Blowhards Sailing Downwind

J

Joe

Guest
There sure seems to be a lot of people in need of remedial
reading-for-content involved in the thread about sailing downwind.

First of all, in all the posts that I can stand to read, John Larkin is
NOT saying that his wind-propelled object would move FASTER than the
tailwind, just that it WOULD move in the direction of the tailwind.

Second, some people seem to misinterpret John's comments and argue against
their erroneous interpretation of John's comment, or seem to say (*seem
to*, because some of their rants are not very coherent) that an object
cannot be wind propelled at all by a tailwind, regardless of the
contrivance (e.g., windmill driving a gearbox).

Third, I don't know why John hasn't set these people straight, nor do I
understand why this thread has forked in two:

Direct Downwind Faster Than the Wind (DDWFTTW)

vs

Direct Downwind NOT Faster Than the Wind (ddwNfttw).

Those that are arguing against ddwNfttw probably would argue that an
electrical generator cannot supply the electricity that powers its own
field ELECTROmagnets.

Sheesh!

--- Joe
 
In article
<none-3107101753220001@dialup-4.231.172.30.dial1.losangeles1.level3.net>,
none@given.now (Joe) wrote:

There sure seems to be a lot of people in need of remedial
reading-for-content involved in the thread about sailing downwind.

First of all, in all the posts that I can stand to read, John Larkin is
NOT saying that his wind-propelled object would move FASTER than the
tailwind, just that it WOULD move in the direction of the tailwind.

Second, some people seem to misinterpret John's comments and argue against
their erroneous interpretation of John's comment, or seem to say (*seem
to*, because some of their rants are not very coherent) that an object
cannot be wind propelled at all by a tailwind, regardless of the
contrivance (e.g., windmill driving a gearbox).

Third, I don't know why John hasn't set these people straight, nor do I
understand why this thread has forked in two:

Direct Downwind Faster Than the Wind (DDWFTTW)

vs

Direct Downwind NOT Faster Than the Wind (ddwNfttw).

Those that are arguing against ddwNfttw probably would argue that an
electrical generator cannot supply the electricity that powers its own
field ELECTROmagnets.

Sheesh!

--- Joe
Click to expand...
Gulp!

I read too much of that thread and became addled. What John said is so
amazingly simple and obvious, and the people that were arguing against it
so confused, that it seems to have rubbed off on me.

John merely said that an object could be wind propelled directly into a
headwind by way of say, a windmill turning a gearbox and some wheels.

As long as the widmill is allowed to orient itself into the wind (they
usually swivel) the wind powered wheeled vehicle can go in *any*
direction.

--- Joe
 
On Sat, 31 Jul 2010 18:12:26 -0700, none@given.now (Joe) wrote:

In article
none-3107101753220001@dialup-4.231.172.30.dial1.losangeles1.level3.net>,
none@given.now (Joe) wrote:

There sure seems to be a lot of people in need of remedial
reading-for-content involved in the thread about sailing downwind.

First of all, in all the posts that I can stand to read, John Larkin is
NOT saying that his wind-propelled object would move FASTER than the
tailwind, just that it WOULD move in the direction of the tailwind.

Second, some people seem to misinterpret John's comments and argue against
their erroneous interpretation of John's comment, or seem to say (*seem
to*, because some of their rants are not very coherent) that an object
cannot be wind propelled at all by a tailwind, regardless of the
contrivance (e.g., windmill driving a gearbox).

Third, I don't know why John hasn't set these people straight, nor do I
understand why this thread has forked in two:

Direct Downwind Faster Than the Wind (DDWFTTW)

vs

Direct Downwind NOT Faster Than the Wind (ddwNfttw).

Those that are arguing against ddwNfttw probably would argue that an
electrical generator cannot supply the electricity that powers its own
field ELECTROmagnets.

Sheesh!

--- Joe

Gulp!

I read too much of that thread and became addled. What John said is so
amazingly simple and obvious, and the people that were arguing against it
so confused, that it seems to have rubbed off on me.

John merely said that an object could be wind propelled directly into a
headwind by way of say, a windmill turning a gearbox and some wheels.
Click to expand...
Yes, I did say that. It's fairly obvious. What I don't know is how
fast it could move windward, and whether it could actually move faster
upwind than the wind speed. Apparently people have hit numbers like
60% or some such.

The straight downwind, faster than the wind, case probably works too.
It is sure counter-intuitive.

As long as the widmill is allowed to orient itself into the wind (they
usually swivel) the wind powered wheeled vehicle can go in *any*
direction.
Click to expand...
Yup.

John
 
John Larkin wrote:
On Sat, 31 Jul 2010 18:12:26 -0700, none@given.now (Joe) wrote:

In article
none-3107101753220001@dialup-4.231.172.30.dial1.losangeles1.level3.net>,
none@given.now (Joe) wrote:

There sure seems to be a lot of people in need of remedial
reading-for-content involved in the thread about sailing downwind.

