tedeb

Hi
After starting my DA-100 and allowing it to warm up I adjust the idle using throttle trim. I then fly for 12 minutes. On approach to land the idle is so high a landing is impossible. Have to adjust the idle down about 6 or seven clicks to get the engine slow enough to be able to land. On the landing roll I then have to increase the trim to keep the thing running. This engine has unbelievable power. Have had over 200 flights. It's just the $%#@#$ idle that is a problem. Have tried different oils, no difference. Any one got any ideas???>.......................Ted

JLB

My Feedback: (2)

Both my flying partner and I are using the DA 100 and see a similar
characteristic but not to that extent. After I get it warmed up a bit and
get the idle set using the trim it is always too high when landing but I only
have to drop it a click or maybe two at the most to get it down. On most
of I my engines I can set the low needle so that I can let the engine idle
for several minutes and they will still accelerate very clean. My DA does not
seem to like this. After the warmup and taxi out, which is a short period, the
engine is a little rough (rich) when I bring up the power for takeoff. It never
does this while flying so no big deal. My suggestion would be to try
richening up the bottom a little and see if that doesn't help. I prefer not to
do this but it's such a great engine this is a very minor issue. Mine has never
quit on landing so I'll live with it. Hope this helps.

Silvanskii

My Feedback: (17)

First off there better not be one person that starts an argument.

That being said, my 3W-100 has a very similar characteristic described above also. I never saw it as that big of a deal either. I did notice Amsoil at 85:1 helped even it out some though.

Diablo-RCU

My Feedback: (1)

It's just a function of engine temperature. Hot engines idle faster, cold engines slower on the same throttle opening. Richening the low end mixture will help to minimize the difference. I just reduce the throttle trim by about 3 clicks for the landing. But that's with one of those awful 3W motors....

Paul Cataldo

My Feedback: (10)

Diablo is right.
I don't personally do this, but A LOT of guys set their THR CUT function on their radios. Basically, you flip a switch before you land, to lower the idle.
Many guys use this, to be SURE the engine doesn't cut off at low throttle settings, while in the middle of a 3D maneuver. Most quality radios have this function. I think my Futaba 9C calls it "THR CUT". Some may call it "THR DOWN" or "IDLE DOWN". I can't really remember, but you get the point....

OnTheEdge

This might be far fetched but what kind of push rod do you use for the throttle? If you use Nyron it can expand throughout the flight if the temps of the inside nyrod get too hot (i.e. runns too close to the mufflers, headers, cans etc). This happened to a friend of mine who couldn't get his motor to idle down low enough to land.

rc4flying

My Feedback: (21)

Tedeb, I was just going to suggest the same as what OnTheEdge-RCU stated. I always experienced this, when I was first told to use nyrod for the throttle. I have since changed to a metal pushrod with ball link ends and have never seen the idle adjustment problem since. And before anyone jumps me, no I have never had interference problems of any kind using this setup on throttle linkage. It is also more predictable in setting the idle.

rcplanefan

My Feedback: (2)

Another BIG source of idle problems is a cheap throttle servo. If you don't use a good quality servo, you will see things changing on the low end because it isn't returning to exactly the same place every time. Many people overlook this, but on a good, 100cc engine, you will see idle problems with cheap servos.

Ken

RickP

My Feedback: (2)

Shoot,
My idle is rock solid; no idle up - no trim clicking - land or flying it's the same. I'd call DA and see what they say. Perhaps you need a vent hole cut in the cowl? Sounds like under way the pressure in you cowl is different then when on the runway. This could be the cause of the fluctuations.
RickP