A while back, I began experimenting with using paper cone darts in a 3/4 in PVC pipe to make a blow-gun. When shot straight up, they reached an impressive height of about 120 feet. However, I wasn't satisfied. I came up with the idea to use a stomp pad (instead of my lungs) to power the darts.
This was an enormous success. The darts now go 300-450 feet in the air. That's twice the published distance that the commercial Stomp Rockets (R) go!
Warning: this contraption can be very dangerous. Do not point it at anyone or anything you care for. The tips of the darts usually crumple upon impact with a hard surface, but can still go through cardboard and leave welts on skin. I am not responsible for damage resulting from or relating to the use of this idea.
Step 1: Gather Supplies
2 to 8 ft of 3/4" PVC pipe for the barrel. 2ft makes the dart go much slower than 8ft. Pictured is 4ft.
6 inches to 2 feet of 3/4" PVC pipe for the horizontal air pipe. Pictured is ~8in.
1 3/4in 90 degree elbow (PVC)
1 small paper bag, which forms the base for the stomp pad.
Several sheets of scrap computer paper (one for every dart you want plus one for the pad).
Masking tape, for the darts.
Duct tape, for reinforcing the stomp pad.
For choosing the barrel length:
2' shoots about 150ft up.
4' shoots about 300ft up.
6' shoots 350-400ft up.
8' shoots even higher.
Keep in mind that these heights are derived from measured hang times and the simple d=v*t-1/2g*t2 equation from Newtonian physics. They don't account for air resistance, and therefore are not completely accurate. They give a rough estimate.
Step 2: Apply First Layer of Duct Tape to the Bag
Start the first layer of duct tape at the top of the wide side of the bag. With a single piece, go all the way under the bottom and then up the other side. Add more strips next to this one with ~1/4 inch overlap until the wide side is completely covered.
Step 3: Tape the Short Side of the Bag
The first layer on the skinny side of the bag also becomes the second layer on the bottom. Repeat step 2, but this time covering the short side of the bag.
Multiple layers of duct tape may seem silly - but believe me, they are necessary to keep it from ripping.
Step 4: Tape the Edges
Add strips of duct tape along the four longest edges of the bag (not the bottom edges), extending the tape an extra inch past the bottom. Cut this excess down the middle and fold each part down.
Step 5: Add the Second Layer to the Sides
Make three to four loops of duct tape around the sides, running perpendicular to the first layer of tape. It's okay to leave gaps in this part to save on both tape and time.
Step 6: Begin the Taper
On the open end of the bag, fold each of the corners in a triangular pleat to reduce the size of the opening. Tape both the inside and outside of these pleats.
Step 7: Finish Taper With Paper Cone
Cut a sheet of paper in half on the long side (making two 81/2 by 5 1/2 pieces). Roll up one of these and insert it into the end of the bag. Wrestle it into a rough cone, the less overlapping paper on the inside the better. The other end of this cone should fit snugly over the 1ft 3/4in pipe. Tape this cone in place with small bits of tape to hold it there.
Add four pieces of tape starting an inch onto the pipe and ending three inches onto the bag. Add short cross pieces to cover the the remaining exposed paper and reinforce the taper.
Step 8: Launcher, Final Assembly
On one end of the elbow, insert the stomp pad and on the other, insert the barrel pipe. Glue is not necessary.
Step 9: Making the Paper Darts
Take a sheet of computer paper and orient it like a letter. Fold up the bottom about 3in. This makes the tip of the dart heavy and sturdy. Fold a thin and slim triangle starting in the middle of the paper and extending to the edge. Unfold this and fold another, half the size. Add a piece of masking tape to the back of the opposite corner of the first fold, sticky side up.
Using this triangular shape, begin rolling the dart. Keep it very thin. At the half-way point, carefully insert the large end of the dart into the barrel. Relax your grip a bit the big end unrolls to fit snugly into the barrel.
Continue rolling right onto the tape. To finish up, trim the end of the dart until it slides smoothly, by gravity alone, through the barrel.
Step 10: Launch!
To fire, drop dart big-end-first into the barrel, blowing into the barrel (if necessary) to make it go to the bottom.
Make sure everyone is clear away from the business end and then stomp as hard as you can (with both feet) on the stomp pad. You have to hold the barrel upright while doing this. Make sure you are looking up - otherwise, you are likely not to see it go up and up and... out of sight. 5-15 seconds later (depending on ferocity of stomp and barrel length), there will be a thunk, and the dart will come down. I have only once spotted it on its descent.