Merged DDWFTTW in a “Real” Wind

[humber]

Ivanpah is a dry lake bed surrounded by low hills. It's been remarked several times now that the record-setting run was conducted somewhere else. Is that not so?

Oh, that may be from the Carteers. I have all of them on ignore, so I don't see what they post. I am tired of their unsupported opinions.
Sorry about the confusion.
It's this one.
http://www.windfinder.com/forecast/el_mirage_dry_lake_bed. There are extensive records. Run way length was known before the test etc.
All remarks apply to that lake.

Yes. It went fast enough to do the job. It went faster than the following wind, by a large margin.

Not steady-state. That is the point. There is not valid scientific reason for saying that acceleration is proof. That detail was kept quiet. The claim is on record as being steady state. But the claim wasddw. Neither were met. The claim that the average deviation was 10 degrees is flawed for several reasons, and 4 degrees for the test run is BS.

(1) The wind vane is designed to meet static use to NIST standards. It does not have the necessary dynamic performance to allow use on a moving vehicle. When a vane of that sort is moved away from the apparent wind by more than 10 degrees, it will certainly oscillate. That may be "averaged out" to some degree, but the data must be captured. From the manufacture's data on the vane, I have calculated that a minimum sampling rate of 200Hz is necessary. The rate used was 5hz. A wind tunnel test of a similar device used 350Hz.

(2) Wind vanes are second-order devices, and have a preferred position in the wind field - they point into the apparent wind. There will be a time before settling occurs. That depends on the damping facor, which is a function of the L/D ratio of the vane. That damping is non-linear and will cause the vane to be biased to one direction, and make the response time dependent upon deviation. Without the logged data, there is no means of correcting for that.

(3) The anemometer is first-order device, so will have an exponential response time. Thus, the vane and the anemometer cannot be directly correlated. The presents a problem for calculation of the true wind from the apparent. And certainly not this way:
NALSA
"The true wind speed and direction were calculated from the vector sum of the speed, heading and apparent wind of the chase vehicle and the speed and heading of the craft."

It seems NALSA had some doubts.
" There is some increase in measurement uncertainty from 'subtracting
large numbers' effects. It is the feeling of the observers and TAD team that this uncertainty increase is not excessive and is an appropriate tradeoff for the advantages of taking measurements in closer proximity to the craft while avoiding the confounding effects of the large propeller."

I am certain that TAD would be happy to accept the error when they are sure it is in their favour. Since when does the referee consult with the goal-keeper? It is out of bounds for the contestant to handle the data.
Again, as a challenger, would you be happy about that?

The putative - not proven - "confounding error" will be much smaller than the errors forced by the use of a CV. What errors which may have appeared, could be corrected for via calibration. The CV was used because TAD did not deliver the promised instruments on the cart.

(4) The cart is constantly accelerating, and the CV tracks it. That will impose a load on both the vane and the anemometer related to the force produced by the acceleration of the devices against the air mass. That will be substantial for the vane, and suppress the true wind reading. Again, the data is not adequate to allow for analysis that could ameliorate that error.

(5) It is absolutely not correct to determine the overall deviation by the simple method of the arithmetic mean as NALSA have done. The result is best found through means if statistical analysis, but the data is too poor to support that. A common approach is to use the RMS value. When that is done for the 10 second run, the deviation for the test run, becomes 15 degrees, not 4 degrees.

It's a funny old world. As a student, I was involved in a project to measure the wind and other factors for an artificial sheep used in New Zealand. I never thought that would come in handy. I know of the GT31's SiRF chip, because I evaluated it.

And when measured, it was still accelerating. The amount of acceleration is not an issue, but the fact that it was accelerating is an issue.

It is not relevant to the claim as I have explained, but it is not accelerating.

