Hovercraft

INTRODUCTION:

Our hovercraft is a self propelled single person transport. It can also carry objects. It works through the inflation of an air chamber, and said air comes out through some holes on the bottom, that then create an air cushion. We decided to build it because we thought it would be super fun, and also a good test of our abilities.

SCIENTIFIC CORPUS:

To understand what’s behind our hovercraft we need to think about the behaviour of air under pressure. The air comes out at an high speed, and inflates the air chamber, and since it has no other place to go, it comes out of the holes. The large amount of air coming out creates an air cushion that is enough to cancel the friction between the floor and the hovercraft. Because of this, a small push is enough to slide for a pretty long distance.

MATERIALS:

  • 2 Plywood sheets (125x140x1,5 cm)
  • Leaf Blower
  • Shower Curtain
  • Duct Tape
  • Tube (5cm)
  • Metal platesRisultato immagini per plate of metalRisultato immagini per plate of metal
  • Nails
  • Screws

TOOLS:

  • Jigsaw
  • Files for wood
  • Drill (with tips for wood, and a blade for circular cuts)
  • Screwdrivers
  • Hammer
  • Glue (both for wood and plastic)
  • Handsaw
  • Box-cutter 

RISK ASSESSMENT:

The possible hazards are all connected to the workshop, and all the tools inside. It ranges from cutting, electrocuting, blunt and puncture wounds(Minor to Moderate hazards). Since each member of the group received the proper instructions, the probability of someone getting injured are extremely low.

STEP BY STEP:

  • having predefined we chose the largest diameter, that is about 56 cm
  • mark the center by tracing the diagonals
  • plant a nail in the center
  • take a string as long as the diameter, make two eyelets at the ends and insert one into the nail
  • use the other buttonhole to trace the circumference using a pencil
  • with the electric hacksaw cut the circumference of both plywood boards
  • file the edge of both boards
  • unscrew the extension tube of the leaf blower
  • take the plastic tube and cut it to 9.5 from one end (6 cm the widest part and 3.5 cm after the shrinkage)
  • file the cut end
  • cut a hole in both boards with a diameter of 5 cm (tube diameter) with a center 21 cm away from the edge
  • cut the inner tube in the shape of a circle with a larger diameter (10 cm more) than that of the hovercraft
  • fix the inner tube with the bostik to plywood panel
  • cut fifty nails (if they are too long) 
  • drive the nails along the part of the shower towel fixed with glue
  • glue the two wooden boards with the bostik and screw them by 3.5 (16)
  • leave to dry overnight
  • cut 6 holes in the shower courtain of 5 cm in diameter with 18 cm from the center and equidistant from each other (vertices of a hexagon) with the cutter
  • with resistant tape reinforce the holes and the entire edge
  • create the appropriate shims (e.g. glue small scraps of wood onto each other)
  • creates corner plates by hammering one side of the flat perforated plates
  • fix the wooden shims on the table so that they are on the sides of the suction hole of the leaf blower
  • creates corner plates by hammering perforated metal plates
  • take the measurements and cut the supports of the appropriate shape, to support the sides of the leaf blower, to prevent undulating movements and make it more stable
  • use the corner plates to nail the supports to the base
  • stick scotch flaps in the tube and a piece of triangular foam to distribute the air flow
  • screw handles created with longer metal plates for the convenience of the operator and to facilitate transport
  • press the switch

PROBLEMS:

The main problems we encountered were the deafening noise made by the leaf blower and the research of a suitable place to put the leaf blower without screwing it in place. To reduce the noise we tried to prevent the air from hitting the bottom at full power, by deviating the air flow towards the middle of the chamber. To do that we built a buffer out of foam and some tape flaps. To solve the issue of the place of the leaf blower we chose to put it vertically and build some supports out of plywood. Then we secured it by tying the whole thing with a plastic belt.

UTILITY:

Our project is really suitable for a physics lesson because it is a good example of fluid dynamics and friction. Some questions could be: “Determine the maximum weight the leaf blower can support”, or “Given the Force of the push, how far will the Hovercraft slide?