On Thu, 25 Oct 2018 18:07:44 +0100, Ed Pawlowski wrote:

On 10/25/2018 12:15 PM, Gym Sulkinson Fork wrote:
On Thu, 25 Oct 2018 17:10:21 +0100, Pat wrote:

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. 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.

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.

I suspect you are just trolling,

I'm not.

but I'll chime in anyway. These
devices use the motion of the air traveling past your building (ie,
horizontal motion) into suction that draws hot air up and out of your
building. They work better than just using the upward motion of the
air created by hot air being lighter than cooler air.

I find it hard to believe it really matters whether the air goes in our
out.
If not trolling, just a hardhead that refuses to accept a better idea
that works. Have you tried one?

No, I was just asking how it works.... It would appear Mr Speed has provided a satisfactory answer.

Gym Sulkinson Fork wrote:
On Thu, 25 Oct 2018 17:11:41 +0100, Nightjar
wrote:
On 25/10/2018 16:07, Gym Sulkinson Fork wrote:
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? How can you
take power from the wind to then give it back to make it faster? Isn't
that breaking the laws of physics?

They are a Savonius rotor, which uses the wind to rotate a shaft.
There is a fan attached to the shaft, which, unlike a simple hole,
actively extracts air from the vehicle. They are also widely used on
boats, to keep them ventilated while sitting at their moorings.

I'd just open the window (with a rain guard of course).

Another Hucker troll.

On Thu, 25 Oct 2018 19:17:15 +0100, Mr Pounder Esquire wrote:

Gym Sulkinson Fork wrote:
On Thu, 25 Oct 2018 17:11:41 +0100, Nightjar
wrote:
On 25/10/2018 16:07, Gym Sulkinson Fork wrote:
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? How can you
take power from the wind to then give it back to make it faster? Isn't
that breaking the laws of physics?

They are a Savonius rotor, which uses the wind to rotate a shaft.
There is a fan attached to the shaft, which, unlike a simple hole,
actively extracts air from the vehicle. They are also widely used on
boats, to keep them ventilated while sitting at their moorings.

I'd just open the window (with a rain guard of course).

Another Hucker troll.

No, a question. But despite having a van half your working life, you couldn't answer it. Mind you, you admitted you couldn't even reverse it!

On Thu, 25 Oct 2018 12:10:21 -0400, Pat wrote:


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.

I suspect you are just trolling,

He's none other than sociopathic Scottish ****** Peter Hucker, using his
newest nym!

but I'll chime in anyway.

That was a mistake, poor fool!

On Fri, 26 Oct 2018 03:34:23 +1100, cantankerous trolling senile geezer Rot

FLUSH the two village idiots' latest idiotic bull**** unread

--
Latest retarded conversation between out two village idiots, Birdbrain and
Rot Speed:

Birdbrain: "You beat me to it. Plain sex is boring."

Senile Rot: "Then **** the cats. That wont be boring."

Birdbrain: "Sell me a de-clawing tool first."

Senile Rot: "Wont help with the teeth."

Birdbrain: "They've never gone for me with their mouths."

Rot Speed: "They will if you are stupid enough to try ****ing them."

Birdbrain: "No, they always use claws."

Rot Speed: "They wont if you try ****ing them. Try it and see."

Message-ID:

On Thu, 25 Oct 2018 13:07:44 -0400, Ed Pawlowski wrote:


If not trolling,

"If"??? SERIOUSLY! LOL

just a hardhead that refuses to accept a better idea
that works. Have you tried one?

His baits (or his cock) just taste too good to you to resist, eh, senile
fool? BG

On Thu, 25 Oct 2018 17:11:41 +0100, Nightjar, another brain damaged,
troll-feeding senile idiot, blathered:


They are a Savonius rotor, which uses the wind to rotate a shaft. There
is a fan attached to the shaft, which, unlike a simple hole, actively
extracts air from the vehicle. They are also widely used on boats, to
keep them ventilated while sitting at their moorings.

And yet another senile idiot fell for the retarded Scottish attention
whore's latest idiotic bait, hook, line and sinker! LOL

On Fri, 26 Oct 2018 03:35:48 +1100, cantankerous trolling senile geezer Rot
Speed blabbered, again:

FLUSH the two sick trolls' latest troll ****

--
Another retarded "conversation" between Birdbrain and senile Rot:

Senile Rot: " Did you ever dig a hole to bury your own ****?"

Birdbrain: "I do if there's no flush toilet around."

Senile Rot: "Yeah, I prefer camping like that, off by myself with
no dunnys around and have always buried the ****."

MID:

On Thu, 25 Oct 2018 13:07:55 -0400, , the mentally
deficient, troll-feeding senile idiot, blathered:



Any ambient wind will spin the turbine and pump air out. On a
perfectly calm day, I doubt there is much gain at all.

You turned out to be one of the gay Scottish ******'s most devoted
cocksuckers! LOL

On Fri, 26 Oct 2018 03:27:20 +1100, cantankerous trolling senile geezer Rot
Speed blabbered, again:

FUSH another load of the two resident idiots' latest idiotic drivel unread

--
Typical retarded "conversation" between the Scottish ****** and senile
Ozzietard:

Birdbrain: "Horse **** doesn't stink."

Senile Rot: "It does if you roll in it."

Birdbrain: "I've never worked out why, I assumed it was maybe meateaters
that made stinky ****, but then why does vegetarian human **** stink? Is it
just the fact that we're capable of digesting meat?"

Senile Rot: "Nope, some cow **** stinks too."

Message-ID:

On Fri, 26 Oct 2018 03:31:23 +1100, cantankerous trolling senile geezer Rot
Speed blabbered, again:

FLUSH yet more sick troll **** unread

....and much better air in here again!

--
TYPICAL retarded "conversation" between sociopath Rot and sociopath
Birdbrain from August 26th:

Birdbrain: "I have one head but 5 fingers."

Senile Rot: "Obvious lie. You hairy legged cross dressers are so inbred that
you all
have two heads."

