>> ^Barbar:

The point I was making was that if air passes through the turbine, (I am assuming) it leaves with a portion of the turbine's forward velocity imparted upon it. If this is the case, then doesn't it mean that the car's chassis, following directly behind the turbine will experience less drag, since the relative wind speed is lower?


You'd have to do extensive wind tunnel testing, but I suspect the turbulent air following the fan's passage would actually make the rest of the car drag more. Look at properly done wind tunnel testing, it's all about smooth flow, the most aerodynamic model is the one with the least eddies in the wind. In this model you propose there are tons of eddies and unpredictable wind currents before you even begin to introduce the body of the car.

If you could somehow design something that worked as you propose (which I doubt is possible, but it might be if you threw enough money at the problem), the infinitesimal gain would almost certainly be lost through the inefficiencies introduced by the necessary (for safety) fan shroud, and the generator itself.

The point I was making was that if air passes through the turbine, (I am assuming) it leaves with a portion of the turbine's forward velocity imparted upon it. If this is the case, then doesn't it mean that the car's chassis, following directly behind the turbine will experience less drag, since the relative wind speed is lower? So if the drag on the car's chassis is reduced, and a portion of the drag increase from the turbine is gathered by the generator, doesn't it get a bit more complicated? Again, this isn't the same as the trivial example of a fan on a sail boat (which due to triangular sails and keels actually can work in a very limited fashion).

Yeah I know this is only likely to make me look more stupider, but I'm okay with that.

Tags for this video have been changed from 'airbus, a330, fly, hover, headwind, airspeed vs groundspeed' to 'airbus, a330, fly, hover, headwind, airspeed vs groundspeed, relative wind' - edited by calvados

"Ok, the cart has been accelerated to 10mph and at this point the wind is exerting the maximum force upon the cart that it can exert."

No. The wind is exerting 0 force on the cart. The maximum force is when the cart is standing still, there is a difference of 10 mph at 0 mph for the cart and 10 for the wind. At 10 mph for the cart and 10 for the wind the difference is 0. There is no energy, ergo it is impossible.

Think of it in simpler terms. The wind is a car, driving 10mph you are on a very efficient tricycle being pushed by the car. Now, assuming that you're frictionless you'll go 10 miles per hour but how can you go faster? Even if you could outpace the car you'd no longer be getting any energy from it.

The principle is the same with the wind. If you're travelling 10 mph in a 10 mph tailwind the air appears perfectly still to you, since there is no 'relative' wind you cannot be getting energy from it.