Wind turbine on the front of a car.

[oil pan 4]

Tell me all the reasons why putting a wind turbine on the front of a car is a stupid idea.
And no I don't want to do it. I think its a stupid idea.
I think this idea ranks up there with putting an alternator in an electric vehicle to charge the batteries as you drive.

[Frank Lee]

Smokey Yunick did it on a race car but that was only because it had a problem throwing belts.

It seems to me that such a set-up would increase aero drag thus cancelling or more than cancelling out any gains. I had that "brilliant" idea as a kid but my engineer uncle explained why it probably wouldn't work. For sure it would fail bolted on the roof, for example.

Someone recently suggested putting one in the engine compartment, an already draggy place with lots of airflow(?). I think it would either still increase aero drag but maybe not enough to notice. And/or it might not spin enough, enough of the time to keep the battery charged.

Maybe the answer isn't simple?

[jamesqf]

Not actually that dumb of an idea. It actually works if you happen to have a nice, windy dry lake to play on: https://en.wikipedia.org/wiki/Blackbird_(land_yacht)

But for an ordinary vehicle, I think the biggest drawbacks are 1) carrying around all that excess weight when the wind's not blowing; and 2) chopping up other vehicles, pedestrians, and so on with the propellor :-)

[UFO]

A sail would look better.

[kach22i]

FYI:

Ram air turbine
https://en.wikipedia.org/wiki/Ram_air_turbine

A ram air turbine (commonly known by the acronym RAT) is a small turbine that is connected to a hydraulic pump, or electrical generator, installed in an aircraft and used as a power source. The RAT generates power from the airstream by ram pressure due to the speed of the aircraft.
With the exception of crop dusters (see below), modern aircraft only use RATs in an emergency—in case of the loss of both primary and auxiliary power sources the RAT will power vital systems (flight controls, linked hydraulics and also flight-critical instrumentation). Some RATs produce only hydraulic power, which is in turn used to power electrical generators. In some early aircraft (including airships), small RATs were permanently mounted and operated a small electrical generator or fuel pump.

From the same link:

An Me 163B Komet, showing its nose-mount ram-air turbine.

Again the same link as sourced:

Many modern types of commercial airliners are equipped with RATs. In the 1960s the Vickers VC10 was one of the first types of airliner equipped with a RAT. The Airbus A380 has the largest RAT propeller in the world at 1.63 metres (5.3 ft) in diameter, but around 80 centimetres (2.6 ft) is more common. A typical large RAT on a commercial aircraft can be capable of producing, depending on the generator, from 5 to 70 kW. Smaller, low airspeed models may generate as little as 400 watts.

https://www.flickr.com/photos/bernd2011/7759518858


Airbus A380
http://a380flightdeck.tumblr.com/pos...am-air-turbine

Ram air turbine (RAT).

A ram air turbine (commonly known by the acronym RAT) is a small turbine that is connected to a hydraulic pump, or electrical generator, installed in an aircraft and used as a power source. The RAT generates power from the airstream by ram pressure due to the speed of the aircraft.

An engineer would have to do the math for me, but I suspect for cars direct to the engine is going to be most efficient.

However, maybe if you are far from the main power source as with a train car or a caboose, and have a power requirement while underway, then it might make sense. Then again, train cars have wheels and axles, which could be mechanically/parasitically drawn upon for generator power, right?

[freebeard]

I don't think it's a stupid idea. Expecting it to work anywhere but parked facing into a headwind is stupid.

[user removed]

Lots of ways to recover energy normally lost in braking. The best is to not brake in the first place.

regards
mech

[kach22i]

Underway, or not underway, this 4x4 RV has roof mounted solar panels.

EarthCruiser FAQS- Questions we want you to ask….. | Earth Cruiser


The RAT will give way to solar panels in most automotive use applications I suspect.

[Cd]

Around 2000, Popular Science / Mechanics had a small write up on an electric van with a fan on the roof. ( It was mounted horizontally. )
The blades were designed in such a way that they would fold flat as they turned, thereby reducing drag.
They claimed that even in a parking garage, the wind would turn the blades.

So agreed - not such a stupid idea after all. I wonder what became of the prototype though.

[aerohead]

Originally Posted by oil pan 4

Tell me all the reasons why putting a wind turbine on the front of a car is a stupid idea.
And no I don't want to do it. I think its a stupid idea.
I think this idea ranks up there with putting an alternator in an electric vehicle to charge the batteries as you drive.

*The mechanical efficiency of the turbine would around 80%.
*The mechanical efficiency of the generator might be 98%.
*Combined,for every 746-Watts of power extracted,you'd have to overcome 964-Watts of drag for the turbine alone,then add in the drag of the nacelle,supporting strut,interference drag at the attachment interface,plus you'd be driving in the turbulent wake of the turbine; of which it's kinetic energy could never be converted back to useful pressure,disturbing local body airflow,increasing the car's overall aerodynamic drag.
*Think of a side-view mirror the size of the rotating disc of the turbine!
*It could be the poster child for Entropy.