Birdbrain: "You're the one that likes hairy legs remember?"

Senile Rot: "The problem isnt the hairy legs, it's the gross inbreeding that
produces two headed unemployables like you."

Birdbrain: "So why did you mention hairy legs?"

Senile Rot: "Because that's what those who arent actually stupid enough to
shave
their legs have."

Birdbrain: "You only have hairy legs if both of the following are true:
1) You're quite far back on the evolutionary scale.
2) You haven't learned what a razor is for."

Senile Rot: "Only a terminal ****wit or a woman shaves their legs."

Birdbrain: "There is literally zero point in having hair all over your
body."

Senile Rot: "There is even less point in wasting your
time changing what you are born with."

MID:

Brian Gaff wrote

Hang on though,

Too radical by far...

to make it spin it has to have drag.

But a tiny part of the drag of the whole van.

If it has drag its using fuel.

Not when stationary and most of them are
stationary much more than they are moving.

Might be moor efficient then to streamline the van

That should be done anyway.

and run the fan from the van electrics which is there already.

Sure, but that wouldn’t work as well when stationary.

"Rod Speed" wrote in message
...
Gym Sulkinson Fork wrote

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

They act like a pump.

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.

It isnt from the place you want to move it from.

Surely that's like fitting a generator to your bicycle to power a motor
to make you go faster?

Nope, more like using a wind generator to generate
electricity and using the electricity to drive a fan, but
without the losses involved with the electricity
generation and the electrical fan.

"Gym Sulkinson Fork" wrote in message
news
On Thu, 25 Oct 2018 17:27:20 +0100, Rod Speed
wrote:



"Gym Sulkinson Fork" wrote in message
news
On Thu, 25 Oct 2018 17:04:57 +0100, Rod Speed
wrote:



"Gym Sulkinson Fork" wrote in message
news On Thu, 25 Oct 2018 16:20:54 +0100, Ralph Mowery
wrote:

In article ,
says...

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 powered by the wind that is blowing, not wind they are
making.

Why not just channel the blowing wind where you want it instead of
converting energy twice?

Because those things are extracting air from the house or van so that
isnt
possible.

Why is it better to move it out instead of in?

Because the hot air in the roofspace is already trying to get
out and it works better to help it do what its trying to do
than to try to stop it doing what it is already trying to do.

It still has to go in somewhere and out somewhere else.

Yes, but its better to help it move faster in the direction
it already wants to go.

Same ventilation takes place overall.

Nope, you move more hot air when you help it to go
in the direction it already wants to go, with a fan.

Ok, I accept your explanation. What surprises me though is just how much
hot air rises. Is there a formula to determine for example, in a
container of certain dimensions, how much hotter the top will be than the
bottom?

Yes, but its complicated.

In the case of the van, they are powered by the wind pressure the van
creates when moving.

The above link claims it works when stationary too (by wind).

Yes it does. You've likely noticed that houses don't actually move very
fast
and do have those vents too.

I've occasionally seen them on old houses on chimneys. I thought that
was
to disperse the smoke.

Nope, its just another example of a wind powered fan which
helps the air in the chimney move the way it wants to go.

I rarely see them here, on any type of boiler/fireplace arrangement.

Yeah, basically because the standard chimney pot works pretty well
when the chimney itself is properly designed so it draws well initially
when you are first lighting the fire and are maintenance free.

"Gym Sulkinson Fork" wrote in message
news
On Thu, 25 Oct 2018 17:31:23 +0100, Rod Speed
wrote:



"Gym Sulkinson Fork" wrote in message
news
On Thu, 25 Oct 2018 17:09:56 +0100, Rod Speed
wrote:



"Gym Sulkinson Fork" wrote in message
news On Thu, 25 Oct 2018 16:25:20 +0100, Rod Speed

wrote:

Gym Sulkinson Fork wrote

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

They act like a pump.

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.

It isnt from the place you want to move it from.

Surely that's like fitting a generator to your bicycle to power a
motor
to
make you go faster?

Nope, more like using a wind generator to generate
electricity and using the electricity to drive a fan, but
without the losses involved with the electricity
generation and the electrical fan.

But the point is to move air into or out of (shouldn't matter which,
air
still goes through the van) where the vent is.

It does actually, particularly when getting it to
remove the hot air in the roof space in summer.

but if you let the wind blow it in, then it goes out where it's
currently
coming in.

Yes, but is going against the natural flow of the hot air
coming out of the roofspace, so doesn't work as well.

Think of electrically powered exhaust fans.

The work much getter moving the air out of the roofspace
than moving outside air into the the roofspace.

Makes no difference how that fan is powered,
still works better to move the hot air in the
roofspace in the way it wants to go by convection.

I tend to do that when designing desktop computers,

I only bother with the cpu fan, but don't run mine with covers on.

but mainly because of where the hot chips are and what needs the most
cooling. I have intake fans front bottom cooling the disks,

I don't bother cooling mine but I use the lower speed ones
that only get warm to the touch when the room is over 30C
before I turn the air cooler on.

then across the graphics card,

I'm not into gaming so mine don't even have a fan.
The only game I ever play is Freecell Pro and it isnt
exactly demanding of the video card.

then over the CPU then out the top back and/or top.

On Thu, 25 Oct 2018 21:05:11 +0100, Rod Speed wrote:



"Gym Sulkinson Fork" wrote in message
news
On Thu, 25 Oct 2018 17:27:20 +0100, Rod Speed
wrote:



"Gym Sulkinson Fork" wrote in message
news On Thu, 25 Oct 2018 17:04:57 +0100, Rod Speed
wrote:



"Gym Sulkinson Fork" wrote in message
news On Thu, 25 Oct 2018 16:20:54 +0100, Ralph Mowery
wrote:

In article ,
says...

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 powered by the wind that is blowing, not wind they are
making.

Why not just channel the blowing wind where you want it instead of
converting energy twice?

Because those things are extracting air from the house or van so that
isnt
possible.

Why is it better to move it out instead of in?