The GT31 updates its Doppler output once a second. The resolution of that is too low to calculate the acceleration over such a short time. It is a matter of FFT analysis, to name but one limitation. Also, it would not be possible to guarantee the result, because being Doppler, the reading is sensitive to angular motion. Waving it at arms length will produce a large enough error to void the calculation. Three units were fitted to the cart. The GT31 has a small internal patch antenna. If they are separated by more than half the wavelength of the GPS carrier, each will read differently. They should be placed back-to back to ensure they are close enough together.

The spacing used makes it impossible to separate small linear speed changes, from those produced by turning. There is a discrepancy between NALSA's data, and the data produced by TAD's chart. That makes the claim suspect at the very least.

NALSA should have used the GT32, which has direct-reading accelerometers. Both units are popular with windsurfing and other groups, so there is a wealth of information available on their use in such sports, and of their accuracy. That provides enough raw data to say the reading is not secure enough for the purposes of validation, especially of such a complex matter. To name but one academic, Nobel Laureate, Dan Kammen, has been called an "idiot" over this claim, and the evidence should meet the mouth.
The GT31 is a nice device, and a breakthrough in terms of price/performance, but it's a consumer hand-held with a market in mind. It has no traceable calibration standard.

NALSA had their doubts over the acceleration..
"One of the reviewers of this report pointed out that the true wind speed (black line in separation graph) was 4-5 mph faster a few seconds before the measurement period(MP) than the speeds during the period yet it continued to accelerate in the lighter winds present in the MP . This brings up the question if there is some way the energy associated with the higher wind can provide acceleration during the measurement period. The observers see no meaningful way this could happen without using stored energy. Blackbird
has no such capability."

If they have ruled out momentum storage, and the wind becomes lighter, what do they think could cause the acceleration? The trial is not Voodoo.
Because the lighter wind should see the acceleration fall, ( there is no reason to support the contrary), then along with the objections I have raised, it would be reasonable to assume that instrument error is the source of the apparent contradiction.

It was travelling downwind, faster than the wind, and the wind was making it speed up even more. The only points in dispute, so far as I can see, are whether its instrumentation was good enough (which I know nothing about) and whether its "directly downwind" heading was sufficiently direct. So far as I can see from the information presented, when the course closed to within a couple of degrees of being directly downwind, the craft continued to accelerate. That looks like pretty good evidence to me.

I can expand on the instruments and provide the math if you wish, but that is time consuming. But, I can say that even without analysis, the readings are close to worthless.

It is absurd to claim 4 degrees for the reasons I mentioned, but one is obvious: the vane is on a vehicle.
Do you think you could guarantee that if you were driving the CV, you could say you were accurate enough to support that small number over 10 seconds? The GPS is of no help, because it must use the C/A position code,
for that purpose, and there is no way it can be accurate enough for that. It would take many runs to gain enough data to even begin. One run is worthless.

The question of ddw is one of thermodynamics I really don't think it is.

Dan Kammen thinks it is. Dr Camp thinks it is. As do so many more. In fact, it is. The claim would violate the conservation of energy.

I should add that the claim is bogus for reasons other than poor instrumentation.

It is said that the cart "extracts" energy from the headwind it sees above WS, so driving it even faster. That is a recipe for perpetual motion, but in the case of the BB, there is a further snag.

The prop has a ratchet which prevents the prop from driving the wheel. Even if the rotor were to extract that energy, it can't drive the wheel. If the claim then becomes that the prop generates "thrust" or whatever, such that drive to the wheel is unnecessary, then the hypothesis around the gears must be wrong. Lose one way or the other.

Given that the supporting theory has a hole below the waterline, I think it is safe to say the result is due to poor instrumentation, and the cart is not traveling ddw.

 

[humber]

I met humber before, when I was a newbie here. I think he's open to reason: I thought he was mistaken about something and we had a nice chat about a graph he made and then suddenly he stopped posting and didn't post anything for about 15 months. I may be wrong and goodness knows I wasn't the only one involved in the conversation but I think that might be his way of showing he was convinced.

I remember, JBTH. I think at that time I stopped posting altogether.

I tested that cart for my own curiosity. I used a small strain-gauge, and it says I am right, but it is very hard to avoid impulse force.
But, you see, it's a bit "counter-intuitive"

 

[spork]

I met humber before, when I was a newbie here. I think he's open to reason...

I can assure you he's not.

 

[humber]

I can assure you he's not.

Your cart is busted, Chief. One of your many claims of how the cart works, was that the ground drove the wheels. Literally "ground power". When you adopted the "air lever" argument you got from your NASA pal Steve Smith ( he put that same argument to me in the emails we exchanged *), you forgot about the ratchet that was there to exclude the possibility of the prop driving the wheel.

That fossil has come back to haunt you, because there is no means by which the prop can "extract" energy from the wind, so as to drive the wheel, because of the ratchet.

If you posit any other means by which the prop can aid the cart, that makes a mockery of the role you claim that gearing plays in the cart's theory.

You could of course claim that the ratchet does not work, but that would lend the impression of careless ineptitude, but you never actually demonstrated if the ratchet works or not, so you will have to repeat the trial to sustain your claim.

ETA: Sweet.
* NASA later replied saying they held no official position on the cart.

 

[Llyricist]

Your cart is busted, Chief. One of your many claims of how the cart works, was that the ground drove the wheels. Literally "ground power". When you adopted the "air lever" argument you got from your NASA pal Steve Smith ( he put that same argument to me in the emails we exchanged), you forgot about the ratchet that was there to exclude the possibility of the prop driving the wheel.

That fossil has come back to haunt you, because there is no means by which the prop can "extract" energy from the wind, so as to drive the wheel because of the ratchet.

If you posit any other means by which the prop can aid the cart, that makes a mockery of the role you claim that gearing plays in the cart's theory.

You could of course claim that the ratchet does not work, but that does lend the impression of careless ineptitude, but you never actually demonstrated if it works or not, so you will have to repeat the trial to sustain you claim.

You;re getting really good at being wrong in every detail.

 

[Llyricist]

Your cart is busted, Chief. One of your many claims of how the cart works, was that the ground drove the wheels. Literally "ground power".

That claim never changed

When you adopted the "air lever" argument you got from your NASA pal Steve Smith ( he put that same argument to me in the emails we exchanged), you forgot about the ratchet that was there to exclude the possibility of the prop driving the wheel.

Leverage was always the explanation with the power analysis. The ratchet is irrelevant, there was never a claim that the prop powered the wheels.

That fossil has come back to haunt you, because there is no means by which the prop can "extract" energy from the wind,

Wrong, it extracts energy by slowing the wind down wrt the ground

so as to drive the wheel, because of the ratchet.

It does not drive the wheels it pushes the cart forward directly. the ground drives the wheels.

If you posit any other means by which the prop can aid the cart, that makes a mockery of the role you claim that gearing plays in the cart's theory.

No, it doesn't, the gearing is what provides the necessary leverage between the air and the ground.

You could of course claim that the ratchet does not work, but that would lend the impression of careless ineptitude, but you never actually demonstrated if the ratchetg works or not, so you will have to repeat the trial to sustain your claim.

No need to claim it does not work, it's presence does not effect the normal operation of the cart, it only protects the prop and drive train in case of heavy braking.

And you don't think it was demonstrated working to the relevant observers? That would be a really bad assumption. Pretty much guaranteed to be wrong.

 

[Llyricist]

I'm not going to bother with the WoT of wrongness unless someone else thinks he made a valid point in there somewhere.

 

[Subduction Zone]

I'm not going to bother with the WoT of wrongness unless someone else thinks he made a valid point in there somewhere.

Are you kidding us? That was humber after all.

 

[humber]

There are two options for the role of the apparent wind generated by the cart's motion. It can drive the rotor CCW ( when viewed from the rear), but that would oppose the wheel, and drive the cart backwards.

If that same wind were to drive the rotor CW, (prop mode), then the ratchet would disengage the rotor from the wheel.

If the claim is that the prop produces thrust as a free-wheeling prop, that leaves no place for the gearing that is said to be the essential to the theory.

If the ratchet is not fitted, nor operational, that leaves the cart open to the argument that momentum storage is responsible for the cart's behavior, something which has hitherto been discounted because of the ratchet, and the direct claims that it was fitted.

The ratchet has been the source of many breakages, but the passage below suggests it is not fitted, whereas there are abundant responses from TAD, saying the ratchet prevents momentum transfer to the wheel. That is both confounding and misleading.

From Spork's Submission report;
Proof that the vehicle performs best Dead Downwind
"As can readily be seen from the above analysis, the vehicle performance is
driven significantly by the prop efficiency. This of course is primarily a function of the Lift/Drag ratio of the propeller airfoil at its operating angle of attack. The propeller on the Blackbird is based on the NACA 6412 airfoil which has it’s maximum L/D at 4.0 degrees, and has a twist such that the airfoil at each spanwise station is presented at that angle of attack (AOA).

When the relative flow is aligned with the propeller axis, that AOA can be maintained at all spanwise stations throughout the complete rotation. As the prop rotates counter-clockwise when viewed from in front of the vehicle, any cross-wind component from the right will cause the AOA for the top blade to increase while the angle of attack of the bottom blade is decreased. A cross wind component from the left will have the same effect in the opposite direction. In both cases the AOA will depart from its optimum value to varying degrees over the full rotation of the prop in this case – reducing the propeller performance – and thus the overall performance of the cart. The cart employs no other aerodynamic surfaces that can take advantage of a cross-wind component."

Without the ratchet, those same cross-winds will allow energy to be stored and released by the elastic deformation of the tower and prop blades, and in denial of the claim that the cart works best when ddw. As I have said, and the trial chart shows, acceleration increases when the cart is not ddw.

The most likely mechanism for mechanical momentum storage, is the wind gradient. As the rotor turns, each blade passes through the low speed air near the ground, and then the higher speed air several meters above.

That produces and oscillator, which will stress the blades and tower, storing and releasing energy with each turn. At 27mph, that occurs at around 100Hz. The cart needs but 300/s, and that means only 30J per cycle need be extracted from the wind. Such oscillation has destroyed wind turbines.

The NALSA data shows the wind changes of 20 degrees in 0.2 seconds, so strong cross-winds are certainly there, and will be much faster than the average of wind speed of 10mph.

ETA:
The arguments about steady state and the energy level of the wind still apply, but now there this additional mechanism. Along with the minimum of 15 degrees deviation from ddw, there is no reason to
uphold the claim of ddwdtw, steady-state.

 

[spork]

I wish he'd at least learn to condense his delusions and insults into just a few lines. I just can't be bothered to read all the ******** diatribes that he spews. And I know I miss some real gems because of it.

 

[Llyricist]

I wish he'd at least learn to condense his delusions and insults into just a few lines. I just can't be bothered to read all the ******** diatribes that he spews. And I know I miss some real gems because of it.

In that last post he just condensed a bunch of old PRATTs into one WoT.

 

[Llyricist]

And he ETA'd that the BB is the most amazing conventional sail craft ever built, as usual, without realizing that is what he said.

 

[humber]

I wish he'd at least learn to condense his delusions and insults into just a few lines. I just can't be bothered to read all the ******** diatribes that he spews. And I know I miss some real gems because of it.

It that your best rebuttal in support of a claim that you see gives you license to call Prof Allain, Prof Whiteman, Dan Kammen and Charles Platt, idiots?

I am directly accusing you of manipulation of NASLA's data to hide the gusty and variable wind that allows the cart to operate as seen. I have asked you several times to address that, or make public the raw data, so that others may analysis it. Do you have such a rebuttal, and will you post the data?

