Help please servo arm length

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Help please servo arm length

Postby Simon W on Fri Jul 15, 2016 8:20 pm

Putting my new Pilot 100cc Edge together and need urgent advice on servo arm length as I intend shopping for arms at Cosford Saturday or Sunday.

The control horns on the surfaces- from hinge line to outer hole are just over 50mm on all control surfaces.

I have 40mm singles for direct connection and and 80mm doubles for the closed loop on the rudder. I seem to remember that the ideal for freestyle with good quality servos was a 1:1 match with expo used to give a soft/ precise centre.

Is there some magic formula regarding offsets on the rudder too, the outer holes on the rudder horn is on hinge centre and taking it inwards moves the line aft of the hinge. the wires will cross so i wont manage perpendicular to the servo horn either.

Gizza clue?
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Re: Help please servo arm length

Postby Dave Wilshere on Fri Jul 15, 2016 9:11 pm

You will need at least 3.5" Rudder is close to 1:1 as 45 degree each way on servo will give you the same on the rudder.
SECRAFT do a 3.5" straight or cranked arm.
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Re: Help please servo arm length

Postby isnicol on Sat Jul 16, 2016 8:57 am


Have a look at the supplied arms in the kit for dimensions, the distance away from the hinge line is normally about the offset you need on the servo arm, and keep the distance between the attachment point on the horns the same as on the servo,
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