Power Case Fans on Batterys

[aSc1@3]

Is there a way to power case fans trough batterys? By that I mean, can I just hookup a aa/aaa battery to the wires on the fan, or will I need a resistor/capacitor? All I know is that aa/aaa are 1.5 volts and the fan I want to power says 12v 0.15 amp.

 

[mac550]

firstly aa/aaa run on 1.2-1.5 volt so no you cant use just 1, you would need 8 of them wired in series. second, no you dont need a resistor/capacitor because battery's and computer fans run on DC. why do you want to run those fans from battery's? not really much point, 1 fan would drain 8 aa/aaa battery's in like 2 hours, maybe less.

 

[pokethesmot]

i guess you can use AAs but your gunna need a few of them i just tried and it took 2 of them just to power on the leds to a spare red 80 fan i had now might i ask you why you would need this

 

[aSc1@3]

I have a toy parachute that i could tie to a tiny little 40mm fan I have, and I was wondering if I could battery power it so I could mount batteries to fan symetrically, and have it blowing air up into the little parachute in hopes of it flying...

 

[Vizy]

lol

 

[mac550]

indeed, lol! riiiiiight?!?!?!?!?! i can tell you now, if you do that it wont fly, two reasons 1, you need the fan flowing down and 2, it will make parachute fall faster because there will be to much weight and not enough down force from the fan to slow it down.

 

[aSc1@3]

Why would the fan be blowing down? I want it to blow air up to the parachute, filling it, and lifting it. Plus, even if it won't work, ut would still be fun.
P.S. See Diagram:
Parachute
__--------------__
| |
| ^ ^ ^ |
| | | | | Air
| | | | |
_______________
| Fan |
-----------------
^
|

 

[mac550]

Why would the fan be blowing down? I want it to blow air up to the parachute, filling it, and lifting it. Plus, even if it won't work, ut would still be fun.
P.S. See Diagram:
Parachute
__--------------__
| |
| ^ ^ ^ |
| | | | | Air
| | | | |
_______________
| Fan |
-----------------
^
|

riiiiight?!?!?!?! so a choppers rotors push air upwards? no they force air down.

For ever action there is an equal and opposite reaction

therefor you need to force the air down to give lift and for what you want to do you need that because if the air is forced down then it will give more resistance and it will stay in the air longer. you only want the air forced up if the air your blowing up is hotter than the surrounding air around the parachute. hot air is lighter than cold air.
This stuff is basic physics.

 

[PohTayToez]

Basically, this wont work because it violated a fundamental law of physics... for every action, there is an equal and opposite reaction. Although the the air moved by the fan will exert a force on the parachute in the up direction, it is also exerting a force on the fan in the down direction.

I'm sure you've seen an airboat before:
http://www.floridaconservation.org/boating/access/airboat/Airboat.jpg

Imagine if you tied a parachute to the back of it and had the giant fan blow into it.... do you really think that the boat would be able to move? Of course not.

 

[mac550]

Basically, this wont work because it violated a fundamental law of physics... for every action, there is an equal and opposite reaction. Although the the air moved by the fan will exert a force on the parachute in the up direction, it is also exerting a force on the fan in the down direction.

I'm sure you've seen an airboat before:
http://www.floridaconservation.org/boating/access/airboat/Airboat.jpg

Imagine if you tied a parachute to the back of it and had the giant fan blow into it.... do you really think that the boat would be able to move? Of course not.

exactly what i mean. the boat would prob move really slow, less than 5 knots.