Electric Pusher prop?

[Xringer]

theshreves.com - Project: Prop Car



Electric pusher props can generate a pretty fast air flow. Some of the little RC model airplanes I've seen can fly over 80 MPH with a tiny prop driven by a bushless motor. Those little fans can blow your hat off from 50 feet away!
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Anyways, my question of the day has to do with toaster shaped cars like vans or square back SUVs (like my CRV).

What if, I had a 3' pusher prop mounted in the center of the rear hatch?
And once I got out on the highway, I turned on about 10 HP of thrust?

How would blasting the area of turbulence & drag with prop air effect the over-all cd of a van or CRV?




I already have an idea what would happen to my MPG...

Edit:

[BBsGarage]

I guess you could start by looking at these.

[Xringer]

Originally Posted by BBsGarage

I guess you could start by looking at these.

Those are pretty low profile in the front, except for the people..

My question is what effect would a pusher prop (or even a rack of ducted fans) have on the cd of an SUV or van.

If the air-mover was mounted in the center of the back of a square shaped van, would it help the cd ??

[i_am_socket]

That is a very ... yes it is a question. You may want to look into the legality of having whirling blades of death on the back of your vehicle first.

Being able to tell whether or not it helps Cd would be difficult to tell without a windtunnel as the extra propulsion would first need to be calculated out from the drag forces. Then to see if its worth it is to compare fuel consumption of standard vs possibly lower drag but with extra energy consumption.

I'd love to see the test.

[Xringer]

Yeah, after thinking about it for an extra 8 seconds, I decided that a bank of four ducted fans (16" OD) might work just as well.

Here's what they are using for fake jet engines in RC models these days.



If the impeller housing was made out of heavy gauge stuff, they would be safe enough.

Maybe use 4 of these motors..?.
Battery Powered Systems

[BrianAbington]

Originally Posted by Xringer

Those are pretty low profile in the front, except for the people..

Beer usualy adds a lot of weight to those boats...yet they are still pretty fast...lack of teeth must be a pretty efficent weight reduction.

[FastPlastic]

Originally Posted by i_am_socket

That is a very ... yes it is a question. You may want to look into the legality of having whirling blades of death on the back of your vehicle first.

Being able to tell whether or not it helps Cd would be difficult to tell without a windtunnel as the extra propulsion would first need to be calculated out from the drag forces. Then to see if its worth it is to compare fuel consumption of standard vs possibly lower drag but with extra energy consumption.

I'd love to see the test.

It could be run on a secondary battery that was charged at home. Can we say plug in hybrid?

[Xringer]

Originally Posted by FastPlastic

It could be run on a secondary battery that was charged at home. Can we say plug in hybrid?

That's where my mind has been lately. How to convert my CR-V into a plug-in mild-hybrid.?.

Even with all the hardware (old 4WD setup) I've got to work with, it's still gonna be a biaash to get a pre-charged battery pack to deliver me some better MPG out of the old V..

But, could a motor like the Mars ME-0708 PM Pancake 12-48 VDC Brushed

Battery Powered Systems

deliver a thrust equal to 4 or 5 HP?
Assuming one could be installed in a 20" or 30" OD ducted fan? Modeled after the little RC Ducted Fans?

Humm, I might have get a MUCH bigger lathe..

Edit:
Looking at the plots in this RC EDF manual,
http://manuals.hobbico.com/gpm/gpmg3...anual-v1_1.pdf
it sure looks like the thrust goes up nicely with RPMs..
Maybe I should buy one of these and see if it's possible to scale it up..?.
(And, I could stick in on top on my little glider and make it say ZOOM!).

[Xringer]

Dang!! Check out this mod..
Jet Beetle

[BBsGarage]

your also adding an abundance of weight that also needs to be pushed.
interesting idea though.