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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
-Bradley Powers
bpowers.org
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Signing UpStep 1Chassis 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.
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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oh yeah...
NUKE LAUNCHER XD
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
Good luck!