Homebuilt Hovercraft

[calbiterol]

Now that I have your attention...

 

Out of utter curiosity, how many people here have built a hovercraft from scratch?

 

P.S. Couldn't think of a thread title. If any mods want to, uh, rename it with something more... intelligent, feel free.

[nomadd22]

I did with a shop vac and plywood. It crashed a lot.

[RICHARDBATTY]

Yes but it was a radio controled one. The Bontempi organ just didnt cut it so I borrowed its fan.

[Master Gee]

I saw one get made on telly once.

 

They used a leaf blower on a piece of circular plywood with a high strength bag with punctures in wrapped around its base. There was a hole in the plywood so the leaf blower blew into that and kind of vaguely hovered. They used CO2 cylinders for propulsion.

 

Wasn't great but it moved.

[calbiterol]

Quick question for those of you who have: how well does it hover? I ask this because I have built/am building/like to modify/frequently revise my own design for a hovercraft. The last time I tested it after a series of modifications, it was producing enough upward force to allow me to push it, and it'd travel a foot or so . Keep in mind it weighed... Well it had a built-in vaccum cleaner motor so it weighed a chunk, but I wasn't on it or anything...

 

So, in short, can I expect better performance than this? I saw on one site that a single push got his going across the entire room, and, well, that wouldn't happen with this one...

 

The mod I'm working on right now is a custom-molded plastic motor mount (I'm using resin and a hand-made mold) and some changes on the positioning of things. Any suggestions?

[ski_power]

what'll happen if you use thermocole. It'd be super light. And you could tape it up for re-inforcing the 'cole.

[RICHARDBATTY]

You realy need to post a simple drawing or link to one so we can see how to help. Make sure things like your skirt design and other crtical features are in enough detail. What suface were you running it on.

[calbiterol]

I had it on a tile floor. It's the flattest thing I have available. I'll put up a diagram sometime this weekend. It's not gonna be accurate when it comes to the motor mount, as that's not... done. Ski power, what's a thermocole?

[akcapr]

my friend made one with computer fans (12 v ones and 3 of em) on a plexiglass sheet about 1.5 ft across and like 1/4 in thick. He used a tire tube on the bottom as the skirt. it was really simple and didnt work like at all. With hover crafts it is very, very important to have them be as light as possible and just have one super strong fan blowing down the skirt. And the plexiglass he used was way to heavy. U can buy alot of the parts needed online like proper motors and skirts and such.

[reverse]

hovercrafts blow.

 

http://www.rqriley.com/hc-calc.html

[ski_power]

well i think it's called styrofoam, the white thing that's light and can be only cut properly with hot lnife or something hot. If cut cold, it doesn't get cut properly, but instead into large granular things. Well i dont know what you call it properly but over here it's called thermocole, or am i missing something.

[RICHARDBATTY]

Its called expanded polystyrene foam (eps for short)and you are right a composite would make a nice chassis. A thin layer of pva glue and a wrap in plastic sheet would be nice. Don't use other glues like super glue as they are likely to melt it.

[calbiterol]

hovercrafts blow.

 

http://www.rqriley.com/hc-calc.html

 

I am almost positive that there's an error(s) in his calculations/formulas. Read his source code. He converts pounds / square feet into pounds / square inches by dividing by 144.

[calbiterol]

Here's my hovercraft so far:

 

 

I don't know what I'm doing for a skirt (yet) but I have the material I'm using. It's some (vinyl? I don't know, but I'm almost positive it's vinyl) shower curtain that's a really heavy guage. I don't quite have the motor mount finished yet, but that's what it'll look like when it's done, sans skirt. And I'm not sure exactly how much the PVC pipe goes into the platform / baseboard, because I haven't really measured it.

 

[EDIT: Oh and my motor mount will be much more rounded and curvy and cool-looking, but seeing as that takes forever to draw on a computer and it still isn't done, I just left it all rectangular.]

[J.C.MacSwell]

I am almost positive that there's an error(s) in his calculations/formulas. Read his source code. He converts pounds / square feet into pounds / square inches by dividing by 144.

 

So 144 pounds / square feet would convert to 1 pound / square inch?

[calbiterol]

DOH! Nevermind, his formulas are quite correct...

[akcapr]

try using cut tire tubing for the skirt. it may be heavy tho

[calbiterol]

The hovercraft is a little big for that, isn't it? Or do you mean car tire tubes? If yeah... Where would I get a hold of one of those?! Keep in mind, I've spent a net of like $5 on this project and built the rest from various scrap lying around the house (yes, I had a spare vaccum).

[YT2095]

I`ve built a model HC before, never a "Man Sized" one though.

 

we used a tire inner tube for the skirt, cut a thick sheet of plastic to fit (the sort used in the old BSB satelite dishes) glued and pop riveted the skirt in place, got the blower fan out of an old car found the center of balance marked the edge and cut our hole and attatched that, then using a pair of 12v SLA alarm batteries in parallel either side of the blower and connected up.

 

it worked like a charm

[RICHARDBATTY]

Just some thoughts for you on the skirt. The holes in the bottom of the skirt form a cutain of fast moving air directed inwards that helps stop the air from escaping. The fingers along the bottom of the skirt help seal the skirt to the ground but should be very fine and not offer resistance. Plastic bags that are fairly robust make good skirts that are light and strong enough to deal with a small craft like this. They are also easy to cut . These things will make your craft more efficient. http://www.scienceforums.net/forums/attachment.php?attachmentid=764&stc=1

[calbiterol]

What's the best way to make the skirt inflate into a certain kind of shape? Also, if I put a cardboard piece at the bottom of the skirt to flatten it out, will that help or hurt the performance of it?

[RICHARDBATTY]

You need to shape sections and then fasten them together. A bit like this

( ========) x 4 would give a square when glued together but with curved sides. Just basicaly make your sections so they sort of fold up when joined to form the shape you want. Its a bit like designing a box on a flat peice of paper.