Building Tips and technical articles. > ARF'S

ARF Nobler

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Alan Hahn:
Bob R.
Ordinarily you would be right that since F=ma (force=mass*acceleration), that a rapid change in motion (acceleration) would require a larger force.
But (a major but!), in the case of our control surfaces, it isn't just the rotation of the  elevator/flaps that requires a force, but also the air pressure coming from the relative wind hiting the control surface. This force is a function of airspeed and the angle between the relative wind and the control suface. So assuming we are dominated by the aerodynamic force and not the simple inertial force or rotating the elevator/flap, the speed of application doesn't really matter. However it is true that a rapid input could make a have the control surface make a large angle before the plane itself starts to rotate, and this would be a large force.

You still can't exert more force than the Netzband limit---again assuming the bellcrank isn't bottoming out on a stop in the wing). And I am not clear how much force the RC snap role puts on the clevis either--those are pretty large deflections as well as large control surfaces. I don't think most of us know, so that's why I say that it isn't obvious that we are stressing the clevis more than RC'ers.

Anyway, my 2 cents (maybe 4 cents now).

hoythawkins:
Anyone interested in modifying the ARF Nobler to be a "take apart" check out the 50 photos with edited descriptions/comments I have added.  They are in the Photo-Album in the Album Section titled "ARF Nobler Take Apart."  Some fine engineering by Ed Prohaska.

Hawk

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