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Old Feb 06, 2012, 02:27 PM
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hog2soar's Avatar
Central California
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Question
Elevator mix with throttle or not

I'm getting ready to maiden my Oly III,and was wondering if any of you mix your elevator to your throttle during launch? Or do you just thumb it?

Eddie
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Old Feb 06, 2012, 02:32 PM
AMA7224 LSF1832
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I thumb it, but that's just me.
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Old Feb 06, 2012, 02:33 PM
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USA, IL, Wheeling
Joined Jan 2003
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I do, but if you have no idea how much to use (maiden flight) I would just thumb it rather than make a mistake by putting too much in. A fixed stab/elevator will need much less than a full flying stab.
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Old Feb 06, 2012, 05:23 PM
turn, turn, turn.
Athol, Massachusetts
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Thumb it.... Mine flies under power, where you point it.
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Old Feb 06, 2012, 06:14 PM
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Littleton, CO
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You definately want to thumb it at first. Hopefully you can balance out your plane to where it doesn't need a throttle-elevator mix. If not and you are inclined to use a mix, start very low and then work up slowly. The first time I tried a throttle-elevator mix I overdid it and it was pretty exciting for a few seconds while I figured out how to handle it. If your Tx will do it, a bit of delay on the mix is nice.
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Old Feb 06, 2012, 06:17 PM
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Thumb it. No mix will cover all the variations in launch winds and weather.

Ed
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Old Feb 07, 2012, 08:20 AM
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Goshen, IN
Joined Dec 2003
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Hi Eddie
I never launch a new model myself. I ask someone else, and that person must know how to launch an electric sailplane, launch it for me. That way, if the model does anything unexpected,
both of my hands are on the sticks and I can correct the problem quickly. If the model pitches up when the motor is on, you may want to use elevator trim or mix elevator with motor.
Good luck!
Mike
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Old Feb 07, 2012, 08:43 AM
turn, turn, turn.
Athol, Massachusetts
Joined Oct 2005
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Quote:
Originally Posted by Ed Franz View Post
Thumb it. No mix will cover all the variations in launch winds and weather.

Ed
This is so true!
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Old Feb 07, 2012, 05:55 PM
Tailspin
Grand Blanc, Michigan
Joined Feb 2006
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If you do use a mix, put it on a switch so you can get off of it quickly. I tried it once and went back to flying it out. More trouble than it is worth.

Jack
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Old Feb 07, 2012, 06:30 PM
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I mix elevator with throttle on my Paragon and Sensor 117 both of which I converted to electric. Both have throttle actuated on the gear switch to free up the throttle stick for flap/spoiler. Throttle is either off or 100% full. I maiden a new airframe with no throttle/elevator mix and have a friend hand launch as mcramer mentions – you never know. I first trim the elevator in cruise flight and assure correct CG, then launch again to see how much elevator to compensate for motor. Several factors come into play. With motor launch the wing is flying at much higher airspeed than in cruise flight. High speed means higher drag and because the wing (especially polyhedral) is above the vertical CG, and motor on or near the vertical CG, the airframe will climb. A few degrees of motor down thrust will also negate the climb tendency during motor launch. Either way, by having pitch compensation the climb-out is smoother.
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Old Feb 08, 2012, 02:00 PM
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The Northeast Kingdom, Vermont
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I've only owned polyhedrals , so I have used a little down elevator mix for as long as I've had a radio with the capability. When I maiden my (new to me) 2M Poly Pulsar this Spring, be assured that one of my fellow fliers will do the launch and there will not be any mix until I see how it responds to power on launch.
Since I spend much time flying aerobatic gas/glow powered models and don't fly full house sailplanes, I'll never use the throttle stick for anything other than thrust. Flaps on the PP will be on the left slider control of the radio. I'm an old dog, so I'm not looking to learn new tricks
This past season, one of our "senior" members (you have to be well into your 80's to be considered a senior at our field) was getting frustrated with his Radian, since it pitched up so much under power. I set up the mix on his DX6i, tried a couple of launches, then handed it back to him. He's a very happy camper now!
Pete
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Old Feb 08, 2012, 04:44 PM
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I have instructed several people with their new electric sailplanes (mostly Radians). The technique that I have used is to do a number of hand launches with the motor off to set up a CG and elevator trim that gives a nice flat glide with minimal pitch oscillations.

Having done that, the next step is to hand launch and then ease in some power. This will test whether the nose pitches up or down with power. It usually pitches up. Some elevator-to-throttle coupling is put in and the process repeated. Eventually, we get to the point where the nose doesn't pitch up as the power is cranked up. At that point, higher-power launches can be done without the plane doing a pitch up and death loop. The elevator control is still used to adjust the climb angle on the way up.
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Old Feb 09, 2012, 07:50 PM
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Marietta, GA
Joined Jun 1999
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Never. If it needs it that bad, adjust the motor angle to compensate.
..a
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Old Feb 09, 2012, 08:43 PM
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hog2soar's Avatar
Central California
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Thanks guys

I put 5 degrees of down thrust on the motor when I installed it. I hope that takes care of any bad tendencies it may have.

I'll take it slow and basically do as Williamson said. Hand tosses without power untill I get it trimed. Then hand toss with a small amount of power. Then hand toss with a little more power untill I feel comfortable with what it's doing.

Thanks again,

Eddie
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Old Feb 23, 2012, 09:37 AM
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I have the same issue with my 2M Minimoa. I thumbed it at first to get the feel than went with 30% down elev at full throttle... Much much easier to fly without all the elev down pressure needed...
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