Scratch - Popsicle Monocopter {Scratch} Original Design / Scratch Built

Contributed by Art Applewhite

Manufacturer: Scratch
(Contributed - by Art Applewhite - 04/13/08)

scratch_popsicle-monocopterBrief:
This is a 13mm monocopter made from popsicle sticks and index cards.

Construction: Parts consist of:

  • 6 popsicle sticks
  • (2) 3x5 index cards
  • 18" of nylon cord
Construction takes about 2 hours. A craft knife, electric drill and 1/8" bit are needed. White glue (Elmer's Glue-All®) is the only adhesive recommended. Better instructions with more pictures are available at my website.

The wing of the monocopter consists of two popsicle sticks and one 3x5 cards. The 3x5 card is cut down to 2.5" x 5" and folded in the middle lengthwise. Two popsicle sticks are glued to the index card at on edge and along the fold. The index card is folded over the popsicle sticks and glued flat.

scratch_popsicle-monocopter_wing
The balance beam for the monocopter consists of 2 whole popsicle sticks and 4 partial sticks. You cut 2 popsicle sticks into 3 pieces each. The ends should be 1.6 inches long each. Save the middle part for later. Glue 2 of the ends to a whole popsicle stick so that they are even with the ends of the whole popsicle stick. The remaining 2 ends are glued perpendicular and in the middle of the whole stick (See photo). Take the last whole stick and glue it on top of the balance beam.

scratch_popsicle-monocopter_motor1The motor mount is made from the left over parts of the popsicle stick and some index card. Start by making the motor tube out of a 0.75" x 3" strip of index card. Wrap the index card around a spent 13mm motor casing and glue it together. Be careful not to wrap it too tight because some 13mm motor are fatter than others. Also be careful not to glue the motor tube to the casing. Cut another strip of index card 0.75" x 3". Make two lines across the card one inch apart. Cut off on end on the line. The result should be 0.75" x 2" piece of index card with a line down the middle shortwise. Glue the two left over pieces of popsicle stick to the index card with the end against the line. Don't worry that a part of the sticks will stick out over the end of the index card. Fold the index card over and glue flat to the sticks. Flip the resulting motor mount over and cut off the extra part of the sticks that stick out past the index card.

scratch_popsicle-monocopter_motor2Make a small notch on each side of the motor mount about 0.3 inches from one end. Make a 0.4 inch long, shallow notch at the other end of the motor mount. Glue the motor tube to the end of the motor mount without the notch. Put a fillet of glue on both side of the joint between the motor tube and motor mount.

Note: Don't not be tempted to skip the following steps. The forces on the motor are enormous and it will break loose from the rocket if you don't reinforce scratch_popsicle-monocopter_motor3the motor mount with nylon cord. Feel free to substitute Kevlar® string if you have it. Tie a knot at each end of the nylon cord to prevent it from unraveling. Put one end of the nylon cord in one of the side notches on the motor mount and hold it in place with a dab of glue. Wrap the nylon cord 4 times around the motor tube and motor mount being careful not to distort the shape of the motor tube. Secure the nylon cord in the other notch on the side of the motor mount and hold it in place with a dab of glue. Coat the nylon cord with glue and work it into the cord, motor tube and motor mount. Trim off any excess cord once the glue has dried.

Glue the end of the wing with the popsicle sticks to the center of one side of the balance beam. One edge of the wing should be on top of the popsicle stick and the other edge below the other popsicle stick. This forms the necessary angle of attack for proper flight. Make sure the wing is perpendicular to the balance beam.

Glue the motor mount to the other side of the balance beam with the motor mount tilted in the opposite direction from the wing. Put a heavy fillet of glue alone ALL the joints. Careful drill a 1/8" hole all the way through the balance beam in the exact center.

scratch_popsicle-monocopter_buildcomplete

scratch_popsicle-monocopter_onthepadFlight:
The best available motor for this rocket is the Estes A3-4T but it will fly nicely on the 1/2A3-2T, A10-0T, A10-3T and A10-PT. Wrap 3 turns of masking tape 0.25 inches from the nozzle end of the motor to form a thrust ring. Trim off the excess tape. Friction fit the motor into the motor tube. Launch the rocket off a 1/8" launch rod, 1" long. That's right, ONE INCH LONG, trust me. I made mine launch rod from a 3 inch long piece of thick coat hanger wire stuck into an Estes Port-a-pad.

scratch_popsicle-monocopter_inflightIn all the flights I've made so far this rocket has done very well. Several flights were made in 15 mph winds and it still flew very straight with no weather cocking and landed close to the pad. Flights with A3-4Ts went about 60 to 75 feet up. Flight with A10-PTs were a little lower because of the shorter burn time of the A10 motor.

Summary:
This rocket makes a great introduction to the "Mysteries of Monocopters". It flies well in any condition and is a great backyard and windy-day flier. The smoke and the rapid rotation make a dramatic display with a small motor. Finally, you can't beat the price. The motors are cheap and most of the parts you'll find in your desk drawer and refrigerator.

This rocket shows what you can accomplish with almost nothing for parts as long as you are willing to "think outside the box."


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