Down wind faster than the wind

[sol invictus]

Nope. Nice try though but that cart aint moving at all with respect to the air.

I'm really starting to lose my patience here. If the car is moving at the speefd of the wind, it isn't moving with respect to the air (by definition). That's exactly like the treadmill.

That's the last time I'm going to explain that - if you can't comprehend even that, you're never going to understand this.

 

[ThinAirDesigns]

Humber:

JWideman has seen the light.

-

When someone familiar with your stuff says:
"The treadmill is merely a misdirection"
That's a winQUOTE]


LOL -- JW is not even "familiar" with the basic premise of inertial frames of reference, let alone "our stuff", but if you wish to consider JW as a win for you, excellent. He must make you very proud.

JB

 

[sol invictus]

No, still air vs a moving treadmill is NOT the same as moving air vs still pavement. You forgot that the drag of the slope will be exactly equal to the power being input from the treadmill's belt. That power input is what moves the cart 'relative' to the belt.

If there's a slope, the situation when you first let it go is identical to a car moving up (or down, depending on how you tilt it) a slope at the speed of the wind. The wind is blowing parallel to the slope.

This is absurdly easy to see. Just take every velocity that's relevant - in this case car, air, and treadmill belt - and subtract the velocity of the belt from it. That new situation is completely and totally identical to the original (so long as nothing else with a different velocity, like the floor, gets into it). Done.

 

[ThinAirDesigns]

I'm really starting to lose my patience here. If the car is moving at the speefd of the wind, it isn't moving with respect to the air (by definition). That's exactly like the treadmill.

That's the last time I'm going to explain that - if you can't comprehend even that, you're never going to understand this.

-


I know Sol -- I have no idea how to explain it better either. Forget whether the device works, or has a motor -- let's just work on the treadmill/street thing.

We are going to mount a wheel driven speedometer and a *chassis mounted* air speed indicator on the device.

Let's just take the case of "as fast as the wind" and compare:

Case "A": cart is going down the street at 10mph in a 10mph tailwind.

Speedometer: 10mph
Air speed indicator: 0mph

Case "B": cart is on the treadmill(TR) which is set at 10mph and is neither moving towards the front of the TR nor to the rear of the TR.

Speedometer: 10mph
Air speed indicator: 0mph


Is there any chance that JW or humber sees the similarities in those two readouts?

humber, since you disagree, tell me what the readouts will be on those instruments in *your* world.

JW, since you disagree, tell me what the readouts will be on those instruments in *your* world.

Remember, I don't give a rip if device is powered by a Hemi right now -- and I don't care if it's being towed -- I only care about the speedometer readout and the wind speed indicator readout.

Case "A" numbers please.

Case "B" numbers please.

Thanks

JB

 

[humber]

Humber:

When someone familiar with your stuff says:
"The treadmill is merely a misdirection"
That's a winQUOTE]

LOL -- JW is not even "familiar" with the basic premise of inertial frames of reference, let alone "our stuff", but if you wish to consider JW as a win for you, excellent. He must make you very proud.

JB

Hello again JW. Did you read my post #134?

If your interested in an exchange on the subject of inertial frames of reference, I would love to have one with you.

You must have changed your frame of integrity.

 

[humber]

-


I know Sol -- I have no idea how to explain it better either. Forget whether the device works, or has a motor -- let's just work on the treadmill/street thing.

We are going to mount a wheel driven speedometer and a *chassis mounted* air speed indicator on the device.

Let's just take the case of "as fast as the wind" and compare:

Case "A": cart is going down the street at 10mph in a 10mph tailwind.

Speedometer: 10mph
Air speed indicator: 0mph

Case "B": cart is on the treadmill(TR) which is set at 10mph and is neither moving towards the front of the TR nor to the rear of the TR.

Speedometer: 10mph
Air speed indicator: 0mph


Is there any chance that JW or humber sees the similarities in those two readouts?

humber, since you disagree, tell me what the readouts will be on those instruments in *your* world.

JW, since you disagree, tell me what the readouts will be on those instruments in *your* world.

Remember, I don't give a rip if device is powered by a Hemi right now -- and I don't care if it's being towed -- I only care about the speedometer readout and the wind speed indicator readout.

Case "A" numbers please.

Case "B" numbers please.

Thanks

JB

Elephants are gray
Mice are gray
Mice are elephants

Where's my $100K ?

 

[technoextreme]

I'm really starting to lose my patience here. If the car is moving at the speefd of the wind, it isn't moving with respect to the air (by definition). That's exactly like the treadmill.

That's the last time I'm going to explain that - if you can't comprehend even that, you're never going to understand this.

I can comprehend it. The problem is that the end result is the car going slower than wind speed. Windspeed is the break even point. After that you have only momentum which is being slowed down by the drag which then means negative acceleration which then means your back to zero relative speed with the air.

 

[spork]

No, still air vs a moving treadmill is NOT the same as moving air vs still pavement.

Well Galileo, Newton, and Einstein thought they were the same, but those guys are dead, so maybe you've worked out something new they hadn't thought of.

You forgot that the drag of the slope will be exactly equal to the power being input from the treadmill's belt.

How is it that every yahoo with a keyboard and monitor (that hasn't even read the thread) is able to figure out exactly what I "forgot"?

Read the thread, study some physics, build the cart as I describe here, and then get back to me.

I think I'll need to see some air speed indicators, hull speedometer, and independent verification before I'll lose my skepticism here.

Excellent! Please post that all on youtube as we have with the cart we built.

 

[sol invictus]

Elephants are gray
Mice are gray
Mice are elephants

Where's my $100K ?

I see - so now not only is this device impossible, the laws of physics are wrong too. Ironically it's on the basis of those laws that you think it's impossible... yuck.

