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HelicopterBeginners Corner › During hover engine speed gradually increases
05-05-2005 03:44 AM  12 years agoPost 1
Valveman

rrNovice

Marshalltown, Iowa

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Here's the problem.

I start my heli and position it in a location ready for takeoff. The heli idles just fine. As I increase the throttle the heli begins to spool up and gets faster and faster. At about half stick and just before lift off the heli is still picking up speed. Now I can keep it hold there just before lift off but the engine seems to keep getting faster. I can tell by the sound of it. I then lift it off the ground and hold it in hover. After about 10 to 30 seconds the engine seems to pick up even more speed. I'm not sure what is causing this. Once the heli gets to the higher speed I know it hovers really well and is very responsive like it should be. So something is not quite right.

Sometimes I can just force it to get off the ground right away but I know that something is not right and the headspeed seems to low. After forcing it to hold a hover for awhile it seems to run much better. But during this process you can hear the engine speed pick up some and stabilize. The engine is fairly new with no serious maneuvors (I'm not that good yet). Just looking for some hints and help

The ship is a Concept 30 SRT with an OS32. I was running 15% Sig Plus for about 1/5 of a gallon and now I'm using CoolPower 15% with about 3/4 of a gallon gone. Obviously changing fuels made a difference but I just can't seem to get it to straighten out. Pitch settings are roughly -2 6 10 and throttle is 10% 63% 100%. Once it gets up to speed the heli seems to fly just fine.

Looking for some general advice and help.

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05-05-2005 04:28 AM  12 years agoPost 2
orlee008

rrVeteran

Miami, FL USA

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is this a new problem?

do you know what your rpms are when you hover? sounds to me like your pitch curve is flattening out somewhere in the middle so your engine has to produce more rpm (power) to get your heli off the ground.

what radio do you have? check both your thottle and pitch curves... is your engine still running rich?

orlee

Flying in Miami, FL (Kendall Area)

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05-05-2005 06:27 AM  12 years agoPost 3
GreggyPoo

rrApprentice

Where it rains all the time

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Is it possible...

...that the engine is running too rich?

If the engine is bogging or the headspeed is low off idle and then it starts to pick up speed into a hover it could be just clearing/ leaning out which would explain what you are describing.

Have you tried a pinch test at idle as a quick sanity check?

Greg

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05-05-2005 05:32 PM  12 years agoPost 4
BC Don

rrElite Veteran

Calgary, AB Canada

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Yup, I agree, sounds like it is too rich on the low end. Once you get it into the air it'll take 30 seconds or so to "clean out" the excess fuel and then it'll be running properly. You can pinch off the fuel flow to the carb before you leave the Heli, you'll hear the speed pick up as the excess fuel is cleaned out, then let the fuel line go and now advance the throttle. It should be more responsive and keep the speed up.

Got Money? Send it to me, I'm a Heli Addict.

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05-05-2005 07:17 PM  12 years agoPost 5
BarracudaHockey

rrMaster

Jacksonville FL

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Or its set too lean.

Or you have a pin hole in a fuel line or are drawing air somewhere like the carb to crank case seal.

Andy
AMA 77227
http://www.jaxrc.com

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05-06-2005 02:53 AM  12 years agoPost 6
Valveman

rrNovice

Marshalltown, Iowa

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Orlee008,
The problem became noticeable when I changed over from the 15% Sig Plus to 15% CoolPower. I half suspected that changing brands of fuel would require some fine tuning. I just wasn't sure how much so. Its sort of like a car being used to running on super-premium high-grade octane unlead fuel and then switching over to the cheapest watered-down piss-grade octane unleaded fuel. It does make a difference. Especially in our little heli engines that seem to be very sensitive to change.
As for a radio it is a JR XF622. It only has three points for the pitch and throttle curves in normal mode while in stunt mode (idle up if thats correct terminology) it has three pitch points and two throttle points. I double check my pitch settings and they are -1, 7, 11 for normal mode. I haven't even tried stunt mode yet. Two reasons are 1) Not sure how to set it up exactly, and 2) not quite skilled enough if things get out of hand. But I'm going to try soon or later.

GreggyPoo & BC Don,
Yeah, finally did a pinch test. After a few seconds or so the engine began to pick up speed which meant that it was beginning to lean out just like you said. I goosed the throttle and it was very responsive. I took off right away and it seems fine. But it still had a slight tendency to lean out a bit during the hover but no where near as much without pinching the fuel line.
One thing I noticed is that as soon as I get done fueling the heli I try to start it right away to get going. It does appear to start fairly easily. I did two flights tonight and I pinched the fuel line before I got ready for liftoff. It did make a big difference. I also payed closer attention to how I fueled my heli. After filling it I notice that there seems to be significant amount of back pressure from the tank trying to push fuel into the engine. Maybe this is why it seems rich for the first minute or two and then leans itself out after running a bit.

barracudahockey,
Yes, I don't want to run it too lean. I'd rather error on the rich side instead of burning up the engine.

I appreciate all the help. What I've learned all of this is that maybe my fueling technique (and just the fact that this is the way my heli behaves) will require that I pinch the line after its started. Its not a big deal to do but each machine has its own temperment and attitude. We've just got to learn them.

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05-06-2005 03:01 AM  12 years agoPost 7
biggster

rrApprentice

Harrisburg, Pennsylvania, USA

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i pinch the line(while) I'm fueling , unless you have a fuel valve that stops your pump from forcing fuel into the carb, try pinching it as your fueling.....just my 2Centz

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05-06-2005 03:06 AM  12 years agoPost 8
Ted Toth

rrElite Veteran

Myrtle Beach S.C.

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on the 32 in hover the low and high needle work together
are you adjusting the low end?

.

You don't stop laughing because you grow old, you grow old because you stopped laughing.

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05-06-2005 03:33 AM  12 years agoPost 9
Valveman

rrNovice

Marshalltown, Iowa

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Ted Toth,

I haven't touched the low needle yet. I've only messed around with the high needle. I do know that they have an interaction with each. When I turn the high needle up or down by about 5 clicks max either I can barely tell the difference. One way I can tell is by the amount of smoke coming from it. When I go lean it won't smoke as much whereas if I go rich it tends to smoke more. But the difference is not easily distinguishable. I'm afraid of running it too lean. The other thing I know is that if its too rich the response will be sluggish while being too lean it will be over responsive.

Any suggest on how to tune it? Because at idle I won't know if its to rich or too lean? How can you tell. Sure I can tweak it one way or the other but which way for my situation?

I am rich but unfortunately its not monetarily. Rats!

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05-06-2005 01:26 PM  12 years agoPost 10
airdodger

rrElite Veteran

Johnston USA

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What glow plug are you using, and did you try a new one yet? How can you have back pressure from filling the tank? Chris

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HelicopterBeginners Corner › During hover engine speed gradually increases
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