It’s easier if you have an extra set of hands. My assistants are
applying clear mailing tape around the open edge of the bottom
deck. The sticky side of the tape holds it firmly to the Correplast.
The skirt tapes to the bottom deck, but the edge
of the Correplast is sharp enough to cut the plastic
skirt, so we’re going to cover the edges before
proceeding any further. Use two inch wide mailing
tape as a bumper; apply it over the open edge of the
deck and fold it over as illustrated below.
Lift Fan Clamps
Now that the top and bottom deck are cut out,
it’s time to think about mounting the lift fan. Rather
than hot-glue the lift fan between the HoverBot’s top
and bottom decks, we’ll use two Styrofoam rings.
Each ring is glued to its deck so when the decks
come together, the lift fan is trapped firmly within
the clamps.
Cut two squares of 10 mm thick Cellfoam 88.
The squares are three inches on a side and have
holes 2-1/8 inches in diameter cut in their middle.
Glue the first fan clamp to the bottom face of the
top deck and the other to the top face of the bottom
deck.
hole, you may want to place a bolt through it to help keep
the decks in alignment while you drill the rest. After drilling
the riser holes, separate the decks and set the top one
aside.
The lift fan is easily removed from the HoverBot because of
the Styrofoam bands holding it in place.
Note the bottom of the top deck with its fan clamp and the
ducted fan that it’s holding in place.
Lift Nozzle
Air from the lift fan must fill a flexible skirt to create
the HoverBot’s cushion of air. Air pressure inside the skirt
attempts to keep the skirt in contact with the ground and
only a thin stream of air jetting evenly out of the sides of
the skirt lifts the HoverBot. For the skirt to do its job, the
outside edges of the skirt must be lower than the center as
illustrated below.
The material for the HoverBot skirt is 0.7 mil-thick
plastic drop cloth. A bag of drop cloth has enough material
for a fleet of HoverBots and is available at most paint and
hardware stores and many big box retailers. Don’t use the
1.0 mil or thicker drop cloth since this isn’t as flexible and
doesn’t conform as well to variations in the floor.
For the skirt to do its job, the center of the bag must
be closer to the lift fan while still allowing air from the fan
to flow into the skirt to inflate it. Some toy hovercrafts keep
the center of the skirt close to the lift fan with strips of
clear plastic tape. Rather than use tape, I built a plastic
nozzle for the HoverBot skirt. Here’s how to build this
simple, lightweight nozzle.
Draw two octagon shapes on a 20 thousandths of an
inch thick polystyrene plastic sheet that measures three
inches across. In the center of these octagons, draw a
62 SERVO 09.2010