First of all, in all the posts that I can stand to read, John Larkin is
NOT saying that his wind-propelled object would move FASTER than the
tailwind, just that it WOULD move in the direction of the tailwind.

Second, some people seem to misinterpret John's comments and argue against
their erroneous interpretation of John's comment, or seem to say (*seem
to*, because some of their rants are not very coherent) that an object
cannot be wind propelled at all by a tailwind, regardless of the
contrivance (e.g., windmill driving a gearbox).

Third, I don't know why John hasn't set these people straight, nor do I
understand why this thread has forked in two:

Direct Downwind Faster Than the Wind (DDWFTTW)

vs

Direct Downwind NOT Faster Than the Wind (ddwNfttw).

Those that are arguing against ddwNfttw probably would argue that an
electrical generator cannot supply the electricity that powers its own
field ELECTROmagnets.

Sheesh!

--- Joe
Gulp!

I read too much of that thread and became addled. What John said is so
amazingly simple and obvious, and the people that were arguing against it
so confused, that it seems to have rubbed off on me.

John merely said that an object could be wind propelled directly into a
headwind by way of say, a windmill turning a gearbox and some wheels.

Yes, I did say that. It's fairly obvious. What I don't know is how
fast it could move windward, and whether it could actually move faster
upwind than the wind speed. Apparently people have hit numbers like
60% or some such.

The straight downwind, faster than the wind, case probably works too.
It is sure counter-intuitive.

As long as the widmill is allowed to orient itself into the wind (they
usually swivel) the wind powered wheeled vehicle can go in *any*
direction.

Yup.

John
Click to expand...
Light sailing boats can sail faster than the wind but not downwind or
with the wind abaft the beam. They are not reliant on the wind pushing
the concave side of the sail but the combined effect of low pressure on
the convex side of the sail, (Bernoullis Law) and the centrifugal force
of the wind rotating in the concave curve of the sail.
 
On Sat, 31 Jul 2010 17:53:21 -0700, Joe wrote:

There sure seems to be a lot of people in need of remedial
reading-for-content involved in the thread about sailing downwind.
Click to expand...
Feel free to go fuck yourself, you ostentatious windbag!
--
I have multiple DUIS, beat my kids, paid $360K for a house worth $275K
got handed a divorce and a Restaining Order to keep away from all of
them. I'm 36, got a beer belly that looks like I'm pregnant 9 months.
Gawd, isn't life good!
 
On Fri, 13 Aug 2010 21:16:14 -0700 (PDT), Bill Bowden
<wrongaddress@att.net> wrote:

On Jul 31, 11:27 pm, John Larkin
jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Sat, 31 Jul 2010 18:12:26 -0700, n...@given.now (Joe) wrote:
In article
none-3107101753220...@dialup-4.231.172.30.dial1.losangeles1.level3.net>,
n...@given.now (Joe) wrote:

There sure seems to be a lot of people in need of remedial
reading-for-content involved in the thread about sailing downwind.

First of all, in all the posts that I can stand to read, John Larkin is
NOT saying that his wind-propelled object would move FASTER than the
tailwind, just that it WOULD move in the direction of the tailwind.

Second, some people seem to misinterpret John's comments and argue against
their erroneous interpretation of John's comment, or seem to say (*seem
to*, because some of their rants are not very coherent) that an object
cannot be wind propelled at all by a tailwind, regardless of the
contrivance (e.g., windmill driving a gearbox).

Third, I don't know why John hasn't set these people straight, nor do I
understand why this thread has forked in two:  

Direct Downwind Faster Than the Wind (DDWFTTW)

vs

Direct Downwind NOT Faster Than the Wind (ddwNfttw).

Those that are arguing against ddwNfttw probably would argue that an
electrical generator cannot supply the electricity that powers its own
field ELECTROmagnets.

Sheesh!

---  Joe

Gulp!

I read too much of that thread and became addled.  What John said is so
amazingly simple and obvious, and the people that were arguing against it
so confused, that it seems to have rubbed off on me.

John merely said that an object could be wind propelled directly into a
headwind by way of say, a windmill turning a gearbox and some wheels.

Yes, I did say that. It's fairly obvious. What I don't know is how
fast it could move windward, and whether it could actually move faster
upwind than the wind speed. Apparently people have hit numbers like
60% or some such.

The straight downwind, faster than the wind, case probably works too.
It is sure counter-intuitive.



As long as the widmill is allowed to orient itself into the wind (they
usually swivel) the wind powered wheeled vehicle can go in *any*
direction.

Yup.

John

So, what did you conclude about sailing downwind faster than the wind?
I read quite a few posts but still didn't figure it out. It seems the
propeller prop extracts kinetic energy from the moving car and propels
it faster, but that doesn't seem to provide any gain of kinetic
energy. How does the car accelerate faster than the wind going
downwind? Eventually, there would be a headwind if the car moved
faster than the wind, which would provide a drag. How do you explain
it in simple terms?

