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Computer Fan hovercraft

cpu fans hovercraft

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#1

warmachine2598
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Posted 07 October 2012 - 04:44 AM

I had an idea ( i know it's been done before, or thought of) to make a "hovercraft" out of computer fans. My Question is, can a series of fans be hooked up to a cuircuit to control speed, direction and stabilizing?

By curcuit i mean a chip like the adriuno, that can be programmed.

I think this is pretty cool, and i might actually do this. What do you guys think?
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#2

fm87
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Posted 07 October 2012 - 05:44 AM

Not going to work for the simple reason that the fans do not go to a high enough RPM or push enough air (even the fastest ones). You would need to make your own.

But to answer your other questions, yes, but more than likely only if they are the 4 pin fans (with the blue wire which controls speed).

Computer fans are also never at a constant RPM, and it fluxuates enough to where the craft would be unstable.

#3

Shpaget
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Posted 07 October 2012 - 06:11 AM

My brother and I made a few hovercrafts, and from my experience computer fans don't have enough umpf.

We went for high speed dc motors run via Electronic Speed Controller (ESC) you find in model cars and controlled via radio. The last model of our hovercraft could take more than a kilogram of cargo and, on a smooth surface, float as fast as you can run (steering and stopping is hard at those speeds).

There are motor shields for arduino that can take the job of ESC so you just need to find some more powerful motors.

edit
Those motors eat up quite a bit of electric power, sou your hovercraft needs to be large enough to carry at least 300 grams of batteries.
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#4

SeaWry
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Posted 07 October 2012 - 08:53 AM

Typical computer fans do not have true directional airflow, if you notice most blow around the sides in a cone pattern, instead a line. Blowerfans are more logical what you want. As these are what gives a great pushing effect, like a jet engine. Turbine "as I call em" or just normall computer fans have uneven airflow unlike Blowers "directional"

However the bad thing is blower fans normally require a casing to create their strong airflow, and depending on the weight of the object, its hard to say. Also they can remain though at a constant RPM and pressure, but no way to control them unless a variable resistor.

But there is a science factoring here you should know if not then you know now.

For the equal air being pulled, there is a equal push. Meaning if your fans do not have a clear area around them to get fresh air, the craft will never work.

"good suggestion what I mean, watch Mythbusters and the honey bees and the laptop carrying myth, google that tbh".

#5

teckmaster
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Posted 07 October 2012 - 09:27 AM

a single fan needs to have enough power to lift itself up on its own, only then you can put a bunch together for a hovercraft. I suppose you can modify it to make it louder and severely overvolt it, and maybe use some 5200rpm delta fans:



I personally wouldn't really bother though.
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#6

Shpaget
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Posted 07 October 2012 - 09:38 AM

You don't need a motor that can lift itself.
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#7

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Posted 07 October 2012 - 03:36 PM

Quote

a single fan needs to have enough power to lift itself up on its own, only then you can put a bunch together

That'd be true if you were trying to build a helicopter but hovercrafts don't work on the principle of thrust (at least not for the lifting part, their propulsion definitely does, but that propulsion certainly does not need to have a TWR greater than one).  See my below explanation.

View PostShpaget, on 07 October 2012 - 09:38 AM, said:

You don't need a motor that can lift itself.

Exactly, that's the whole point of a hovercraft, the fan by itself would never be able to actually lift that kind of weight.  What you need is a fan that can support the largest static pressure difference possible.  That pressure difference is what's going to do the lifting.

That pressure difference gets spread over the entire area of the skirt, which results in a proportionally larger lifting force.  That's why you can build a hovercraft big enough to lift a person out of a leaf blower, which could never get anywhere near lifting its own weight let alone a person.

In this case, volumetric flow rate isn't too big of a deal as long as you have a proper skirt on your hovercraft (one that conforms well to the surface over which your hovercraft travels and doesn't let a lot of air out).  The most important thing is the pressure difference the fan can support.  The larger the better.

Now, that's not to say flow rate is completely unimportant.  Air will escape from the bottom of the hovercraft causing the skirt to deflate a little bit and you'll want that to generally re-inflate as quickly as possible.  So higher flow rate fans are better, so long as they also support larger pressure differences.


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#8

warmachine2598
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Posted 08 October 2012 - 12:38 AM

Well  I was thinking of 4 fans to lift cardboard wi the only cargo being a missle....

Today I just crashed my rc airplane... Not a cheap airhogs by the way, it's a sky fly. Anyway... It blows a lot of air and thrust. I can stand in the other side of my shop and still fell the blowing of the air. that should be enough right?
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#9

SeaWry
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Posted 08 October 2012 - 03:33 AM

Yes such AiO blower like that will work. If the RC plane is busted up, might as well salvage it and turn into something else. Also more better if you can utilize the entire controller system, for maybe remote control?