So when I was younger I ordered instruction on how to build a hovercraft out of a house hold vacuum cleaner from mad magazine. well after a few years of trying to talk my mother into handing over Mr. Hover to my experiments I gave up and lost the instructions. my aspirations crushed as a child, now as an adult im going about it in a much more sane fashion.... without instructions and still without my mothers permission.
With any luck this project is going to take on two stages, the first will be an RC drivable machine, once the vehicle is proven to operate I am going to install a OOPic II and try to give it some of its own mobile logic. I have no idea how plausible that is but what the heck tinkering losses all of its fun if you always know what your doing.
Above you see a picture of the craft lifted off of the ground but not quite hovering due to air escaping through the carpeting. Hover craft of this size are not very good on anything other than smooth air tight surfaces. However the image is taken with the unit fully powered up and supporting all of the parts that still need to go into it. the fact that it has lift on carpeting shows good promise for operation on smoother surfaces.
Everything about this project is weight and balance, to heavy it wont hover, not balanced and it wont move straight. I ended up needing to build this craft twice before I got the weight and balance correct. Generally speaking hover craft come in two different styles one that has a single pusher prop doing all the work by diverting some of its air downward into the skirts, and the other style is what you see here with one lift prop and another pusher prop.
Surprisingly lift was easy I used a cheep prop from a hobby store and a surplus motor with a direct feed to the battery. Turn it on and you can slide it all around a coffee table for about 45 min before the batteries run down. Unfortunately the pusher prop is a whole different ball game. Test one ended with a catastrophic breakage that sent shards of balsa flying everywhere. after rebuilding a sturdier and shorter rear motor stand run two surprised me even further with plenty of blowing air but very little if no forward motion on linoleum.
I think the lack of forward movement was a result of the craft pitching forward when the pusher prop started up, that dug the front of the craft into the ground just a bit more than usual and generated extra drag where there shouldn't be any. I am going to have to play with the pitch of the pusher prop to fix this. I may need to also design a horizontal stabalizer into the rear stearing rudder.
I have two Shark 14 speed controls for this project. I picked this speed control due to its small size and high current capability. I am currently undecided on weather or not both motors need a speed control, it would be nice to be able to change lift on the fly depending on terrain to reserve energy but I am also constantly battling total weight with this project so its a toss up. I do want to be able to hover without moving so I have decided tying both motors into the same speed control is not an option.
I did experiment with a little gas model aircraft engine but noise factor alone made me want to get as far away from the craft as I could plus those little engines spray unspent fuel oil everywhere, it did show tremendous promise for the 90 seconds the fuel lasted. The other thing that factored in was there is Soooooooo much force behind that little gas engine I did not want to consider what might happen if it tore free from its mount like my first electric test did. or what might happen if the craft flipped and started shredding itself. After one white knuckled stationary test I packed up that little engine and have not even considered returning to that design.
Once I have an operational mobile platform I have a pipe dream of slapping an OOPic II on top of this thing and integrating basic object avoidance logic to allow it to hover around on its own. Currently this part of the project is on hold till I can find better capitol investors than my house plants.We will not speak of the ex-girlfriend who damaged the better of the two prototypes beyond repair and blamed it on a cat!