Blowhards Sailing Downwind

On Mon, 16 Aug 2010 20:29:36 -0700, Beryl wrote:

Your gizmo beats using a generator to supply juice to an electric motor,
which then spins the generator, which feeds the motor, which spins...
Your gizmo surpasses the mere 100% efficiency of that perpetual motion
machine, it creates excess power out of nothingness.

No it doesn't. The truck supplies power for both vehicles, and the truck's
fuel consumption will reflect this.

On 2010-08-17, Beryl <fourl_at_road.net> wrote:
Jasen Betts wrote:

However, the propeller isn't working at 0 MPH. If it is, then it isn't
working, so it isn't.
But if it's a good *spinning* propeller, 90% efficient, and the
generator/motor stuff is all 90% efficient too, then this miracle
propulsion system has wasted just 20% of the power it robbed.

so 80% of the power extracted from the ground possing at 15mph is
converted into force exerted exerted against the air that passing
at 5mph meaning a force

F*0.8*15/5 = F*2.4

which is over twice the force slowing the vehicle dure to the machineery
driven by the wheel)

Traveling near windspeed divisor is lower which suggestes that even greater
force could be exerted but I suspect at thaose speeds the propellor is
much less efficient in converting energy into force.

ツ

!!!

It's a Katakana charcter and it looks like a smile, here's one with a
circle. ㋛ and the usual smile symbol ☺

---
¡spu�ɥ ou '�ꟽ ʞooꞀ

Nobody wrote:
On Mon, 16 Aug 2010 20:29:36 -0700, Beryl wrote:

Your gizmo beats using a generator to supply juice to an electric motor,
which then spins the generator, which feeds the motor, which spins...
Your gizmo surpasses the mere 100% efficiency of that perpetual motion
machine, it creates excess power out of nothingness.

No it doesn't. The truck supplies power for both vehicles, and the truck's
fuel consumption will reflect this.

Yabbut John suggests to use cruise control so you won't notice this.

On Aug 15, 5:36 pm, John Larkin
jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Sun, 15 Aug 2010 15:54:16 -0700 (PDT), Bill Bowden



wrongaddr...@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.

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.

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

Ok, I get the idea about the truck pushing the car faster than the
truck since the jack can be geared to move 2 feet to the rear while
the car moves 1 foot ahead.
Therefore when the truck moves 1 foot ahead, the car moves 2 feet
ahead at increased speed. So as long as the truck can keep pushing,
the car will keep accelerating. Interesting idea.

But in the real world, it seems the truck cannot keep pushing against
another truck that pushes in the reverse direction, when the apparent
wind is zero.

Where is the force when the apparent wind is zero?

-Bill

On Tue, 17 Aug 2010 16:45:43 -0700, Beryl <fourl_at_road.net> wrote:

Nobody wrote:
On Mon, 16 Aug 2010 20:29:36 -0700, Beryl wrote:

Your gizmo beats using a generator to supply juice to an electric motor,
which then spins the generator, which feeds the motor, which spins...
Your gizmo surpasses the mere 100% efficiency of that perpetual motion
machine, it creates excess power out of nothingness.
No it doesn't. The truck supplies power for both vehicles, and the truck's
fuel consumption will reflect this.

Yes. The faster you push the car ahead of the truck, the more work the
truck has to do to maintain 10 MPH.

Yabbut John suggests to use cruise control so you won't notice this.

Whether the 10 MPH is servoed by foot control or cruise control
doesn't matter.

To see fuel consumption, look at the gas gauge. Or an MPG display, if
you have one.

John

On Tue, 17 Aug 2010 20:38:29 -0700 (PDT), Bill Bowden
wrongaddress_at_att.net> wrote:

On Aug 15, 5:36 pm, John Larkin
jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Sun, 15 Aug 2010 15:54:16 -0700 (PDT), Bill Bowden



wrongaddr...@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.
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.
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
Ok, I get the idea about the truck pushing the car faster than the
truck since the jack can be geared to move 2 feet to the rear while
the car moves 1 foot ahead.
Therefore when the truck moves 1 foot ahead, the car moves 2 feet
ahead at increased speed. So as long as the truck can keep pushing,
the car will keep accelerating. Interesting idea.

But in the real world, it seems the truck cannot keep pushing against
another truck that pushes in the reverse direction, when the apparent
wind is zero.

Where is the force when the apparent wind is zero?

-Bill

Not to seem too crabby, but this has been explained a zillion times
already. You extract power from a wheel and feed it to the pusher
prop. The wheel works at ground speed but the prop works at relative
wind speed, which is less. There is a lever-like mechanical advantage,
so the silly thing accelerates.

John

John Larkin wrote:
On Tue, 17 Aug 2010 20:38:29 -0700 (PDT), Bill Bowden
wrongaddress_at_att.net> wrote:

On Aug 15, 5:36 pm, John Larkin
jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Sun, 15 Aug 2010 15:54:16 -0700 (PDT), Bill Bowden



wrongaddr...@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.
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.
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
Ok, I get the idea about the truck pushing the car faster than the
truck since the jack can be geared to move 2 feet to the rear while
the car moves 1 foot ahead.
Therefore when the truck moves 1 foot ahead, the car moves 2 feet
ahead at increased speed. So as long as the truck can keep pushing,
the car will keep accelerating. Interesting idea.

But in the real world, it seems the truck cannot keep pushing against
another truck that pushes in the reverse direction, when the apparent
wind is zero.

Where is the force when the apparent wind is zero?

-Bill

Not to seem too crabby, but this has been explained a zillion times
already. You extract power from a wheel and feed it to the pusher
prop. The wheel works at ground speed but the prop works at relative
wind speed, which is less. There is a lever-like mechanical advantage,
so the silly thing accelerates.

John

No, no. You just finished saying that the truck has to work harder.

"The faster you push the car ahead of the truck, the more work the
truck has to do"

That was five minutes ago.

Extracting power from a wheel ultimately extracts it from the truck's
engine, you already acknowledged that too.

"Naturally. It's from the truck engine."

So explain exactly WHAT a generator or pump on the wheel is good for.

On Sun, 15 Aug 2010 15:54:16 -0700 (PDT), Bill Bowden



wrongaddr...@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.

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.

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 Tue, 17 Aug 2010 22:02:39 -0700, Beryl <fourl_at_road.net> wrote:

John Larkin wrote:
On Tue, 17 Aug 2010 20:38:29 -0700 (PDT), Bill Bowden
wrongaddress_at_att.net> wrote:

On Aug 15, 5:36 pm, John Larkin
jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
On Sun, 15 Aug 2010 15:54:16 -0700 (PDT), Bill Bowden



wrongaddr...@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.
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.
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
Ok, I get the idea about the truck pushing the car faster than the
truck since the jack can be geared to move 2 feet to the rear while
the car moves 1 foot ahead.
Therefore when the truck moves 1 foot ahead, the car moves 2 feet
ahead at increased speed. So as long as the truck can keep pushing,
the car will keep accelerating. Interesting idea.

But in the real world, it seems the truck cannot keep pushing against
another truck that pushes in the reverse direction, when the apparent
wind is zero.

Where is the force when the apparent wind is zero?

-Bill
Not to seem too crabby, but this has been explained a zillion times
already. You extract power from a wheel and feed it to the pusher
prop. The wheel works at ground speed but the prop works at relative
wind speed, which is less. There is a lever-like mechanical advantage,
so the silly thing accelerates.

John
No, no. You just finished saying that the truck has to work harder.

Of course. If it's pushing a car that's going 10 MPH, it has to do
some work. If it's pushing a car that's pushing back, so that the car
is moving 12 MPH, the truck engine has to do more work, even though
the truck is still going 10 MPH.

"The faster you push the car ahead of the truck, the more work the
truck has to do"

That was five minutes ago.

Extracting power from a wheel ultimately extracts it from the truck's
engine, you already acknowledged that too.

"Naturally. It's from the truck engine."

So explain exactly WHAT a generator or pump on the wheel is good for.

To produce the power needed to run the hydraulic jack (in one example)
or the propeller (in the other.) In other words, to provide the power
that lets the car move faster than the thing (truck in one case, wind
in the other) that it's pushing against. In the big picture, that
wheel power comes from whatever is doing the pushing, namely the truck
or the wind.

But I'm sure you're not going to get it.

John

On 2010-08-17, Beryl <fourl_at_road.net> wrote:
Jasen Betts wrote:

However, the propeller isn't working at 0 MPH. If it is, then it isn't
working, so it isn't.
But if it's a good *spinning* propeller, 90% efficient, and the
generator/motor stuff is all 90% efficient too, then this miracle
propulsion system has wasted just 20% of the power it robbed.

so 80% of the power extracted from the ground possing at 15mph is
converted into force exerted exerted against the air that passing
at 5mph meaning a force

F*0.8*15/5 = F*2.4

which is over twice the force slowing the vehicle dure to the machineery
driven by the wheel)

On Tue, 17 Aug 2010 16:45:43 -0700, Beryl <fourl_at_road.net> wrote:

Nobody wrote:
On Mon, 16 Aug 2010 20:29:36 -0700, Beryl wrote:

Your gizmo beats using a generator to supply juice to an electric motor,
which then spins the generator, which feeds the motor, which spins...
Your gizmo surpasses the mere 100% efficiency of that perpetual motion
machine, it creates excess power out of nothingness.

No it doesn't. The truck supplies power for both vehicles, and the truck's
fuel consumption will reflect this.

Yes. The faster you push the car ahead of the truck, the more work the
truck has to do to maintain 10 MPH.


Yabbut John suggests to use cruise control so you won't notice this.

Whether the 10 MPH is servoed by foot control or cruise control
doesn't matter.

To see fuel consumption, look at the gas gauge. Or an MPG display, if
you have one.

Jasen Betts wrote:

Here's how the other half works:
With a headwind, airspeed is greater than groundspeed. For the same
Power (P) at each end of the system, there is less Force (drag) exerted
on the propeller, and more Force, as thrust, output at the wheel. Viola!
The propeller now powers the wheel.

And there's almost always some wind.
Every Big Rig on the highways needs to have this system installed.
Ships can put propellers up in the wind and attach generators to their
water propellers to reap the benefits too.
Why isn't this system being used?

¡spu�ɥ ou '�ꟽ ʞooꞀ

I almost thought I had an Aussie font installed.

Where is the force when the apparent wind is zero?

Ok, I get the idea about the truck pushing the car faster than the
truck since the jack can be geared to move 2 feet to the rear while
the car moves 1 foot ahead.
Therefore when the truck moves 1 foot ahead, the car moves 2 feet
ahead at increased speed. So as long as the truck can keep pushing,
the car will keep accelerating. Interesting idea.

But in the real world, it seems the truck cannot keep pushing against
another truck that pushes in the reverse direction, when the apparent
wind is zero.

Where is the force when the apparent wind is zero?

Of course. If it's pushing a car that's going 10 MPH, it has to do
some work. If it's pushing a car that's pushing back, so that the car
is moving 12 MPH, the truck engine has to do more work, even though
the truck is still going 10 MPH.

Sounds familiar.
The jack is

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

If they were the Bentley and S-10, it would appear that the car was
still going 10 MPH and the truck slowed to 8.
Or they'd go 9 and 11 if they were equal weight.
So the jack is pushing two masses apart at 2 MPH, no net gain.

You know that the truck has to work harder or else it slows down. What
about the wind? Same deal, it has to work harder, or else slow down.
Will you deploy more sail when the system turns on? That will help
maintain the car's speed close to, but less than, the 10 MPH tailwind.

But I'm sure you're not going to get it.

The Rube Goldberg setup returns most of the power that it has taken from
the external source that's really pushing the car along. I get that.