Because the hot air in the roofspace is already trying to get
out and it works better to help it do what its trying to do
than to try to stop it doing what it is already trying to do.

It still has to go in somewhere and out somewhere else.

Yes, but its better to help it move faster in the direction
it already wants to go.

Same ventilation takes place overall.

Nope, you move more hot air when you help it to go
in the direction it already wants to go, with a fan.

Ok, I accept your explanation. What surprises me though is just how much
hot air rises. Is there a formula to determine for example, in a
container of certain dimensions, how much hotter the top will be than the
bottom?

Yes, but its complicated.

Surely if I gave you some facts like....

A room 10m by 10m by 10m.
No external sources of heat or draughts, like open windows, heaters etc.
The air near the floor measures 20C.

How warm is the air near the ceiling?

In the case of the van, they are powered by the wind pressure the van
creates when moving.

The above link claims it works when stationary too (by wind).

Yes it does. You've likely noticed that houses don't actually move very
fast
and do have those vents too.

I've occasionally seen them on old houses on chimneys. I thought that
was
to disperse the smoke.

Nope, its just another example of a wind powered fan which
helps the air in the chimney move the way it wants to go.

I rarely see them here, on any type of boiler/fireplace arrangement.

Yeah, basically because the standard chimney pot works pretty well
when the chimney itself is properly designed so it draws well initially
when you are first lighting the fire and are maintenance free.

Except it lets all the cold air in when the fire is out.

On Thu, 25 Oct 2018 21:00:36 +0100, Rod Speed wrote:

Brian Gaff wrote

Hang on though,

Too radical by far...

Why is hanging on radical?

to make it spin it has to have drag.

But a tiny part of the drag of the whole van.

If it has drag its using fuel.

Not when stationary and most of them are
stationary much more than they are moving.

Might be moor efficient then to streamline the van

That should be done anyway.

and run the fan from the van electrics which is there already.

Sure, but that wouldnt work as well when stationary.

"Rod Speed" wrote in message
...
Gym Sulkinson Fork wrote

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

They act like a pump.

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.

It isnt from the place you want to move it from.

Surely that's like fitting a generator to your bicycle to power a motor
to make you go faster?

Nope, more like using a wind generator to generate
electricity and using the electricity to drive a fan, but
without the losses involved with the electricity
generation and the electrical fan.

"Gym Sulkinson Fork" wrote in message
news
On Thu, 25 Oct 2018 17:34:23 +0100, Rod Speed
wrote:



"Gym Sulkinson Fork" wrote in message
news
On Thu, 25 Oct 2018 17:10:21 +0100, Pat wrote:

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. 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.

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.

I suspect you are just trolling,

I'm not.

but I'll chime in anyway. These
devices use the motion of the air traveling past your building (ie,
horizontal motion) into suction that draws hot air up and out of your
building. They work better than just using the upward motion of the
air created by hot air being lighter than cooler air.

I find it hard to believe it really matters whether the air goes in our
out.

Think of an electrically power exhaust fan.

Surely even you can understand that one that is mounted horizontally
at the peak of the roof will work better moving the hot air out of the
roofspace than moving external air into the roofspace.

That's what those things are, but wind powered instead of electrically
powered.

I would have believed it might make it more comfortable if you're sat
lower down in a building, but once it's been running for a while, the hot
air should still have escaped, no matter where it's going.

There is still more being heated by the less than ideal
insulation of the walls and roof and windows of the van.

And the furious wanking of the occupant in your case too.

And surely a van just isn't tall enough to have much of a temperature
differential by height?

It does actually.

"Gym Sulkinson Fork" wrote in message
news
On Thu, 25 Oct 2018 17:35:48 +0100, Rod Speed
wrote:



"Gym Sulkinson Fork" wrote in message
news
On Thu, 25 Oct 2018 17:11:41 +0100, Nightjar wrote:

On 25/10/2018 16:07, Gym Sulkinson Fork wrote:
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? How can you take
power from the wind to then give it back to make it faster? Isn't
that
breaking the laws of physics?

They are a Savonius rotor, which uses the wind to rotate a shaft. There
is a fan attached to the shaft, which, unlike a simple hole, actively
extracts air from the vehicle. They are also widely used on boats, to
keep them ventilated while sitting at their moorings.

I'd just open the window (with a rain guard of course).

Doesn't work when the boat is unattended and those things are
completely automatic, you don't need to know when it might rain
and when to shut the window.

That's why I said rain guard. I've seen caravans with a roof vent with a
hat n top to stop the rain.

Sure, but those rotating ones work better.

On Thu, 25 Oct 2018 21:09:51 +0100, Rod Speed wrote:



"Gym Sulkinson Fork" wrote in message
news
On Thu, 25 Oct 2018 17:31:23 +0100, Rod Speed
wrote:



"Gym Sulkinson Fork" wrote in message
news On Thu, 25 Oct 2018 17:09:56 +0100, Rod Speed
wrote:



"Gym Sulkinson Fork" wrote in message
news On Thu, 25 Oct 2018 16:25:20 +0100, Rod Speed

wrote:

Gym Sulkinson Fork wrote

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

They act like a pump.

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.

It isnt from the place you want to move it from.

Surely that's like fitting a generator to your bicycle to power a
motor
to
make you go faster?

Nope, more like using a wind generator to generate
electricity and using the electricity to drive a fan, but
without the losses involved with the electricity
generation and the electrical fan.

But the point is to move air into or out of (shouldn't matter which,
air
still goes through the van) where the vent is.

It does actually, particularly when getting it to
remove the hot air in the roof space in summer.

but if you let the wind blow it in, then it goes out where it's
currently
coming in.

Yes, but is going against the natural flow of the hot air
coming out of the roofspace, so doesn't work as well.

Think of electrically powered exhaust fans.

The work much getter moving the air out of the roofspace
than moving outside air into the the roofspace.

Makes no difference how that fan is powered,
still works better to move the hot air in the
roofspace in the way it wants to go by convection.

