UH-10F Hovercraft

The Kalani High School Engineering Class was given a task to publicly display knowledge of science, technology, engineering and math, by recreate a project by reading and understanding it's blueprints. To complete this project, two groups of thirteen students constructed one 10-F Hovercraft, using knowledge gained from the Universal Hovercraft's website about the functionality of a hovercraft as well as the blueprints of the project that we purchased from Universal Hovercraft . Our time constraints were around 36 class sessions (about 48 hours). The group was challenged to use only materials and designs based solely on the blueprints.

Hovercraft was invented by Christopher Cockerell in 1956, originally tested in 1955 using an empty cat food tin inside a coffee tin, an industrial air blower and a pair of kitchen scales. He developed the first practical hovercraft designs, led to the first hovercraft to be produced commercially, the SRN1. In recent decades, the hovercraft has evolved into a multi-purpose vehicle that saves lives in rescue operations, transports military troops, ferries passengers, and provides a vast array of recreational opportunities such as racing and cruising to people throughout the world.

Universal Hovercraft was founded in 1967 by an aeronautical engineer determined to produce hovercraft that were simple to operate, performed well and achieve low operating costs. Universal Hovercraft is a team of talented hovercraft designers that create recreational, commercial and rescue hovercraft designs. They can customize their craft to meet specific application or create new design to achieve requirements of the client. They provide fully assembled hovercraft, or hovercraft kits, parts, plans.

Tools:

• 3/8" Drill
• Jig Saw
• Hammer
• Screw driver set
• Wrench set
• Scissors
• Utility knife
• Chalk
• Sanding paper
• Drill bit set
• Spade bits
• Vice grips
• Hand saw
• Hack saw
• Access to table saw
• Glue brushes

Materials (List From Blueprint):

• 3pc 4ft x 8ft x 2 inches thick blue or pink Styrofoam –hull and duct
• 3pc 4ft x 8ft x ⅛ exterior grade plywood –hull, duct, air box &cockpit
• 1pc 2 x 4 x 120 wood or 3pc ¼ x 1½ x 120 wood –hull sides
• 4pc ⅛ x ½ x 3 alum or equivalent –landing skids
• 4pc ¾ x ⅜ x 96 woods and 2pc ¾ x ⅜ x 88 woods –cockpit side stringers
• 2pc ½ x 36¼ DIA plywood –disks for foaming thrust duct
• 1pc 9 x 9 x ⅝ plywood (¾ or 3pc ¼ plywood glued together is ok) –engine mount
• 2pc ¼ x 24 x 4⅛ exterior plywood (grain lengthwise) –engine mount fins
• 2pc 1½ x 1½ x 16½ wood - mount support and nose block
• 1pcs 12 x 48 x 1 inch thick blue or pink Styrofoam –rudders
• 2pc 36 x ¾ hardwood dowel –rudder pivot and guard mount
• 24ft* 1/16 stainless aircraft cable –steering cable (item available from UH)
• 4pc* cable rollers (1 ¼ minimum diameter) (item available from UH)
• 3pc ¼ x 1½ carriage bolts –rudders and steering hinge
• 1pc 1 inch long hinge or any small hinge –mounting steering stick
• 1pc ¾ steel electric tubing (3/4 EMT) –steering stick 18 inches long
• 1pc 48 to 60 long shielded throttle cable
• 6pc ⅛ copper tubing x 1 long –cable clamps for throttle and steering
• 1pc 3¼ x 6 x 1/16 alum throttle lever
• 3pc ¾ x ¾ x120 wood –skirt attach strips and supports +
• 60ft nylon string about 1/16 DIA –skirt attachment
• A pint contact cement (not latex based) –gluing skirt
• 5½yds* 60 inch wide vinyl or neoprene coated nylon (12-18 oz/yd) skirt material (item available from UH)
• 1gal epoxy - all gluing and fiberglass work –see construction book
• 12yds* 2oz/yd fiberglass cloth or 8yds 4 to 6oz fine weave cloth (item available from UH)
• 1pc 12oz can of expanding foam sealant –mounting duct and filling
• 40w ¾ inch wide nylon strip –handles
• 1pc 2 hole handle –front handle
• 10pc 1⅝ drywall screws and 8pc ¾ drywall screws - skids –handle & mount
• 200pc ½ x #6 or ½ x #8 sheet metal screws –skirt and handle attach
• 1pc* 36-18 2 blade propeller (item available from UH)
• 1pc* 4 ½ DIA propeller mounting hub (bore to match engine shaft) (item available from UH)
• 1pc 8 to 12 ⅛ HP lawnmower engine (horizontal shaft)
• 1pc 40 x 40 x 2 inch grid wire (fence wire - 12 GA) –propeller guard
• 24pc 1¼ drywall screws –assembling above disks
• 1oz ¾ x #8 nails –to hold plywood to disks

Item from UH:

