Project 42—Flying Vampire Bat
the pulley to the axle and the support block to keep the bolt from rubbing against the wood. The axle hole should also be drilled a little larger that the diameter of the axle (threaded rod) so it can turn freely in the hole with little friction.
Both axle support blocks are held to a length of 2×4 as shown in Figure 10-4, so that one end of the 2 ×4 has enough room for a drill to sit. The drill side of the axel should also have at least 2 inches of axle sticking out past the support block so it can be securely held in the drill chuck while it is driven. Tighten the two nuts on either side of the drive pulley, add the washers, and then place the two support blocks on the long 2 ×4 to mark out
their position. Keep in mind that the two support blocks should hold the axle in place without causing any friction, so do not sandwich the pulley too tight with the support blocks. Two long
woodscrews placed through the underside of each support block will hold them to the 2 ×4, but you might want to pre-drill the screw holes with a small drill bit first to keep the support blocks from cracking as you tighten up the woodscrews.
You can now connect your hand drill to the drive axle as shown in Figure 10-5. I added a back plate made from some scrap plywood to secure the drill in place while it is being used to drive the pulley, but that is optional. The drill should also be variable speed and reversible or you will only have a bat that can fly one way across your yard at high speed! The support plate for the rear of the drill is nice to have as well because it allows for a one- handed operation, rather than having to hold on to the drill handle at all times when driving the pulley. If you do plan to support the drill on the 2×4, make sure the drill body is in alignment with the axel and has a bit of freedom to move so you do not stress the drive axle or the drill chuck.
A little-known fact is that your 120-volt
AC-operated drill will also run on a DC voltage as low as 12 volts. If you would like to keep the speed and torque of your pulley to a minimum, just connect the power cord from your drill to a large
Figure 10-1 A large clothesline pulley and trolley
Figure 10-2 Bolts hold the pulley and trolley in place
Figure 10-3 Axle support blocks made from pieces of a 2 ×4 wood
12-volt battery, such as a security or car battery, and it will turn with 10 times less speed and force. With the drive side of this project ready for action, you need to create the idler side, which will carry the weight of the flying object and wire across your yard. The idler pulley shown in Figure 10-6 was designed to do this exact job, and can easily be adapted for mounting to any pole or wall by placing it on a board. The idler pulley mounting board has a hole drilled in each corner so a rope or bungee cord with hooks can be used to wrap it tightly to a tree or pole across your yard.
You could probably drag practically any creature across your yard as long as the cable you install on the pulleys can take the weight of the object.
Heavy fishing wire can easily support a few pounds of weight safely, which would allow the creation of any number of Halloween creatures such as ghosts, bats, or caped creatures. I decided to create a lightweight black furry vampire bat with glowing red eyes, which would allow me to use very thin fishing wire that would become invisible as soon as the sun started to set. I made the bat by bending a coathanger into the wing shapes shown in Figure 10-7 so they could be covered in black cloth, then fastened to a small plastic box which will also be covered in fur. The small black box will also carry a 1.5-volt battery to light the two small red LEDs to give the bloodthirsty vampire bat a little bit more of an evil look.
Project 42—Flying Vampire Bat
Figure 10-4 Pulley and support blocks mounted to another 2 ×4
The black stretchy material was first glued to one side of the coathanger wire using a hot glue gun and then it was stretched around the other side and glued to form the wing. Black paper or tissue paper will also work, and you could simply lay the wire wing down on the paper to trace the area to be cut using a marker. Secure the wings to the small plastic box by placing each end of the coathanger through a hole drilled in the side of the box and then bend the end of the wire so it cannot be pulled out of the hole. The completed wings are shown in Figure 10-8 fastened to the black box along with the two red LEDs that will pierce the night with an evil red glow.
The completed vampire bat is shown in Figure 10-9, ready to fly across the yard towards visitors entering the yard in search of Halloween treats. The bat may not look very realistic close up, but it does put on a good show when it appears to fly across the yard all by itself with eyes glowing red. At a distance of several feet, you might
actually think the bat was the real McCoy, well maybe not with the glowing red eyes.
Installing this project is best done in the light before the unsuspecting trick or treaters head out so you can make sure it functions properly and get used to setting the proper drill speed. Start by fastening the drill to the drive pulley system and then secure it to a table or chair in a place that allows a clean cable run to the target pulley across your yard. Cables need to be out of reach of people and high enough so the bat will seem to come in from above as if dive bombing the victim. Your drive system should also be in a place that does not look obvious yet allows a clear view of the yard and target area so you can know when to launch the bat. You could also place the idler pulley at the target destination and run the drive system from the other side of the yard for a more covert and quiet operation if you have another person handing out the treats. My drive system was strapped to the
Project 42—Flying Vampire Bat
Figure 10-6 Large idler pulley bolted to a board
Figure 10-7 Forming wings by bending coathanger wire
Figure 10-8 Bat wings and glowing eyes added to the plastic box
workbench in my garage as shown in Figure 10-10, where I can wait on Halloween night to hand out tricks rather than treats. When you are installing the fishing wire, make two or three wraps around the drive pulley to start so there will be sufficient friction to keep the wire from slipping. From there, you will just unspool as much wire as you need to make it to the idler pulley and back.
The idler pulley is strapped to a tree or nailed to a post across the yard so that the bat will travel from above to the target destination. The wire does not have to make multiple wraps around the idler pulley, since it is not required for drive, so just place the wire around it once like it would be
done on a clothesline. The bat or flying critter can be fastened to the wire using a screw or hook placed on the top of its back, which will allow a point to tie the wire. Now, you can test your flying creature by running the drill in both
directions to make a back and forth trip across the yard. Start by using a slow speed on your drill, and slowly work up to the desired speed just to make sure there is no excessive friction or anything rubbing on the wire that may cause a breakage. Figure 10-11 shows my evil vampire bat ready to lurch from the top of the tall fence directly across the yard as trick or treaters head to the door expecting to see more friendly ghosts
Project 42—Flying Vampire Bat
Figure 10-10 Securing the drive system to a workbench
and smiling ghouls. Won’t they be shocked when the bat with glowing red eyes does a fast flyby as they approach the front door where many other evil machines await their arrival? Yes, indeed, this
is one house in the neighborhood where adults as well as kids can sometimes find themselves jumping for cover—but that’s what Halloween is all about.