Thursday, December 6, 2012

DIY RC Hovercraft

This adventure came to be when i was doing nerdy things one day and inspired myself: "I should make a hovercraft." As a matter of fact that's pretty much how most of my projects came to be. For ex: one day on youtube a few years ago: "What?! how did i get here?(youtube is famous for having totally random "related" videos). oh, this is cool, i should make a quadcopter."

Back on topic; this project is a DIY RC hovercraft made of foam, a servo, 3s LiPo, TX/RX, 1400kz blue wonder, 9x4 prop, hot glue, zipties etc. and measures: L21xW12in. Basically, its left overs from my BB that was too big for the motor.

The Storming... 

Soooo after this great idea, i had to actually build it. That didn't happen until i came across the perfect material: EPP like foam. This stuff is fairly strong and super light so its good for RC (used a lot in planes.) Then i had to think of the shape. The EPP was in circle form with a radius of ~6.5in.

The Build 

Base Frame

I cut a bite shaped (sorry) piece out of one and made them fit together ( the incide of where the two circles meet). Now i had an oval shaped piece of foam hot glued together. Trying my best to cut straight, i took off the side curves (black lines) so that it has a front and rear "bumper". The final shape is the area in red diamonds.

Motor Mount

This part was probably the hardest part as it had to be light but still sturdy and stable. The current design consists of a 1/4 circle of foam with the motor mounted on acrylic and zipties. It tends move a little and thus bring in a lot of unwanted vibrations. Soon i think i will replace it with a balsa or something like popicle sticks. I also attempted to counter the motor torque a bit  by tilting the motor. In terms of location, it is centered by half (width) and ~3/4in back from the front.
This looks (and works) horrible and will be rebuilt with some balsa wood or Popsicle sticks etc.

Propeller Shroud 

This was simply another piece of foam traced to the outline of the propeller and then i cut a 2in larger radius circle around it for strength.

Air Cushion

I didn't really know what i was going to do for this, but i figured it was made entirely foam already, so i might as well make the cushion out of foam too. The shape was simply traced from the base and then cut out with a X-acto knife. The cushion thickness was an educated guess. i figured it could be too thin where it would crack, and not too thick where it would have too much ground resistance and weight. I decided on 1 inch.

A simple cross-section. 
Also, this its not just hot glue in there. i took some tooth pics and glued them into the bottom and then pushed the base on top to prevent shearing. Then I used some glue to seal it.

Rudder System

This is simply a 900 servo that is hot glued into the base foam sheet. It then has the servo arm mounted on it as a place to attach the cardboard rudder. This obviously didn't work well with nothing holding it on the top side. When i was finishing some other stuff for it, i was letting the hot glue gun warming up. Inspiration struck! I had the tooth pics out for the previous step so i used those as a make shift hinge! this isn't fancy as it is a bare bones DIY hovercraft, so, this worked out great. It prevented the rudder from swaying under the force of the air = mission accomplished. 

No hinge.

I thought i took a picture of it up close, but i guess not. This is all i got for it.

Lift Fans

This (these) go in the base and significantly reduce the friction between the ground and the bottom of the craft. this means faster acceleration, higher top speed, slower direction changes ( drifting!!!), more efficiency. I dont have any brushless motors fit for this task, so this part is on hold. :(


I think i should note that the thrust on this thing is crazy! Even without lift fans in the base, it zips around like crazy.

1 comment:

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