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Throttle Response

Old 12-02-2007, 01:36 AM
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Default Throttle Response

Okay Guys,
I am running a DA 100 on KS 86 Canisters with a Mezjlik 27 X 10 Prop at sea level and I am looking for a way to increase the throttle response. I am using very fast JR digital servo for my throttle servo and my linkage is a straight throw linkage, no bends or slop in the linkage at all. The engine is relatively new with about 7 gallons through it and is now running 100:1 Amsoil. The engine has NO cooling issues and the baffling in my cowl directs the air right through the engine's cooling fins. The plane is an aeroworks 100CC Extra 260 weighing in at 27 pounds 4 ounces loaded with 32 ounces of fuel!

At present when trying to hover, the engine seems to be slow to spool up when advancing (blipping) the throttle...of course I do not want this to happen when I am down on the deck...

Any and all suggestions welcome!
PS I have to run canisters to stay under our club noise bylaws!
Old 12-02-2007, 01:42 AM
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Default RE: Throttle Response

MTW cannisters may give you a slight increase. A pilot like me probably wouldn't be able to tell [&o]

Also, a 28 x 10 may give you more of that torque you're looking for.
Old 12-02-2007, 02:10 AM
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Default RE: Throttle Response

Hmm, could be as simple as a little too lean on the low end. I'd do the check to see if the low end is rich or lean, let it idle for 10-15 sec...goose it...if it lags and has to clear out spitting smoke, etc...it's rich. If the idle RPM increases as it's sitting there, it's lean. If it's still running at the DA factory settings, it's almost always way too rich. But I'd do the check to see which way you need to go.

My guess is that you are lean on the low end. Richen it up a 1/16 - 1/8 at a time and see if it transitions better. A little rich is better than a little lean.
Old 12-02-2007, 08:27 AM
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Default RE: Throttle Response

I was using cannister's on a past plane, and could never get the throttle response like I wanted. No matter how much I fiddled with it, it was never the way I wanted when hovering, and 3Ding. I went back with standard mufflers, and the problem went away. No more cannister's for me until I see one run right, which as of yet, I haven't. Scott
Old 12-02-2007, 08:51 AM
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Default RE: Throttle Response

I'd agree with Joe on this one. It does sound out of tune.

The other thing is a a Mezjlik prop is going to spool up a bit slower than a lite wood one. The problem is you will not get the nice low idle with a wood prop as you would with the Mezjlik prop.

Another thing to try if it's not out of tune is to raise your idle a couple of hundred rpm once you are flying, thiswill certainly help throttle response. Check the tune first though
Old 12-02-2007, 09:09 AM
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Default RE: Throttle Response

Anyone considered header length as well? A small change can have a large effect. A combinition of needle setting and pipe length can have very large impacts on throttle performance. The pipe length effects intake and exhaust pressures and can easily boost or delay throttle resonnse. All of the above combines with the size and type of prop used. Pipes and cans are tremendous benefits to the hobby but their introduction to the masses have increased the amount of "fiddleing" required to reach the desired results. There's now a lot more to play with when it comes to performance.
Old 12-02-2007, 09:14 AM
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Default RE: Throttle Response

Dang it Pat, I hate when you do that . Makes me feel like C.R.S. has gotten really bad again Just Kidding

Pat's also correct, DOH....
Old 12-02-2007, 09:56 AM
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Default RE: Throttle Response

With a 115 I took the flex section of the headers out. They were made for a DA modded for BME. The cans were KS 86. At that length the torque and instant throttle responce would almost flip the plane. Flying it like that was a no no. It had idle and wide open. Putting about 3/4" back in settled it back down. Since then I have moved the cans way back for balancing purposes and have a slightly sluggish throttle.
Old 12-02-2007, 01:57 PM
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Default RE: Throttle Response

matching pipe length with prop load is simply "exhaust 101"
basically the DA100 on a 27x10 Mejzlic is maxed out for a usable load and once a tuned setup is added you are on the ragged edge of getting good transition.
best bet - lower the load get a thin 27x10 -ANYTHING that will allow more revs
On the in cowl thingys -that prop may not have the steppy midrange but it's a sound/ power / midrange problem that many have tried to compromise and few get it right.
NONE of those lovely canisters will give a big power increase and still have smooth transition with a big prop
sorry bout that ---
Old 12-02-2007, 06:24 PM
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Default RE: Throttle Response

I am running a very similar set up,35% SD 260,DA 100,KS 86 rear exhaust,and 25x12 blade or Vess 28b . The plane is 27lbs auw, no lack in throttle response at all,maybe a little fine tune on needles are needed?
Donnie
Old 12-02-2007, 06:48 PM
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Default RE: Throttle Response

Could also be a leak around the cylinder heads. Have you tightened/checked the bolts recently.
Old 12-02-2007, 09:04 PM
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Default RE: Throttle Response

Hooked, what is your high and low throttle ATV settings on your radio?
Old 12-12-2007, 02:25 AM
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Default RE: Throttle Response

Thanks guys for the suggestions I will try the tuning thing and see what happens...I will check on my throttle ATV settings, I know I tried as hard as I could to get them as close to the same both ways
Old 12-12-2007, 08:38 AM
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Default RE: Throttle Response

And the ATV's should be as max'd out as possible for the best resolution.
Old 12-12-2007, 11:45 AM
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Default RE: Throttle Response

Chipping in a bit late here but thought I'd bit add my bit in! I have been through all of the issues you are having and spent a huge amount of time testing props, headers and oils.

Your motor is probably a little lean on the bottom end, check that first. What length of header are you running? You will need at least 11", any shorter and the motor will show symtoms that you are experiencing. The only other point is your oil ratio is very lean. Why not try 50:1, just try it and I would be suprised if you don't see an improvement.

I have 2 DA100's. One is DA100, 11" headers with K&S cans, CHP 27x10. Oil 45:1. The second one id DA100, 11 1/2" headers, MTW75 cans, Mejzlik 26x12, fuel the same. The first motor has 12+ hours on it and turns at 6600rpm. MSL.

Hope this helps.

Rob


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