I bought an Alpha Trainer, I tried to fly it with the help of my instructor,but the engine died after a few minutes in the air.
My instructor did all kind s of adjustments but still it died after a few minutes on the ground or in the air.

Any inputs appreciated.

First, check that everything is as it should be. Don't assume that anything at all is 'right'. Check all the basics such as:
- Engine not running lean (too lean a needle valve setting, or too large a prop for the engine)
- Engine and engine mounts are solidly fastened and not causing undue vibration
- Fuel is fresh and has the proper nitro and oil content for your engine
- Fuel tank has padding around it, and fuel is not foaming up due to engine vibration
- Glow plug is of the proper type as recommended in the owners manual

Next, I would check the plumbing into and inside the tank. Can you hear the clunk rattle around? Perhaps the plane took a hard landing and the clunk flipped forward. Are the fuel lines OK, or are they nicked and leaking air? Is your muffler pressure line OK? Is the fuel line inside the tank OK? If it was nicked and leaking, then as soon as the tank level got down to the level of the tubing, the engine would suck air in and stop.

Always check the basics first (i.e., is the lamp plugged in?) before looking for the 'exotic' problems. The majority of the time, your problem will be something that you 'assume' is OK, such as pinholes in the fuel line (nah, that fuel line HAS to be OK. It couldn't be THAT simple, could it???)

Just a few ideas to get you started... I'm sure that others will contribute ideas too.

Bob

Ok, just with what you have said, about your plane I could not even begin to think what is wrong with your engine. you need to describe engines problem in detail with symptoms the engine is currently exhibiting and what exactly have you done to correct the problem, your solutions may have aggrievate the problem.

Just from my extensive knowledge of Alpha and Arrow trainers, and the Evolution engine, check to make sure the fuel feeds from the tank and the small section between the remote needle assembly and the fuel inlet are not knicked and the same with the pressure line between the exhaust and the tank. I am one of three instructors at our field and in 8 out of 10 times, I have found these knicked and had to replace them. Also give your plane a hard jolt see if your clunk is in the right direction it may have curled forward if it was left on its nose for a while.

Other than that you have not informed us in the peanut gallery as to what the engine does, does it idle smoothly, does it burble at idle, is your high end idle too lean, causing your engine to heat up and lock up? If it has had a lean run and gotten hot, your glow plug may act like its good until it heats up and then loses its reaction and kills your engine. You have to give us more information to help you out!!!!! Has it acted like this from day one or have you had any good flights?

will

Thanks for your inputs,
But I am a beginner and I can not undestand half of terms you used and I do not now how to explain it I just know the engine stops working out of sudden.

thanks

Sometimes the details and terms can be quite overwhelming for a brand new modelt/flyer. Your instructor is your best source to explain the terms in the above replies and for providing answers to your questions Since your instructor was present when the problems occurred, he/she is in the best position to find the cuase and correct the problem.

IMHO, N1EDM has already outlined very good points. I'll try to restate some for your understanding;

If, when the engine is running, you can see ANY air bubbles in the fuel tubing from the tank to the engine you have air in the line. This can be caused by loose fit of the fuel line on any connection -- at the engine, at the tank, or inside the tank. It could also be caused by a hole, even tiny pin ***** size, in the fuel tubing -- between the tank and the engine, or inside the tank. Replacing all the fuel tubing is often the least time consuming fix for these causes. I have seen cuts/holes in the fuel line on several RTF trainers, like the Alpha. Almost all were where the fuel line connects to the tube from the fuel tank. Perhaps they happen during manufacturer assembly or during shipping. One was at the engine connection, and may have caused by the trainee.

Another possible cause of bubbles in the fuel line is 'foaming' of the fuel in the tank, when the engine is running. This is stems from engine vibration shaking the tank and mixing air into tiny air bubbles in the fuel. The Alpha does not come with padding around the tank, and I have seen 'foaming' occur in about 10% of the Alpha trainers flying at our field in the past 18 months. Placing some thin foam rubber between the fuel tank and any parts of the fuselage which might touch it usually eliminates this problem.