• 1 x UH-10F Entry Level PlansUH-10F Entry Level Plans - $29.95
• 1 x UH-10F Hardware KitUH-10F Hardware Kit - $349.95
• 1 x UH-10F Drive Component KitUH-10F Drive Component Kit - $159.95

Sub-Total: $539.85

Three different pieces of 2” foam board will be marked with cutting line (Tape and marker) follow the blueprint. Note that table saw will not be enough since some cut will be made in the middle, in our case we used a jig saw to complete those inner cuts. Three pieces of ⅛” plywood will be use to skin the top of the foam, with a little different in dimension to prevent joints at the same location on both layer. Create landing skirt and skirt-attach strips using ¾” x ¾” wood and foam by following the plan. Make sure they have the right dimension before gluing all of them together using epoxy glue and secure the piece in place while glue cures. Note that only use epoxy glue on Styrofoam. In our hovercraft construction we skipped the step of vacuum bagging because we don't expect to use the hovercraft on water, more detail on vacuum bagging will be found on the UH-10F “Hovercraft Construction and Operation” manual.

**Warning** Do not let fiberglass resin come into contact with skin. Could result in itchiness, irritation, and even chemical burns.

Cover the hull with one or two layers of 6oz fiberglass cloth, use stables or glue to hold them down. Then evenly spread out the fiberglass resin on the cloth. Because we skipped the vacuum bagging step, we have to start at a corner then slowly advance to reduce air bubbles, but we still not able to eliminate all of them.

Note: We had to use fabric weed barrier to cover the hull since we were unable to obtain the actual material that was required.

After completing the hull, we start on the air chamber. the air chamber capture part of the fan output and distribute air into the skirt and area below the hovercraft. We use leftovers from the 3 pieces of 4ft x 8ft x ⅛ exterior grade plywood from the hull construction to build the air chamber. It is consist of four pieces of plywood acording to the blueprint, but one of the piece were too big to make from the leftover so we put together two smaller pieces. We also added strips of wood on the sides of the air box.

To put together the Air Duct required cutting out two pieces of Styrofoam. The dimensions for each are laid out in the blueprints. After cutting out each piece begin to line the foam with half (1/2) inch marks vertically, for six (6) inches, going inwards from each end. After six (6) inches make lines every one (1) inch until complete. After all of these lines are made, cut down into these marks about one (1) inch in depth.

Note: Use solder iron to widen the cuts on the Styrofoam.

After that is done cut out two 36 inch in diameter circles and connect them together with 1" X 2" X 3/4" wood pieces. Then wrap a 1' X 112" plywood piece around the frame. Slowly begin to bend the foam around the frame. when the foam is wrapped around consult the "Hovercraft Construction and Operation" handbook on how to apply the fiberglass.

Having all of this done once again look at the "Hovercraft Construction and Operation" handbook and also the blueprints to see how to shave the foam for better lift.

First we made the measurement of the skirt using CAD program. Then we mark out the measurement on the skirt material with tapes before cutting it using scissor to avoid mistake. We attach the shorter sides of each four pieces to the skirt-attachment-wood-strip/landing-strip with contact cement and sheet metal screws, and then connected the round edges of the four pieces with vinyl cement and hold them with clips before they dry. We flip the skirt so that the smooth side faces out, and lastly attach the longer sides of each piece to the side of the hull with screws and liquid nail.

The Propeller Bore Hole:

Drilled a 1/8" pilot hole into the center of the pre-constructed propeller that was given to us. We then drilled a hole that is the same size of our shaft which was (insert shaft diameter here).

**Please note that the size of the hole you drill in the center of your propeller may change due to varying sizes of you shaft**

The Propeller Bolt Holes:

Line up the holes on the propeller with the aluminum hub, secure it down with clamps, and drill straight through the aluminum and fan. Make 1/8" pilot holes for each bolt, then widen the hole with a 3/8" hole.

Rudder:

• 12 x 24 x 1 foam (x2) –rudder
• ¾ x 1½ x 13 wood (x2) –upper rudder mount
• ¾ x 1½ x 5 wood (x2) –lower rudder mount
• 5 x 1 x ½ wood (x2) –lower rudder arm
• ⅛ x 13 x 1 alum –rudder bar
• 36 x ¾ hardwood dowels (x2) –rudder pivot and guard mount

Steering:

• ¼ x 1½ carriage bolts (x3) –rudders and steering hinge
• 1” long hinge or any small hinge –mounting steering stick
• 24ft x 1/16 stainless steel aircraft cable –steering cable
• 1 ¼ minimum diameter Cable roller (x4)
• ¾ x 18 EMT –steering stick

Throttle:

• 48 to 60 long shielded throttle cable
• ⅛ Copper tubing x 1 long (x6) –cable clamps for throttle and steering
• 3¼ x 6 x 1/16 alum throttle lever

Unfortunately, our class didn't able to finish the hovercraft project by the end of the semester, but I hope our experience will help those who tries to build it later on.

Below is our CAD files in .rar compressed form (made with Creo Parametric 3.0)

If you are a student or a teacher, you can download Creo Parametric 3.0 for free in their website.