I tend to do that when designing desktop computers,

I only bother with the cpu fan, but don't run mine with covers on.

It has been said (but I've never tested it) that you get better cooling of at least some of the components with the cover on. Hard disks for example I can believe it with. Or indeed anything that doesn't have its own fan.

but mainly because of where the hot chips are and what needs the most
cooling. I have intake fans front bottom cooling the disks,

I don't bother cooling mine but I use the lower speed ones
that only get warm to the touch when the room is over 30C
before I turn the air cooler on.

Never buy the high speed WD drives. I once had a 6 disk array of 1TB WD Caviar blacks. They did have some cooling, although not a fan blowing directly onto them, and every single one failed over 2 years. Must have cost WD a fortune. They were uncomfortable to touch for more than a few seconds.

then across the graphics card,

I'm not into gaming so mine don't even have a fan.

I also use graphics cards for scientific research and bitcoin mining (used to for that last one - it's not profitable).

The only game I ever play is Freecell Pro and it isnt
exactly demanding of the video card.

You're odd.

then over the CPU then out the top back and/or top.

On Thu, 25 Oct 2018 21:14:40 +0100, Rod Speed wrote:



"Gym Sulkinson Fork" wrote in message
news
On Thu, 25 Oct 2018 17:35:48 +0100, Rod Speed
wrote:



"Gym Sulkinson Fork" wrote in message
news On Thu, 25 Oct 2018 17:11:41 +0100, Nightjar wrote:

On 25/10/2018 16:07, Gym Sulkinson Fork wrote:
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? How can you take
power from the wind to then give it back to make it faster? Isn't
that
breaking the laws of physics?

They are a Savonius rotor, which uses the wind to rotate a shaft. There
is a fan attached to the shaft, which, unlike a simple hole, actively
extracts air from the vehicle. They are also widely used on boats, to
keep them ventilated while sitting at their moorings.

I'd just open the window (with a rain guard of course).

Doesn't work when the boat is unattended and those things are
completely automatic, you don't need to know when it might rain
and when to shut the window.

That's why I said rain guard. I've seen caravans with a roof vent with a
hat n top to stop the rain.

Sure, but those rotating ones work better.

Then why do caravans never have them?

On Thu, 25 Oct 2018 21:13:42 +0100, Rod Speed wrote:



"Gym Sulkinson Fork" wrote in message
news
On Thu, 25 Oct 2018 17:34:23 +0100, Rod Speed
wrote:



"Gym Sulkinson Fork" wrote in message
news On Thu, 25 Oct 2018 17:10:21 +0100, Pat wrote:

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. 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.

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.

I suspect you are just trolling,

I'm not.

but I'll chime in anyway. These
devices use the motion of the air traveling past your building (ie,
horizontal motion) into suction that draws hot air up and out of your
building. They work better than just using the upward motion of the
air created by hot air being lighter than cooler air.

I find it hard to believe it really matters whether the air goes in our
out.

Think of an electrically power exhaust fan.

Surely even you can understand that one that is mounted horizontally
at the peak of the roof will work better moving the hot air out of the
roofspace than moving external air into the roofspace.

That's what those things are, but wind powered instead of electrically
powered.

I would have believed it might make it more comfortable if you're sat
lower down in a building, but once it's been running for a while, the hot
air should still have escaped, no matter where it's going.

There is still more being heated by the less than ideal
insulation of the walls and roof and windows of the van.

And the furious wanking of the occupant in your case too.

It amuses me that you think of me in that way. Do you dream about me every night?

Gym Sulkinson Fork wrote

But the power taken from the alternator
would surely be just as bad as the wind drag?

No, because of the worse efficiency of going thru the
electricity. Alternators arent anything even remotely
like 100% efficient, and neither are electric fans.

Both are putting extra strain on the engine.

Yes, but not the same extra load, particularly given
that the van is already a considerable extra drag at
anything more than very low road speeds.

I wonder if anyone has ever studied whether you should
(for fuel efficiency) open your car window when driving on a
hot day or use the cooling fan (ignoring AC for the moment).

Yes they have and the Mythbusters tested it too, but ****ed that up a bit.

Brian Gaff wrote

Hang on though, to make it spin it has to have drag. If it has drag
its using fuel. Might be moor efficient then to streamline the van
and run the fan from the van electrics which is there already.

"Joe Silkinson Spoon" wrote in message
news
On Thu, 25 Oct 2018 21:05:11 +0100, Rod Speed
wrote:



"Gym Sulkinson Fork" wrote in message
news
On Thu, 25 Oct 2018 17:27:20 +0100, Rod Speed
wrote:



"Gym Sulkinson Fork" wrote in message
news On Thu, 25 Oct 2018 17:04:57 +0100, Rod Speed

wrote:



"Gym Sulkinson Fork" wrote in message
news On Thu, 25 Oct 2018 16:20:54 +0100, Ralph Mowery
wrote:

In article ,

says...

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 powered by the wind that is blowing, not wind they are
making.

Why not just channel the blowing wind where you want it instead of
converting energy twice?

Because those things are extracting air from the house or van so that
isnt
possible.

Why is it better to move it out instead of in?

Because the hot air in the roofspace is already trying to get
out and it works better to help it do what its trying to do
than to try to stop it doing what it is already trying to do.

It still has to go in somewhere and out somewhere else.

Yes, but its better to help it move faster in the direction
it already wants to go.

Same ventilation takes place overall.

Nope, you move more hot air when you help it to go
in the direction it already wants to go, with a fan.

Ok, I accept your explanation. What surprises me though is just how
much
hot air rises. Is there a formula to determine for example, in a
container of certain dimensions, how much hotter the top will be than
the
bottom?

Yes, but its complicated.

Surely if I gave you some facts like....

A room 10m by 10m by 10m.
No external sources of heat or draughts, like open windows, heaters etc.
The air near the floor measures 20C.

How warm is the air near the ceiling?

In the case of the van, they are powered by the wind pressure the
van
creates when moving.

The above link claims it works when stationary too (by wind).

