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HelicopterGasser Model RC HelicoptersOther › Hover Throttle % on 26cc gasser?
08-09-2007 12:35 AM  10 years agoPost 1
Gas and Go

rrApprentice

Western Wisconsin-​USA

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Was wondering how much throttle your helis are useing at hover?
I have a 26cc hanson-mod engine in the predator; with stock air filter and v2 muffler. Fuel= 92 octane with amsoil at 50:1

I am running 60% throttle opening at hover; which seems high to me.

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08-09-2007 01:50 AM  10 years agoPost 2
helicenter

rrVeteran

Winter Haven Fl.

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RPM

With a head speed of 1500 at hover my throttle opening is about 25%, stock engine.

Doug

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08-09-2007 02:07 AM  10 years agoPost 3
Gas and Go

rrApprentice

Western Wisconsin-​USA

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my current head speed is around 1650rpm. 60 % still seems high

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08-09-2007 05:10 AM  10 years agoPost 4
Stet

rrElite Veteran

Key Largo FL

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sounds like your setup is not linear or something

in the past I have found gas helis to hover at about 18%, but that is considering that zero% is at idle makes using governors tricky because they like to shut off below certain % if set up with stick switching on

keepin' it real

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08-09-2007 05:20 AM  10 years agoPost 5
Gas and Go

rrApprentice

Western Wisconsin-​USA

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my setup has the butterfly closed when throttle stick and trim are all the way closed, and butterfly fully open when at full stick.
I set up this way so I can shut off motor by closing the butterfly; I just use the the trim for setting idle and shutting off the motor.
Is this the correct setup on a gas helicopter?

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08-09-2007 05:28 AM  10 years agoPost 6
shuttlepilot

rrElite Veteran

Mullins, South​Carolina

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When you push the throttle stick up to where it is while hovering, how far open in the butterfly? I had low throttle percentages when I first set up my gasser. When I set up a linear throw with the servo and butterfly arm, my percentages went up to around where yours are. I did this in order to get my RL10 to working properly. The main thing is how far is the butterfly open at hover stick. According to how you have your servo set up to open the carb, percentages will vary. I'm in the 50's myself, but that was after I changed the setup mechanically.

Gas is Great
Camper Fuel is Better!!
QWW Helis

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08-09-2007 06:10 AM  10 years agoPost 7
Excalibur

rrKey Veteran

Destination: Earth

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At 1750 RPM, my 231PUH butterfly is open ~50 to 55% at hover from what I can tell. This is 50% FROM IDLE POSITION. My idle position is about 20 to 30% above fully CLOSED position.

The higher you set your head speed the more you have to open the butterfly with your throttle curve.

Xcal

Camper Fuel: It's Not Just for Breakfast Anymore

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08-09-2007 06:11 AM  10 years agoPost 8
Stet

rrElite Veteran

Key Largo FL

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on jr when you lower the trim, you will notice the throttle curve bends down, effectively adding more throw to the low end. when I say zero at idle, this would be at the point where the curve is straight (at default 0-50-100) and in the case of jr I think this is when the trim tab is right in the middle.

keepin' it real

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08-09-2007 06:07 PM  10 years agoPost 9
AceBird

rrElite Veteran

Utica, NY USA

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I'm in the 50's myself, but that was after I changed the setup mechanically.
And this will be the case with every setup. Throttle percentages will also vary with; blade selection, gearing, headspeed, engine modifications, muffler, the total weight of the helicopter, fuel mixture, needle settings, air density, air filter, and design of your radio. Generally speaking though, if your engine has been modified to give more horsepower it should yield a lower throttle position at hover. But maybe not! That horsepower gain may be at the top end and yield a lower rating (compared to a stock engine) in the mid ranges.

If you hover the bird and note the stick position then land and shut it down you can move the stick to hover position and note how far the butterfly is open. You should be able to fit a 1/8-3/16 dia. rod between the throat of the carb and the butterfly. If the opening is larger I would ask others that own your engine to measure the gap they have for comparison keeping in mind the other variables. If there is a sizeable difference than rule out gearing and check your needles.

If you are breaking in an engine don’t go by what everyone else is doing. Do what is right for your engine. Your mixture should be rich and if this is the cause of a high throttle curve don’t lean it out to match someone else’s curve.

Ace
What could be more fun?

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08-09-2007 08:26 PM  10 years agoPost 10
Gas and Go

rrApprentice

Western Wisconsin-​USA

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thanks guys, I pulled off the air filter and looked the butterfly movement, now it makes better sence.

Stet:
I Looked at radio setup and on my JR 9303 radio, when I drop the trim lever all the way down it auctually shows a negative number on the output display; auctually extending the travel, giving me the higher hover percentage.

Ace Bird:
I eye balled the opening on the butterfly, and its about 1/8" of an inch open, so I guess I am in the ballpark.

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08-09-2007 08:52 PM  10 years agoPost 11
Stet

rrElite Veteran

Key Largo FL

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Exactly

But when that extra travel is added on the bottom, it is in addition to the normal travel. Therefore if you set your throttle curve to say 0-10-15-75-100 for instance, the hover value of 18/20 will not take into account the extra throw on the bottom end caused by bringing your trim tab down. This extra throw caused by the throttle trim slider is akin to the futaba setup for the "cut" switch, which also extends the travel below the zero position on the throttle percentage.

keepin' it real

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