Intro: Powerful RC Hovercraft
Hi guys, this is my first instructable and I hope you will like it. Here I will try my best to instruct you how to build a powerful RC hovercraft. I will try to instruct in as less step as possible. I used RC place building materials and electronics. The body is constructed using balsa. As it is low-density but high in strength, balsa is a very popular material to use when making light, stiff structures and for the construction of model aircraft. I also used foam. For propulsion I used 1500 KV (rpm/v) brushless motor and for lift I used 950 KV. Powered by 2200 mAh Lipo pack.
Below are the complete list of electronics and material:
1) 1500 KV Out Runner Brushless Motor X 1
2) 950 KV Out Runner Brushless Motor X 1
3) 40 amp EAC X 2
4) 2200 mAh Lipo 3S 25 - 35 C 11.1 V
5) 9 gram servo X 1
6) 16 AWG wire
7) 3.5mm Gold Connectors X 10
8) E Power Slow Fly Prop 8x3.8 SF X 2
9) Prop adapter
10) Balsa Sheet (1000 X 100 X 4 mm) X 4
11) Dean Connectors pair X 3
12) Fly Sky 6 channel 2.4 GHz Transmitter and Receiver
13) M4 Screws and Nuts
14) Aluminum sheet (not required much, just to make L - clamps)
Step 1: Cutting the Balsa and Make the Base
This step is very simple. You need to cut the balsa to make the base which will be fixed with foam later. I have not mentioned any specific dimensions for cutting. The length of my craft was around 650 mm. I used a hacksaw to cut the balsa. You can also use a sharp surgical blade. Be careful while cutting the balsa because it is very soft.
- Cut the three balsa sheet on equal dimension. It depends on how big you wanna make it. It will not have much weight since we are using balsa.
- On the third image you can see I cut the sheet into two pieces. It where the lift motor will be mounted.
- On the fourth image you can see how I cut the balsa for the side body.
- This balsa sheet will form the body of the craft.
- Next you can see how I fixed the three balsa sheets together. Just measure it and according to the dimensions drill four holes on the sheet. You don't need a drill machine to drill it. Any pointed object will do. I used a screw driver!
- Next just use some balsa glue and stick it, then fix the nuts and bolts
Step 2: Fixing the Balsa Sheets
This step is easy and simple. You just need to make a L bracket. I have shown an example of L bracket (first photo). I used aluminum to make the L bracket, since it light weight and flexible. I cut it using scissors, bend it to shape and used a paper punch to make the hole. In order to make it easy I added notes in each image. Please read the notes for easy understanding.
You need to make two air ducts, one for lift propeller and one for propulsion propeller. I used transparent plastic sheet in circular form for the air ducts.
On picture 6 and 7 you can find out how I fixed the balsa with aluminum. Read the notes on the picture for more details. This is where we will be mounting our brushless motors. Please check next step more details on how to fix the motors.
Step 3: Fixing the Brushless Motor
This step is very simple if you have the required motor mounts with you. Usually when you buy brushless motor a mount comes with it. I used that mount only for the lift motor. For propulsion motor I used a different design. I bought it from a online RC store. It looks like it was made with some kind of ceramics and was very light and strong. Please read the notes on the images for more details.
Next step: Shaping and fixing the foam to the base.
Step 4: Shaping, Cutting and Fixing the Foam
I took out the foam from a life jacket to fix it underneath the base. I didn't took photos of the foam after shaping it. So I created a CAD model of the exact design and shape of the foam. I marked the foam according to the dimension of the base and cut it using a hacksaw. It cuts very easily. On the last image you can see the foam after it has been fixed to base. Sorry I have only one photo of it! You can fixed it by whichever way is more convenient for you. It is best if you use a double side tape.
Step 5: Electronics, Wiring, Tx and Rx
If you are a RC Hobbyist and have previous soldering experience, you can do this step easily.
1) The brushless motor that I bought came with gold bullet connectors. I soldered female bullet connectors to the ESC. If you don't know how to solder or if you are new to bullet connector please watch the following YouTube video.
2) Next step is to solder the power input of the ESC with deans connector. On image number four you can see an example of deans connectors. Be sure to solder it with male deans connectors. The following video shows how to solder a deans connectors.
3) Solder female deans connector to the Lipo.
4) You will need to power two brushless motor with one Lipo pack. So you need to create a Y Harness for connecting one Lipo battery pack to 2 ESCs. The second last image of this step shows an example of Y Harness.
5) Now you need to connect the ESCs to the receiver. ESCs comes with an inbuilt BEC (battery eliminator circuit). Some ESC manufacturers require that you remove the center conductor on one of the receiver leads when connecting two ESCs to the same receiver (often orange or red in color).
6) Tx and Rx: I used a cheap $32 Flysky CT 6B Tx and Rx. I used the throttle channel for propulsion and AUX channel for lift. The video below shows how to bind a Rx.
Step 6: Making the Hovercraft Skirt
At first I though making the skirt would be the most difficult task. But it turned out to be one of the most easy. I tried to find online information on making the skirt. But most of them were very complicated, tutorials like cutting the fabric in certain geometry and stitching it in sewing machine.
So I decided to go with my own idea by making it with good quality polythene. Windcheater fabric is also a perfect material for the skirt.
I didn't took photos after cutting the polythene to required shape. But its not a bid deal for you! Just cut it to the shape of the foam and base balsa sheets but with bigger dimensions, so that you can wrap around the foam and base balsa sheets. I used used high strength fiber tape to fix the skirt to the balsa.
If you have any confusion on what shape to cut the fabric/polythene, please comment below and I will make a CAD model and send it to you.
Step 7: Assembling the Servo With Rudder
I came out with a design of using two rudders. The rudders were mounted inside the air duct. I made the rudder mount and the rudder using balsa. I used nylon hinges to attach the rudder to the rudder mount.
1) The first image shows the rudder mount fixed with the air duct using nut/bolts and aluminum clamp.
2) The second image show the nylon hinges I used to attach the balsa rudder to the rudder mount. I glued the hinges to the balsa and used high strength fiber tape.
3) Third image shows the rudder fixed with the rudder mount with hinges.
4) Fourth image shows the servo. I fixed it by screwing it through the balsa.
5) The fifth image shows the entire assemble.
Is it hard to understand? Don't worry, I will soon make a CAD model of the rudder assemble. For better understanding the design, I created a rough CAD model using Autodesk Inventor. The last two images shows the rudder mount inside the air duct and rudder attached with hinges.
Step 8: Testing the Hovercraft
This was my first RC project and I didn't had any prior experience on radio control. It take only 20 % to propel it. Maneuvering was not so easy at first. Crashed it few times, hit a concrete wall and the balsa on the side broke! Repaired it and tested again and again. Works fine and it is very fast! The following is a short 12 second video showing testing the craft.
Thanks for reading and don't forget to comment below!