Yes it does. You've likely noticed that houses don't actually move
very
fast
and do have those vents too.

I've occasionally seen them on old houses on chimneys. I thought that
was to disperse the smoke.

Nope, its just another example of a wind powered fan which
helps the air in the chimney move the way it wants to go.

I rarely see them here, on any type of boiler/fireplace arrangement.

Yeah, basically because the standard chimney pot works pretty well
when the chimney itself is properly designed so it draws well initially
when you are first lighting the fire and are maintenance free.

Except it lets all the cold air in when the fire is out.

Yep, but so do the spinning ones. The fix for that is a door
down the bottom that can be closed when the fire isnt lit.

Joe Silkinson Spoon wrote
Rod Speed wrote
Brian Gaff wrote

Hang on though,

Too radical by far...

Why is hanging on radical?

Because you can look rather silly when he drives off
with you hanging on, screaming your little heart out.

to make it spin it has to have drag.

But a tiny part of the drag of the whole van.

If it has drag its using fuel.

Not when stationary and most of them are
stationary much more than they are moving.

Might be moor efficient then to streamline the van

That should be done anyway.

and run the fan from the van electrics which is there already.

Sure, but that wouldnt work as well when stationary.

"Rod Speed" wrote in message
...
Gym Sulkinson Fork wrote

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

They act like a pump.

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.

It isnt from the place you want to move it from.

Surely that's like fitting a generator to your bicycle to power a
motor
to make you go faster?

Nope, more like using a wind generator to generate
electricity and using the electricity to drive a fan, but
without the losses involved with the electricity
generation and the electrical fan.

"Joe Silkinson Spoon" wrote in message
news
On Thu, 25 Oct 2018 21:09:51 +0100, Rod Speed
wrote:



"Gym Sulkinson Fork" wrote in message
news
On Thu, 25 Oct 2018 17:31:23 +0100, Rod Speed
wrote:



"Gym Sulkinson Fork" wrote in message
news On Thu, 25 Oct 2018 17:09:56 +0100, Rod Speed

wrote:



"Gym Sulkinson Fork" wrote in message
news On Thu, 25 Oct 2018 16:25:20 +0100, Rod Speed

wrote:

Gym Sulkinson Fork wrote

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

They act like a pump.

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.

It isnt from the place you want to move it from.

Surely that's like fitting a generator to your bicycle to power a
motor
to
make you go faster?

Nope, more like using a wind generator to generate
electricity and using the electricity to drive a fan, but
without the losses involved with the electricity
generation and the electrical fan.

But the point is to move air into or out of (shouldn't matter which,
air
still goes through the van) where the vent is.

It does actually, particularly when getting it to
remove the hot air in the roof space in summer.

but if you let the wind blow it in, then it goes out where it's
currently
coming in.

Yes, but is going against the natural flow of the hot air
coming out of the roofspace, so doesn't work as well.

Think of electrically powered exhaust fans.

The work much getter moving the air out of the roofspace
than moving outside air into the the roofspace.

Makes no difference how that fan is powered,
still works better to move the hot air in the
roofspace in the way it wants to go by convection.

I tend to do that when designing desktop computers,

I only bother with the cpu fan, but don't run mine with covers on.

It has been said (but I've never tested it) that you get better cooling of
at least some of the components with the cover on.

Yes you do, but like I said,, the only hot thing in mine is the cpu and
it has its own fan which actually works better with the covers off.

Hard disks for example I can believe it with.

Yes, but like I said, mine don't get hot
even with the room temp is over 30C

Or indeed anything that doesn't have its own fan.

Not with the stuff that isnt in the airflow. Those
run cooler when the hot air off them convects
out of the case that has no covers on.

but mainly because of where the hot chips are and what needs the most
cooling. I have intake fans front bottom cooling the disks,

I don't bother cooling mine but I use the lower speed ones that only get
warm to the touch when the room is over 30C before I turn the air cooler
on.

Never buy the high speed WD drives.

Yeah, I don't, but because the data isnt recoverable if they die.

I choose not backup the PVR files, essentially because I would
need double the storage and its no big deal if they get lost.

I once had a 6 disk array of 1TB WD Caviar blacks. They did have some
cooling, although not a fan blowing directly onto them, and every single
one failed over 2 years.

Yeah, that happened with a mate of mine even with drive cooling.

Must have cost WD a fortune.

Yeah, and only the duopoly ensured that they didn't go broke.

They were uncomfortable to touch for more than a few seconds.

Yeah, I stopped using the highest speed one a couple of
decades ago now. I leave my system on 24/7/365.25 and
don't close apps that I wont be using for days and always
have enough physical ram so the swap file is never used
except at boot time, so I just don't need hard drive speed,
the slowest are fine and they run the coolest.

then across the graphics card,

I'm not into gaming so mine don't even have a fan.

I also use graphics cards for scientific research and bitcoin mining (used
to for that last one - it's not profitable).

Yeah, I never bothered for that reason. Prefer stock market
speculation and made a lot of money from that.

The only game I ever play is Freecell Pro and it isnt exactly demanding
of the video card.

You're odd.

Don't see the point in games and only play freecell pro
when watching videos etc instead of staring at the screen.

then over the CPU then out the top back and/or top.

"Joe Silkinson Spoon" wrote in message
news
On Thu, 25 Oct 2018 21:14:40 +0100, Rod Speed
wrote:



"Gym Sulkinson Fork" wrote in message
news
On Thu, 25 Oct 2018 17:35:48 +0100, Rod Speed
wrote:



"Gym Sulkinson Fork" wrote in message
news On Thu, 25 Oct 2018 17:11:41 +0100, Nightjar
wrote:

On 25/10/2018 16:07, Gym Sulkinson Fork wrote:
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? How can you
take
power from the wind to then give it back to make it faster? Isn't
that
breaking the laws of physics?

They are a Savonius rotor, which uses the wind to rotate a shaft.
There
is a fan attached to the shaft, which, unlike a simple hole, actively
extracts air from the vehicle. They are also widely used on boats, to
keep them ventilated while sitting at their moorings.