-Bill
Click to expand...
Imagine you're in the car and the groundspeed of the wind is 10 MPH.
The car is moving downwind at 10 MPH. The relative wind, what you
feel, is zero. You have a big lazy pusher propeller on a pylon, and it
sees zero relative wind.

So connect a generator to one wheel and make electricity. And use that
to turn a motor to spin the prop, in the push-the-car-downwind
direction. (Or use a mechanical linkage, same thing.) The wheel is
spinning fast, so generates a decent amount of power. You only have to
turn the prop a little to make thrust. The result is acceleration
downwind.

The trick is that the prop is pushing against the tailwind, and
against a zero relative wind. It doesn't have to work very hard to
make a goodly chunk of thrust... less than the wheel drag needed to
make the power.

Another way to look at it: instead of a tailwind, imagine a truck
behind you, going 10 MPH and pushing your car. You pull out a big
hydraulic jack and arrange to mount it on your car and push against
the truck. Get the hydraulic pressure to pump the jack off one of your
spinning wheels. Wheel spins, pumps jack, pushes the car and the truck
apart. Now the car is moving faster than the truck, ahead of the
truck. Same idea: push against the tailwind instead of the truck, use
a prop instead of a jack.

You can do this in an electronic circuit, too:

http://www.panoramio.com/photo/38968555

Imagine the 12 volt battery is equivalent to a 12 MPH wind. Suppose
the DC/DC converter inputs 17 volts (on the right) and outputs 5 volts
(on the left). The stacked 12v battery and 5v dc/dc output make 17
volts, namely V+. The 17 volts (17 to ground!) powers the input of the
dc/dc converter. The voltage stepdown allows a current step-up, so
there's plenty of V+ amps available to power the converter input.
Tricky, but no paradox, no violation of conservation of energy. You
could buy a $6, 12v to 5v isolated dc/dc converter from Mouser and
build this.

You can push that around a little

http://www.panoramio.com/photo/38968667

and simulate a car that uses a propeller to drive the wheels and move
into the wind.

Cute trick, but not worth getting obsessed about. As some people are.


John
 
On Jul 31, 11:27 pm, John Larkin
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Sat, 31 Jul 2010 18:12:26 -0700, n...@given.now (Joe) wrote:
In article
none-3107101753220...@dialup-4.231.172.30.dial1.losangeles1.level3.net>,
n...@given.now (Joe) wrote:

There sure seems to be a lot of people in need of remedial
reading-for-content involved in the thread about sailing downwind.

First of all, in all the posts that I can stand to read, John Larkin is
NOT saying that his wind-propelled object would move FASTER than the
tailwind, just that it WOULD move in the direction of the tailwind.

Second, some people seem to misinterpret John's comments and argue against
their erroneous interpretation of John's comment, or seem to say (*seem
to*, because some of their rants are not very coherent) that an object
cannot be wind propelled at all by a tailwind, regardless of the
contrivance (e.g., windmill driving a gearbox).

Third, I don't know why John hasn't set these people straight, nor do I
understand why this thread has forked in two:  

Direct Downwind Faster Than the Wind (DDWFTTW)

vs

Direct Downwind NOT Faster Than the Wind (ddwNfttw).

Those that are arguing against ddwNfttw probably would argue that an
electrical generator cannot supply the electricity that powers its own
field ELECTROmagnets.

Sheesh!

---  Joe

Gulp!

I read too much of that thread and became addled.  What John said is so
amazingly simple and obvious, and the people that were arguing against it
so confused, that it seems to have rubbed off on me.

John merely said that an object could be wind propelled directly into a
headwind by way of say, a windmill turning a gearbox and some wheels.

Yes, I did say that. It's fairly obvious. What I don't know is how
fast it could move windward, and whether it could actually move faster
upwind than the wind speed. Apparently people have hit numbers like
60% or some such.

The straight downwind, faster than the wind, case probably works too.
It is sure counter-intuitive.



As long as the widmill is allowed to orient itself into the wind (they
usually swivel) the wind powered wheeled vehicle can go in *any*
direction.

Yup.

John
Click to expand...
So, what did you conclude about sailing downwind faster than the wind?
I read quite a few posts but still didn't figure it out. It seems the
propeller prop extracts kinetic energy from the moving car and propels
it faster, but that doesn't seem to provide any gain of kinetic
energy. How does the car accelerate faster than the wind going
downwind? Eventually, there would be a headwind if the car moved
faster than the wind, which would provide a drag. How do you explain
it in simple terms?

-Bill
 
John Larkin wrote:

Imagine you're in the car and the groundspeed of the wind is 10 MPH.
The car is moving downwind at 10 MPH. The relative wind, what you
feel, is zero. You have a big lazy pusher propeller on a pylon, and it
sees zero relative wind.

