[revoman]

I have an idea that is difficult to research online.

I am thinking of putting electrically driven fans (squirrel cage?)
in the bed of my pickup to give my ICE a boost on the highway.

Anyone have some thoughts on it? It is difficult to convert
from HP to thrust so it will probably be a trial and error thing.

I see it as possibly a very easy way to get some MPG boost
but there are obvious problems.

 

[gottdi]

Really! How much thought went into this idea?
Did you test your hypothesis or just open .......... and insert foot.

 

[revoman]

You choose
Obviously you have already thought it through and rejected it.
Why?

 

[helluvaengineer96]

Conservation of energy in an enclosed system. I'm sure there is a law that can be named, but I've been our of school for a while now.

Whatever energy you get from your fans.... you are spending as added resistance (your motor must work hard to spin those fans hence you are spending more energy).

You will burn more energy than you gain due to system components be inefficient.

You choose
Obviously you have already thought it through and rejected it.
Why?

 

[revoman]

Conservation of energy in an enclosed system. I'm sure there is a law that can be named, but I've been our of school for a while now.

Whatever energy you get from your fans.... you are spending as added resistance (your motor must work hard to spin those fans hence you are spending more energy).

You will burn more energy than you gain due to system components be inefficient.

Maybe I didn't make it clear.

Instead of batteries running wheels on the ground as an assist
push as in a trailer, I would use fans blowing out the back of my
truck to assist the ICE at highway speeds.

The fans aren't charging anything; I would do that at home from the grid.

 

[helluvaengineer96]

Oh... My bad I read your post too quickly...

You would want a turbine... but trust me, most efficient use of your power is applying it directly to the ground...

Maybe I didn't make it clear.

Instead of batteries running wheels on the ground as an assist
push as in a trailer, I would use fans blowing out the back of my
truck to assist the ICE at highway speeds.

 

[revoman]

Oh... My bad I read your post too quickly...

You would want a turbine... but trust me, most efficient use of your power is applying it directly to the ground...

Sure, I know it is, but it could be technically complex to do it
as a pushing mechanism and I am not in the position to make my
truck all electric. I just wondered what the forum's thoughts would be
on doing something simple like this and if there would be appreciable
gains.

I think that there would be and it could be fairly simple and cheap to
execute for a %25 or better gain in mileage.

 

[Jimdear2]

You would want a turbine... but trust me, most efficient use of your power is applying it directly to the ground...

Better bet would be applying you electric power directly to the drive train as mechanical energy. It is considerably more efficient.

Using electric motors to move air to produce thrust/pressure is probably near the bottom of a list of efficient uses of power.

The only possible boost I could see coming from such a system would be if you could evacuate the high pressure area in front of the vehicle while using less power then you would use to just push it out of the way.

 

[revoman]

Better bet would be applying you electric power directly to the drive train as mechanical energy. It is considerably more efficient.

Using electric motors to move air to produce thrust/pressure is probably near the bottom of a list of efficient uses of power.

The only possible boost I could see coming from such a system would be if you could evacuate the high pressure area in front of the vehicle while using less power then you would use to just push it out of the way.

Sure, I know it is, but it could be technically complex to do it
as a pushing mechanism and I am not in the position to make my
truck all electric (expensive). I just wondered what the forum's thoughts would be on doing something simple like this and if there would be appreciable
gains.

I think that there would be and it could be fairly simple and cheap to
execute for a %25 or better gain in mileage.

 

[jeremyjs]

I seriously doubt you'd ever seen any noticeable gains. Even with a lot of battery power and some big blowers.

 

[newenergy]

My gut feeling would be that it would be very inefficient, but airplanes are pretty efficient, right?

I think the idea of evacuating air in front of the car to improve aerodynamics sounds good. Like a wide narrow inlet that sucks air out in front and then propels it out the back.

Seems like the fan/turbine would have to spin very fast though for the drag to be small compared to the thrust.

from wikipedia on turbines:

"As a general rule, the smaller the engine the higher the rotation rate of the shaft(s) needs to be to maintain top speed. Turbine blade top speed determines the maximum pressure that can be gained,this produces the maximum power possible independent of the size of the engine. Jet engines operate around 10,000 rpm and micro turbines around 100,000 rpm."

Seems like such a set up would cost more than putting power to the wheels.

 

[DavidDymaxion]

I was thinking of doing the same idea for my bicycle. I think it would be less efficient than driving the wheels, but it would be really simple to build, would just need a switch (no controller needed), and would be really easy to put on or take off (just strap it to the rear rack). You would learn a lot both faster and cheaper by trying a bike version first.

 

[Jimdear2]

For a bicycle you might look into one of those powered parasailing backpacks.

Probably be VERY fast (??land speed record??)

What revoman is missing, is that at 60 mph in his vehicle, he would have to spin the fans at the equivalent of 60 mph just to get nothing.

 

[Mark C]

revoman, when all is said and done, I think you'd do better on the http://ecomodder.com/ website. There are many avenues discussed on ecomodder about ways to increase the distance traveled versus the fuel you buy. The cost for doing ranges from $0.00 for adjusting the "nut behind the wheel," to some serious aerodynamic modifications that can cost as much as you want to spend.

Either way you choose to go, reducing the amount of fuel you burn to propel your vehicle of choice is a worthy goal that most here would encourage. Later, when the budget allows, you can buy or build an EV to completely eliminate the oil man.

 

[revoman]

For a bicycle you might look into one of those powered parasailing backpacks.

Probably be VERY fast (??land speed record??)

What revoman is missing, is that at 60 mph in his vehicle, he would have to spin the fans at the equivalent of 60 mph just to get nothing.

No, I get that. Just trying to make it as easy and cheap as possible.

Also considering a rear frame attached electric pusher, but it will probably
be more expensive and complex.

 

[Bottomfeeder]

I agree with Mark C. There are lots better ways to improve mileage, and almost all of them are on ecomodder. I understand the desire to try some new idea that you have, but rarely is that practice the most economical. Since you'd be trying new things, you'll spend a lot of effort and money toying with the idea trying to find a decent solution. Sometimes you have to swallow your engineering pride and try the well worn solutions first. That being said, keep us updated with your harebrained schemes.

 

[Roy Von Rogers]

http://www.youtube.com/watch?v=UWSr62Xnb2M

Now if you took that motor and coupled it directly to the wheels of an automobile, which do you think is more economical and faster, the car or the boat.

Roy

 

[Soundboats]

To see if this concept is feasible I would suggest you look into the operating parameters of an air boat. These use a big propeller to move a boat. By researching this technology you might find out how much horsepower the props produce and how it might improve your vehicle's performance.

One issue that comes up with propellers is the speed of the tip. For the type of application you are considering the tip of the propeller cannot be moving faster than the speed of sound. There is a tradeoff between rpm and length of prop. You will get more power with a bigger prop moving at a lower rpm (just like in boats).

 

[poprock]

I have an idea that is difficult to research online.

I am thinking of putting electrically driven fans (squirrel cage?)
in the bed of my pickup to give my ICE a boost on the highway.

Anyone have some thoughts on it? It is difficult to convert
from HP to thrust so it will probably be a trial and error thing.

I see it as possibly a very easy way to get some MPG boost
but there are obvious problems.

When I was 10 I tried to lift myself up by my shoelaces.It didn't work either.

 

[gottdi]

When I was 10 I tried to lift myself up by my shoelaces.It didn't work either.

What do ya mean? It worked fine for me as long as I only lifted one foot at a time. Arm assist is what you might call it. Works to assist the leg. Like you when I tried both feet at once I'd fall down, go boom