TDEHovercraft

This is a final project that was done in a Robotics Education Lab at NC State University.

• For our final project we decided to design and construct a remote controlled hovercraft. This hovercraft will be wireless and be able to go across a multitude of surfaces. The following tutorial will show our documented progress throughout the semester to create this hovercraft.

• We began our research with looking up basic hovercrafts and how they work.
• We found a video of a simple one and an explanation of how hovercrafts work.
  • The video showed that by attaching an inflated balloon to a CD disk, that it can hover for a few seconds.
  • This CD disk can hover, because the force of the air escaping lifts the disk up and a pocket of air is between the disk and the table which allows for the disk to hover.
• We broadened our research to find several instructables on hovercrafts.
• We decided to make the body out of Styrofoam board, because it is lightweight.
• Our skirt material will be rip stocked nylon, because it is similar to kite material so it will catch all the air and have a smooth surface for the hovercraft to glide on.
• We decided to have two separate motors to power our hovercraft.
  • One to fill the skirt with air and another to propel it forward.
• For our back motor, we decided to mount it on a servo to turn the whole motor as opposed to making fins that turn.
  • We decided on this design, because we believe that it gave us more maneuverability to turn the whole motor.

• The first big obstacle we had to overcome was to decide on which type of motor to use.
• It had to be light weight but powerful enough to lift our hovercraft.
• We deciding on two different motors to be tested:
  • The small motor was a hubsan x4 motor
    • We tested this motor to see what kind of thrust it can put out.
    • With an Anemometer the average thrust was 20 mph and the peak was 21 mph
  • The bigger motor was a Hovership H2204X 2300Kv mini brushless motor

    • This motor was rated at 2200 rpm.

• We decided that in order to get a good final hovercraft we will have to make a small scale.
• For the small scale we decided to use the hubsan x4 to power it.
• For the large scale we decided on the H2204X 2300Kv mini brushless motors.
• We decided to use the same motors on each scaled version of the hovercraft to allow for similar weight and thrust ratios.

• Materials
  • Body
    • We made the body out of 1/2" foam board. This was light weight material that was sturdy enough for fans to be mounted on.
    • We cut the foam using a hot wire and sanded the foam to the desired shape.
  • Motors & Battery
    • We used the hubsan x4 motors to generate enough power to lift the hovercraft
    • We drilled a hole in a piece of balsa wood to place the motor in to be in the center of the hovercraft.
    • We soldered connection cables to the motors so they can be connected to the batteries.
    • The batteries we used were Mini 3.7V/750mAh 25C Lipo battery.
  • Propeller
    • The propeller attached to the hubsan motors were 72 mm in length.
  • Skirt
    • For the small scale we decided to use trash bag material to try out different designs.
    • The different designs we tested were varying number sizes of openings in the bottom of the skirt and how baggy to make the skirt.

• To test the small scale hovercraft we decided to keep the hubsan x4 motor running at a constant speed without a controller.
• We decided to use the small scale test to ultimately decide on what design of a skirt we were to use on the large scale test.

• The small scale taught us a few crucial points to implement in our large scale model.
• We decided that two circular holes in the skirt were to be used, because it distributed the air evenly and tested the best between the other designs.
• We also decided that our top piece of foam board was to be changed to be 1/8". This will cut down on weight for our large scale model.
• We also decided that we needed to redesign a motor mount for our large scale. This mount will be 3D printed and be a cylinder that the motor and fan will be in so that the fan blade doesn't sit beneath the body of the hovercraft and get caught up in the skirt.

• Components of Large Scale Build
  • • Motors
      • Two Hovership H2204X 2300Kv mini brushless motors will be used.
      • One motor will be used to inflate the skirt and get the hovercraft off the ground.
      • The second motor will be used to propel the hovercraft forward and steer it.
    • Body of Hovercraft
      • The Body will consist of two different types of foam board.
      • The bottom piece will be 1/2" thick that will be what the skirt is secured to.
      • the top piece will be 1/8" thick and we be what the other components will sit on.
      • Both pieces will have a hole cut into it allowing the fan to inflate the skirt.
      • The dimensions of the foam is 7"x14"
    • Servo
      • We are using a servo to allow the back fan to have a 180 degree of motion to control the direction the hovercraft moves.
      • This will be secured to the back of the hovercraft and be connected to the RC controller to operate.
    • Motor mounts
      • Both the motor mounts were designed and 3D printed to ensure accuracy of fit.
      • the main motor mount will be placed in the center of the hovercraft and allow one motor to be aimed down to inflate the skirt.
      • The second motor mount will be designed with a flat surface on the bottom to allow it to be connected to the servo that will turn it.
    • Controller
      • Spektrum DX 6i( RC Transmitter)
      • Spektrum RC Reciever
      • (You can use any combination of controller and reciver just do some reasearch. The DX 6i has an issue with the mixing needed to control two separate motors so you will want to find your own.)
      • Mess around with the travel adjustments to change motor speed and start area.
      • Use Mix to combine components on certain channels, check user manual for controller for information on menus. (User Manual:
    • Skirt
      • The skirt will be made out of rip stock nylon.
      • This material has a low coefficient of friction and is non porous to not allow air to leak through anywhere other than the holes cut out.
    • To configure the electronics together we have included a video that demonstrates how to properly set up each component.

• Our large scale test showed us that we have a working hovercraft.
• Unfortunately the battery on the hovercraft died before we could get a video of it working.

• Major problems we had during large scale build.
  • The 3D printer motor mount was too brittle and snapped off during assembly.
    • By gluing and reinforcing the motor mount we found that it would still work properly.
  • The distribution of weight was something that needed to be worked out.
    • The arrangement of the different cables and other components around on the hovercraft effected how it ran.
    • We had to evenly distribute the wires and place the battery on the front of the hovercraft to counteract the servo and back fans weight.
  • The main fan and back propelling fan did not work simultaneously.
    • We had to reconfigure the fans to the controller and set limiting ratios on the main fan to get them to work together.

• Reflecting on the work we had done we came up with ideas on how to make a better hovercraft if we were to do it again.
  
  • The overall length and width of the hovercraft would be slightly increased. This is to help with the weight distribution. This will also help the hovercraft be more stable when moving.
  • Instead of using a servo to turn the entire motor to operate the hovercraft, we would use the servo to turn flaps to maneuver the hovercraft. This will help with balancing the weight of the hovercraft and make it more stable when hovering.
  • We would invest more time in testing different skirt designs to see what distributed the air more evenly.
  • We would also try to test different controllers to operate the hovercraft. The controller we used didn't allow us to run two different motors on separate channels. We had to run both motors on one channel and had to limit how much power could potentially go to each individual motor.