How to Build a Hovercraft

October 20042

Patrick Wenzell

How to Build a Hovercraft

A Cobb CountyTechnology-Based Integration School

Special Thanks to Mr. Joe Baker @ Dickerson Middle

School for the idea

October 20043

Patrick Wenzell

Primary Steps & Materials• Make Circular Platform• Work from Center to:

– Drill holes per plan– Add riser for seating– Mount seating – Mount blower– Attach envelope

• Duct Tape Edges• Cut & Attach Envelope• Paint as you wish…

• Required Materials:– 4x4’ ¾” Plywood– 6x6 8mil Plastic– 2x2 ¾” Plywood– 12” ¾” Diameter Particle Bd.– 1 ½” x 3/8” Carriage Bolt/Nut– 2 ½” wood screws– Coffee Lid– Lots of Duct Tape– Sandpaper/Sanding Block– Paint

October 20044

Patrick Wenzell

• Tape Measure• Tri-Square

• Utility Knife• Chalk Line

• Sandpaper/Block

… and MATH SKILLS

Tools Required

• Jig Saw• Circular Saw• String• Drill & Bits & Screws• Staple Gun & Staples• Paintbrush & ‘guides’

October 20045

Patrick Wenzell

Experimental Hovercraft

• Goal:– Understand textual plans

– Convert into a project plan

– Manufacture components

– Assemble components

– Fine tune craft

– Test and experiment

– Create interactive experiments

• What I learned:– How to outline a step by step plan

– How to layout the plan on wood

– How to use certain tools

– How to make ‘jigs’ to guide tools

– How to troubleshoot problems

– Not to get all my friends over to see it work BEFORE I test it first

October 20046

Patrick Wenzell

Project Plana. Step 1b. cut a 2’ section of string (with a little extra).c. tie the string to a pencil and the other to a tack or nail.d. place the tack/nail in the center of the board.e. keeping the string tight, draw a circle.f. Step 2g. cut a circle with a jigsaw.h. Step 3i. measure the diameter of your vacuums hose and drill the hole size accordingly. j. drill a hole using the 1 ½ or appropriately sized bit approximately 1 foot from the center of the hover craft.k. Step 4l. sand the edge of the disk on the top and bottom.m. tape around the disk. n. Step 5o. drill a 11/4 hole in the center of the plywood for attaching the plastic skirtp. cut the plastic sheet into a 54 x 54 square and lay it out on plywood diskq. the carriage bolt washer coffee lid apparatus will be used to hold the plastic sheet to the plywood disk.r. Poke small hole in the center of the plastic sheet.s. Reinforce the hole with duct tape and then pass the bolt through the plastic sheet and bolt securely to the ply wood disk

October 20047

Patrick Wenzell

Project Plan (continued)• Step 6• a.       trim the plastic sheet into a circle a little bit larger than the ply wood disk.• b.      The plastic should be cut approximately 2 inches larger than the disk all the way around• Step 7• a.       looking down on the hovercraft plastic side up draw 3 x3 squares on the plastic approximately 1 ft from

the center with 120-degree angles between each square.• b.      The holes should not be directly above the hole where the shop vac will be attached • c.       Space the shop vac hole between two of the square holes .• d.      Use scissiors to cut• Step 8 • a.       over lap the plastic onto the opposite side of the ply wood disk leaving some play in the plastic .• b.      staple the plastic to the ply wood on the top all the way around the disk leaving about 11/4 gap between

staples.• Step 9• a.       wrap duct tape at least 2 times around the edges for protection.• Step 10• a.       place chair centered on ply wood disk.• b.      Place the shop vac or any blowing device (leaf blower/ air blower for air track behind the chair.• c.       Connect the hose of the vacuum to blow the orifice and attach the other end of the hose to the hole on the

hovercraft.