So connect a generator to one wheel and make electricity. And use that
to turn a motor to spin the prop, in the push-the-car-downwind
direction. (Or use a mechanical linkage, same thing.) The wheel is
spinning fast, so generates a decent amount of power. You only have to
turn the prop a little to make thrust. The result is acceleration
downwind.
Click to expand...
Really???
Rather than a prop, use another wheel, a 5th one, driving against the
pavement. Why not?


The trick is that the prop is pushing against the tailwind, and
against a zero relative wind. It doesn't have to work very hard to
make a goodly chunk of thrust... less than the wheel drag needed to
make the power.
Click to expand...
Is this a joke?

Another way to look at it: instead of a tailwind, imagine a
Click to expand...
Imagine a calm, no-wind day, and a propeller, powered by a generator
attached to one of the wheels, pushes a car along.
 
On 2010-08-14, Bill Bowden <wrongaddress@att.net> wrote:

So, what did you conclude about sailing downwind faster than the wind?
I read quite a few posts but still didn't figure it out. It seems the
propeller prop extracts kinetic energy from the moving car and propels
it faster, but that doesn't seem to provide any gain of kinetic
energy. How does the car accelerate faster than the wind going
downwind? Eventually, there would be a headwind if the car moved
faster than the wind, which would provide a drag. How do you explain
it in simple terms?
Click to expand...
Sailing faster than the wind in 4 lines:

P=F.V

landspeed is greater than airspeed.

for the same ampunt of power less force (drag) is exerted on the
ground than is produced (as thrust) at the propellor

--
¡spuɐɥ ou 'ɐꟽ ʞooꞀ

--- news://freenews.netfront.net/ - complaints: news@netfront.net ---
 
On 2010-08-14, Beryl <fourl@road.net> wrote:

Really???
Rather than a prop, use another wheel, a 5th one, driving against the
pavement. Why not?
Click to expand...
P=F.V

--
¡spuɐɥ ou 'ɐꟽ ʞooꞀ

--- news://freenews.netfront.net/ - complaints: news@netfront.net ---
 
Bill Bowden wrote:
On Jul 31, 11:27 pm, John Larkin
jjlar...@highNOTlandTHIStechnologyPART.com> wrote:

On Sat, 31 Jul 2010 18:12:26 -0700, n...@given.now (Joe) wrote:

In article
none-3107101753220...@dialup-4.231.172.30.dial1.losangeles1.level3.net>,
n...@given.now (Joe) wrote:

There sure seems to be a lot of people in need of remedial
reading-for-content involved in the thread about sailing downwind.

First of all, in all the posts that I can stand to read, John Larkin is
NOT saying that his wind-propelled object would move FASTER than the
tailwind, just that it WOULD move in the direction of the tailwind.

Second, some people seem to misinterpret John's comments and argue against
their erroneous interpretation of John's comment, or seem to say (*seem
to*, because some of their rants are not very coherent) that an object
cannot be wind propelled at all by a tailwind, regardless of the
contrivance (e.g., windmill driving a gearbox).

Third, I don't know why John hasn't set these people straight, nor do I
understand why this thread has forked in two:

Direct Downwind Faster Than the Wind (DDWFTTW)

vs

Direct Downwind NOT Faster Than the Wind (ddwNfttw).

Those that are arguing against ddwNfttw probably would argue that an
electrical generator cannot supply the electricity that powers its own
field ELECTROmagnets.

Sheesh!

--- Joe

Gulp!

I read too much of that thread and became addled. What John said is so
amazingly simple and obvious, and the people that were arguing against it
so confused, that it seems to have rubbed off on me.

John merely said that an object could be wind propelled directly into a
headwind by way of say, a windmill turning a gearbox and some wheels.

Yes, I did say that. It's fairly obvious. What I don't know is how
fast it could move windward, and whether it could actually move faster
upwind than the wind speed. Apparently people have hit numbers like
60% or some such.

The straight downwind, faster than the wind, case probably works too.
It is sure counter-intuitive.




As long as the widmill is allowed to orient itself into the wind (they
usually swivel) the wind powered wheeled vehicle can go in *any*
direction.

Yup.

John


So, what did you conclude about sailing downwind faster than the wind?
I read quite a few posts but still didn't figure it out. It seems the
propeller prop extracts kinetic energy from the moving car and propels
it faster, but that doesn't seem to provide any gain of kinetic
energy. How does the car accelerate faster than the wind going
downwind? Eventually, there would be a headwind if the car moved
faster than the wind, which would provide a drag. How do you explain
it in simple terms?

-Bill
Vacuum motors :)
Click to expand...
 
On Sat, 14 Aug 2010 00:06:39 -0700, Beryl <fourl@road.net> wrote:

John Larkin wrote:

Imagine you're in the car and the groundspeed of the wind is 10 MPH.
The car is moving downwind at 10 MPH. The relative wind, what you
feel, is zero. You have a big lazy pusher propeller on a pylon, and it
sees zero relative wind.

