Instructables

Nitro Powered RC Hovercraft

Picture of Nitro Powered RC Hovercraft
My interest in hovercrafts was first incited by Junkyard Wars. I absolutely loved that show. From the constantly changing cast of characters to the equally unique challenge posed every week, I couldn't get enough of the weekly scrap heap showdown. I really wanted to make my own version of whatever the teams where creating any given week, but the hovercrafts really caught my attention. Something about the odd way hovercrafts slide across the ground like everything is covered in ice caused dreams of such a machine for me to pilot. I'm a little big to ride the radio controlled hovercraft that resulted from my obsession, but it's still a fun vehicle to drive around...

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Step 1: Design

The design is based around an 0.049 cubic inch un-throttled Cox engine that came off a control line airplane. It is very powerful for its size and can really move the craft along. Unfortunately, the downside is often difficult to start, especially if you feel the urge to run the craft in the cool air of fall. The glow plugs which cost about $10 and are difficult to find also burn out very easily. There is a fine line between enough juice to start the engine and a fried plug. It would help to have a larger, throttled engine for the greater control and less finicky starts. If you're interested in a Cox engine, eBay has many on sale, often in lots with plenty of extra parts included.

To help with the control issues of an un-throttled engine, I came up with the most unique part of the design: The radio controlled deflector which splits the air between thrust and lifting. It can deflect a maximum of 50 percent of the available thrust to the lift the craft or close off the lift duct completely. While it lets you control the ride height of the craft to some extent, it is most useful for panic stopping by completely cutting off air to the skirt, allowing the craft slid to a stop on the ground.

Steering consists of two balsa uprights which support the two rudders. The rudders are two inches wide and provide plenty of maneuverability, although more rudder surface would probably make it even more maneuverable. A cowling would likely make the rudders more effective too, but the hovercraft is very maneuverable as it is, so it isn't really worth the added frustration in starting the engine to add one.

Materials and Parts
The body is pink insulating foam from a local home center. This stuff works great for this purpose: it is easy to work with and quite stiff on its own. It comes in a variety of thicknesses and usually two foot by eight foot sections. The one inch thick foam is plenty strong for a craft this size. The rest of the structure is made of 1/8 inch thick balsa and, for the engine mount, 1/8 inch plywood from a local craft store.

The remote control system is a two channel set-up meant for cars, boats or other crafts that ride on the surface. It has a range of about 100 feet which is plenty for this hovercraft. The 2 oz fuel tank, fuel lines, fuel, control horns and pusher prop were all bought online at an RC specialty site.
vkarpuram1 year ago
http://www.youtube.com/watch?v=MArNYYv7eIc&feature=youtu.be
smpash2 years ago
Judging from the engine size you could circumvent the start problems by using an electric motor
lukeD2 years ago
can it also be used on water, like a real hover craft?
Jnkyrdguy (author)  lukeD2 years ago
I haven't tried it, but you probably could with a better skirt as long as the water was glassy smooth and wave free.
Aron3132 years ago
That is sick!!!!! How big is the nitro motor?
Jnkyrdguy (author)  Aron3132 years ago
0.049 cubic inch displacement.. it's really small even by rc engine standards!
dlemke2 years ago
Just a tip for cheap linkage rods, etc... I have been using the rods or wire they use to make marking flags to make linkage rods for the race engines I build for racing karts, a very popular country sport. They even make a tool to bend short 90 degree turns in the rods to allow more complex rods. Anyone who has worked on a small briggs engine will understand the linkage concept. My point is you can use this high carbon steel wire to make so many things and it is inexpensive. If you have to buy some, they sell it at all the farm supply stores for about 10.00 a bundle, with about 100 lengths of wire with a colored flag on the end, which is easily removed. They come in two or more lengths, and cost about the same for either, so I just bought a bundle of the long ones, and still have a bunch left to use.

They also sell it at the Harbor Freight stores for less then 10.00, if you are fortunate to have this kind of store near you. I don't. so I paid the premium price, but have more than got my money's worth for the many projects I have used this on.

One caution when using this wire, it is possible for it to "break", when making tight bends and will leave a wickedly sharp end when it does, so use with care, and use safety glasses when working with stiff wire, as it can easily poke you in an eye or other places for that matter..

Just thought of another use that I have used coat hangers for, and that is to put a straight length into a drill and use it to mark holes like when locating a place to run cables, heating ducts, etc This will drill through the depth of a 2x12 easily, so it will drill through your floor like butter and just leave a tiny hole if you cannot use that location.This flag wire should work well for this application. This is a great tool when working alone, as you can make up a bunch of them about 12" long, drill them in to the floor to mark your locations, remove the drill with them still in the floor, and then go locate the other end in the basement, crawlspace, and make sure that you are in a good spot before making a larger hole. Use a side cutter or like tool to cut the rod end at an angle to make it drill better. You will be amazed at how well it drills through most any floor, and even allows you to drill in tight places, as you can literally drill around corners, the wire is that flexable.

