Build a car-top carrier

Make your own highway hangar

Do you have to leave the kids at home to make room in the car for your favorite flyer? Or is "hangar rash" reaching epidemic proportions? If you answered "yes" to either of these questions, this car-top carrier could be just the thing for you.

It's inexpensive (less than $25) and can be built in a few evenings. It's lightweight (under 20 pounds) and weather resistant. You can store it outside or hang it inside. The secret? A combination of the old Quonset hut design and modern "stitch and glue" kayak-building technology.

The materials list is short: two 4x8-foot sheets of 1/8-inch Philippine mahogany plywood; 25 feet of 22-gauge copper wire; 25 feet of fiberglass tape for the seams; resin or glue; and varnish.

STARTING OUT

First, pick the best-looking sheet for the top. Decide how long to make your carrier but resist the temptation to use all 8 feet. I did that on my prototype and found that it was difficult to maneuver, store and mount. I decided on an 86-inch length for this model. The finished carrier weighs only 161h pounds and, with its 80inch wing and 70-inch fuselage, readily accepts my Sig* Senior.

Use the sheet's finished edge for the back, and measure forward from it. You don't want to draw radii to plot the curves because plywood will bend more like a parabola (the ends have a very gradual curve, and the center has a sharp curve). A cheap wooden yardstick will form the proper curve for you automatically!

Drive in screws at the endpoints of the curves on one side of the front only. Notice that I have two screws about 6 inches apart where the two curves blend together. You must cut all the way to that back screw to relieve stress on the plywood as the bends change direction. You don't have to drive screws into the other half; simply use some scrap cut out to match the first half. Using this template, the process is easier and you'll be assured of a perfect match.

Now lay the yardstick between the screws and bow the center enough so that the curve forms gradually. Clamp the center point and draw a pencil line on the outside of the curve (where the screws are). You will need to clamp the edges where you can't drive a screw. When you have drawn the four curves (the fourth being the front edge), cut the piece out with a jigsaw.

Now take the scrap, flip it over and line it up with the edges of the other side. Using the scrap as a stencil, trace the curves, then cut them out. Remember to extend the cut about 6 inches beyond where the two curves meet to provide the transitional stress relief.

Mark holes for wire ties starting inch from the back edge, lk inch in from the side edge and evenly spaced every 4 inches. Then, drill sz-inch holes in each of these marks, except on the back.

The bottom of my carrier is 33 inches wide and 16 inches high. If your plane has a taller tail with less width, you might make a narrower base. Try bowing a 48inch wire around your plane's tail feathers to gauge the best proportion.

The curves of the bottom piece do not need to be cut now because they will be created by tracing along the top piece after stitching. For now, make the bottom 33 inches wide.

Now put the handles on the top. These come in very handy during the construction and facilitate mounting the carrier on your vehicle. Drill two pairs of holes (sized to match your handle material) at the centerline (CL) of the top, about a third of the way in on each side. Knot the ends on the inside, and seal it when you glass the seams.

STITCHING THE HOSE

For the stitching, I recommend fine, 22gauge copper wire. I glassed only the outside, right over the stitching. This works well if the wire is fine enough and the twists can be flattened out to blend under the seams. Stitch one pair of holes at a time, and tie each stitch with a twist.

Placing the twists on the outside allows you to pull the pieces together for a neater fit. Pull the whole nose assembly together, going back and forth and tightening to keep the edges evenly butted for the best appearance.

BOWING THE TOP PIECE

To bow the top, first make two clamp bars out of 1x2x36-inch scrap. In each bar, make two notches 33 inches apart; these notches will hold the plywood in a curve. Pull the edges of the top piece together and slip a bar onto the middle. Place the other bar at the back as shown in the photo.

Now secure the bowed shape by wiring temporary cross wires about every 12 inches and holding the 33-inch width at each wire position. Then you can remove the clamp bars.

Now, lay the bottom piece across two sawhorses with the best-looking side facing down. Flip the top over and match the top and bottom. Stitch at one back corner and then the other. Leave the cross wires on until you have stitched the top and bottom together. Now stitch back and forth on the straight edges until you reach the point where the nose curves in. Remember to keep the edges even as you tighten the stitches.

PULLING THE NOSE TOGETHER

Mark a CL on the top and bottom of the nose. Temporarily close the nose at the front with the CLs together and trace the top onto the bottom piece. Also mark the bottom hole locations so they will match. Reopen the nose and cut along this mark. Drill the marked holes. Temporarily stitch the front edges back together.