2. Methods

Methods:

          We have to research and find hovercraft designs to follow and guide us through with simple instructions and clear steps to build the hovercraft. At the end of our research we have come up with a full set of instructions and materials which have help us further our project.

          This guide (Instructables, 2014) is an instruction sheet which we will follow to build our project. 

          We have chosen this design out of the other two we have found as it has clearer instructions. Furthermore, it has provided a partial equipment list which will help us immensely. However we will modify some aspects of the design to compensate for the extra weight of more batteries that we will be adding to have a longer drive time.


          We then have to compile an equipment list to help us buy our materials with ease and accuracy. To do that, we have to compile the equipment list with extreme accuracy and diligence from the instructions that we have found.

Equipment List :
 - 2mm Gold Connectors for connecting motors to ESC's
 - NTM Prop Drive 28-26 1350KV / 310W
 - 2x 3mm Heat shrink tube (one black and one red)
 - Emax BL 2215/25 950KV Outrunner Brushless Motor
 - 2x Silicone wires (one black and one red)
 - Propeller: SF E-Prop 10x3.8 / 254x96.5mm w/ Adapters Black (5pcs/set)
 - 4x LiPo Battery: Turnigy 2200mAh 3S (11.1v) 25C Lipo Pac:
 - ESC: 2 x HOBBYKING SKYWALKER 20A ESC
 - Connectors: XT60 
 - 2x Styrofoam board(120cm x 60cm)
 - Polyethylene lightweight tarp
 - BSI Super Gold Plus glue (CA Glue) 
 - Arduino Black (Leonardo Model)
 - Annikken Andee (IOS)
 - USB Cable (USB to USB-mini)
 - A medium thick piece of balsa wood


Step 1: Making the Body

Note : Penknives are sharp and will cut you, caution when using it.

          Sandpaper will be used for smoothing the edges and   penknives are used to cut the styrofoam into the desired shapes.
          The first step to building our hovercraft is to cut out two styrofoam boards with 95cm X 46cm for the main body as shown in  figure 1.0


Figure 1.0: Two boards with the size of 95cm X 46cm cut out for the body (Instructables, 2014).

          A circular hole will be placed in the middle of one of the boards. The hole will have to be centred of the width and the sides are cut at an angle to better the airflow into the hole for lift as shown in figure 1.1
Figure 1.1: The hole cut in the middle is to direct airflow and improve the inflation of the skirt (Instructables, 2014)

          The other board will be cut such that a border of 6cm will be kept.

Step 2: Making the Skirt


          A skirt will be made out of the polyethylene tarp which is lightweight and easy to install onto the hovercraft. The tarp will be slightly larger than our board (as shown in figure 2.0)  to allow inflation of the skirt and installing will be made easier by taping it to the board with the hole in the middle (as shown in figure 2.1), sandwiching the tarp between the styrofoam boards and glueing them together with a foam adhesive glue to better the solidity of the vehicle. 
Figure 2.0: As shown the skirt is bigger than the body to create a better skirt (Instructables, 2014).

Figure 2.1: The skirt is overlapped and taped onto the board to make it much more stable (Instructables, 2014).
          Small holes with a diameter of 5 cm will be made in the middle to allow less friction which will improve the vehicle speed. Smaller holes will be made near areas where the hovercraft will be heavier to assist in mobility. These are shown in figure 2.2 and 2.3.
Figure 2.2: Holes are cut out in each side to help better mobility (Instructables, 2014).
Figure2.3: Small holes are created to allow a much more even inflation (Instructables, 2014).

Step 3: Creating a lift duct

          Lift ducts, used to direct the airflow into the propellors for better inflation. As ready made lift ducts are expensive, we decided to make one out of styrofoam although it may be of a lower quality.
          Eight identical pieces of styrofoam, the size is 13cm X 8cm.
We started bigger (15cm X 10cm) to allow for a larger margin of error and then cut it much more precisely into our desired size. A 45 degree angle cut will be made on only one side of the piece so that a flat side glued onto a slanted side, which will be repeated for all the pieces until it for a octagonal lift duct which perfectly fits our propeller size. These are shown in figure 3.0 and 3.1

Figure 3.0: Wood spars are used to hold the motor in place (Instructables, 2014).

Figure 3.1: A lift duct created out of styrofoam and glued together to direct airflow (Instructables, 2014).


The motor and propeller will be hanging inside of this lift duct. To get the motor in the middle, two wood spars will be used. Cutting four gaps in the foam pieces made, where the spars will fit in.

Place the wood spars in the gaps with glue. Making sure the spars are holded firmly so that the motor is secured.

Step 4: Motortower and rudder


In this step we're making a motortower for the thrust-motor and we're going to start making the rudder.

For the motortower 5 cm thick EPP foam will be used. The motor will be standing on the flat surface facing the back of the hovercraft. The motor is mounted on a 90 folded little aluminium mount, which is screwed on a piece of wood. The wood is glued on the foam surface. 

Right behind the pusher motor,  we'll be placing the rudder. Using balsa wood for the rudder, one part of the rudder stands in the 2cm styrofoam, the other part is hanging on this. Just connect the two parts with duct tape. Keeping a little space between them to make it moveable.


Step 5: Soldering


For testing the motors, you first have to solder an electric circuit to connect the battery to the ESC's and motors.

Use the gold connectors for connections between ESC and motor, and between ESC and thick black/red wire. Cover the connectors with heat shrink to avoid them from touching other connectors.


The three-colored cable from the servo can be plugged directly into your receiver. (the servo runs on the receiver-battery.)

The three-colored cable from the ESC's can also be plugged directly into your receiver, but...
! Do not plug the red/power (probably the ones in the middle) wires from these cables into your receiver. Just fold the red wires back and cover them with heat shrink or tape.

Step 6: Mounting the motors

Now the circuit is soldered, and the lift-duct and motortower are placed, it's time to assemble the motors on the hovercraft. 

For the liftmotor: mount the motor on a light piece of wood. Glue this piece on top of the wood-spars, use wood glue, making sure the motor/propeller is exactly in the middle of your lift-duct.

- Mounting the thrust-motor is a bit more complicated. The motor is mounted on a 90 folded little aluminium mount. 

> Take a 90 folded aluminium plate.
> On one side, drill holes, so you can mount the aluminium plate on a little piece of wood which will be glued on the foam
> On the other side, drill littles holes (very precisely) where we are mounting the motor.
> Mount the motor with short screws, or we will damage the inside of the motor!
> I glued another piece of balsa wood under the first little wood block. We do this to make sure the motor is stable.

After mounting the motors, test them.

Step 8: Mounting the servo

There's one more motor to mount. This is the servo-motor which has to be connected to the rudder.

Placing the servo right behind the not-moveable part of the rudder. Glue it on the foam. Be careful with glueing on foam. Some kinds of glue will damage your foam. Glue down a little piece of foam to the side of the servo for more stability.

Now connect the servo arm with the rudder. Pushrods are used to help steer.


Step 9: Testing

Test should go well.

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