Model Airplane News: How to make sewn hinges

Model Airplane News, Aug 1998 by Randolph, Randy

THE INCREASED INTEREST in slow-flight, indoor R/C and small R/C airplanes has made it necessary to hinge control surfaces in a way that offers the least resistance to miniature and sub-miniature servos, as well as magnetic actuators. The hinge that offers the least resistance to movement is one that's sewn with a baseball stitch and silk thread. It's probably the strongest, lightest hinging system available to modelers. The photos show the way.

1 The only tools necessary, other than a needle and thread, are a ruler and a pin. The pin is much easier to use if you remove the head and insert it in a pin vise or modeling knife. Both surfaces to be hinged should already be covered.

2 The job will be much easier if you pre-punch the needle holes with the pin. Using the ruler as a gauge, punch the holes through the mating surfaces at the hinge locations. One-eighth-inch centers are ideal, and about five or six holes in each surface are usually sufficient.

3 Thread the needle with a 12-inch loop of thread and tie a knot in the end of the loop. Start with the first pre-punched hole and insert the needle from the bottom of one surface, pulling the thread through until the knot touches the surface.

4 Bring the needle between the surfaces and through the bottom of the mating surface, then again between the surfaces and through the bottom of the first surface. Notice that the stitch always starts at the bottom side of each surface.

5 After two or three stitches, pull the thread up tight and hold the two surfaces in place while you finish sewing them together. The needle will pass easily between the surfaces, and after the last stitch, gently pull the thread to remove any slack.

6 A drop of glue at the knot and end of the last stitch will hold them permanently in place. When the glue has set, trim the thread and the knot flush with the surface.

7 The finished hinge line is tight and very free moving. In this case, four sets of hinges do an adequate job on the elevator. Two hinges will usually suffice for the rudder. Although it looks clear, this stab is covered with Oracover* Light Transparent film. The complete hinge job added less than a gram to the total weight of the stab.