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

Step 1: Chassis Fabrication Using Blue Insulation Foam and Carbon Fiber Hand Layup.

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.
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 ?????
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.
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.
is wireless the autonomous one ? if not how du we make an autonomous one ? <br> <br>
v-pitch props are EXPENSIVE!!!!!!!
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.
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
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!
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
its missing something.....<br/><br/>oh yeah...<br/><br/><strong>NUKE LAUNCHER</strong> XD<br/>
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 :(
&nbsp;Hi<br /> <br /> Is the speed controller(ESC) for this project&nbsp;similar to those available on RC sites&nbsp;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&nbsp;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 &nbsp;on the throttle position, if so then what is the PWM frequency??<br /> <br /> Thanks&nbsp;<br />
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...
Hey guys! Google 'Hobby Supply'
How much did this cost to make?
Roughly $300, although we had some stuff in our stockrooms and such.
Hey can u send me some more detailed plans?
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 <a rel="nofollow" href="http://www.bradleyp.com/BigBird">here</a>. Hope that helps. <br/>
yea it helps alot thank u for the site.
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!
Awesome ! Special mention for the ZigBee communication system ! Very great idea !
Thank you!
Brushless motors for propulsion. Nice.. Whats the top speed and what radio did you use? i have an Optic 6 maybe i could try this once my plane projects are done.
Oh, and for the radio, we used an Xbee connected to a PIC microcontroller on the computer to send sensor data, and to transmit commands if necessary. When we removed all of our own electronics and used an RC controller, it was a Futaba Fasst 6EX
I'm not sure of the top speed, I didn't really have the guts to put it at full throttle, but I'd estimate in the high 20's to 30's. If you do give this a try, let me know, I want to see some pictures/video!
that looks pretty awesome, seems to have plenty of power to boot, but i do think if you added a control surface on the front of the craft with a couple rudders you could get a much higher speed and stability to boot. it would prevent it from catching up with itself so to speak, either that or add an additional fan for a powered yaw axis on the front of the craft. of course, i havent built one, so thats about all of the critique i feel entitled to offer.
The yaw is handled by difference in thrust provided by the variable pitch propellors at the rear of the craft. I have however considered putting an adjustable "spoiler" at the front of the craft, as hovercraft can sometimes flip over at speed.
Where can I get those???
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 : )
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.
The propulsion fan had no effect on the torque, but trimming a rudder to counteract this much torque would basically only allow to move one way. For my initial solution I built a "rudder" directly below my lift fan that would redirect the air in opposition to the the motor's direction of spin. Although it did help, I was still barely able to compensate for the yaw. My second idea was to place small vents in the fuselage (front right side, and rear left side) The two together (although decreasing lift slightly) were effective in countering the torque enough for someone who knows to compensate, but it is very still difficult to maneuver.As of right now in the plans, the next one will have twin fans rotating opposite directions as you suggested (I didn't do that the first time because of weight, but that won't be an issue with the hollow carbon fiber fuselage I'm making for it. I did think about mounting the lift fan horizontally (in opposition to the propulsion fan) and ducting the air downward, but I'm not sure if airflow would be a problem while moving at high speeds. Any thoughts and or suggestions?
One possibility is to use centrifugal fans. You could use one of them vertically, which could work very well, at least in my experience, they don't have the same issues with airflow at high speeds. You could also use two counter-rotating centrifugal fans. The research that I've been doing has suggested that centrifugal fans are definitely the way to go, despite being harder to buy/make. The reason is that they are good at providing higher pressures with lower flow for a given rpm, as opposed to propellors, which give high flow and low pressure. Basically, this increased pressure (up to a point) will allow you to carry more weight for a given sized chassis, since the force being exerted by a pressure is equal to that pressure times the surface area of the craft. In essence, there are two ways to carry extra weight: make the craft bigger, or the underskirt pressure higher. This makes it possible to compensate for the extra lift fan without reducing the weight of any other component. I know for version two of my hovercraft, I'm going to have two counter-rotating centrifugal fans, a chassis 24" x 16" made of two carbon fiber plates with standoffs in between, with two high performance ducted fans with variable pitch and variable direction. I'm also going to switch from using PICs to using an Arduino, as PICs are much, much harder to use. I'm also learning how to weld nylon, as I would like to make a much better skirt, with fewer leaks that need to be patched, etc. I would definitely encourage you to take a look at centrifugal fan design, because propellors basically give the hovercraft the opposite of what it needs. We need high pressure and very low flow, where props give the opposite. One last thing, if you do go with a centrifugal fan, is to use backward curved blades. This configuration is basically designed for low particulate, high pressure low flow situations, and its very energy efficient (longer run times are always a plus!).
very impressive!!! Very awesome!!
Very nice job! Wish I had time to build one of these, yours is awesome! Actually, I built something similar some years ago, same foam and all. It was just a junk prototype, so there were serious issues, but a great learning experience and if I made another it would be very similar to yours. My biggest difference is that I used a similar mount for the pusher motor, but mounted it to the top of a servo to steer. It didn't work great with only 45 degrees of travel, but a 180 servo would solve that. Do you have any trouble with the lift fan causing the craft to rotate? That was the other big change I wanted was dual counter-rotating lift fans to deal with that, but if you ad a better solution I'd like to hear it.

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