I'd just open the window (with a rain guard of course).

Doesn't work when the boat is unattended and those things are
completely automatic, you don't need to know when it might rain
and when to shut the window.

That's why I said rain guard. I've seen caravans with a roof vent with
a hat n top to stop the rain.

Sure, but those rotating ones work better.

Then why do caravans never have them?

The designers are too stupid and you don't get
the same level of those prepared to spend heaps
like you do with boats. Even Winnebagos are much
cheaper than the flasher boats.

"Joe Silkinson Spoon" wrote in message
news
On Thu, 25 Oct 2018 21:13:42 +0100, Rod Speed
wrote:



"Gym Sulkinson Fork" wrote in message
news
On Thu, 25 Oct 2018 17:34:23 +0100, Rod Speed
wrote:



"Gym Sulkinson Fork" wrote in message
news On Thu, 25 Oct 2018 17:10:21 +0100, Pat
wrote:

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. 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.

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.

I suspect you are just trolling,

I'm not.

but I'll chime in anyway. These
devices use the motion of the air traveling past your building (ie,
horizontal motion) into suction that draws hot air up and out of your
building. They work better than just using the upward motion of the
air created by hot air being lighter than cooler air.

I find it hard to believe it really matters whether the air goes in
our
out.

Think of an electrically power exhaust fan.

Surely even you can understand that one that is mounted horizontally
at the peak of the roof will work better moving the hot air out of the
roofspace than moving external air into the roofspace.

That's what those things are, but wind powered instead of electrically
powered.

I would have believed it might make it more comfortable if you're sat
lower down in a building, but once it's been running for a while, the
hot
air should still have escaped, no matter where it's going.

There is still more being heated by the less than ideal
insulation of the walls and roof and windows of the van.

And the furious wanking of the occupant in your case too.

It amuses me that you think of me in that way.

Know that that's what you get up to, actually.
We've got the drone footage.

On Thu, 25 Oct 2018 21:19:46 +0100, Rod Speed wrote:

Gym Sulkinson Fork wrote

But the power taken from the alternator
would surely be just as bad as the wind drag?

No, because of the worse efficiency of going thru the
electricity. Alternators arent anything even remotely
like 100% efficient, and neither are electric fans.

Both are putting extra strain on the engine.

Yes, but not the same extra load, particularly given
that the van is already a considerable extra drag at
anything more than very low road speeds.

I wonder if anyone has ever studied whether you should
(for fuel efficiency) open your car window when driving on a
hot day or use the cooling fan (ignoring AC for the moment).

Yes they have and the Mythbusters tested it too, but ****ed that up a bit.

And what was the result?

Brian Gaff wrote

Hang on though, to make it spin it has to have drag. If it has drag
its using fuel. Might be moor efficient then to streamline the van
and run the fan from the van electrics which is there already.

On Thu, 25 Oct 2018 21:43:06 +0100, Rod Speed wrote:



"Joe Silkinson Spoon" wrote in message
news
On Thu, 25 Oct 2018 21:05:11 +0100, Rod Speed
wrote:



"Gym Sulkinson Fork" wrote in message
news On Thu, 25 Oct 2018 17:27:20 +0100, Rod Speed
wrote:



"Gym Sulkinson Fork" wrote in message
news On Thu, 25 Oct 2018 17:04:57 +0100, Rod Speed

wrote:



"Gym Sulkinson Fork" wrote in message
news On Thu, 25 Oct 2018 16:20:54 +0100, Ralph Mowery
wrote:

In article ,

says...

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 powered by the wind that is blowing, not wind they are
making.

Why not just channel the blowing wind where you want it instead of
converting energy twice?

Because those things are extracting air from the house or van so that
isnt
possible.

Why is it better to move it out instead of in?

Because the hot air in the roofspace is already trying to get
out and it works better to help it do what its trying to do
than to try to stop it doing what it is already trying to do.

It still has to go in somewhere and out somewhere else.

Yes, but its better to help it move faster in the direction
it already wants to go.

Same ventilation takes place overall.

Nope, you move more hot air when you help it to go
in the direction it already wants to go, with a fan.

Ok, I accept your explanation. What surprises me though is just how
much
hot air rises. Is there a formula to determine for example, in a
container of certain dimensions, how much hotter the top will be than
the
bottom?

Yes, but its complicated.

Surely if I gave you some facts like....

A room 10m by 10m by 10m.
No external sources of heat or draughts, like open windows, heaters etc.
The air near the floor measures 20C.

How warm is the air near the ceiling?

so you don't know then.....

In the case of the van, they are powered by the wind pressure the
van
creates when moving.

The above link claims it works when stationary too (by wind).

Yes it does. You've likely noticed that houses don't actually move
very
fast
and do have those vents too.

I've occasionally seen them on old houses on chimneys. I thought that
was to disperse the smoke.

Nope, its just another example of a wind powered fan which
helps the air in the chimney move the way it wants to go.

I rarely see them here, on any type of boiler/fireplace arrangement.

Yeah, basically because the standard chimney pot works pretty well
when the chimney itself is properly designed so it draws well initially
when you are first lighting the fire and are maintenance free.

Except it lets all the cold air in when the fire is out.

Yep, but so do the spinning ones. The fix for that is a door
down the bottom that can be closed when the fire isnt lit.

You also can hear outside as though a window were open. A barking neighbour's dog coming down the chimney is quite odd.

On Thu, 25 Oct 2018 22:03:07 +0100, Rod Speed wrote:



"Joe Silkinson Spoon" wrote in message
news
On Thu, 25 Oct 2018 21:13:42 +0100, Rod Speed
wrote:



"Gym Sulkinson Fork" wrote in message
news On Thu, 25 Oct 2018 17:34:23 +0100, Rod Speed
wrote:



"Gym Sulkinson Fork" wrote in message
news On Thu, 25 Oct 2018 17:10:21 +0100, Pat
wrote:

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. 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.

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.