So connect a generator to one wheel and make electricity. And use that
to turn a motor to spin the prop, in the push-the-car-downwind
direction. (Or use a mechanical linkage, same thing.) The wheel is
spinning fast, so generates a decent amount of power. You only have to
turn the prop a little to make thrust. The result is acceleration
downwind.

Really???
Rather than a prop, use another wheel, a 5th one, driving against the
pavement. Why not?
Click to expand...
Because the pavement is moving 10 mph relative to the car. So it takes
a lot of power to push the cart using a driven wheen, obviously more
power than you can extract from a different wheel. But it's easy to
push against the tailwind because it is moving AT THE SAME SPEED as
the car. It's like pushing against the truck in my example.

It's just an impedance matching problem.

The trick is that the prop is pushing against the tailwind, and
against a zero relative wind. It doesn't have to work very hard to
make a goodly chunk of thrust... less than the wheel drag needed to
make the power.

Is this a joke?
Click to expand...
To you, apparently.

Another way to look at it: instead of a tailwind, imagine a

Imagine a calm, no-wind day, and a propeller, powered by a generator
attached to one of the wheels, pushes a car along.
Click to expand...
Wind-powered cars tend to not work when there's no wind.

The car is WIND POWERED. It extracts energy from the wind. It violates
no conservation principles.

You snipped my truck and electronics examples.

John
 
John Larkin wrote:
On Sat, 14 Aug 2010 00:06:39 -0700, Beryl <fourl@road.net> wrote:

John Larkin wrote:

Imagine you're in the car and the groundspeed of the wind is 10 MPH.
The car is moving downwind at 10 MPH. The relative wind, what you
feel, is zero. You have a big lazy pusher propeller on a pylon, and it
sees zero relative wind.

So connect a generator to one wheel and make electricity. And use that
to turn a motor to spin the prop, in the push-the-car-downwind
direction. (Or use a mechanical linkage, same thing.) The wheel is
spinning fast, so generates a decent amount of power. You only have to
turn the prop a little to make thrust. The result is acceleration
downwind.
Really???
Rather than a prop, use another wheel, a 5th one, driving against the
pavement. Why not?

Because the pavement is moving 10 mph relative to the car.
Click to expand...
But so what?

So it takes a lot of power to push the cart using a driven wheen,
Click to expand...
You jumped that conclusion out of nowhere.

obviously more power than you can extract from a different wheel. But it's easy to
push against the tailwind because it is moving AT THE SAME SPEED as
the car. It's like pushing against the truck in my example.
Click to expand...
Your truck is a towtruck. It has a long flat bed, and it's carrying the
car. Now the car sees it's speed over pavement as zero. A generator on a
wheel of the truck can power the car's propeller, and the car will help
push the truck faster. You can probably see that the car really isn't
needed, the prop can be fixed directly to the truck. Now you're going to
become rich selling this miracle invention that produces extra power and
increases fuel mileage out of nothing.

It's just an impedance matching problem.


The trick is that the prop is pushing against the tailwind, and
against a zero relative wind. It doesn't have to work very hard to
make a goodly chunk of thrust... less than the wheel drag needed to
make the power.
Is this a joke?

To you, apparently.

Another way to look at it: instead of a tailwind, imagine a
Imagine a calm, no-wind day, and a propeller, powered by a generator
attached to one of the wheels, pushes a car along.

Wind-powered cars tend to not work when there's no wind.
Click to expand...
Mine is going to work just like yours, it just goes 10mph slower.

The car is WIND POWERED. It extracts energy from the wind. It violates
no conservation principles.

You snipped my truck and electronics examples.

John
Click to expand...
 
On Sun, 15 Aug 2010 15:54:16 -0700 (PDT), Bill Bowden
<wrongaddress@att.net> wrote:

On Aug 13, 9:53 pm, John Larkin
jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Fri, 13 Aug 2010 21:16:14 -0700 (PDT), Bill Bowden



wrongaddr...@att.net> wrote:
On Jul 31, 11:27 pm, John Larkin
jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Sat, 31 Jul 2010 18:12:26 -0700, n...@given.now (Joe) wrote:
In article
none-3107101753220...@dialup-4.231.172.30.dial1.losangeles1.level3.net>,
n...@given.now (Joe) wrote:

There sure seems to be a lot of people in need of remedial
reading-for-content involved in the thread about sailing downwind.

First of all, in all the posts that I can stand to read, John Larkin is
NOT saying that his wind-propelled object would move FASTER than the
tailwind, just that it WOULD move in the direction of the tailwind.

Second, some people seem to misinterpret John's comments and argue against
their erroneous interpretation of John's comment, or seem to say (*seem
to*, because some of their rants are not very coherent) that an object
cannot be wind propelled at all by a tailwind, regardless of the
contrivance (e.g., windmill driving a gearbox).

Third, I don't know why John hasn't set these people straight, nor do I
understand why this thread has forked in two:  

Direct Downwind Faster Than the Wind (DDWFTTW)

vs

Direct Downwind NOT Faster Than the Wind (ddwNfttw).

Those that are arguing against ddwNfttw probably would argue that an
electrical generator cannot supply the electricity that powers its own
field ELECTROmagnets.

Sheesh!

---  Joe

Gulp!

I read too much of that thread and became addled.  What John said is so
amazingly simple and obvious, and the people that were arguing against it
so confused, that it seems to have rubbed off on me.

John merely said that an object could be wind propelled directly into a
headwind by way of say, a windmill turning a gearbox and some wheels.

Yes, I did say that. It's fairly obvious. What I don't know is how
fast it could move windward, and whether it could actually move faster
upwind than the wind speed. Apparently people have hit numbers like
60% or some such.

The straight downwind, faster than the wind, case probably works too.
It is sure counter-intuitive.

As long as the widmill is allowed to orient itself into the wind (they
usually swivel) the wind powered wheeled vehicle can go in *any*
direction.

Yup.

John

So, what did you conclude about sailing downwind faster than the wind?
I read quite a few posts but still didn't figure it out. It seems the
propeller prop extracts kinetic energy from the moving car and propels
it faster, but that doesn't seem to provide any gain of kinetic
energy. How does the car accelerate faster than the wind going
downwind? Eventually, there would be a headwind if the car moved
faster than the wind, which would provide a drag. How do you explain
it in simple terms?

-Bill

Imagine you're in the car and the groundspeed of the wind is 10 MPH.
The car is moving downwind at 10 MPH. The relative wind, what you
feel, is zero. You have a big lazy pusher propeller on a pylon, and it
sees zero relative wind.

So connect a generator to one wheel and make electricity. And use that
to turn a motor to spin the prop, in the push-the-car-downwind
direction. (Or use a mechanical linkage, same thing.) The wheel is
spinning fast, so generates a decent amount of power. You only have to
turn the prop a little to make thrust. The result is acceleration
downwind.

The trick is that the prop is pushing against the tailwind, and
against a zero relative wind. It doesn't have to work very hard to
make a goodly chunk of thrust... less than the wheel drag needed to
make the power.

Another way to look at it: instead of a tailwind, imagine a truck
behind you, going 10 MPH and pushing your car. You pull out a big
hydraulic jack and arrange to mount it on your car and push against
the truck. Get the hydraulic pressure to pump the jack off one of your
spinning wheels. Wheel spins, pumps jack, pushes the car and the truck
apart. Now the car is moving faster than the truck, ahead of the
truck. Same idea: push against the tailwind instead of the truck, use
a prop instead of a jack.

You can do this in an electronic circuit, too:

http://www.panoramio.com/photo/38968555

Imagine the 12 volt battery is equivalent to a 12 MPH wind. Suppose
the DC/DC converter inputs 17 volts (on the right) and outputs 5 volts
(on the left). The stacked 12v battery and 5v dc/dc output make 17
volts, namely V+. The 17 volts (17 to ground!) powers the input of the
dc/dc converter. The voltage stepdown allows a current step-up, so
there's plenty of V+ amps available to power the converter input.
Tricky, but no paradox, no violation of conservation of energy. You
could buy a $6, 12v to 5v isolated dc/dc converter from Mouser and
build this.

You can push that around a little

http://www.panoramio.com/photo/38968667

and simulate a car that uses a propeller to drive the wheels and move
into the wind.

Cute trick, but not worth getting obsessed about. As some people are.

John

Yes, good ideas. But it the case of the truck pushing the car, there
seems to be some energy storage prior to using the jack to push the
car away from the truck and go faster than the truck.
Click to expand...

I can't see any storage, beyond the momentun of the car itself. The
wheel drives a hydraulic pump which operates the jack. It will work
for as long as the jack can extend.


You could use
the same idea and run a generator to charge a battery for a couple
hours (while being pushed by the truck), and then use a motor to go
much faster than the truck. So, it appears possible to go much faster
than the wind downhill, using some energy storage technique supplied
by the wind.
Click to expand...
Certainly. You could park for a while, raise a windmill, and store
energy. Then haul it down, tuck everything in, and run like hell on
the stored energy. That could go much faster, on average, than the
wind, and probably faster than the beanie-propeller go-kart thing. But
the BeanieMobile can do it steady-state with no stored energy. *Why*
do it is a whole nother issue.

John
 
On Aug 13, 9:53 pm, John Larkin
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Fri, 13 Aug 2010 21:16:14 -0700 (PDT), Bill Bowden



wrongaddr...@att.net> wrote:
On Jul 31, 11:27 pm, John Larkin
jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Sat, 31 Jul 2010 18:12:26 -0700, n...@given.now (Joe) wrote:
In article
none-3107101753220...@dialup-4.231.172.30.dial1.losangeles1.level3.net>,
n...@given.now (Joe) wrote:

There sure seems to be a lot of people in need of remedial
reading-for-content involved in the thread about sailing downwind.

First of all, in all the posts that I can stand to read, John Larkin is
NOT saying that his wind-propelled object would move FASTER than the
tailwind, just that it WOULD move in the direction of the tailwind.

Second, some people seem to misinterpret John's comments and argue against
their erroneous interpretation of John's comment, or seem to say (*seem
to*, because some of their rants are not very coherent) that an object
cannot be wind propelled at all by a tailwind, regardless of the
contrivance (e.g., windmill driving a gearbox).

Third, I don't know why John hasn't set these people straight, nor do I
understand why this thread has forked in two:  

Direct Downwind Faster Than the Wind (DDWFTTW)

vs

Direct Downwind NOT Faster Than the Wind (ddwNfttw).

Those that are arguing against ddwNfttw probably would argue that an
electrical generator cannot supply the electricity that powers its own
field ELECTROmagnets.

Sheesh!

---  Joe

Gulp!

I read too much of that thread and became addled.  What John said is so
amazingly simple and obvious, and the people that were arguing against it
so confused, that it seems to have rubbed off on me.

John merely said that an object could be wind propelled directly into a
headwind by way of say, a windmill turning a gearbox and some wheels.

Yes, I did say that. It's fairly obvious. What I don't know is how
fast it could move windward, and whether it could actually move faster
upwind than the wind speed. Apparently people have hit numbers like
60% or some such.

The straight downwind, faster than the wind, case probably works too.
It is sure counter-intuitive.

As long as the widmill is allowed to orient itself into the wind (they
usually swivel) the wind powered wheeled vehicle can go in *any*
direction.

Yup.

John

So, what did you conclude about sailing downwind faster than the wind?
I read quite a few posts but still didn't figure it out. It seems the
propeller prop extracts kinetic energy from the moving car and propels
it faster, but that doesn't seem to provide any gain of kinetic
energy. How does the car accelerate faster than the wind going
downwind? Eventually, there would be a headwind if the car moved
faster than the wind, which would provide a drag. How do you explain
it in simple terms?

-Bill

Imagine you're in the car and the groundspeed of the wind is 10 MPH.
The car is moving downwind at 10 MPH. The relative wind, what you
feel, is zero. You have a big lazy pusher propeller on a pylon, and it
sees zero relative wind.

So connect a generator to one wheel and make electricity. And use that
to turn a motor to spin the prop, in the push-the-car-downwind
direction. (Or use a mechanical linkage, same thing.) The wheel is
spinning fast, so generates a decent amount of power. You only have to
turn the prop a little to make thrust. The result is acceleration
downwind.

The trick is that the prop is pushing against the tailwind, and
against a zero relative wind. It doesn't have to work very hard to
make a goodly chunk of thrust... less than the wheel drag needed to
make the power.

Another way to look at it: instead of a tailwind, imagine a truck
behind you, going 10 MPH and pushing your car. You pull out a big
hydraulic jack and arrange to mount it on your car and push against
the truck. Get the hydraulic pressure to pump the jack off one of your
spinning wheels. Wheel spins, pumps jack, pushes the car and the truck
apart. Now the car is moving faster than the truck, ahead of the
truck. Same idea: push against the tailwind instead of the truck, use
a prop instead of a jack.

You can do this in an electronic circuit, too:

http://www.panoramio.com/photo/38968555

Imagine the 12 volt battery is equivalent to a 12 MPH wind. Suppose
the DC/DC converter inputs 17 volts (on the right) and outputs 5 volts
(on the left). The stacked 12v battery and 5v dc/dc output make 17
volts, namely V+. The 17 volts (17 to ground!) powers the input of the
dc/dc converter. The voltage stepdown allows a current step-up, so
there's plenty of V+ amps available to power the converter input.
Tricky, but no paradox, no violation of conservation of energy. You
could buy a $6, 12v to 5v isolated dc/dc converter from Mouser and
build this.

You can push that around a little

http://www.panoramio.com/photo/38968667

and simulate a car that uses a propeller to drive the wheels and move
into the wind.

Cute trick, but not worth getting obsessed about. As some people are.

John
Click to expand...
Yes, good ideas. But it the case of the truck pushing the car, there
seems to be some energy storage prior to using the jack to push the
car away from the truck and go faster than the truck. You could use
the same idea and run a generator to charge a battery for a couple
hours (while being pushed by the truck), and then use a motor to go
much faster than the truck. So, it appears possible to go much faster
than the wind downhill, using some energy storage technique supplied
by the wind. You might use smaller increments of energy storage, say
charge the battery for 1 second, and then run the motor for 1 second
and work your way down to the point where the battery and motor are
not needed and energy just flows from the wind directly into the car
with no storage. That's the hard part to visualize, but seems
possible.

-Bill
 
John Larkin wrote:
I can't see any storage, beyond the momentun of the car itself. The
wheel drives a hydraulic pump which operates the jack. It will work
for as long as the jack can extend.
Click to expand...
The jack.. what's it really doing?

(1) Speeding up car
+ (-1) Holding back truck
-----------------------------
*ZERO*
 
On Sun, 15 Aug 2010 19:17:42 -0700, Beryl <fourl@road.net> wrote:

John Larkin wrote:

I can't see any storage, beyond the momentun of the car itself. The
wheel drives a hydraulic pump which operates the jack. It will work
for as long as the jack can extend.

The jack.. what's it really doing?
Click to expand...
Pushing the car to go faster than 10 MPH. Using power from a wheel.

(1) Speeding up car
+ (-1) Holding back truck
-----------------------------
*ZERO*
Click to expand...
I assume that the truck can maintain 10 MPH because, well, it's a
truck. And because I said it was going 10 MPH.

Same thing with pushing against a 10 MPH tailwind. The only problem
there is that the prop isn't as efficient or as stiff as a hydraulic
jack, but it seems to work anyhow.

John
 
John Larkin wrote:
On Sun, 15 Aug 2010 19:17:42 -0700, Beryl <fourl@road.net> wrote:

John Larkin wrote:
I can't see any storage, beyond the momentun of the car itself. The
wheel drives a hydraulic pump which operates the jack. It will work
for as long as the jack can extend.
The jack.. what's it really doing?

Pushing the car to go faster than 10 MPH. Using power from a wheel.
Click to expand...
The "power from a wheel" is from either the car engine or the truck engine.

(1) Speeding up car
+ (-1) Holding back truck
-----------------------------
*ZERO*

I assume that the truck can maintain 10 MPH because, well, it's a
truck. And because I said it was going 10 MPH.
Click to expand...
Well, a Bentley outweighs an S-10, so you goofed.

Same thing with pushing against a 10 MPH tailwind. The only problem
there is that the prop isn't as efficient or as stiff as a hydraulic
jack, but it seems to work anyhow.
Click to expand...
You're tapping off power at the front end to re-apply it at the back,
and some gets wasted along the way.

John
Click to expand...
 
On Sun, 15 Aug 2010 22:26:38 -0700, Beryl <fourl@road.net> wrote:

John Larkin wrote:
On Sun, 15 Aug 2010 19:17:42 -0700, Beryl <fourl@road.net> wrote:

John Larkin wrote:
I can't see any storage, beyond the momentun of the car itself. The
wheel drives a hydraulic pump which operates the jack. It will work
for as long as the jack can extend.
The jack.. what's it really doing?

Pushing the car to go faster than 10 MPH. Using power from a wheel.

The "power from a wheel" is from either the car engine or the truck engine.
Click to expand...
Naturally. It's from the truck engine. Or in the other case, from the
tailwind.


(1) Speeding up car
+ (-1) Holding back truck
-----------------------------
*ZERO*

I assume that the truck can maintain 10 MPH because, well, it's a
truck. And because I said it was going 10 MPH.

Well, a Bentley outweighs an S-10, so you goofed.
Click to expand...
I said the truck was going 10 MPH. You don't think an S-10 can be
driven at a steady 10 MPH, even pushing a Bentley? Use the cruise
control!

Besides, the BeanieMobile is small and very light, and it has a big
prop so is pushed by a lot of wind cross-section.

Same thing with pushing against a 10 MPH tailwind. The only problem
there is that the prop isn't as efficient or as stiff as a hydraulic
jack, but it seems to work anyhow.

You're tapping off power at the front end to re-apply it at the back,
and some gets wasted along the way.
Click to expand...
Sure, a little in the linkages. But you still come out way ahead.

You don't seem to be getting it:

You get more power from the wheel than you need to run the prop to
accelerate past 10 MPH. That's because the prop is pushing against the
tailwind, so it doesn't need much shaft power to make a lot of push.
My electronic examples work on exactly the same math.

OK, I've done my best.

John
 
John Larkin wrote:
On Sun, 15 Aug 2010 22:26:38 -0700, Beryl <fourl@road.net> wrote:
John Larkin wrote:
On Sun, 15 Aug 2010 19:17:42 -0700, Beryl <fourl@road.net> wrote:
John Larkin wrote:
I can't see any storage, beyond the momentun of the car itself. The
wheel drives a hydraulic pump which operates the jack. It will work
for as long as the jack can extend.
The jack.. what's it really doing?
Pushing the car to go faster than 10 MPH. Using power from a wheel.
The "power from a wheel" is from either the car engine or the truck engine.

Naturally. It's from the truck engine.
Click to expand...
Now that power isn't delivered to the truck's rear axle.

Or in the other case, from the tailwind.
Click to expand...
You imagine the car is pushed to a full 10 MPH in a 10 MPH tailwind.
That's impossible. Matching the wind speed at 10 MPH, the car feels no
wind at its back. No push from behind, no wind blast up front. It's in
still air.
 
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