Merged DDWFTTW in a “Real” Wind

[3point14]

Never? Really? What happens when the wind speed is zero; what velocity is the balloon moving with then?

I wanna hear the answer to this one!

 

[CORed]

The initial question was settled long ago; all we have left are distractions, and humber's twisting of reality and physics has provided plenty of them.

As I recall, this latest derail started when humber said "name one" when accused of having made a lot of mistakes. I am the guilty party in raising the issue of balloons in the wind, because it's one of humbers more ridiculous misconceptions.

 

[humber]

Why the derail about hot air balloons? What does that have to do with ddwfttw?

Good question. It's a straw man.
The original claim, and the basis of the TM, is faux Galilean Relativity.
To stake the claim that the still air of a room (0m/s wrt the cart), is the same as the cart at wind speed, then objects driven by the wind, must be capable of reaching 0m/s wrt the wind. Exactly the speed of the wind.
They don't. Not even a weather balloon does that.

 

[humber]

Seems like a silly distraction considering neither heat nor engines are required for neutral buoyancy.

The anecdotal evidence provided by week-end balloonists, is used to support the claim the NB balloons ( though it seems any balloon) can reach wind speed, but they have an engine, so it is no surprise that they may. If fact they can exceed wind speed, by using the potential energy gained from gravity. Chalk and cheese.
When they are excluded, there is not even anecdotal evidence to support the claim for WS balloons, whereas theory says they won't reach WS.

 

[humber]

I wanna hear the answer to this one!

If you want to be fussy, then we must consider what "still air" is.
The average velocity of an air molecule in a room is 500m/s.
All objects are bombarded by that, and the effect can be seen as Brownian motion. The balloon would behave like that, so would never be completely still, but the average velocity will be zero. Not necessarily. Some microbes are not symmetrical to that same molecular motion of water, and use it to move.

 

[humber]

As I recall, this latest derail started when humber said "name one" when accused of having made a lot of mistakes. I am the guilty party in raising the issue of balloons in the wind, because it's one of humbers more ridiculous misconceptions.

And I asked you to provide evidence that they do.
You don't like the math, but this graphic, and countless real tests, say no.
http://www.ma.iup.edu/projects/CalcDEMma/drag/drag3.html

 

[temporalillusion]

yes, it's difficult to remain lurking with this stuff flying about.

I hope you didn't miss the posts where the heat source on a hot-air balloon is an engine and the other howler that an internal-combustion engine is a heat engine.

I'm still stuck on him not knowing how an airplane's lift is generated in a thread where lift seems to be a pretty central issue.

 

[CORed]

... Some microbes are not symmetrical to that same molecular motion of water, and use it to move.

Got a source for that? I'm pretty sure it's impossible. Sounds like Maxwell's Demon.

 

[CORed]

And I asked you to provide evidence that they do.
You don't like the math, but this graphic, and countless real tests, say no.
http://www.ma.iup.edu/projects/CalcDEMma/drag/drag3.html

What real tests?

The graphic does not show what you claim it does.

ETA: Or to use a humberism: Assumes its conclusion.

 

[CORed]

I'm still stuck on him not knowing how an airplane's lift is generated in a thread where lift seems to be a pretty central issue.

And, turning it on his side, I don't think he knows how a sail on a broad reach generates lift, or a prop blade with similar geometry.

It seems that, a year after the Blackbird was announced and tested, he got ahold of some test data, saw that the wind was a bit off axis (thouhg much of that appears to be windvane oscillation), and grasping at straws, said, Aha! The cart was tacking. However, he has offered no explanation of how a propeller could benefit from an off axis wind (in fact, its performace degrades) except "propellers are like sails".

He seems to accept the idea that a sail or vertical wing (as in the greenbird) can achieve VMG > wind speed, but not that the blade of a propeller has similar dynamics.

 

[phunk]

If you want to be fussy, then we must consider what "still air" is.
The average velocity of an air molecule in a room is 500m/s.

No, the average speed is 500m/s (assuming that's the right number).

Still air is when the average velocity is 0.

 

[zooterkin]

The anecdotal evidence provided by week-end balloonists, is used to support the claim the NB balloons ( though it seems any balloon) can reach wind speed, but they have an engine, so it is no surprise that they may.

How does something which provides lift impart lateral motion?

If fact they can exceed wind speed, by using the potential energy gained from gravity.

Is anyone claiming that balloons can exceed wind speed?

Chalk and cheese.
When they are excluded, there is not even anecdotal evidence to support the claim for WS balloons, whereas theory says they won't reach WS.

What theory says they won't?

 

[CORed]

How does something which provides lift impart lateral motion?


Is anyone claiming that balloons can exceed wind speed?

What theory says they won't?

The 132nd Law of Humberphysics.

See also. humberneogeocentrism and the theory of earth drag at a distance.

 

[humber]

No, the average speed is 500m/s (assuming that's the right number).

Still air is when the average velocity is 0.

Don't go there, girlfriend.
Air is a mixture of gases and also water. Contrary to what may be expected, water vapor reduces air density. One H2O molecule is less massive than one O2 molecule.
Each gas has its own Velo-speed. Nitrogen is about 400m/s.
But, the velocity is the RMS value, because the motion is random, and in all 3 dimension. The velocity is not zero, and neither is the speed.

 

[humber]

How does something which provides lift impart lateral motion?

Turn on heater. Allow balloon to rise. Turn off heater. Gravity pulls on cooling air and accelerates it towards the ground. Follow a tractrix for example, and you can gain forward velocity.
http://mathworld.wolfram.com/Tractrix.html

Balloons driven by the wind alone, will not reach windspeed.

 

[CORed]

No, the average speed is 500m/s (assuming that's the right number).

Still air is when the average velocity is 0.

I'm not sure humber grasps that distinction.

 

[Dr. Keith]

What real tests?

The graphic does not show what you claim it does.

ETA: Or to use a humberism: Assumes its conclusion.

Yeah, it seems he completely misunderstands that drag is why the balloon will eventually be at WS and instead argues that drag is why the balloon can not reach WS.

 

[CORed]

Don't go there, girlfriend.
Air is a mixture of gases and also water. Contrary to what may be expected, water vapor reduces air density. One H2O molecule is less massive than one O2 molecule.
Each gas has its own Velo-speed. Nitrogen is about 400m/s.
But, the velocity is the RMS value, because the motion is random, and in all 3 dimension. The velocity is not zero, and neither is the speed.

No, he doesn't grasp that distinction. Yet he keeps trying to pass himself off as someone knowledgeable in physics.

 

[Dr. Keith]

I'm not sure humber grasps that distinction.

And at the same time refuse to address the real question: how will a neutrally buoyant balloon move in still air? (assuming it is large enough to ignore brownian motion)

 

[CORed]

Yeah, it seems he completely misunderstands that drag is why the balloon will eventually be at WS and instead argues that drag is why the balloon can not reach WS.

Well, it's pretty clear that any frame of reference other than the ground seriously confuses humber. And if humber is confused, it must be because those evil cart supporters are trying to put one over on him.