O.S. .40 LA engine
 

hi, you've probably seen me before on the biginners forum and anwsered some of my questions and if you have, then thank you lots.

but... i'm still kinda new to this and i was wondering if any of you could give me an in depth step by step to how the o.s. .40 LA engine on my avistar really works, i'd just kinda like to get to know what's taking my 200 dallor plane up in the air. so if you could give me an indepth step by step how it works, i'd love it, thanks and God bless

RE: O.S. .40 LA engine
 

The basics of any engine is that it is an air pump and requires fuel,air and heat (Glow plug) to run. Other factor effect the performance, such as compression and timing. With a 2 stroke engine the engine fires once every rotation of the crank shaft. Anyway the glow plug works much like the catalitic converter in your car. When sufficiently heated it will stay hot to burn the Hydrocarbons present (Fuel). If you look down the open throat of the carburetor while rotating the crank shaft you will see that the crank shaft has an opening in it and that from that opening to the back of the crank shaft is hollow. As the piston is comming down and that opening is facing up (to the carburetor) the suction (vacume) produced by the pistons movement draws air and fuel into the crank case and into the cylinder. Thus providing fuel and lubrication to the engine. As the piston comes back up it compresses the fuel air mixture in the cylinder and the glow plug ignites the mixture forcing the piston downward again to repeat the cycle. As the piston is going down the exhaust port (ports are openings machined into the cylinder wall) is the first to be exposed allowing the burnt fuel to escape. Then the intake ports are cleared and more fuel/air mixture is drawn into the cylinder accelerated by the rush of exhaust gasses escaping in the opposite direction.

I'm sure there are more technical explainations but this is my understanding of the two stroke engine.

Others; feel free to elaborate or correct as you see fit.

RE: O.S. .40 LA engine
 

[link]http://www.easyrc.com/engines/[/link]

Ken

RE: O.S. .40 LA engine
 

on the down stroke the opening of the crankshaft is also facing down from the carb thereby acting like a check valve.
As the piston travels down it also force the fuel mixture up through the side chamber.
it is imperative to get a good seal. some people use selicone to seal the back plate.
this will prevent the engine from running too lean (too much air) thereby running too hot, therby blowing out the glow plug.
As the exhuast travels out of the cylinder it will also acts as a seal. Back presure is needed.

the exhuast will also provide pressure to the fuel tank, thereby forcing fuel to the carb or needle valve.

once up in higher altitude, with the prop spining and the model moving forward. More air will be forced into
the carb. You must tune for a rich (more fuel) setting on the ground to compensate.

Weather also plays a role. if you tuned your engine prefect in the afternoon in warmer air (thiner).
it's not going to run the same the next morning (denser air).

the cylinder (sleeving) on nitro engine are also tappered. The diameter is less on top. this is also
how nitro 2 stroke engines create a seal. unlike the 4 strokes with rings on the piston.
This is why you need to break in the engine.

RE: O.S. .40 LA engine
 

tha actual ignition is by chemical process the heat just helps it along.
there are two strokes with rings& have been for years.nothing wrong with ringed engines. they are more tolerant of dirt than ABC setups and break in quickly. the ABC setup has the tapered cylinder liner .this allows more power to be developed along with schnnerle porting which most modern engines have. the Aluminum piston running in a Brass sleeve Crome plated.your carburator in the FP/La engines is really a simple airvalve as opposed to true carburation adjustment with high and low speed adjustments .the air bleed works but not always that effective . it does work however.with bushed engines such as yours opposed to ball bearing engines its more important to insure lubrication to the front bushings via some additonal castor in the fuel or at least as was mentioned ,slightly rich setting.lack of ball bearings makes it much less expensive to manufactuer& maintain.the small size of the carb is what holds back the FP/LA series more than anything. it also makes it have good fuel draw & reliable idle.
one other thing should be mentioned.unless you live in an ususual place where weather/temp changes drasticly through out the day , needle valve adjustments should not be neccesary once set.minor ones perhaps but constant fiddle & tuning indicates other problems & often indicates lack of knowlege of the real trouble.

RE: O.S. .40 LA engine
 

IGNITION
COMPRESSION
CARBURETION

If you dont understand these three terms and their relation to the internal combution engine, you have some homework to do!
These are the three systems of any engine.

In order to understand how these systems power an engine, you must understand the four Strokes that complete one revolution of the engine's crankshaft (you know the part that turns linear[back and forth] motion into radial motion[Turning]).
the four Strokes are :
IGNITION
COMPRESSION
POWER
EXHAUST

in a two stroke cycle engine (glow), power and exhaust take place almost simotaneously. Also, compression and ignition also happen in the same stroke. That is why we label a glow engine a 2C (two [Stroke]Cycle).

A gas or spark ignition engine takes 1 stroke to do each job! That is why they have less power per given displacement. The power stroke happens 1 stroke out of 4.

Hope this info may help. But please look up the 3 systems and 4 strokes. Im sure others have explained them better
hope this helps!
PAT