Instructables
Picture of Autonomous, Wirelessly Controlled Hovercraft
This is an instructable that takes you through an entire month and a half of work, designing and creating a wirelessly controlled modular hovercraft, that can be controlled with an RC controller, or made completely autonomous. I'll walk you through how we built our hovercraft, including all circuitry, firmware, and software. This instructable will also include ways to build a significantly cheaper hovercraft with all of the same functionality, but slightly lower performance. Lastly, I'll show you some of the things we learned, as well as some propositions for "Big Bird 2.0." Hope you enjoy it!

-Bradley Powers
bpowers.org

 
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Step 1: Chassis Fabrication using Blue insulation foam and Carbon Fiber hand layup.

Picture of Chassis Fabrication using Blue insulation foam and Carbon Fiber hand layup.
Chassis Blue Foam Core.png
In this step, I'll go over how we made the chassis for our hovercraft, as well as how you could make one without all of the mess. I don't have any pictures for this step, as I was literally covered in blue foam chips or epoxy resin.

The chassis was made using blue insulation foam, which can be purchased at home improvement stores, coated in carbon fiber composite. The blue foam was cut to specification on a CNC mill (Cad file will be included, picture shown here), and then coated in composite using a process using hand layup. I don’t have any pictures of the process, as I was covered in sticky gross resin, but I’ll try to explain (this is a very easy process, it is important to take your time and make everything look good). To begin, you want to get all of your materials and supplies for the hand layup. MAKE SURE YOU ARE WEARING NITRILE gloves, latex won't cut it with epoxy resin!!!

To begin, it's a good idea to just do a dry run. We basically cut all of our Carbon Fiber fabric (5.7 Oz/Sq Yd, 50" Wide, .012" Thick, 12.5 x 12.5 Plain Weave, available at [http://www.fibreglast.com/showproducts-category-Carbon%20Fiber%20(Graphite)%20Fabrics%20&%20Tapes-15.html Fibreglast]. We cut a piece for the top and the bottom, leaving about 1" of overlap on each side. We also very carefully cut holes for the duct, and for the "pocket in our design. We also cut strips for the inside of the "Pocket" as well as for the sides of the chassis. Then we cut reinforcement strips, basically so we could get extra stiffness where needed. Lastly, we cut a strip to line the inside of the duct, which ended up working quite nicely, as we were able to cut holes for the holes in the duct (which, by the way are CRUCIAL) which feed air into the skirt.

Now for the fun part! No joke, put on your nitrile gloves, and clothes you don't like. One other very important thing to do is to find a well ventilated area to work in, or to wear a ventilator. We used a chemical lab fume hood. Now that safety is covered, we can get into the fun stuff. The very first thing that you need to do is mix your resin. We used System 2000 epoxy resin, with 2060 epoxy hardener, available here. We used about one pint of resin, and about a third of a pint of hardener, which you mix in a 3:1 ratio by volume. It is very important to stir that very well, as it will ensure that all of your epoxy actually hardens. Next, paint that mixture on the bottom of the chassis (for example) very generously, and then place your CF fabric on the chassis where you want it. Then, press down, and watch the resin soak through the fabric. You can use a squeegee to make sure that the resin wets out the carbon fiber everywhere. At this point you can either let it dry, or cover it in tinfoil and move on. Basically from here, rinse and repeat. Keep in mind that the better you do the hand layup, the less grinding out rough spots you have to do. Take your time, and make sure that everything is as you want it, as working with carbon fiber when it is dry is basically no fun.

There are a few other ways to go about making the chassis. You could completely skip the carbon fiber process, and just use foam, but you will probably want to go with an EPP foam, as it will stand up to abuse much more than other foams. You could also fabricate it out of wood, or use sheet metal bent to shape. Really, all that matters is that you can fasten things to your chassis, and that it has the proper holes to make the lift fan and skirt work.
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Awesome! Now... for an autonomous full-sized hovercraft! Seriously though, nice work! I'm working on an autonomous (sort of) vehicle in school with a couple of my friends. It doesn't have to do more than go in a straight line and stop at a predetermined distance, but the project is still proving difficult. This is great man, keep it up!
how r u making an autonomous one ?????
bradpowers (author)  T3h_Muffinator6 years ago
What kind of vehicle are you trying to make? If it has wheels, I might have some suggestions, drop me a line. If not, things get a little bit more complicated, but still very doable. Let me look in my notes, I might find something that would help.
It's for a competition in Science Olympiad called "electric vehicle" Basically, a wheeled vehicle that has to travel and in a straight line for a predetermined distance. We've got most of the coding done, like I said. We're using an attiny2313 to control our motor driver. We're just working out the timing and distances right now, but we're having trouble with battery drainage, 'cause the motor runs slightly slower each time we run it (we get two trials). We were thinking of implementing a wheel rotation meter, but we'll see what happens.
bradpowers (author)  T3h_Muffinator6 years ago
You could try using a few optical encoders and an encoder wheel using gray code, that would give you consistent readings as far as distance goes. Might be worth a shot.
jazzzzz11 months ago
is wireless the autonomous one ? if not how du we make an autonomous one ?

