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Old Sep 03, 2014, 07:52 AM
Am I inverted?
privatepilot's Avatar
Joined May 2003
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Slow roll rate

Hello all,

I have a 73" Slick 540 (30cc size) that has a slow roll rate. I have about 60 degrees of aileron travel on high rates and probably 40ish on low rates. Roll rate is slow on high rates and obviously slower on low rate. I also have a 70" yak running a similar setup but with lower throws that has twice the roll rate.

I'm a little baffled as to why the 540 rolls slowly. I've tried running differential aileron throws which just turned rolls into an ugly maneuver.

I'm running HS5625MG servos with servo arm extensions that were supplied in the kit and am using a LiFe battery.

Any ideas?

Thanks
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Old Sep 03, 2014, 07:06 PM
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exf3bguy's Avatar
Joined Oct 2011
372 Posts
Not really enough info to go on but my first impression is that the servo torque is not getting to the aileron. Either the servo is not getting enough current or your control geometry is bad. You said you are using extended servo arms, how long? What is the distance between hinge line and control arm? Pictures of your servo and linkage and a picture of your RX install would tell volumes.
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Old Sep 03, 2014, 09:17 PM
Am I inverted?
privatepilot's Avatar
Joined May 2003
96 Posts
Servo arm extensions were supplied in the kit and are 1.5" long center to center at longest position (which is where I have them). The control arm pivot points are on the hinge center line and about 3/4" tall.

All of the servos are direct wired to the receiver and as I mentioned above are supplied from a single 1450mah LiFe battery.

Thanks
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Old Sep 03, 2014, 10:05 PM
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372 Posts
Measure the distance between the hinge line and the control horn pivot. I get that you say the horn is about 3/4" but we need the length of the horn plus half the thickness of the aileron. That would be the total pivot moment. If it is shorter then 1.5" then you have mechanically reduced the servos leverage and thus the power.

All this means is that the servo may not be able to overcome the force applied to the aileron by airflow. You should lengthen the control horn and shorten the servo arm. If you need to get more throw after making those adjustments then do it in the TX with dual rates and ATVs.

Another thing to consider is how you are getting power to the RX. For this type of airplane with digital servos you really need to have a heavy duty switch with 20 gauge wire. I personally would be using a switch that had dual outputs so I would not be feeding the RX with a single connector. 1450 mah is a bit on the light side for a 30cc airplane as well. Again it's no so much having run time as it is being able to supply enough current to the servos.

The Extra in my avatar has dual 5000 mah packs, gotta feed the servos and give them the correct leverage.
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Old Sep 04, 2014, 08:16 AM
Am I inverted?
privatepilot's Avatar
Joined May 2003
96 Posts
Makes sense. I'll take some measurements and adjust linkages as needed.

Regarding the pack, it's a 25C battery so aside from the capacity, it should certainly be able to provide the necessary current (assuming the switch can). So I'll look into alternate switch options as well. My receiver is fully loaded and I have the battery coming in on a Y-adapter already so I'd have to add a second Y for a dual output switch, which I can certainly do.

Thanks for the info.
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Old Oct 01, 2014, 07:05 PM
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Joined Apr 2009
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You have way too much aileron deflection. Your ailerons are acting like airbrakes. Try knocking them down to around 36-38 degrees max deflection. Also try adding a little differential by going one degree less on down. To further increase aileron efficiency be sure to seal your hinge gaps. We use ultrakote and cut around the hinges. Here's a video showing our EF 88" Edge with a max aileron throw of 38degrees. Jase also fly's with only one rate programed into his Tx.

...hope this helps

Jase Dussia 2014 Joe Nall Thursday Noon Demo (7 min 53 sec)
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