| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 1678.1 | Some things to be aware of. | ANGLIN::SPOHR | | Wed Aug 16 1995 15:23 | 17 |
| The 50 may be leaning out once it warms up and gets in the air. Tell
him to try setting the high end a couple of clicks richer.
The 45 sounds like it may have a fuel draw problem.
On both engines, he should make sure that the prssure tap from the
muffler is clear and not obstructed. Also, the position of the fuel
tank is critical on some engines. Ideally, the centerline of the fuel
tank should be in line with the carb on the engine. More than 3/4" or
so and some engines won't run consistently.
Also, have him try another brand of fuel. Borrow a tank from a couple
different flying buddies. One with more nitro and one with less. He
should also try changing glow plugs. Try a different brand with and
w/o the idle bar.
|
| 1678.2 | Some thoughts | SNAX::SMITH | I FEEL THE NEED | Thu Aug 17 1995 08:40 | 50 |
| Not sure what you mean by "surges" after it get's into the air, but if
you mean leans out and dies, the high end needle is probably too lean.
Have him set the needle on the ground and hold the nose up. If the
engine speeds up and dies, it's too lean. Set the high end needle
richer. An engine will always run faster in the air after it (unloads)
and will run a little leaner. If he's tweeking the needle on the ground
for maximum rpm, again the engine is probably leaning out once
airborne.
Check and make sure the fuel tank clunk is not stuck forward in the
tank. Typical symptom of a forward clunk is that the engine runs fine
on the ground, but once you take off and start climbing out, the engine
quits.
Running for a couple of minutes and then dying is another indication of
a fuel tank problem or too lean a mixture setting. If the engine slowly
looses power and then dies, it's leaning out in the air, and
overheating. If it maintaines good power but quites after a couple of
minutes, again check the fuel tank. Make sure the clunk line reaches
the back of the tank but moves freely up, down, and sideways. The clunk
should always rest on the bottom of the tank regardless of attitude. In
other words, if you flip the plane inverted, the clunk should be able
to drop to the "top" of the tank which is now the bottom.
Check for a leak in the clunk line which is another indication of an
engine that runs for maybe half a tank and then dies. With a full tank,
the leak is covered with fuel and therefore has no effect. However as
the tank empties, the hole becomes exposed and starts sucking air
instead of fuel.
As Chris mentioned, tank hight and location is another consideration.
It would help to know what type of planes these engines are being run
in.
Low end needle setting is also important and works in conjunction with
the high end needle. If, for example the low end needle is too lean,
and you throttle back in the air, when you try and throttle up, you get
no fuel and the engine dies. If too rich, the engine will load up and
die. A correct low end needle setting should allow for a reliable idle
and smooth transition to full power. You should be able to let the
engine idle for a minute or so with the engine maintaining a constant
rpm. When you throttle up, it should be smooth with no sputtering or
hesitation. If, after a minute of idle the engine sputters and blows a
fair amount of smoke when you throttle up, the low end is too rich. If
the engine sags or outright dies, the low end is too lean. Low end
mixture settings should be made a "little" at a time. Only turn the
screw about an eighth of an inch at a time. ALWAYS reset the high end
needle every time you change the low end. Like I said, they work
together.
|
| 1678.3 | THANK YOU! | WRKSYS::HOLT | | Mon Aug 21 1995 12:06 | 6 |
|
Thank you both, very much! I mailed up your replies to my Dad on
Friday, so he should be getting the stuff today/Tuesday. I really
appreciate it! :^)
Regards, Betsy
|
| 1678.4 | As was said earlier - try new fuel | SPEZKO::FRASER | Mobius Loop; see other side | Mon Aug 21 1995 14:49 | 13 |
| Just as another data point on this one - I've had engine problems
for the last couple of club sessions with what was a consistently
strong stable engine (OS 46) up till this. Engine would peak out
fine on the ground, plenty of power but would cut out after maybe
4 minutes in the air. Needle cleaned, adjusted, readjusted, new
plug, etc. - same result.
To cut a long story short, the fuel was bad. Scrounged a tankful
from one of the guys and the engine was back to it's old self
immediately.
Andy
|
| 1678.5 | why did this help? | CSLALL::ONEILL | | Tue Aug 22 1995 14:48 | 12 |
| Funny you should mention fuel. A friend of mine was haveing alot
of trouble keeping his Thundertiger engine running on 5% notro.
Tank postion and plug changes didn't seem to help. The only way to
keep it running was to run it rich, real rich. Takeoffs were
dangerously near stall and throttle response sucked. He switched
to 15% nitro and we were able to lean out to a nice two stroke
sound and still have a faint smoke trail out the exaust. This is the
.40 size engine and as a side bar, we were having the same problem
with my brother in laws O.S .40. unfortunatly, he had to return home
to So. Carolina before we could try the higher nitro in his ship.
Jim
|
| 1678.6 | IMHO | ANGLIN::SPOHR | | Wed Aug 23 1995 13:30 | 30 |
| The notro content has an effect on the engine performance due to
several factors, the most significant being compression ratio and port
timing.
My preference these days is Cool Power 12.5% Heli fuel in ALL of my
engines. It has extra oil and a dark color (better to see) and just
enough nitro to run well, actually very well, in all of my engines. I
run heli's and high-end sport engines currently (OS, YS, and Webra).
Typically, I have found that lower compression "SPORT" engines like 10% or
15% fuels. High compression "SPORT" engines seem to run best on 5%,
maybe 10%. It varies from engine to engine. High-perf and ducted fans
engines, piped engines are a whole new ball game.
These are just my own observations, so experiment with different fuels,
plugs, props, etc... until you get the right combination. Each has an
effect, some small - some large. Take the time to find out works best
for each plane/engine combo. It will greatly enhance your flying
pleasure.
I know my engines are setup right when I can snap the spinner backwards
and it runs within one or two tries. Warm or cold! This happens about
95% of the time when I go flying. If not, I know I have a problem.
Strong suggestion: Change one thing at a time. Does it get better or
worse. Go from there. Changing more than one thing at a time will
sometimes induce new problems that will further frustrate you.
For what it's worth,
|
| 1678.7 | tank position | CSLALL::ONEILL | | Wed Aug 23 1995 14:31 | 13 |
| Thanks,
One other thing has puzzled me for some time. When
I got into this hobby, I was told, and read, the center line of
the fuel tank should be even with the center of the carb. If it's to
low, the engine will lean out. It was obvious with the last two
people I was helping out that their tanks were below the center but
moving tank helped little if any. As I said, my brother in law had to
return home before we could try the other fuel. We did get to raise his
tank which helped a bit but it would have been interesting to see how
his plane responded to the higher nitro. So I guess what Im asking is,
were do people stand on tank vs. spray bar height?
Jim
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| 1678.8 | Fox engine fix | ALFSS1::HOWE | Ron Howe - Project Manager - DTN 343-0065 | Tue Apr 23 1996 10:30 | 7 |
| I just read your note. I love my Fox 45 and 46 engines. The secret
was going to the new style carburetor. I never met anyone who could
get the old style to hold a setting more than one day.
I almost threw the engines in the river. Now I love them.
Let me know, if your Dad still has trouble.
Ron
|