The Flying Scrooge: Ornithopter of Household Items

This instructable will show you how to make a nifty flying model known as an ornithopter from cheap to free stuff.

An ornithopter is a lot like a model airplane, but it flaps its wings like a bird or an insect, and is a lovely sight to watch in flight.

This is pretty easy to build; you really only have to make sure the bearings are all parallel. Everything else can be crooked and this will STILL fly just fine. It is also VERY sturdy and can take many, many crashes without breaking. As an added bonus (and due to my personal tightwaddery) it is CHEAP. You can make this ornithopter out of household items. Mine cost about $1.30 to make.

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Supplies:
Bamboo Place Mat -- $1 at the local dollar store. We bought one too many for our table.
Gel Super Glue -- $1 for a 3 pack at the dollar store. Found it in a cupboard.
Plastic Grocery Bag -- Usually use them for tying up stinky diapers.
Coffee Filters -- Free from work (I don't drink coffee). And, no, I didn't steal them.
Paper Clips
Rubber Bands
Bic Pen
White School Glue
Clear Tape -- All free stuff I found lying around

Optional:
CA accelerator -- $4 at the local hobby store. Sets super glue almost instantly.

Tools:
Sharp Blade
Diagonal Cutters
Scissors
Needlenosed pliers
Regular Pliers

I looked up "ornithopter plans" on Google and can up with these plans. However, I wanted to make an ornithopter with four wings, like this. So I decided to base my ornithopter on the free bird plans, but modified it to make it four-winged and for use with my bamboo construction materials.

Start by removing some flat bamboo strips from the place mat and laying out the body shapes. I made some triangles. Using a pencil, carefully mark lines where they overlap. Cut along the lines with your dikes. Carefully clean up the edges with a knife. Glue together with a bit of superglue and spray with accelerator.

Continue for all the joints.

The top and bottom of the body need to be parallel, so add a few pieces to make the bottom rectangular.

I made some thin support pieces by cutting the bamboo in half lengthwise.

Make three bearings by wrapping a large paperclip around another large paperclip. Straighten the paperclips out before you begin. Coil the wire onto a small screwdriver or a dirll bit that is slightly (slightly!) larger than the diameter of the paperclip wire. This slight diameter change allows the paperclip to rotate freely inside the coil. Clip off excess wire. Based on user feedback, it seems this step is harder than it appears. When you are done making your bearings, test them for smoothness of turning.

When you have three bearings, make some bearing support pieces as pictured. Glue a bearing to the bottom of the body. This is the main crank bearing. Glue two bearings to the top, side by side in the channels created by the support pieces. These are the wing bearings.

I found it helpful to slip a couple straight pieces of paperclip inside the bearings as I was positioning them. This helped me ensure they were all parrallel.

Mix white glue half and half with water in a disposable cup. Cut out some rectangles of coffee filter tissue and glue onto the body, making sure that the tissue is throughly moistened with glue. Apply two layers. Let dry.

Finish the body using the photo as guidance. Add another triangle shape at the rear. The two rear spars are half-thickness to allow the tail hook to fit between. Form the tail hook from a large paperclip. Scuff the tail hook and superglue to the rear triangle. Reinforce tail hook with tissue paper.

After flying and crashing my ornithopter for several days, it broke right at the weak point between the triangles. So I added a third spar high enough to avoid the rubber band motion. I recommend you add one as well, as pictured.

The wing spars need to be longer than any one piece of bamboo. Join two straight bamboo pieces together by cutting as shown and gluing. The stepped cut gives more surface area for the glue to grab, strengthening the joint. Reinforce the joint with tissue. Drill a small hole through the joint.

You can make a drill by squishing the end of a paper clip and cutting it at an angle with dikes. Bend into a stepped shape and hand crank away. I made a motorized drill for this project from a VCR motor I had lying around and a thumbtack. Super glue the tack to the motor, squish the tip with pliers, and cut at an angle. Attach to 9-volt battery. I found the VCR lying beside the road a few years ago and scavenged it for parts before I threw the case away.

Form two wing cranks from paperclips as pictured. The little "jog" in the left wing crank allows good wing movement. Insert cranks into wing spars and superglue in place. Reinforce with a layer of tissue. Take two smaller pieces of bamboo and drill several holes at regular intervals. These will be the adjustable arms.

Insert the left and then right wing spar and slide the adjustable arms onto the wing and main cranks. Test wing movement. You might have to add a piece of Bic ink tube as a spacer to one of the wing cranks for easy movement.

Disassemble wings and adjustable arms.

Straighten a paper clip and bend a hook on one end. Insert into the bottom bearing and bend a stepped shape (the crank handle) into it.

Make a bead for the crank from a Bic Pen. Pull a Bic pen apart with pliers. Cut off a few rings of the ink tube. Fill the rings with super glue and let dry. Slide one onto the crank handle and glue in place with super glue. Be sure not to get any glue on bearing.

Save the outlines.jpg file attached to this step. Print it full size. {In Windows XP, right click on the file name and click "print". A dialog box will open. Keep clicking "Next" until it prints.} Cut out the tail section from the paper and trace onto the grocery bag. I taped my grocery bag to the back of a clipboard to have a smooth surface.

Using similar techniques as before, cut and glue two bamboo pieces together at an angle for the tail booms. I also thinned my tail booms to cut down on weight. Glue a large, straightened piece of paperclip as a tail boom. Cut a small circle out of tissue and reinforce the joint with it. Carefully cut the tail out of the grocery bag with a sharp knife. The tail should be about 6.5 inches long. Super glue the tail to the tail spars.

Cut out the wing outline from the paper you printed in the last step. Trace onto the grocery bag. Flip, and trace the other half of the wing. Trace a second wing the same way. Carefully cut out both wings. Cut a rectangle out at the middle of the straight edge of each wing piece. This allows the mechanics to move freely. Super glue the wings to the wing spars, starting at the center. Cut the right wing down the middle.

Insert the left wing into the left wing bearing. Insert the right wing and make sure that the wings can move freely. You might have to add a bit of ink tube as a spacer. When you have them moving well, remove the right wing. Glue the left wing to the the "spine" of the body. Add the right wing and just tape the centerline of the wing flaps to the left wing.

Scuff up the tail boom with dikes and superglue to the body. Reinforce with filter paper. Using pliers, bend the tail boom up about ten degrees.

Hook a rubber band onto both hooks.

Wind up your ornithopter and test fly it. Wind it clockwise and counterclockwise to see which direction gives you smoother movement.

Here's my second test flight:



If your ornithopter zooms upwards and stalls, try adjusting the tail boom down a bit. If it still stalls, you may need to tape a coin to the front of your 'thopter.

If it turns in a slow circle, you can tape a piece of wire to the wing tip on the outside of the turn. I left my wing spars long, and so I just cut off excess from the wing tips on the inside of the turn to fix that.

Experiment with different arm lengths (you know, the adjustable arm) and different rubber bands. I found that two or three narrow rubber bands gave me more consistent torque than one thick band (and also lasted longer).

Now go play with it! My daughters love watching this thing.

*Update*

I've added a couple pictures to show where to attach the rubber band (actually, I use four regular rubber bands at once) and where you wind it up.

As per forum request, here are a few close-up pictures showing the wing and crank bearings in their final form.