For the last 450 years or so physicists have understood that all motion is relative and that the laws of physics are invariant under boosts (i.e. identical in all situations that differ only by an overall shift in velocity). That's referred to as Galilean relativity - the "Galilean" part should give you a hint how old it is. Apparently that hasn't been enough time for it to percolate into some people's brains.

Anyway, we finally know where the difficulty lies - it has nothing to do with this device, it's just a failure to understand the basics of physics.

 

[technoextreme]

How is it that every yahoo with a keyboard and monitor (that hasn't even read the thread) is able to figure out exactly what I "forgot"?

I'm an engineer too and the one thing I remember from my physics class is that this is the easiest problem on the face of the earth to screw up.

 

[humber]

Well Galileo, Newton, and Einstein thought they were the same, but those guys are dead, so maybe you've worked out something new they hadn't thought of.



How is it that every yahoo with a keyboard and monitor (that hasn't even read the thread) is able to figure out exactly what I "forgot"?

Read the thread, study some physics, build the cart as I describe here, and then get back to me.



Excellent! Please post that all on youtube as we have with the cart we built.

While you are at it, why not build a craft powered by the torque of the first three mentioned gentlemen, as the spin in their graves.

Where's my $100K?

 

[Modified]

The fact that an ice boat can exceed the wind speed in certain directions doesn't necessarily imply that it can exceed the wind speed in all directions (steady state).

It implies that a connected system of such vehicles can do so. If a vehicle can average faster than the wind in some direction, then a connected pair or system of such vehicles which together constitute a single vehicle can maintain steady travel at (close to) that average speed. That step is a given, but you can come up with an actual construction if you like, such as attaching several boats with sliding connections to spokes with free-turning connections to a big center axle. Given semi-ideal components, a trivial amount of energy would be required to maintain the boat positions relative to the spokes such that the center of the axle moves at a constant speed in a straight line.

What I'm showing is that, starting from facts someone with limited physics knowledge can agree on, there is no theoretical reason that a DWFTTW vehicle is impossible (or any direction faster than the wind, now that you bring it up).

 

[sol invictus]

I can comprehend it. The problem is that the end result is the car going slower than wind speed. Windspeed is the break even point. After that you have only momentum which is being slowed down by the drag which then means negative acceleration which then means your back to zero relative speed with the air.

You just contradicted yourself. Either you end up at windspeed - which means zero speed relative to the air, which means the cart stays at fixed position on the treadmill - or you go slower. Make up your mind.

Of course you'll be wrong either way. You can't seem to understand that the motion of the cart is not powered by the wind alone, it's powered by the difference between the speed of the wind and the speed of the ground. That difference has nothing to do with the speed of the cart, and (in principle at least) one can always extract energy from it.

 

[spork]

The "tacking" used by sailors is used as an example model of how ground wind speed vs apparent wind speed relative to a craft can produce craft velocities greater than the wind speed relative to the ground. By itself it doesn't prove this craft works

It does if you understand the kinematics of this craft and how the prop blades are directly analagous to the sail of the ice boat on a downwind tack.

I do have some differences with some pro people here concerning the equivalency of a bidirectional analysis of force vectors, but only wrt efficiency.

That's because we are saying there is no "bidirectional analysis of force vectors". You can put whatever instrumentation you like on the cart - accelerometers, pitot-static system, measure the torque in the transmission, etc. and you will not find any difference between the cart on the belt and the cart on a stationary roadway with a tailwind. The first hint that should prove this case is that there is no such thing as a stationary roadway - not even remotely.

 

[spork]

the resistance of an object to motion through a fluid increases as the cube of the velocity.

Assuming a constant coefficient of drag, the resistance increases with the square of velocity. It's the power required that increases with the cube of velocity.

So even though it is always possible for any given design to be improved to add some amount of top end speed, larger prop cross-section, etc., there remains an approximate practical limit.

The theoretical top end speed of this cart (relative to the wind) is given by the advance ratio (i.e. the distance the prop would theoretically carve forward through the air vs. the distance the wheels would drive it forward given one rotation of the prop). All other factors would simply reduce that top end.

 

[humber]

I see - so now not only is this device impossible, the laws of physics are wrong too. Ironically it's on the basis of those laws that you think it's impossible... yuck.

For the last 450 years or so physicists have understood that all motion is relative and that the laws of physics are invariant under boosts (i.e. identical in all situations that differ only by an overall shift in velocity). That's referred to as Galilean relativity - the "Galilean" part should give you a hint how old it is. Apparently that hasn't been enough time for it to percolate into some people's brains.

Anyway, we finally know where the difficulty lies - it has nothing to do with this device, it's just a failure to understand the basics of physics.

I see. We have 450 years of understanding, yet it seems that you are suggesting that the understanding of these laws is yuckky?

 

[spork]

Where's my $100K ?

I don't have the faintest clue. But if you find it you can put it in an escrow account with my $100K and we'll bet on what this cart does.

 

[spork]

I'm an engineer too ...

I find that disturbing and terrifying if true.

 

[spork]

If a vehicle can average faster than the wind in some direction, then a connected pair or system of such vehicles which together constitute a single vehicle can maintain steady travel at (close to) that average speed.

Yes, but unless you show that the vehicles in question can average a downwind velocity component faster than the wind, connecting such vehicles doesn't get you there.

 

[technoextreme]

I find that disturbing and terrifying if true.

Same here buddy. Same here.

It does if you understand the kinematics of this craft and how the prop blades are directly analagous to the sail of the ice boat on a downwind tack.

No the prop blades are directly analagous to a sail boat running directly into the wind. Your going backwards.