Well, they don't call me "motor mouth" for nuthin.......

Dan
cyprian9162 years ago
http://bentley-marine.com/images/BM_Hovercraft.jpg
gmana4 years ago
do they go on water
Jnkyrdguy (author)  gmana4 years ago
Hovercrafts do go on water in general, but this one doesn't since the skirt is not designed for it.
jjj_9 Jnkyrdguy4 years ago
no of any type of skirt that would work?
Jnkyrdguy (author)  jjj_94 years ago
Your best bet is probably to look up skirt designs for full size hovercrafts to get some ideas for better designs.
so, you know those hover crafts that kids build as science fair projects? would that type off bottom work?
Jnkyrdguy (author)  ducktape.mac3 years ago
It could as long as you use a water resistant material. That design doesn't give you much ride height or stability though. It would probably only work well on calm water and smooth land.
okay, thanks for the information.
jj.inc jjj_93 years ago
big black trashbags
paul12563 years ago
how did you connect the rudders to the servos
jj.inc paul12563 years ago
I actually used two sewing pins and strapped a piece of cardboard to my servo so I get 90 degree travel, it is slightly flimsy though
Jnkyrdguy (author)  paul12563 years ago
I used a thin metal rod bent to the right shape that connects the servo arm to a plastic connector (I got it from a hobby shop) that screws into the rudder.
jj.inc3 years ago
I am done with mine, it doesn't look as nice but it works great, I used old parts from a sky fly2 and love how much lift and speed I get. I will post a video soon.
mr. clean3 years ago
do u run this engine in reverse to move air in the correct direction and how do u start it if the spring for staring it is wound the wrong way
Jnkyrdguy (author)  mr. clean3 years ago
I use a pusher prop that's made with the blades reversed. It turns the right way when pointing backwards. Probably easiest to get an electric starter if you want to start it in the other direction and use a standard prob pointing backwards.
ahh ok i dont have time to get a pusher prop so i will run it backwards thanks though
YupHio3 years ago
Cool, I might try that with my spare .25 airplane engine.
ahmad52043 years ago
just bought thanks for your suggestion!! BTW KOOL INSTRUCTABLE!! THANXXX
ahmad52043 years ago
Hi guys i need to actually repair my hovercraft i don't have the remote is there any way to make one thanxx
Buy one! You cant make one
NXTreme4 years ago
I have a quick question. I'm making a hovercraft of my own and I'm looking at servos to try to figure out what specs would be best. The servos you used are the Futaba S3003, right? That clocks them in at about 3.2 kg-cm at 4.8. Are the servos you used strong enough? I am using a smallish brushless RC motor so I probably wouldn't need something that powerful but.... Just trying to figure out what I need. Thanks!
Jnkyrdguy (author)  NXTreme4 years ago
They are futaba s3003 and they are more than powerful enough. In fact, you could probably get away with micro sized servos if weight is an issue and especially if you're using a smaller motor. The standard size servos are often cheaper and I had a few lying around already so I used them.
Thanks for the quick reply! Ok, seeing as they are powerful enough I think I will use some micro servos with about 2 kg-cm, they should be enough. If/when I get my hovercraft finished I will post a picture or two. Thanks!
snowpenguin4 years ago
Hmmmmm, on other hovercrafts I've seen there are two motors: one to propel air downwards to keep the hovercraft lifted, and another to thrust it sideways and forward and whatnot. On yours I only see the one motor, to thrust it. What keeps it off the ground?
Jnkyrdguy (author)  snowpenguin4 years ago
The lift flap deflects some of the thrust from the engine under the craft so the one engine can do both jobs.
jmeister154 years ago
did you see the junkyard wars where they made the gliders
Jnkyrdguy (author)  jmeister154 years ago
I think I remember that one. I'm pretty sure I've seen every episode except maybe one that I had to miss and forgot to tape. Wish I could get them all on DVD...
robot7974 years ago
may i make a own hovercarft instructable with another design (dont like to kill your copyright) and with a better to start cox engine
Jnkyrdguy (author)  robot7974 years ago
I don't mind. Post back here when you're done with the instructable cause I'd like to see it!
XD oke
Would this work on water? XD love it
Jnkyrdguy (author)  MadBricoleur4 years ago
Hovercrafts do go on water in general, but this one doesn't since the skirt is not designed for it.
Mr.NHRA4 years ago
What size engine is that? Where did you get it for how much?
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