I suspect you are just trolling,

I'm not.

but I'll chime in anyway. These
devices use the motion of the air traveling past your building (ie,
horizontal motion) into suction that draws hot air up and out of your
building. They work better than just using the upward motion of the
air created by hot air being lighter than cooler air.

I find it hard to believe it really matters whether the air goes in
our
out.

Think of an electrically power exhaust fan.

Surely even you can understand that one that is mounted horizontally
at the peak of the roof will work better moving the hot air out of the
roofspace than moving external air into the roofspace.

That's what those things are, but wind powered instead of electrically
powered.

I would have believed it might make it more comfortable if you're sat
lower down in a building, but once it's been running for a while, the
hot
air should still have escaped, no matter where it's going.

There is still more being heated by the less than ideal
insulation of the walls and roof and windows of the van.

And the furious wanking of the occupant in your case too.

It amuses me that you think of me in that way.

Know that that's what you get up to, actually.
We've got the drone footage.

I would have seen the drone. And my roof isn't transparent.

On Thu, 25 Oct 2018 22:01:36 +0100, Rod Speed wrote:



"Joe Silkinson Spoon" wrote in message
news
On Thu, 25 Oct 2018 21:14:40 +0100, Rod Speed
wrote:



"Gym Sulkinson Fork" wrote in message
news On Thu, 25 Oct 2018 17:35:48 +0100, Rod Speed
wrote:



"Gym Sulkinson Fork" wrote in message
news On Thu, 25 Oct 2018 17:11:41 +0100, Nightjar
wrote:

On 25/10/2018 16:07, Gym Sulkinson Fork wrote:
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? How can you
take
power from the wind to then give it back to make it faster? Isn't
that
breaking the laws of physics?

They are a Savonius rotor, which uses the wind to rotate a shaft.
There
is a fan attached to the shaft, which, unlike a simple hole, actively
extracts air from the vehicle. They are also widely used on boats, to
keep them ventilated while sitting at their moorings.

I'd just open the window (with a rain guard of course).

Doesn't work when the boat is unattended and those things are
completely automatic, you don't need to know when it might rain
and when to shut the window.

That's why I said rain guard. I've seen caravans with a roof vent with
a hat n top to stop the rain.

Sure, but those rotating ones work better.

Then why do caravans never have them?

The designers are too stupid and you don't get
the same level of those prepared to spend heaps
like you do with boats. Even Winnebagos are much
cheaper than the flasher boats.

surely a van, and the spinny thing, are both pretty cheap.

On Thu, 25 Oct 2018 21:44:48 +0100, Rod Speed wrote:

Joe Silkinson Spoon wrote
Rod Speed wrote
Brian Gaff wrote

Hang on though,

Too radical by far...

Why is hanging on radical?

Because you can look rather silly when he drives off
with you hanging on, screaming your little heart out.

You've been watching too many Harrison Ford films.

to make it spin it has to have drag.

But a tiny part of the drag of the whole van.

If it has drag its using fuel.

Not when stationary and most of them are
stationary much more than they are moving.

Might be moor efficient then to streamline the van

That should be done anyway.

and run the fan from the van electrics which is there already.

Sure, but that wouldnt work as well when stationary.

"Rod Speed" wrote in message
...
Gym Sulkinson Fork wrote

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

They act like a pump.

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.

It isnt from the place you want to move it from.

Surely that's like fitting a generator to your bicycle to power a
motor
to make you go faster?

Nope, more like using a wind generator to generate
electricity and using the electricity to drive a fan, but
without the losses involved with the electricity
generation and the electrical fan.

On Fri, 26 Oct 2018 07:13:42 +1100, cantankerous trolling senile geezer Rot
Speed blabbered, again:

FUSH another 109 lines of the two village idiots' stinking troll ****

--
Another retarded "conversation" between Birdbrain and senile Rot:

Senile Rot: " Did you ever dig a hole to bury your own ****?"

Birdbrain: "I do if there's no flush toilet around."

Senile Rot: "Yeah, I prefer camping like that, off by myself with
no dunnys around and have always buried the ****."

MID:

On Fri, 26 Oct 2018 07:14:40 +1100, cantankerous trolling senile geezer Rot
Speed blabbered, again:

FLUSH the two congenital idiots' latest sick bull****

--
Latest retarded conversation between out two village idiots, Birdbrain and
Rot Speed:

Birdbrain: "You beat me to it. Plain sex is boring."

Senile Rot: "Then **** the cats. That wont be boring."

Birdbrain: "Sell me a de-clawing tool first."

Senile Rot: "Wont help with the teeth."

Birdbrain: "They've never gone for me with their mouths."

Rot Speed: "They will if you are stupid enough to try ****ing them."

Birdbrain: "No, they always use claws."

Rot Speed: "They wont if you try ****ing them. Try it and see."

Message-ID:

....and much better air in here again!

--
Typical retarded "conversation" between the Scottish ****** and senile
Ozzietard:

Birdbrain: "Horse **** doesn't stink."

Senile Rot: "It does if you roll in it."

Birdbrain: "I've never worked out why, I assumed it was maybe meateaters
that made stinky ****, but then why does vegetarian human **** stink? Is it
just the fact that we're capable of digesting meat?"

Senile Rot: "Nope, some cow **** stinks too."

Message-ID:

On Fri, 26 Oct 2018 07:19:46 +1100, cantankerous trolling senile geezer Rot
Speed blabbered, again:

FLUSH the two village idiots' endless idiotic drivel unread again

--
Latest retarded conversation between out two village idiots, Birdbrain and
Rot Speed:

Birdbrain: "You beat me to it. Plain sex is boring."

Senile Rot: "Then **** the cats. That wont be boring."

Birdbrain: "Sell me a de-clawing tool first."

Senile Rot: "Wont help with the teeth."

Birdbrain: "They've never gone for me with their mouths."

Rot Speed: "They will if you are stupid enough to try ****ing them."

Birdbrain: "No, they always use claws."

Rot Speed: "They wont if you try ****ing them. Try it and see."

