Merged DDWFTTW in a “Real” Wind

[jduffy77]

It's embarrassing to be told that the mighty iconoclastic cart was pushed to above WS, isn't it?

Why on earth would you think that? On the contrary, I don't know why the rules don't make pushing to WS mandatory since below WS is irrelevant.

 

[Jack by the hedge]

A firm grasp on straw aids construction of strawmen...

I wonder if the proposed record-busting SuperCart^TM will have a momentum scavenging system which clutches windblown straws from the air and throws them backwards. It seems fitting, somehow.

 

[EHocking]

SKERS?
Straw Kinetic Energy Recovery System?

 

[I Ratant]

The record will fall to the next contestant with a bucket.

.
There's no way to remove the wheels and substitute say, skates, and try the thing on a ice lake, as the propellor would rotate in the wrong direction in the tailwind with no mechanical connection to the ground supports.
The skate-cart would move downwind due to the rotating sail, but not faster than the wind.
The wheels add the extra grunt to assist the sail.
Arguing about the power required...meh!
With only downwind potential, the four mile trip to Albertson's would result in a 23,996 mile return trip.

 

[I Ratant]

.

And when that is done, consider why you believe a cart can go ddwfttw (I believe it works because I can understand how it works, and I have seen evidence of its working).

.
???
This is not an answer.
Explain why it works.
Would that be so difficult?
It works.
The wheels and the rotating sail push it.

 

[Jack by the hedge]

As half that quote is humber and half is me, I'm not sure if you're asking me or humber to explain ourselves.

 

[humber]

.
There's no way to remove the wheels and substitute say, skates, and try the thing on a ice lake, as the propellor would rotate in the wrong direction in the tailwind with no mechanical connection to the ground supports.

Below windspeed. Yes, above WS, prop turns CW.

.
The skate-cart would move downwind due to the rotating sail, but not faster than the wind.

The BB does not move ddw. RMS wind deviation 20+ degrees.

But it is possible to do that for a short time.
Enough to take the record. That is my proposal.
It was made 2 years ago. Easy.

.
The wheels add the extra grunt to assist the sail.
Arguing about the power required...meh!
With only downwind potential, the four mile trip to Albertson's would result in a 23,996 mile return trip.

"grunt"?
The vehicle has no practical use. It's about the theory, I Ratant.

 

[I Ratant]

As half that quote is humber and half is me, I'm not sure if you're asking me or humber to explain ourselves.

.
Why not both?

 

[I Ratant]

Below windspeed. Yes, above WS, prop turns CW.

.
The CCW turning prop moves the cart downwind, -if- it's not connected to the wheels. A CW turning prop does the same thing, not connected to the wheels.
They're rotating sails.
.

The BB does not move ddw. RMS wind deviation 20+ degrees.

But it is possible to do that for a short time.
Enough to take the record. That is my proposal.
It was made 2 years ago. Easy.


"grunt"?
The vehicle has no practical use. It's about the theory, I Ratant.

.
The technical jargon slips by once in awhile.
Just about everyone acknowledges it's just a toy. It's escalated into very expensive toys, that merely duplicate what the first proof-of-concept wire framed and wood things did.

 

[humber]

.
There's no way to remove the wheels and substitute say, skates, and try the thing on a ice lake, as the propellor would rotate in the wrong direction in the tailwind with no mechanical connection to the ground supports.

Below windspeed, yes. Above WS, prop turns CW.

V is the incoming stream.
V' is the slip-stream
V'> V
Note: Props mounted on the rear of the plane, do not have the parasitic drag produced as the faster slip-stream runs over the fuselage.

dv = V'- V

Since V' > V for positive thrust, the area of the slip stream is smaller in the wake of the propeller than in front of it. The absolute velocity in the slip stream is ΔV = V' - V. It extends from a diameter of 0.2D on the axis to 0.8D - 0.9D.

The propeller produces a pressure difference Δp that is turned into a velocity difference in a short distance. The thrust can now be expressed as;


T = (Pi*D2/4)Δp = QρΔV.
The energy equation in the gives
Δp = ρΔV(V + ΔV/2).

ΔV/2 comes from an engine. Freewheeling props do not provide thrust.
The wheels can not by any means drive the prop faster, than dictated by the air stream. No thrust even then.

.
The skate-cart would move downwind due to the rotating sail, but not faster than the wind.

The BB does not move ddw. RMS wind deviation 20+ degrees.

But it is possible to do that for a short time.
Enough to take the record. That is my proposal.
It was made 2 years ago. Easy.

.
The wheels add the extra grunt to assist the sail.
Arguing about the power required...meh!
With only downwind potential, the four mile trip to Albertson's would result in a 23,996 mile return trip.

"grunt"?
The vehicle has no practical use. It's about the theory, I Ratant.

 

[humber]

.
The technical jargon slips by once in awhile.
Just about everyone acknowledges it's just a toy. It's escalated into very expensive toys, that merely duplicate what the first proof-of-concept wire framed and wood things did.

They did not work, either. Same exploitation of the varying wind.
It's about to escalate into an upwind cart and then power generation. All 3 bogus.

