On Fri, 26 Oct 2018 06:50:39 +0100, micky wrote:

In alt.home.repair, on Thu, 25 Oct 2018 16:58:21 +0100, "Gym Sulkinson
Fork" wrote:

On Thu, 25 Oct 2018 16:31:38 +0100, Rod Speed wrote:



"Gym Sulkinson Fork" wrote in message
news On Thu, 25 Oct 2018 16:03:22 +0100, wrote:

On Thu, 25 Oct 2018 15:47:48 +0100, "Gym Sulkinson Fork"
wrote:

Why are these fitted instead of just a stationary vent like you see on
caravans?

http://www.flettner.co.uk/van-roof-vents/

I don't see the point in using the wind to power a vent, when the air
was already moving. Surely that's like fitting a generator to your
bicycle to power a motor to make you go faster?

They are just more efficient than a simple hole in the roof with
sufficient cover to keep the rain out. If there was a better mouse
trap, somebody would have made one in the last 200 years.

Yes I know they claim to be more efficient, but why?

Because they are a fan, powered by the wind.

A turbine converts wind to electricity. A fan converts electricity to wind.

Not this one. No electricity. It converts horizontal wind to
vertical wind.

What we have here is something that converts it and then straight back, pointless. You might aswell put a wind turbine and an electric fan connected together on there, it would be no more stupid.

If you would stand under one, you wouldn't say this.



How can you take power from the wind to then give it back to make it
faster?

That isnt how they work. Think of it as a fan,
which even you should realise is better than
no fan, and powering that fan with the wind.

Isn't that breaking the laws of physics?

Nope.

But you're powering that "fan" by the motion of the air, then using the power to create motion of air, which was already there anyway. It would be like having a solar powered lightbulb.

That's a good idea! And they already have them. Lights that store
electricity in the day so that they run without power cords at night

Except the van thing has no storage.