Self-propelled hovercraft Materials: Styrofoam Meat Tray [20S] 1.5v DC Motor Plastic Propeller (3-Blade, 3.25”dia) or similar AAA Cell Battery Holder (For 2 Batteries) [2] AAA Batteries [2] 8” Lead Wires (Red/Black) [1] 8.5 x 11 Cardstock Sheet Adhesives: Double-Sided Tape, White Glue, Masking Tape Utility/X-Acto Knife Build time: 1 Hour Model adapted from “Fifteen Minute, Self-Propelled Hovercraft,” posted by “Dr. No,” July 30, 2006, on www.instructables.com Step 1: Make the Intake The science: • As the propeller displaces the air that it’s moving through, the intake redirects that air below the tray, creating the air cushion that makes the craft hover. • The intake also supports the motor. Build it: We’ve attached a pattern for the intake — see following page. 1 Print the pattern onto 8.5 x 11 cardstock. 2 Using an X-Acto knife (or similar), cut out the intake: Cut along all solid gray lines and the four magenta lines. Fold along all blue dotted lines. 3 Place a strip of adhesive — double-stick tape — on the “Adhesive” tabs, and attach the tabs to the underside of the intake’s back panel. Make sure to line up the Adhesive tabs’ blue dotted lines with the edge of the back panel. Once everything is lined up correctly, the back panel will incline down at 45 degrees, and the side panels will be at 90-degree angles to the top of the intake. To fit standard 20S styrofoam meat tray INTAKE CUT-OUT Cut Along Solid Gray Lines Cut Through Magenta Lines Fold Along Blue Dotted Lines ve Ad h es iv e si he Ad Back Edge of Intake DECK CUT-OUT Adhesive A Front Adhesive Back Edge of Intake CUT OUT AND REMOVE THIS AREA A Adhesive Step 2: Make the Deck Build it: We’ve attached a pattern for the deck — see preceding page. 1 Using an utility/X-Acto knife, cut out the deck. 2 Cut out and remove the light gray square in the center of the deck. 3 Using double-sided tape, attach the deck to the bottom of the styrofoam tray. 4 Using a utility/X-Acto knife, cut out and remove the styrofoam square below the opening in the deck. Step 3: Attach the Intake Build it: 1 Apply double-sided tape/white glue to the deck inside all areas labeled either “Adhesive” or “A.” 2 Carefully align the 1/2-inch intake flaps with the corresponding markings on the deck pattern and apply. ! The two triangle folds in front of the intake must be parallel to the opening as shown below. Step 4: Motor/Prop Assembly Build it: 1 Attach the propeller to the motor shaft (wrap it in tape if it’s too narrow). You may also fill the hole in the propeller with hot glue, allow the hot glue to cure, and drill a new hole that matches the diameter of the shaft. 2 Center the motor and propeller on top of the intake. The propeller should be as close to the intake’s opening (without touching the opening) as possible. 3 Secure the motor across the intake with masking or other tape. Step 5: Wire the Batteries Build it: 1 Wire the battery holder to the motor. Attach the positive lead (+) to the (+) side of the motor. Similarly, wire the negative lead (-) to the (-) side. ! DC Motors spin in either direction, depending on how the leads are connected. If you plan to solder the connections, first make sure that, when the propeller turns, air is flowing into the intake. 2 Attach the battery holder to the deck with masking or other tape. Do this lightly. The performance of the hovercraft depends on having even weight distribution. You may want to relocate your battery holder to balance the craft after testing. Step 6: Test The science: Hovercrafts are also known as Air Cushion Vehicles (ACVs). ACVs work because of “lift.” Attaining lift begins by forcing air into the intake and under the hovercraft where it is trapped by a skirt. When enough air is trapped under the craft, the pressure forces the vehicle off the ground. Once the hovercraft is off the ground, a small amount of air escapes continuously from beneath the skirt, and the vehicle “floats” on this cushion of air. TestinG: Turn on the batteries and...you’re off! ! If the hovercraft seems to drag along one edge, try repositioning your battery pack to balance the weight of the vehicle. ! If the hovercraft turns dramatically, try repositioning the motor by turning it slightly away from the turn. Hovercraft Airflow Map Air pulled through the propeller and INTO the intake a escapes under the hovercraft, creating a cushion of air. The hovercraft floats on this cushion of air. Air pulled through the propeller and PAST the intake moves the hovercraft forward.