October 20048

Patrick Wenzell

The Hovercraft Drawings

October 20049

Patrick Wenzell

Layout Circle on 4x4 Plywood• Find center of square

• Tie pencil to nail in center of square

• Adjust string to desired radius – – 2’ = ½ of diameter = 4’ : 2*r = d

• Draw Circle

• Go ahead and layout:– Label Front/Back

– Blower intake

– Vent locations 120o, • 1’ from center

• At least 1’ from Blower Intake

• 2 rear, 1 front

Lift Vents

Blower Intake

Center Point

120o

120o

120o

BACK

FRONT

October 200410

Patrick Wenzell

Build a Jig to Guide Saw

• Notch the end of a board to fit lip on guide of saw

• Drill hole to set blade at 2’ from center– Hint, on a 4x4 square, center is exactly

2’ from perpendicular sides

• Nail to center of 4x4 sheet

• Note: Safety Goggles & Mask are required for protection!!!

October 200411

Patrick Wenzell

Cut a 4’ Diameter Circle

• Start at the edge

• Slowly and evenly cut the circle using the guide

• Repeat to make even

October 200412

Patrick Wenzell

Smooth and Tape the Circle Edge

• Sand the edges– 100 grit– Round edges to protect plastic

• Apply 3 layers of duct tape– Cut about 1’ sections– Apply tangentially to Top– Fold over edges– Repeat from Bottom– Final layer center around edge

and seal top and bottom

October 200413

Patrick Wenzell

Everything Must Fit Smoothly

• Drill 3/8” hole for carriage bolt in center of circle

• Drill hole for intake slightly smaller than the diameter of the blower

• Sand the inside of the intake hole to widen and make a very tight fit

• Insert blower attachment

October 200414

Patrick Wenzell

Make Template, Build & Attach Riser

• Riser is 2 pieces of scrap wood– Model with cardboard, first

– Layout and cut notches to provide access to center bolt

– Notch both pieces to interlock – for strength and stability

– Screw in from bottom

October 200415

Patrick Wenzell

Center Seat on Riser

• Sand Interlock between Riser components – Must be smooth

– Must be level

• Center 12” Seat on Riser

• Attach with Screws into the riser

• Can cover seat with foam– …or just paint

October 200416

Patrick Wenzell

Cut Plastic 2-3” Larger than Platform

• Plastic provides the Envelope to provide lift for hovering

• Set the platform on plastic

• Cut circle around platform about 3” from the edge

• Use scissors or utility knife

October 200417

Patrick Wenzell

Attach Plastic Envelope

• Fold edges a couple of times for strength

• Staple every ¼” to edge

• Reinforce center and perimeter of plastic with duct tape

• Puncture small hole to receive 3/8” carriage bolt

• Attach Coffee Lid

• Secure with coffee lid, washer & nut

October 200418

Patrick Wenzell

More Duct Tape…

• Duct tape, same as before over the stapled plastic

• Mount 100mph blower

October 200419

Patrick Wenzell

Cut Holes for ‘Lift’ Factor

• Place platform upside down• Center plastic over platform• Draw 3 - 3” squares on the

plastic approximately 1 ft from the center at 120-degree angles.

• The holes should not be directly above the intake hole where the blower will be attached – 1’ away

• Use 3” square template tied to 1’ string & utility knife

October 200420

Patrick Wenzell

Reinforce Holes – More Duct Tape…

• Tape edges of square cutouts

• Tape front and back of edges– 3” pieces of tape

– Tape edge of cutout, then fold over to reinforce inside

– Especially the corners of the cutouts…

• Tape Coffee Lid Washer– Around and across

October 200421

Patrick Wenzell

Ready for Testing & Tuning

• Do Not Call Your Friends, Yet!

• Two people lift platform• Another removes sawhorses• Place gently on clean floor• Test first w/o pilot• Test next w/light weight pilot• UP & DOWN ONLY!!!!!!!!!!

For now…..

October 200422

Patrick Wenzell

Problems Encountered…

• Problem– Coffee can lid ‘washer’

collapsed

– Blow out on side

– 5” lift in back, 3” in front

– Bumper creates imbalance

– Blow out creates imbalance

• Solution– Re-attached/Re-inforced w/

Duct Tape

– Patched with Duct Tape

– Reduced back to 3” lift

– Removed bumper

– Fixed blowout with tape

October 200423

Patrick Wenzell

The Hardest Part of this Project was…

October 200424

Patrick Wenzell

The Most Fun I Had With This Project was: