set up to go with. Until
    you do get familiar. Problem is that people have become comfortable
    with the bars and don't bother to work on their engines set ups
    as they might. Pattern and racing flyers do work on the engines
    and as such the set up are better so the glow plug without the bar
    is a plus. When breaking in a new engine I always use a glow plug
    with idle bar as the settings are usually very rich.
    
    					Tom

    Sorry for the typo's. I was typing fast.
    
    				Tom

Sorry guys, I made a blue on 60.1; got my exhaust and induction mixed up. Quite 
painful.

Induction timing = The timing the induction port is open. Governed by the Crank 
Shaft in front induction engines and by the Drum or Disk valve in rear 
induction engines.

Drum Valve = Used by rear induction engines to gain induction timing. Looks like
a drum in the back plate. 

Disk Valve = Used by rear induction engines to gain induction timing. Would you 
believe it looks like a disk on the back plate.

Re: 60.6 I have opened up an engine tuning note.

John.

    I did a no-no last night.  I was tinkering with my little .15 engine,
    you know, cleaning it up, adjusting loose parts, etc..., and I decided
    to tighten up my shaft.  Well I didn't think it through before I took
    my hammer to it, and I bent the shaft slightly.  I have a friend that
    works in a machine shop and he did the best he could,but it is still
    bent (real hard to see with the naked eye).  On his high speed chuck
    you can't see any odd movement from the prop, but on low speed (500
    RPMs) you can see some deviation.  The bend is near the tip of the
    shaft.
    
    Question.... Will this greatly affect the flight?
    
    Ken

Dear heavy handed,

How slight is a slight bend?. When you say the shaft is bent I am assuming you 
are referring to the crank shaft. 

In a 15 engine I would expect the top RPM would be about 15,000 so an
acceptable runout would be in the order of .003", much more than that could end
up causing radio problems from the vibration. We know that all engines vibrate,
when you have any runout the level of vibration increases. Another effect of
engine vibration is the tendency to increase the possibility of airframe
flutter. 

If you have a bent crank shaft its probably the safest thing to replace it 
before it causes a problem.

A tip for dismantling locked engines is to boil the engine in a pot of water. 
It does two things; 1) it softens the residual oil (particularly if you use 
castor oil fuels) and 2) the effect of heating is to loosen the fit temporarily.

Good luck with the rebuild.

John.

    I'm looking for references (like  a good detailed write-up) on what 
    Schneurle porting is all about.
    
    I would like to see how the concept is implemented in a 2 cycle
    engine.
    
    MD

    one of the recent scale rc model mags had an article written by
    bob davis of davis diesel conversion.  it is about the history of
    schneurle porting and of course at the end he promotes his theories
    on diesel.  i will try to remember to bring the mag in to photocopy.
    whats your mailstop?
    kevin

    I would like any info on the reliability of SUPERTIGRE engines.
    Specifically the .61 ringed ingine.  I've been using OS brands
    up till now, and was just wondering how the SUPERTIGRE engines
    were. I'm in the market for a .60 size if any one wants to get
    rid of one (not beaten up please).
    
    Ken

    
    	I have had not issue with any supertiger that I have owned.
    They are not the most powerfull .61 sized engined built but they
    do run well. What exactly are you going to be putting this engine
    into?
    
    						Tom

    Probably the  Super Chipmunk (64" low winger).  
    
    The price from Tower is around $135.00 for the engine.  I've never
    been up in the 60 size or better engines, so I don't know what would
    be comparible (power to price-wise).
    
    Should I be looking for something different?
    
    I wouldn't mind having a 4 stroke, but the bucks aren't that readily
    available.
    
    Ken

    Ken,
    
    You can find an O.S. .61 [maybe even an ABC] for about the same
    $$$ in Tower.  Like Tom, I have no particular bane to pick with
    Supertigre but their carbs are more _fiddly_ and the O.S. is noticeably
    more powerful...that'd be _my_ choice.
    
    Adios,	Al

    Ken, For my money I'd get an HB 61PDP Blitz. It's a ringed engine
    which will help with the heat and very powerful. For the money I
    think they are the best deal going. They can be had for around 85.00
    They don't come with a muffler. You can get an HB or a K&B muffler.
    They are the same size. If your gong to use it in the chipmunk then
    you could get a pitts style muffler. I wouldn't put an OS long stroke
    in it. I've found that this engine was designed to be run with a
    pipe. It will run with a muffler but then again it isn't any better
    than other muffled engines that are cheaper.
    
    
    						Tom

    and as usual, I'll put in my 2 cents fro FOX. They have a new version
    (IV) of the .60. Despite all the bad press in this file by others,
    (who will remain unamed to protectheir innocence (sic)), The FOX
    engines are good & very powerful and last but not least US made.
    
    md

As usual I say OS ABC engine are best for sport use. Ringed engines make 
better fishing weights.

Seriously it gets confusing as 10 different people will probably have 11 
different answers. Get the product that you can get support on in your area, 
also a good guide is the gear the top performing guys in your club use; if they 
can get it working it is a good guess that they can help you.

John.

    I'm not going to add to the confusion by recommending a particular
    motor, but I would recommend that you do not go buy the cheapest
    one available.  Get one of the motors recommended here even if it
    costs a few bucks more.  What you're after is reliability first,
    performance second, and cost third.  I have seen more people fooling
    around trying to get some of the cheaper engines to run right instead
    of enjoying themselves in the air.  I have never had to do this
    with any of my engines. (Mostly OS)  I do have more money invested
    in my engines than some people, but my priorities are as stated
    above.  I would not touch any of the cheap OS copies that are shown
    in many of the ads at a much lower cost.  What they look like on
    the outside has little to do with how well they are machined in
    the inside where it counts.  If you properly care for a high quality
    motor, it will last many years and give trouble free service.  Also,
    it is not as difficult to order replacement parts for popular brands.
    I have ordered bearings, pistons, rings from Tower for my OS40FSR
    and had them inside of a week.  Our local hobby dealer can get them
    that quick as well.
    
    Charlie