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General control line discussion => Open Forum => Topic started by: Colin McRae on January 24, 2023, 08:57:12 AM
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I have a general question on the preferred location of the bellcrank on a profile model without flaps. Most flapless profile CL models I have come across have the bellcrank on the inboard side of the fuselage. But some models have the bellcrank on the outside (Ringmaster comes to mind). Just curious if there is a preferred location, and if it affects flight performance or weight distribution.
I am currently building a SIG Skyray 35 kit and the bellcrank can be placed in either location.
Thanks
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It really doesn't matter. Some like the inboard location because that helps reduce any exhaust and gunk that may work it's way into the wing where the push rod comes out. Some turn the bell crank around to do this, and in addition, it locates the down line in back, so when the line is pulled the elevator goes down. It's just one of the things I like to do, and it's a long discussion on what this helps or hurts. I have to leave for a dentist appointment, so no time for me to explain it more here. But in the long run, it really doesn't matter and can fall into the class of, "does it make anything easier or work better??" questions.
Type at you later,
Dan McEntee
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Thx Dan
I never thought about the outer location maybe ending up w/ fuel residue in the wing. I surely don't want to go there unless the pushrod opening in the wing is sealed up with an exit guide.
But most models need outer wing tip weight anyway. Just a thought that an outer location will naturally add a bit of needed outboard weight and ultimately reducing the tip weight needed. Will save a bit of overall model weight which is not a bad thing.
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Colin,
It depends what you want, (push rod inside or out) it up to you. If using the outside pushrod you can always make a fairing to cover the pushrod exit hole in the so fuel and oil doesn’t get in the wing. I like to reverse the bell-crank to move the up line to the front (pushrod exits on the left side).
Later,
Mike Pratt