THE FLYING SCREW

Like so many other people over the years, I just assumed that Leonardo’s helical helicopter couldn’t actually fly. The wing wouldn’t create lift so much as just push air down, which is a very inefficient way to get off the ground. But then I thought I should at least give it a try. Using a string to spin it like a top is good enough to get it going. It sort of flies, but I can’t say it flies really well. It won’t pop up toward the ceiling, the way you’d expect. The heavy whirling wing acts like a gyroscope as well as a propeller, and gyroscopes want to move perpendicular to their axis of rotation. In other words, this screw flies sideways, and at great speed. So give yourself lots of room!

1 Wrap the Core Part (1) tightly around a pencil, and glue the outside edge into place. Remove the pencil.

2 Here’s how it will look. The two circles at each end of the dotted line should just touch the seam.

3 Fold up the triangular glue tabs on Wing Parts (2) – (5). Glue Wing Part (2) to Wing Part (3) as shown.

4 Glue Wing Part (4) to (3), and Wing Parts (5) to (4) the same way.

5 Turn the Wing bottom up. Fold the triangular glue tabs on Reinforcement Part (6), and glue it to the Wing as shown.

6 Glue Reinforcement Part (7) to the bottom of the Wing, flush with the edge.

7 Glue the remaining Reinforcement Parts (8) – (10) to the bottom of the Wing the same way.

8 Turn the Wing right side up, and slip the Core through the hole in the center.

9 Glue the triangular tabs to the Core, so that the Wing fits right over the dotted line. The edges of the Wing should just touch the circles at each end of the dotted line. See the bottom of page 27 for tips.

Use about two feet of string or heavy thread to spin the screw. Hold the tip and carefully wind the string counter-clockwise.

Keep the string tight while you slip the screw onto the tip of a chopstick or similar item. Rest it on your thumbnail to keep it from slipping down too far.

Pull the string steadily and without jerking. Accelerate slowly and pull the string right to the end. The screw will fly off sideways.