stunthanger.com
Building Tips and technical articles. => Building techniques => Topic started by: Ron Merrill on September 27, 2007, 01:48:25 PM
-
How do i bush the leadouts at the junction of the gull and the straight part of wing to keep leadouts from cutting into the rib? I am not a machinist, so i can't make pulleys to stop the rubbing. All help would be appreached. y1 #^ y1 Ron.
-
Get two cheap nylon spacers from Home Depot, 1 inch long, 1/2 inch dia. set them into the gull joint ribs on 1/8th brass tubing with a couple of paper clip wire guides to keep the leadout from walking off the end of the rollers. Note, if the wing has a scale amount of gull, when you do the pull test there will be about 6.5 lbs of upward force on the rollers so the ribs and tubing fixings must be able to withstand this force. There will also be about 1.5 lbs of force outward as well. Even though the holes in the spacers are larger than the tubing, they will roll quite nicely, I have done considerable testing of this for the profile Corsair plans I drew up. I feel that curved tubing would have a fair amount of drag on the lines
Don
-
Just as a casual observation:
I can't believe that any leadout system with a bend or pulley in it would work very long or very well. It's been my experience that merely having a leadout rub against a rib or two will cost you.
If I built such a plane, I would make the leadout path arrow-straight and let the leadouts penetrate the tops and/or bottoms of the wing wherver they must and run inside and/or outside as nature requires.
If you must keep everything indoors, you might consider putting the bellcrank at the first dihedral break and just running a short push rod with ball joints at the ends to a secondary bellcrank in the middle of the plane. That way, only the control force (not the line pull) would go through the dihedral angle.