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Merged DDWFTTW in a “Real” Wind

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For the record, I posted the data that shows pretty clearly that the cart performs significantly poorer when the deviation from DDW is varying between 20 and 40 degrees than it does in the first half leading to the test period varying between 0 and 20. the post is here:
http://www.internationalskeptics.com/forums/showthread.php?postid=7150152#post7150152

and for a winged sail cart, a typical velocity polar was posted here:
http://www.internationalskeptics.com/forums/showthread.php?postid=7150210#post7150210

And that chart comes from here:

http://www.tspeer.com/landyachts/per...ce/Single.html
 
profpangloss said:
When the variant is positive and negative, the only proper way to take an average value is to use the RMS method of taking the square root of the mean of the squares. That will give you a fair value for how far off of DDW the craft was for the entire run.
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Why is rms preferred over the mean of the absolute deviation for wind direction? Both methods correct for the issue you raise.
 
humber said:
A) No it isn't
B) RMS is not dependent upon a quadratic relationship of the variable.
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A) Yes it is

B) Of course you can take an RMS of anything you damn well please, but to justify its use over mean of ABS, you need a relevant quadratic relationship.

For NIST, their concern is the force of the wind on structures, and that is quadratically related to wind speed, so it makes good sense to use the RMS of wind speed instead of the mean.

For determining the average KE of the individual molecules of air, it makes sense to use the RMS of their speeds, since KE is quadratically related to speed.

You need to show a relevant quadratic relationship to the relative direction of the air to justify RMS in this case.

Again RMS is not the only way to correct for the +/- "problem". And that problem isn't at all relevant in this case with the relative wind direction so overwhelmingly biased in one direction.
 
Llyricist said:
For the record, I posted the data that shows pretty clearly that the cart performs significantly poorer when the deviation from DDW is varying between 20 and 40 degrees than it does in the first half leading to the test period varying between 0 and 20. the post is here:
http://www.internationalskeptics.com/forums/showthread.php?postid=7150152#post7150152

and for a winged sail cart, a typical velocity polar was posted here:
http://www.internationalskeptics.com/forums/showthread.php?postid=7150210#post7150210

And that chart comes from here:

http://www.tspeer.com/landyachts/per...ce/Single.html
Click to expand...

And that stuff is very helpful in understanding exactly why humbers objections are a bridge too far.

Take any two of his objections and the NALSA trial is impossible. Add any other objections and the whole thing has to be CGI.

Unless, at least on of humbers objections is wrong. I wonder which one is least plausible.
 
Llyricist said:
A) Yes it is

B) Of course you can take an RMS of anything you damn well please, but to justify its use over mean of ABS, you need a relevant quadratic relationship.

For NIST, their concern is the force of the wind on structures, and that is quadratically related to wind speed, so it makes good sense to use the RMS of wind speed instead of the mean.

For determining the average KE of the individual molecules of air, it makes sense to use the RMS of their speeds, since KE is quadratically related to speed.

You need to show a relevant quadratic relationship to the relative direction of the air to justify RMS in this case.

Again RMS is not the only way to correct for the +/- "problem". And that problem isn't at all relevant in this case with the relative wind direction so overwhelmingly biased in one direction.
Click to expand...

Piffle
 
Jack by the hedge said:
The reverse torque means that it will not accelerate as quickly as a simple cart with an equivalent propeller fixed in place, but the pitch of the turning propeller means that it presents a constantly retreating surface to the air in contact with the back of the blades. That means that it continues to accelerate (slowly) past windspeed, since the local condition at the blade surface effectively means that it has not yet reached windspeed.
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Harold, just like humber doesn't understand the difference between initial acceleration and terminal velocity, for different gear ratios. In their reasoning a car would achieve the highest speed in 1st gear, because that is what gives greatest initial acceleration
 
profpangloss said:
I would never say that something is absolutely impossible. Certainly using stored energy a vehicle can be built to achieve DDWFTTW trivially. But I don't see how it can be done in real time, steady state with no stored energy, and I certainly don't see how this propeller cart can even reach wind speed, let alone exceed it.
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Admitting you can't understand how it could reach wind speed is a good first step, but obviously it did. If you would, with an open mind, let the folks on this forum educate you I think you are capable of understanding it. It really isn't all that complicated.
 
Dr. Keith said:
Sorry to rehash old arguments, but I hadn't seen this line of thinking before and I don't know much about land yachts.

