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Apr 19, 2009, 06:35 PM
High Planes Drifter
Rogo's Avatar
Question

Convex hinge lines and hinge bending resistance


Folks -

I've constructed some balsa SGII tailfeathers with kevlar fabric hinges (under 0.75 oz bagged glass) on one side. Both the stab and rudder have some convexity to them along the long axis (tapered towards the tips). I have cut out the triangular hinge gap no problem, but note that there is some bending resistance as the movable surface reaches maximum travel (in both directions), due to the convexity of the hinge line. The resistance is not huge, but I'm wondering if it will make servos work harder than they have to.

Any fixes, or is this something I shouldn't worry about?

- Rogo
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Apr 19, 2009, 06:40 PM
Detail Freak
target's Avatar
If you bag the parts out of the beds, and lay the hinged side flat on the work bench, it fixes the problem. It seems a little late now, but maybe cutting a few slits through the hinges at the apex of the bent part will help.....

Target
Apr 19, 2009, 08:03 PM
Registered User
pyrsly's Avatar
Quote:
Originally Posted by Rogo
Folks -

I've constructed some balsa SGII tailfeathers with kevlar fabric hinges (under 0.75 oz bagged glass) on one side. Both the stab and rudder have some convexity to them along the long axis (tapered towards the tips). I have cut out the triangular hinge gap no problem, but note that there is some bending resistance as the movable surface reaches maximum travel (in both directions), due to the convexity of the hinge line. The resistance is not huge, but I'm wondering if it will make servos work harder than they have to.

Any fixes, or is this something I shouldn't worry about?

- Rogo
Soften hinge little more that should reduce problem
Apr 19, 2009, 09:05 PM
Registered User
soarluck's Avatar
take a triangular file and drag it down the hinge line along the top and bottom of the fin where it makes a bend ,,file until you see fuzz from the kelvar BUT no more than that ..


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