Message-ID:

"Joe Silkinson Spoon" wrote in message
news
On Thu, 25 Oct 2018 21:19:46 +0100, Rod Speed
wrote:

Gym Sulkinson Fork wrote

But the power taken from the alternator
would surely be just as bad as the wind drag?

No, because of the worse efficiency of going thru the
electricity. Alternators arent anything even remotely
like 100% efficient, and neither are electric fans.

Both are putting extra strain on the engine.

Yes, but not the same extra load, particularly given
that the van is already a considerable extra drag at
anything more than very low road speeds.

I wonder if anyone has ever studied whether you should
(for fuel efficiency) open your car window when driving on a
hot day or use the cooling fan (ignoring AC for the moment).

Yes they have and the Mythbusters tested it too, but ****ed that up a
bit.

And what was the result?

Forget now, think it was that there is bugger all in it.

Brian Gaff wrote

Hang on though, to make it spin it has to have drag. If it has drag
its using fuel. Might be moor efficient then to streamline the van
and run the fan from the van electrics which is there already.

"Joe Silkinson Spoon" wrote in message
news
On Thu, 25 Oct 2018 21:43:06 +0100, Rod Speed
wrote:



"Joe Silkinson Spoon" wrote in message
news
On Thu, 25 Oct 2018 21:05:11 +0100, Rod Speed
wrote:



"Gym Sulkinson Fork" wrote in message
news On Thu, 25 Oct 2018 17:27:20 +0100, Rod Speed

wrote:



"Gym Sulkinson Fork" wrote in message
news On Thu, 25 Oct 2018 17:04:57 +0100, Rod Speed

wrote:



"Gym Sulkinson Fork" wrote in message
news On Thu, 25 Oct 2018 16:20:54 +0100, Ralph Mowery
wrote:

In article ,

says...

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 powered by the wind that is blowing, not wind they are
making.

Why not just channel the blowing wind where you want it instead of
converting energy twice?

Because those things are extracting air from the house or van so
that
isnt
possible.

Why is it better to move it out instead of in?

Because the hot air in the roofspace is already trying to get
out and it works better to help it do what its trying to do
than to try to stop it doing what it is already trying to do.

It still has to go in somewhere and out somewhere else.

Yes, but its better to help it move faster in the direction
it already wants to go.

Same ventilation takes place overall.

Nope, you move more hot air when you help it to go
in the direction it already wants to go, with a fan.

Ok, I accept your explanation. What surprises me though is just how
much
hot air rises. Is there a formula to determine for example, in a
container of certain dimensions, how much hotter the top will be than
the
bottom?

Yes, but its complicated.

Surely if I gave you some facts like....

A room 10m by 10m by 10m.
No external sources of heat or draughts, like open windows, heaters etc.
The air near the floor measures 20C.

How warm is the air near the ceiling?

so you don't know then.....

In the case of the van, they are powered by the wind pressure the
van
creates when moving.

The above link claims it works when stationary too (by wind).

Yes it does. You've likely noticed that houses don't actually move
very
fast
and do have those vents too.

I've occasionally seen them on old houses on chimneys. I thought
that
was to disperse the smoke.

Nope, its just another example of a wind powered fan which
helps the air in the chimney move the way it wants to go.

I rarely see them here, on any type of boiler/fireplace arrangement.

Yeah, basically because the standard chimney pot works pretty well
when the chimney itself is properly designed so it draws well initially
when you are first lighting the fire and are maintenance free.

Except it lets all the cold air in when the fire is out.

Yep, but so do the spinning ones. The fix for that is a door
down the bottom that can be closed when the fire isnt lit.

You also can hear outside as though a window were open. A barking
neighbour's dog coming down the chimney is quite odd.

True.

"Joe Silkinson Spoon" wrote in message
news
On Thu, 25 Oct 2018 22:03:07 +0100, Rod Speed
wrote:



"Joe Silkinson Spoon" wrote in message
news
On Thu, 25 Oct 2018 21:13:42 +0100, Rod Speed
wrote:



"Gym Sulkinson Fork" wrote in message
news On Thu, 25 Oct 2018 17:34:23 +0100, Rod Speed

wrote:



"Gym Sulkinson Fork" wrote in message
news On Thu, 25 Oct 2018 17:10:21 +0100, Pat
wrote:

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. 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.

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.

I suspect you are just trolling,

I'm not.

but I'll chime in anyway. These
devices use the motion of the air traveling past your building (ie,
horizontal motion) into suction that draws hot air up and out of
your
building. They work better than just using the upward motion of
the
air created by hot air being lighter than cooler air.

I find it hard to believe it really matters whether the air goes in
our
out.

Think of an electrically power exhaust fan.

Surely even you can understand that one that is mounted horizontally
at the peak of the roof will work better moving the hot air out of
the
roofspace than moving external air into the roofspace.

That's what those things are, but wind powered instead of
electrically
powered.

I would have believed it might make it more comfortable if you're sat
lower down in a building, but once it's been running for a while, the
hot
air should still have escaped, no matter where it's going.

There is still more being heated by the less than ideal
insulation of the walls and roof and windows of the van.

And the furious wanking of the occupant in your case too.

It amuses me that you think of me in that way.

Know that that's what you get up to, actually.
We've got the drone footage.

I would have seen the drone.

Nope, this one is silent.

And my roof isn't transparent.

Doesn't need to be.

On Fri, 26 Oct 2018 07:44:48 +1100, cantankerous trolling senile geezer Rot
Speed blabbered, again:


Why is hanging on radical?

Because you can look rather silly when he drives off
with you hanging on, screaming your little heart out.

He really should have asked, why are you such an asshole, senile Rot! You've
been trolling today since about ONE o'clock am in Australia (it's 07:44
there now) without any break! So, WHY are you such an asshole, senile Rot?

--
Java Jive to senile Rot:
You're getting there, it's clear that you've now reached the level of
"Nyah nyah nanyah nyah!", but surely you can be even more juvenile than
that?
MID: