Merged DDWFTTW in a “Real” Wind

[kmortis]

I had to move a few posts off to AAH. Keep it civil. Keep it on topic. And remember, the topic is NEVER the other posters.

Replying to this modbox in thread will be off topic  Posted By: kmortis

 

[humber]

Yep. Or this version, that could get the car of an old-fashioned chain-driven roller coaster up the hill faster than the chain is going:

[qimg]http://www.internationalskeptics.com/forums/imagehosting/130124925c11c452d4.jpg[/qimg]

Respectfully,
Myriad

F = T/r
Force at wheel circumference = Shaft torque/wheel radius
Power = T*w ( w= angular velocity in radians)
Power = torque*angular velocity

Both wheels on the same shaft, so both wheels must see the same torque
Both wheels on the same shaft, so both wheels must see the same AV
Both wheels on the same shaft, so both wheels must see the same power


Conclusion: Force at inner wheel = 2*force_outer_wheel
Well done, if you apply twice the force, it will go twice as fast, just like a single wheel.
Gears need separate shafts.

No point in talking of Lyricist cart. It will be as expected more power = more speed.
Just like he has not bothered to complicate it. PM machines always make the same mistake.
Myriad's idea gives the general problem. Gears never change power. What goes in comes out.

 

[Llyricist]

Which drives the prop, which drives the wheel.

Wrong.

Above w/s, the ground drives the wheels, which are geared to drive the prop at a lower speed through the air, which pushes the cart forward at a higher speed over the ground, which drives the wheels.......

The energy input to the feedback loop comes from the wind being slowed down by the propeller.

Of course you are free misinterpret, misrepresent and pull crap ideas out of your hind quarters all you want.

 

[Llyricist]

F = T/r
Force at wheel circumference = Shaft torque/wheel radius
Power = T*w ( w= angular velocity in radians)
Power = torque*angular velocity

Both wheels on the same shaft, so both wheels must see the same torque
Both wheels on the same shaft, so both wheels must see the same AV
Both wheels on the same shaft, so both wheels must see the same power


Conclusion: Force at inner wheel = 2*force_outer_wheel
Well done, if you apply twice the force, it will go twice as fast, just like a single wheel.
Gears need separate shafts.

No point in talking of Lyricist cart. It will be as expected more power = more speed.
Just like he has not bothered to complicate it. PM machines always make the same mistake.
Myriad's idea gives the general problem. Gears never change power. What goes in comes out.

What point do you think you're making? No-one has ever claimed it didn't take more power to go faster.

The only one claiming perpetual motion here is YOU.

 

[GlennB]

Yep. Or this version, that could get the car of an old-fashioned chain-driven roller coaster up the hill faster than the chain is going:

http://www.internationalskeptics.com/forums/imagehosting/130124925c11c452d4.jpg

Respectfully,
Myriad

Interesting. That's the 'spool of fishing line' experiment put to good use.

 

[Llyricist]

Interesting. That's the 'spool of fishing line' experiment put to good use.

Only if it somehow worked out more efficient than just speeding up the chain, because of motor speed/torque/HP or chain heat limitations.

 

[humber]

Rule number one. When faced with problems with the cart, talk of engines, planes, tethered ice carts, and imaginary carts with no supporting math.

Anything but the cart, because that is a PM machine, sold as a "brain teaser". A con-trick.
When you "get it" you get the shaft.

The chart says that NALSA will never be able to run the test against another cart ,and reach the same conclusion.

Myriad's gears. Andy Ruina, 1981.

Paper rejected.

 

[Llyricist]

I see you chose the "hind quarters" route.

 

[Jack by the hedge]

Evasion? And you compare a cranky wind cart to a car with an engine?

No. As usual you are not paying attention. Read it again. I am comparing an aeroplane using reverse-pitch propellers for braking with a car using its engine for braking. Don't you ever tire of being so obviously, consistently wrong?

Ironically, I was only doing so to illustrate the irrelevance of your previous daft analogy.

The brakes don't drive the car, but saying that drag drives the cart, is the same thing.

Just as well nobody but you is saying those things, then. Isn't it?

The red line is the BB, but another cart has less mass, so accelerates faster, meaning that at the point of measurement it is faster, but may have a lower terminal (steady-state) speed, yet steals the record from the BB.
That is a major flaw in the entire procedure.

Why is it a flaw? Who loses (except deniers like you) if another team sets a higher record? I'd like to see it.

The deal was steady-state ddw, not "whatever"

I absolutely don't care what you think "the deal" was. I care that BB went directly downwind, faster than the wind, powered by the wind. I don't even care about your bleating that it wasn't directly enough downwind, because BB does not gain any advantage from it (and aside from some handwaving you have nothing to say it does).

 

[Llyricist]

Wrong.

Above w/s, the ground drives the wheels, which are geared to drive the prop at a lower speed through the air, which pushes the cart forward at a higher speed over the ground, which drives the wheels.......

The energy input to the feedback loop comes from the wind being slowed down by the propeller.

Of course you are free misinterpret, misrepresent and pull crap ideas out of your hind quarters all you want.

Heh,

Above g/s, the air drives the turbine, which is geared drive the wheels at a lower speed over the ground, which pushes the cart forward at a higher speed through the air, which drives the turbine.....

The energy input to the feedback loop comes from the ground being slowed down by the wheels.


The upwind turbine analyzed from the FOR of the air mass.

 

[GlennB]

Only if it somehow worked out more efficient than just speeding up the chain, because of motor speed/torque/HP or chain heat limitations.

Just the gearing (if that's the right term) principle, I mean. I had some geeky fun demonstrating this at a bbq last summer

 

[Llyricist]

Just the gearing (if that's the right term) principle, I mean. I had some geeky fun demonstrating this at a bbq last summer

Fair enough, I guess I was just putting a higher bar than necessary on what constitutes "good use".

 

[jadebox]

Which comes full circle back to your belief that the cart travels the same distance through the air as it does over the ground.

For those that don't get it ... and I didn't understand it at first.

By definition, the cart is travelling in the same direction as the wind, but a little faster.

It makes it a little easier to follow, however, if you use the cart as your frame of reference instead of the ground.

If the cart is facing left, the ground will be moving under the cart at some speed from the left to the right. Let's call that speed x.

Since the cart was moving a little faster than the wind speed, from the perspective of the cart, the air will be moving from the left to the right also. But, the speed of the wind passing the cart will be less than the speed of the ground.

Speed is distance divided by time. From start to finish, the time for all three things, cart, wind, and ground are the same. Since the speeds of the ground and wind are different, the distance the ground and wind travel must be different. Therefore, the cart travels a different distance through the wind than it does on the ground.

Another way to understand this is to think of the cart going the same speed and direction as the wind. In relation to the wind, the cart is not moving. And, in relation to the cart, the wind is not moving. But, the ground is moving. Therefore, the cart must be travelling a different speed and distance through the air than along the ground.

If it makes it easier to understand ... replace the cart with an airplane. As the pilot of the plane, how would you determine how fast you're going if you couldn't see out of the cockpit (using your eyes, gps, radar, etc.) and couldn't ask someone outside the plane? You could open a window and see how fast the wind blows in. But, what would that tell you? It would tell you how fast you are moving through the air, but, because the air itself is moving, it won't tell you how fast you are moving in relation to the ground. In any kind of wind, the ground speed and air speed of the plane are different. The same thing is true of the cart.

-- Roger

 

[Llyricist]

Rule number one. When faced with problems with the cart, talk of engines, planes, tethered ice carts, and imaginary carts with no supporting math.

No humber, in most of those cases, they were examples given in answer to you bringing them up.

You brought up the plane using a prop as an air brake. You brought up simply driving another set of wheels, and nobody here mentioned tethered ice-carts.

 

[jadebox]

Rule number one. When faced with problems with the cart, talk of engines, planes, tethered ice carts, and imaginary carts with no supporting math.

Einstein visualized himself as falling in an elevator long before he worked out the math for the Special Theory of Relativity.

Many of us have found that visualizing simple analogies helps us to understand the more complicated problem. It also helps explain difficult concepts to others.

If, for example, we come across someone having difficulty understanding how the "DDWFTTW" cart works, it makes sense to try to explain it first using illustrations or descriptions before jumping into the math.

-- Roger

 

[humber]

Einstein visualized himself as falling in an elevator long before he worked out the math for the Special Theory of Relativity.

Ha Ha Ha.

Many of us have found that visualizing simple analogies helps us to understand the more complicated problem. It also helps explain difficult concepts to others.

Self-deception is easier that way.

If, for example, we come across someone having difficulty understanding how the "DDWFTTW" cart works, it makes sense to try to explain it first using illustrations or descriptions before jumping into the math.
-- Roger

"difficulty" As if.

 

[humber]

For those that don't get it ... and I didn't understand it at first.

By definition, the cart is travelling in the same direction as the wind, but a little faster.

It makes it a little easier to follow, however, if you use the cart as your frame of reference instead of the ground.

If the cart is facing left, the ground will be moving under the cart at some speed from the left to the right. Let's call that speed x.

Since the cart was moving a little faster than the wind speed, from the perspective of the cart, the air will be moving from the left to the right also. But, the speed of the wind passing the cart will be less than the speed of the ground.

Speed is distance divided by time. From start to finish, the time for all three things, cart, wind, and ground are the same. Since the speeds of the ground and wind are different, the distance the ground and wind travel must be different. Therefore, the cart travels a different distance through the wind than it does on the ground.

Another way to understand this is to think of the cart going the same speed and direction as the wind. In relation to the wind, the cart is not moving. And, in relation to the cart, the wind is not moving. But, the ground is moving. Therefore, the cart must be travelling a different speed and distance through the air than along the ground.

If it makes it easier to understand ... replace the cart with an airplane. As the pilot of the plane, how would you determine how fast you're going if you couldn't see out of the cockpit (using your eyes, gps, radar, etc.) and couldn't ask someone outside the plane? You could open a window and see how fast the wind blows in. But, what would that tell you? It would tell you how fast you are moving through the air, but, because the air itself is moving, it won't tell you how fast you are moving in relation to the ground. In any kind of wind, the ground speed and air speed of the plane are different. The same thing is true of the cart.

-- Roger

" viewed form the frame of the chain, a bicycle may be seen as going backwards. That may be "difficult" to understand
But from the frame of the pedals, the whole bike is moving up and down. Using the potential energy gained from gravity seen from that frame, the chain transfers it to the wheel, and the pedals will run themselves."

 

[EHocking]

F = T/r
Force at wheel circumference = Shaft torque/wheel radius
Power = T*w ( w= angular velocity in radians)
Power = torque*angular velocity

Both wheels on the same shaft, so both wheels must see the same torque
Both wheels on the same shaft, so both wheels must see the same AV
Both wheels on the same shaft, so both wheels must see the same power


Conclusion: Force at inner wheel = 2*force_outer_wheel
Well done, if you apply twice the force, it will go twice as fast, just like a single wheel.

It is not about force, it is about circumferential distance travelled.

If the wheel diameter ratio in the example given is 2 : 1, then the outer wheel travels along a surface it is in contact with (roller coaster track) 2 x the distance that the inner wheel travels along a surface it is in contact with (driving chain).

Gears need separate shafts.

?!

You've got to be kidding.

Haven't you ever ridden a bike with gears?

 

[jadebox]

" viewed form the frame of the chain, a bicycle may be seen as going backwards. That may be "difficult" to understand
But from the frame of the pedals, the whole bike is moving up and down. Using the potential energy gained from gravity seen from that frame, the chain transfers it to the wheel, and the pedals will run themselves."

Oh .... You need to back off just a bit. That was a little too obvious.

-- Roger

 

[humber]

It is not about force, it is about circumferential distance travelled.

If the wheel diameter ratio in the example given is 2 : 1, then the outer wheel travels along a surface it is in contact with (roller coaster track) 2 x the distance that the inner wheel travels along a surface it is in contact with (driving chain).
?!

The problem with all Carteers is that they don't understand simple machines, so fall prey to all sorts of imaginings, while equating cows and hats along the way.

The circumference of a wheel is 2pi*r. When it rolls one turn, the axle moves 2pi*r. Work = force*distance. This is true. Otherwise the center of the wheel would not move as far as the rest of the wheel. I know....it's a "brainteaser"

Push a simple wheel one turn, with force F.
Work = F*(2pi*r)

The ratio of the magical wheel, is 2:1, so twice as much force is needed at the smaller wheel.
If may move half the distance, but the force is doubled, so the work is the same. Brilliant. Carteers discover fire.

You've got to be kidding.
Haven't you ever ridden a bike with gears?

The..err...sprocket at the pedals is on a different shaft, so is free to turn
at a different AV from the wheel. The gearing is determined by the ratio of the wheel to pedal sprockets, and not the ratio of the gears within the cassette. The cart was any easy sell.