# 2 bladed fan with 1 motor

1 Motor = 2 Fans
More Efficient Mechanical Energy Usage

There are several examples all around us of mechanical energy being converted into electrical energy. Windmills, for example, and hydroelectric plants.

The first takes the power of the wind to drive fans, and this turns motors that become electrical energy to be stored for use.

The second uses the force of gravity when water either falls down a substantial height or goes from a point of higher pressure to a point of lower pressure, passing through a valve â€“ again with a fan that drives a motor.

A weight suspended at a certain height and attached to a fan that turns while the weight succumbs to gravity is nice, except that eventually the weight would reach the ground, and then the energy would stop, or has to be brought up to the first height again. In that sense it is not practically harnessing energy, because it expends energy to bring the weight up before gravity is taken advantage of.

Similarly, we can also take advantage of electrical energy being converted to mechanical energy, as is the case with the electric fan. The electricity turns the motor, which turns the blade, which provides moving air.

But why only attach the motor to one fan?

With the knowledge of gears or belts, several fans can be connected to the motor to take advantage of its spinning â€“ as much as the space will allow â€“ to drive several fans. If the motors and the fans are sufficiently frictionless, the motor does not have to expend more energy to drive two fans than it does to drive just one fan.

Thus the need to have several fans â€“ all with their own motors â€“ in one room can be eliminated, because having just one motor drawing electricity from the system then sending them out to a lot of fans pointing in different directions can already provide sufficient ventilation for a room.
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## Step 1:

1 Motor = 2 FansMore Efficient Mechanical Energy Usage
There are several examples all around us of mechanical energy being converted into electrical energy. Windmills, for example, and hydroelectric plants.
The first takes the power of the wind to drive fans, and this turns motors that become electrical energy to be stored for use.
The second uses the force of gravity when water either falls down a substantial height or goes from a point of higher pressure to a point of lower pressure, passing through a valve â€“ again with a fan that drives a motor.
A weight suspended at a certain height and attached to a fan that turns while the weight succumbs to gravity is nice, except that eventually the weight would reach the ground, and then the energy would stop, or has to be brought up to the first height again. In that sense it is not practically harnessing energy, because it expends energy to bring the weight up before gravity is taken advantage of.
Similarly, we can also take advantage of electrical energy being converted to mechanical energy, as is the case with the electric fan. The electricity turns the motor, which turns the blade, which provides moving air.
But why only attach the motor to one fan?
With the knowledge of gears or belts, several fans can be connected to the motor to take advantage of its spinning â€“ as much as the space will allow â€“ to drive several fans. If the motors and the fans are sufficiently frictionless, the motor does not have to expend more energy to drive two fans than it does to drive just one fan.
Thus the need to have several fans â€“ all with their own motors â€“ in one room can be eliminated, because having just one motor drawing electricity from the system then sending them out to a lot of fans pointing in different directions can already provide sufficient ventilation for a room.
bigt4616 says: Apr 9, 2009. 4:02 PM
with energy, it all matters on what you need it for, if you need more speed, you lose torque. if you need more torque, you lose speed. thats why cars are more efficiant than trucks, a car usually has a smaller towing capacity also tho
andrew93 says: Jan 28, 2008. 2:58 AM
all i know is that james, zachninme, and all these other guys that posted somethin here are right. But this lego "creation " produces wind but it does not propel them backwards or forwards, but sideways because of that curve on the end. and a paper Does produce more air than that.!!!!!
zachninme says: Aug 25, 2006. 9:17 AM
Is this instructable all theroy? Because I know for a fact that a falling piece of paper would produce more wind than that lego contraption ;-\
James (pseudo-geek) in reply to zachninmeJul 19, 2007. 2:56 AM
true dat. the "blades" have no curve to them, hence they just waste mechanical energy.
James (pseudo-geek) in reply to James (pseudo-geek)Jul 19, 2007. 2:56 AM
and the funnt thing is, is that a paper actually WOULD produce more wind lol
girrrrrrr2 in reply to James (pseudo-geek)Jul 26, 2007. 1:49 AM
the funnier thing is that this could be turned into a nice fan... you know how a vacume works... just put the piece that is on the motor on it... if you get what i am saying... than you have a fan in theory...
James (pseudo-geek) in reply to girrrrrrr2Jul 27, 2007. 2:08 AM
yeah, its called a centrifugal pump, but he doesnt have the casing to make it work.
girrrrrrr2 in reply to James (pseudo-geek)Jul 27, 2007. 4:26 AM
ya... but he didnt have the fan blades either...
James (pseudo-geek) in reply to girrrrrrr2Jul 29, 2007. 7:59 PM
ya. what a nub.
James (pseudo-geek) in reply to James (pseudo-geek)Jul 29, 2007. 8:01 PM
(no offence to him)
girrrrrrr2 in reply to James (pseudo-geek)Jul 1, 2012. 8:46 AM
...lol...
tyeo098 says: Aug 31, 2006. 7:21 PM
so isee you have a nokia phone!
instructa-fan in reply to tyeo098Jun 2, 2007. 12:37 PM
so isee you have a pink stapeler!
lemonie says: Jan 21, 2007. 5:06 PM
I don't see any fans here, and I don't see a point. The pictures may show devices that use energy to move air in some direction, but they are not fans. Also I fail to see any relavence in the majority of your text. What are you trying to teach us here?
ironsmiter says: May 16, 2006. 5:08 AM
the principal works.. sort of. most fan motors are grossly overpowered for what they do.. therefore, the torq needed to drive multiple fans on the same voltage is there. but more CURRENT is needed to drive them. This project works on the same principal as the belt-driven multi-room fan systems of the industrial revolution. One motor would turn one belt, connected to a dual pulley on the fan. the second pully would have a belt run to the second pulley of a different fan. and so on. As long as the total driving force and speed needed does not excede the motors output you're golden. A more modern version of this is an automotive serpintine belt... all from one pully/gear(main drive shaft) the AC condenser, alternator, water pump, and usually the radiator fan, are all run. that's why on some of the very low powered econoboxes, turning the ac on causes the motor to hesitate. More power required than is available. PS. Adding a third blade to each "fan" will add about 1/3rd extra air movement, while requiring only around 1/4 extra energy to push. 4 and more blades though, produce substantially less gains, while requiring more power per blade. That's why most single engine airplanes carry 2 or 3 bladed propellers. Very High torq motors usually go for 4 blades... that seems the point of diminishing returns. this is the common number for high performance home-build airboats.
clint eastwood says: May 5, 2006. 9:12 AM
i can do that
peterthehun says: Apr 4, 2006. 10:15 PM
Pushing air is still work. As you add more load in the form of more fan blades, the motor will respond by drawing more current and therefore more power, even if the added gearing friction is minimal. In other words, there's no free lunch - more air pushed = more power used.
maxwell says: Mar 31, 2006. 4:52 AM
There's alot more friction in gearing than in driving the fan through air. There are ceiling fans that chain a bunch of fans with belts to one motor, it's cheaper to build cuz you only have to buy one motor, but definitely not quite as efficient energy wise. gears, belts, or any other way of splitting the driveline will add more friction than a direct drive
sharath says: Mar 30, 2006. 9:13 AM
I don't quite agree with your statement: "If the motors and the fans are sufficiently frictionless, the motor does not have to expend more energy to drive two fans than it does to drive just one fan.". Because irrespective of the presence or absence of friction,adding one more blade together with a gearing mechanism is bound to increase the load on the motor.
maffiou says: Mar 30, 2006. 6:54 AM
If driving one fan is very close to driving 2, it is because the actual transfer of energy to the fan itself is not efficient at all. I guess most of the energy is lost in friction...