It does seem a rather damning line of analysis: if you take everything humber says as true the BB is even more amazing than claimed.
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You are right of course. This has been the most consistent source of amusement for me since I started reading Humber's post years ago. The real cart is just clever engineering applied to create an interesting diversion. The Humber cart would revolutionize whole industries if it existed. It would truly be one of the most amazing inventions in history.
 
jduffy77 said:
You are right of course. This has been the most consistent source of amusement for me since I started reading Humber's post years ago. The real cart is just clever engineering applied to create an interesting diversion. The Humber cart would revolutionize whole industries if it existed. It would truly be one of the most amazing inventions in history.
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It is a bit embarrassing that it took me so long to add it all up in my mind. The objections are so hard to wrap my mind around individually that the cumulative aspect of them just highlights how wrong they can't all be right.
 
Yep -- one of the wild things to watch over the last few years has been the incredible lengths people like humber and Schroeder/Christoph/Harold/Yev/ChristopherM/prof/etc. (all one poster) will go to to "explain" what has happened.

The claim that vibration on the threadmill can be harvested to make the cart climb the belt is hilarious considering the specific tuning that would be required to (perhaps) make such a device. You can line up a hundred treadmills of all sizes shapes, makes, weights, etc and a properly completed cart will climb them all with no adjustment whatsoever. Tape varying weights to the cart and still it works. All these factors of course point out the absurdity of such a position - capturing vibrational energy at such a low level requires precise tuning -- well, not with our little 'magic' vibration collector. ROFLAO

Same thing with the 'off the wind' argument -- if their theory is true, we've developed the most efficient wind energy collector of all time (by a huge margin).

Their excuses are astonishing in their complexity and technological leaps -- the real story is one of simple wheels, simple gears and a simple propeller.

JB
 
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Interestingly, there is a sort of inverse quadratic relationship to wind speed for the cart moving faster than the wind. In that as the wind speed falls, the relative headwind increases, increasing it's drag in a quadratic relationship with that increase in relative headwind. So as wind speed increases the drag falls in an inverse quadratic relationship with that increase.

Should we use the Square Mean Root of wind speed? ;)
 
Some further points of interest for anyone who hasn't really grasped the full absurdity of the Humber/HyevPrangGloss tacking theory. Absurdity if you don't believe them, specifications of the most revolutionary sailcraft ever invented if you do.

They admit the cart is maintaining a constant heading on average downwind. They maintain the cart is powered to 2.8x WS not by a traditional sail which needs constant broad reach winds to sail at this speed but by invisible sails which can utilize the shifts in wind direction as a power source. This is achieved by two symmetric invisible sails which do not cancel each other out but provide continuous acceleration utilizing millisecond transients as a power source.

These airfoils on the cart are magic as well as invisible because they provide lift in the direction of travel regardless of the winds direction. A glance at the visible structure of the cart shows that any crosswind component of the wind would tend to tip the cart over. So the cart has invisible stabilizers as well as invisible, magic sails.

The symmetric, invisible, magic sails become miraculous, symmetric, invisible, magic sails when we consider that not only must they accelerate the cart in a way no prior sail craft could begin to, they manage this feat all the while fighting the "failed upwind turbine" as Humber calls it. It is not just a plate drag but a turbine trying to send the cart upwind.

The H's truly must believe that spork, and tad are Gods.
 
jduffy77 said:
Some further points of interest for anyone who hasn't really grasped the full absurdity of the Humber/HyevPrangGloss tacking theory. Absurdity if you don't believe them, specifications of the most revolutionary sailcraft ever invented if you do.

They admit the cart is maintaining a constant heading on average downwind. They maintain the cart is powered to 2.8x WS not by a traditional sail which needs constant broad reach winds to sail at this speed but by invisible sails which can utilize the shifts in wind direction as a power source. This is achieved by two symmetric invisible sails which do not cancel each other out but provide continuous acceleration utilizing millisecond transients as a power source.

These airfoils on the cart are magic as well as invisible because they provide lift in the direction of travel regardless of the winds direction. A glance at the visible structure of the cart shows that any crosswind component of the wind would tend to tip the cart over. So the cart has invisible stabilizers as well as invisible, magic sails.

The symmetric, invisible, magic sails become miraculous, symmetric, invisible, magic sails when we consider that not only must they accelerate the cart in a way no prior sail craft could begin to, they manage this feat all the while fighting the "failed upwind turbine" as Humber calls it. It is not just a plate drag but a turbine trying to send the cart upwind.

The H's truly must believe that spork, and tad are Gods.
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Well said.

On a lighter note, my blood pressure has dropped considerably since I employed judicious use of the ignore feature.
 
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