As an aside, who needs a prop?
http://www.grc.nasa.gov/WWW/K-12/airplane/cyl.html

 

[jduffy77]

The BB does not move ddw. RMS wind deviation 20+ degrees.

Repeating this lie does not change the facts Humber. Why do you keep doing it?

 

[Jack by the hedge]

.
Why not both?

Sure. What was the question?

 

[Jack by the hedge]

Same exploitation of the varying wind.

Remember you still haven't explained how.

 

[CORed]

Remember you still haven't explained how.

No, but he's made a truly incredible number of humorously failed attempts to explain how, and many humorously impossible explanations of how all the successful demonstrations of ddwftw really weren't successful, because ddwftw is impossible by the First Law of Humberphysics (anything humber doesn't understand is impossible).

 

[humber]

Remember you still haven't explained how.

Yes, I have, and you are not the arbitrator of that.
Your cart fails 10 times over, and all that is needed is once.
The power fall-short of the wheel and prop kills the cart stone dead.
Wind data will bury it.

 

[Llyricist]

Yes, I have, and you are not the arbitrator of that.
Your cart fails 10 times over, and all that is needed is once.
The power fall-short of the wheel and prop kills the cart stone dead.
Wind data will bury it.

Unfortunately for you, the wind data confirms it.

Anyone interested in charts of the raw data let me know. I included Cart Speed, CV Speed, Wind Speed, Deviation from DDW, Cart Acceleration scaled up to see how it varies against other factors, and Wind Speed Multiple scaled up as well.

I also include the second half of the run in a second chart, where the deviation got way off (20-40 degrees), and the decrease in performance is quite clear.

I won't post them unless someone else manages to get the data and misrepresent it, but can e-mail a vector pdf on request.

 

[jadebox]

In fact nothing special "occurs" at the moment where the cart reaches the speed of the wind. At this point the prop is developing considerable thrust. It was already developing thrust before this point and it keeps on developing thrust after this point. The cart goes from under wind speed to over wind speed without any change in mode.

A simple way to visualize that is to think of motor boat going directly down stream. It's not hard to see that there's no difference in the way the prop works when the boat is going less than the speed of the current, the same speed, or faster than the current.

Motor boats are quite capable of going faster downstream than the current. Airplanes have no problem travelling with the wind at a speed greater than the air.

It's the same for the cart.

-- Roger

 

[CORed]

Unfortunately for you, the wind data confirms it.

Anyone interested in charts of the raw data let me know. I included Cart Speed, CV Speed, Wind Speed, Deviation from DDW, Cart Acceleration scaled up to see how it varies against other factors, and Wind Speed Multiple scaled up as well.

I also include the second half of the run in a second chart, where the deviation got way off (20-40 degrees), and the decrease in performance is quite clear.

I won't post them unless someone else manages to get the data and misrepresent it, but can e-mail a vector pdf on request.

I have no doubt that humber is fully capable of misinterpreting the data in a manner that he will claim shows that ddwftw didn't really happen. Whether he will actually make that effort remains to be seen. I got the impression from his earlier posts that he was overwhelmed by the sheer volume of data.

It's pretty clear that there is no evidence that will convince humber that ddwftw is possible. He rejects anything involving treadmills or the like out of hand, and no test conducted under outdoor conditions is likely to have wind steady enough in velocity or direction to satisfy him. Even if a test were conducted in a wind unusually free from gusts or changes in direction, I am sure that humber would invoke gradients or some other nonsense to claim the test was invalid. His claims regarding gusts and gradients might be plausible if only a small excess of wind speed were involved, but for 2.8 X wind speed it is ridiculous on its face.

At this point, the only reason I can see to continue to debate him is amusement. Humber never ceases to amaze me in how much basic stuff he can get wrong in his futile attempts to explain away experimental results that prove him wrong.

Of course, if we all eventually get bored and quit engaging him, he will be certain that it's because he "won".

 

[Llyricist]

I have no doubt that humber is fully capable of misinterpreting the data in a manner that he will claim shows that ddwftw didn't really happen. Whether he will actually make that effort remains to be seen. I got the impression from his earlier posts that he was overwhelmed by the sheer volume of data.

It's pretty clear that there is no evidence that will convince humber that ddwftw is possible. He rejects anything involving treadmills or the like out of hand, and no test conducted under outdoor conditions is likely to have wind steady enough in velocity or direction to satisfy him. Even if a test were conducted in a wind unusually free from gusts or changes in direction, I am sure that humber would invoke gradients or some other nonsense to claim the test was invalid. His claims regarding gusts and gradients might be plausible if only a small excess of wind speed were involved, but for 2.8 X wind speed it is ridiculous on its face.

At this point, the only reason I can see to continue to debate him is amusement. Humber never ceases to amaze me in how much basic stuff he can get wrong in his futile attempts to explain away experimental results that prove him wrong.

Of course, if we all eventually get bored and quit engaging him, he will be certain that it's because he "won".

I am well beyond debating him, and he has me on effective, if not actual, ignore status. And the rules of this forum prohibit my natural inclinations in dealing with his posts, so I limit myself to just pointing out the occasional "error" he makes that no-one else pounces on.