drew27946 years ago
v-pitch props are EXPENSIVE!!!!!!!
bradpowers (author)  drew27946 years ago
Yeah, but they sure do get the job done!
V-pitch props and those rimfire motors seem overkill for a first or second craft, unless you have money coming out your ears or are designing an advanced autonomous hovercraft. I used all the parts from an old (yet high power and not cheap) R/C car, and controlled with the existing electronics. Hopefully pictures give you an idea, the propulsion fan was probably $35, if my memory serves. It's high torque, with forward and reverse, and is more than adequate.
IMG_0390.jpgIMG_0374.jpg
do you think t xbox 360 fans right next to each other would work as the lift fan?
no. don't spin anywhere near fast enough, and two fans is inefficient, air gets pulled in by one fan and escapes thru the hole for the other.
Hi there,where can I get ahold of a "high torque with forward and reverse,propulsion fan?"Over here in the UK if possible.................if not then, wherever?
Yeah, he's right, if they have them, ask for a motor that goes in hobby aircraft, they have really good torque to weight ratios
bradpowers (author)  bumsugger6 years ago
Really, just find a plain old motor from a hobby store, it will work fine. The reason I listed the specs that I did is because this is a fairly high performance craft, as it was designed to be.
i used to have one of the cars but the steering went out and i went to replace the servo and it was those magnet type ones
I'll do what I can, I have virtually no time with school and work both in full swing, I'll let you know.
oh thanks, that'll be kool when you get the time
you should make an instructable for this because this design looks really good...and this fits more into my budget for if i want to build one!
bradpowers (author)  Jolleyman6 years ago
The V-Pitch props are definitely overkill, but we had them on hand, and they have one major advantage over conventional motor/ propellor systems: you don't have to run the motor in reverse. We certainly could have used regular propellors, but airplane speed controllers are designed to NOT let you go from forward to reverse thrust. We also considered using a simple DC motor, but we would then have to design the control circuitry to allow for reverse thrust, as our design requirement was for the craft to turn in place. As I mentioned in the Instructable, it is absolutely not necessary to use these high end components to make a hovercraft, it will work with very little in the way of cost, maybe $50. Even if you decide to make an RC hovercraft, you still don't need the precision control that our project required, since humans are very good at making really good control decisions on the fly. When you try to make a very high performance autonomous craft, that's when you start to need the variable pitch propellors. You basically never need a brushless motor like the one we used for lift, for example, we never ran our lift motor over 50% power. I really want to make sure that people don't think that the way we went about things is the ONLY way to do it, that is not the case. We used the components that we did because they were on hand, and because we had specific design requirements that we needed to meet. Please keep this in mind.
i got my props from a old rc plane and they work really well
jeymeowmix6 years ago
its missing something.....

oh yeah...

NUKE LAUNCHER XD
you could make a nuke launcher...... with a large rubber band, a servo motor(nothing in specific), a 20oz. bottle, some dead AA batteries and hydrogen peroxide..... just take the carbon rods outta the batteries drop em in the bottle after filling with peroxide and then build a rubber band launcher controlled by the servo and your set. but this will produce nuclear fallout so you would need to have it set up so the carbon rods didn't drop until launching and make sure y9ou are far away.
Jeeze, your scary! Jk
lol.......but actually that didn't work at all, turns out the site i read that on was completely wrong...its actually manganese dioxide, and it produces oxygen. but who's to say you couldn't put a flash powder charge on the outside of the bottle, with a fuse timed just right so it goes off when the bottle bursts
Well, that sounds better than nuclear fallout.
not really :(
 Hi

Is the speed controller(ESC) for this project similar to those available on RC sites or did you design it on your own? Also, could you please shed some more light on how the ESC was used for control without using the receiver or transmitter? It would be really helpful if you could tell me what happens when we press the throttle stick, as in is there a PWM wave created depending  on the throttle position, if so then what is the PWM frequency??

Thanks 
bharatoo6 years ago
hey there, real nice instructable, we are planning to build one but i'm totally blank when it comes to the skirt, no matter how much i read i don think i can get that stupid skirt design, could ya post some pics of the skirt...
QwakHed6 years ago
Hey guys! Google 'Hobby Supply'
Doveman6 years ago
How much did this cost to make?
bradpowers (author)  Doveman6 years ago
Roughly $300, although we had some stuff in our stockrooms and such.
2bad4you6 years ago
Hey can u send me some more detailed plans?
bradpowers (author)  2bad4you6 years ago
Honestly, there aren't really comprehensive plans, we designed the foam portion in CAD software, as well as the two propulsion motor mounts, but everything else was just the product of a month or so of work. Most of it was handmade. The best place to get a good notion of how to do this is our website, which is located here. Hope that helps.
yea it helps alot thank u for the site.
bigpinecone6 years ago
e-flite doesn't make rimfire's... electrifly does... anyway guy check out hobbycity.com, they have almost everything along the lines of power systems for 1/3 the price. i get all my airplane stuff there!
Jolleyman6 years ago
Well done, it reminds me of the R/C Hovercraft I made (I'll do an instructable, give me time) for my 9th grade science fair project to demonstrate Bernoulli’s principle and air pressure differences. I used one high-torque motor for lift, and thus had yaw issues, do you possibly have some insight on how to counter it (I had a couple solutions of varying success) I've wanted to build another one but haven't had the time. Soon I'll head back to my parents house, dig it out of my old room, and take some pictures. Great insructable and thanks for reminding me of mine : )
bradpowers (author)  Jolleyman6 years ago
Well, it depends. If you have a thrust motor with a rudder, or if you have two thrust motors, you can basically build in an offset (kind of like using a trim on an RC controller), that will counteract the torque of the lift motor using a torque from the propulsion system. Another thing you could do is make another lift system, and attach a closely matched lift propellor that counterrotates. I have another idea that I want to try out, I'll let you know what comes of it.
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What works better for turning a rudder or 2 motors Also what material should I use for the skirt I couldn't find that neylon stuff
bradpowers (author)  drew27946 years ago
2 motors. You could use a trash bag if you want, but it won't be very durable. Basically anything that is durable and airtight.
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