Finally, fuel quality... Glow fuel is mostly alcohol, which likes to absorb water and when it has absorbed, it won't run very well. Any cloudiness in the fuel usually indicates it has absorbed water. Nitromethanol is added to our fuel to get more power than pure alcohol. The nitro will evaporate more easily than the alcohol. If this occurs, your engine will probably run after adjusting the mixture needle, but it will seem to lack power. Cure for either problem is to get a new jug of fuel.

Try this, Start the engine, let it run fuul throttle for a minute or two, point it straight up and hold it there for about 10 seconds.

If it dies, it could be as N1EDM suggested in that the clunk in the tank has gotten stuck forward, or maybe the clunk line has fallen off the brass tubing

We had a student that had similar problems with the EVO engine. It took a long time to get it to work worth a darn, but one of the things we ended up with was a hot glow plug. That seemed to make it happy so maybe you could try the same. Option B is to return the engine for a replacement. These engines are marketed as being ready to run right out of the box. Perhaps you should make the manufacturer live up to their claim. This is assuming, of course, that your fuel system has been checked out.

Some Evolution engines are not set as advertised. I have seen a few that have had the high speed needle valve set incorrectly and the limiters only allow about 1/2 turn either way.

To verify this. loosen the allen set screw on the blue collar (limiter) and turn the high speed needle all the way in (clockwise) but do not force it down tight. Now turn it counter-clockwise about 1 1/2 turns. If you want then retighten the allen set screw on the blue collar. You can leave it loose.

Do the same thing for the low speed needle valve. (It inside the blue collar on the carb) Loosen the allen set screw for the low speed needle valve and turn it clockwise until it seats. Now turn it counter clockwise 1 1/2 turns.

In my experience, the low speed needle is set too lean from the factory and the limiter on it only gives you 1/4 turn.

I know you are new and welcome to the hobby. Can you tell me approxiamtely where you have the throttle stick on the radio when it dies. What I mean is: is the stick around halfway up or all the way up or less than halfway.

For future reference, on most glow fuel engines, the low speed needle valve is in effect until approx. half throttle and the high speed needle valve comes into effect from half throttle up to full throttle. This will help with knowing what needle valve is causing you the problem.

Also, there is a small clear fuel line that goes from the high speed needle valve to the carb. Look for bubbles in that line. There is also a line (could be any color) coming from the tank to the high speed needle valve, look for bubble there.

Let us know what you find and just describe it as best you can.

Straight from the EVO factory:

The proper setting for the low end is as follows:

Remove the blue collar,

Close carb so that it is only open 1mm

Close low end needle

Open low end needle 1 1/5 (One and one fifth) turns.

Replace collar.

Sorry Minn

I was wrong on the low speed needle settings....thanks for correcting me...it the age versus memory thing again.

Some Alpha trainers had problems with the fuel tank stopper being overly tight. The result was that the tank would split after a little while. Sometimes on the first flight, sometimes later.

A split tank will cause the engine to run like you describe, you can often get it running on the ground, but it goes lean and quits on take off. And, of course, the fuse fills with fuel.

The other suggestions above about the fuel lines, clunk, etc should be checked. (most likely problems, IMHO, stuck or loose clunk, hole in line, reversed lines).

One way to test your fuel system is to pinch off one line, and blow in to the other, then pinch it off, getting pressuraized air in the tank. (do it with an empty tank, btw, and be careful, glow fuel tastes horrible, and is poisoness). Hold the lines pinched, and gently move them around, pushing, tugging, etc to get the lines to bend in various ways. Then releas a line, you should hear a noticeable hiss as air escapes. A better way is to pull the tank and do the whole pressure test in a sink of water. Any air bubbles and you've found your problem. You want to move the tubing because the silicon fuel tubing we use can hide or even seal up small holes if pressed the right way, but they open up under engine vibration.

Oh, also check that you haven't hooked up the lines backwards. If you hook the muffler line to the carb, you get exactly what you describe, a very short run followed by a quick cut off.

Thanks a lot for your responses,
Any way I took it to day to the local hobby shop where I bought it from,he tested it over there and was working fine though made minor adjustments then he told me most likely the problem was the very cold weather( it was about 35).
What do you think about his response

Again thanks a lot for all comments

I've flown in much colder than 35