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Fly

The title “The Father of Aeronautics” could be bestowed on a lot of different people, but I’d give it to englishman George Cayley (1773–1857), Sixth Baronet of Brompton. Sir George was a gifted inventor who made his mark on ballistics, civil and biomedical engineering, and mathematics. But without doubt his greatest achievements were in aeronautical engineering.

Cayley did most of his work on flying machines around the turn of the 19th century, 100 years before the Wright brothers. At the time, there was no engine light enough or powerful enough to get a vehicle airborne, so Cayley’s most significant inventions were unpowered gliders. Nonetheless, his work was monumental: In 1799, he developed the modern concept of the airplane.

Cayley’s idea, like many others that changed the world, was extremely simple: He was the first to completely separate a flying machine’s propulsion systems from its lifting systems.

Aeronautics

Before Cayley, everyone from Daedalus to da Vinci believed that flapping was the pathway to the air. Flight had been attempted, unsuccessfully, in ornithopters, aircraft that flapped their wings like birds in flight. (See Rubber Band Ornithopter, MAKE Volume 08) In Cayley’s concept, lift was provided by a fixed sail whose surface was held taut by air pressure.

In 1804, Cayley designed, built, and successfully flew the first recognizable airplane-like thing: a small bamboo and paper monoplane glider. More or less modern in appearance, it featured a fuselage, a kite-shaped wing, an adjustable tail and back fins to control the direction of flight, and a moveable weight to adjust the glider’s trim or center of gravity. It was the first man-made object that incorporated the control and aerodynamic concepts of today’s airplanes, and probably the first aircraft in history able to make significant glides. This thing actually flew!

Cayley also recognized that many forces operate simultaneously upon a body in flight. The ideas of thrust, lift, weight, and drag, now the cornerstones of aeronautical engineering, were first articulated by Cayley.

About 50 years later, Cayley returned to glider design and built a really big one. Towed aloft behind a galloping horse, it was big enough to carry his coachman on a 200-yard flight, making it the world’s first successful manned glider.

Build a Cayley Glider

Plan

Let’s build a glider very similar to Cayley’s 1804 design. (I’ve swapped his low-aspect- ratio sail for a high-aspect-ratio wing because, truth be told, the original doesn’t fly all that well.)

The wing and tail are attached with thread or ribbons, and may be moved about on the fuselage stick to obtain the best flight characteristics. The key to making this glider is to shape the upper wing surface to make an airfoil — a curved surface that creates a pressure differential above and below, thus providing lift. You’ll make the curve using common zip ties.

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Steps

Step #1: Rudder.

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Sir George Cayley and the GliderSir George Cayley and the GliderSir George Cayley and the Glider
  • Bend the wire into a rudder shape as shown, with a projecting pin across the bottom. Clip off excess wire, then solder the ends of the wire together.
  • Cover the wire form with silk, tissue paper, or Mylar. Making shallow cuts in the covering at intervals will allow you to turn the fabric under and glue it neatly.
  • Drill a hole in the main fuselage stick just large enough for the rudder’s projecting pin, about 1" from the end.

Step #2: Tailpiece.

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Sir George Cayley and the GliderSir George Cayley and the GliderSir George Cayley and the Glider

Cut and glue the tailpiece out of 3/8" × 1/16" balsa, overlapping the joints. Cover the tail with fabric using glue.

Step #3: Wing.

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Sir George Cayley and the Glider
  • Cut and glue the wing frame out of 3/8" × 1/8" balsa or spruce. Butt-joint the 6 wing ribs inside the two 36" spars, then glue the center rib on top. Let the glue dry.
  • Flip the wing over and hot-glue the 7 cable ties to the spars, opposite each rib. To form the curve of the wing, glue one end of the tie, bend it into a gentle arc 3/8" above the rib at midpoint (use a scrap of 3/8" balsa as a gauge), then glue the other end and trim it neatly (pictured).

Step #4: Wing fabric.

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Sir George Cayley and the GliderSir George Cayley and the GliderSir George Cayley and the Glider

Carefully cover the wing with silk, tissue paper, or Mylar using glue. The wing surface should be smooth and taut on both sides.

Step #5: Tail blocks.

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Sir George Cayley and the Glider

Glue the tail blocks, one atop the other, to make a 1⁄4" high block. Glue it atop the fuselage, 2" from the end.

Step #6: Weight bolt.

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Sir George Cayley and the Glider

Place 3 nuts on the #10 × 2-1⁄2" bolt and hot-glue the tip of the bolt to the nose of the fuselage.

Step #7: Assembly.

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Sir George Cayley and the GliderSir George Cayley and the GliderSir George Cayley and the Glider
  • Use thread or ribbon to lash the long center ribs of the wings and tail to the fuselage. Center the wing 8" back from the nose, and align the back edge of the tail with the middle of the tail block.
  • Insert the rudder’s pin and lash it on too.

Step #8: Fly it!

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Sir George Cayley and the Glider
  • Hold the glider lightly and give it a level toss. If it nosedives, untie the wing and move it back a little. If it rises too steeply and then stalls, move the wing forward.
  • You can make fine attitude adjustments by moving the horizontal tailpiece forward or back, and by spinning the nuts on the nose bolt. You can control yaw (left or right direction) by adjusting the rudder.
  • A well-made glider can travel a surprisingly long distance — experiment!

Conclusion

This project first appeared in MAKE Volume 37, page 80.
William Gurstelle

William Gurstelle

William Gurstelle is a contributing editor of Make: magazine. His new book, Defending Your Castle: Build Catapults, Crossbows, Moats and More is now available.


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