ETA:
The minimum deviation during the test period is 15 degrees RMS. The remainder may be up to 40 degrees. The Jenkins' video shows that deviation and more. Because there is no video of the trial itself, nor a vane on the cart
that would allow the vane to be seen, that data is crucial in support.

 

[CORed]

It that your best rebuttal in support of a claim that you see gives you license to call Prof Allain, Prof Whiteman, Dan Kammen and Charles Platt, idiots?

I am directly accusing you of manipulation of NASLA's data to hide the gusty and variable wind that allows the cart to operate as seen. I have asked you several times to address that, or make public the raw data, so that others may analysis it. Do you have such a rebuttal, and will you post the data?

ETA:
The minimum deviation during the test period is 15 degrees RMS. The remainder may be up to 40 degrees. The Jenkins' video shows that deviation and more. Because there is no video of the trial itself, nor a vane on the cart
that would allow the vane to be seen, that data is crucial in support.

Wasn't Charles Platt the guy that made the ridiculous propeller that looked like it was made out of a bunch of popsicle sticks glued together? If so, he's definitely an idiot.

 

[Andrew Wiggin]

I met humber before, when I was a newbie here. I think he's open to reason: I thought he was mistaken about something and we had a nice chat about a graph he made and then suddenly he stopped posting and didn't post anything for about 15 months. I may be wrong and goodness knows I wasn't the only one involved in the conversation but I think that might be his way of showing he was convinced.

I don't think that indicates being open to reason or being convinced. When I see someone who's response to being proved wrong is to go away for 15 months, what they're doing is posting on another forum somewhere, and hoping that when they return no one will remember their last fail. It's a form of pouting.

The real problem here is that physics is not subject to intuition. This is the same breakdown that happens when people get stuck thinking that particles are little billiard balls, and attack quantum mechanics. humber's intuition says this is wrong. He's stuck there. I'll admit my intuition says this won't work too. Once I tumbled to what was actually going on, intuition stopped mattering. More importantly, this has been shown by tests to work. If intuition doesn't say why, intuition is wrong and it's time to break out the calculations.

 

[humber]

I don't think that indicates being open to reason or being convinced. When I see someone who's response to being proved wrong is to go away for 15 months, what they're doing is posting on another forum somewhere, and hoping that when they return no one will remember their last fail. It's a form of pouting.

I stopped posting anywhere at that time. I posted here a simple model of cart that could travel ddwfttw if the wind was gusty. It is a mechanical analog of a DC/DC converter.
Also the claim of the prop as an oscillator. The trial is as much, is not better evidence that I was right. I have two carts the travel up the belt, without the aid of the prop or air.

The real problem here is that physics is not subject to intuition.

If you note, I put counter-intuitive between quotation marks. It is sarcasm, aimed at Spork, who has nothing but that in support.
The Wired article gives considerable space to that topic.

This is the same breakdown that happens when people get stuck thinking that particles are little billiard balls, and attack quantum mechanics. humber's intuition says this is wrong. He's stuck there.

Hardly. I have seen a QM experiment using long lengths of optical fibre.
To see real oscilloscopes do the "impossible" is quite dumbfounding,.

I'll admit my intuition says this won't work too.

My intuition said nothing. My first exposure was to the TM, but I was not aware of its connection with ddwfttw, but simply of a machine climbing up a belt. I worked out how it did that.

Once I tumbled to what was actually going on, intuition stopped mattering. More importantly, this has been shown by tests to work. If intuition doesn't say why, intuition is wrong and it's time to break out the calculations.

And you find something wrong with my claims over the wind measurements?
If so, please post them, and I will provide the calculations where necessary

 

[spork]

And he ETA'd that the BB is the most amazing conventional sail craft ever built, as usual, without realizing that is what he said.

I'm enjoying the fact that he's running around like Ernest T. Bass yelling at anyone he thinks will listen - because his appeals to NALSA are laughed at or ignored. Does he hope the folks on the forums are going to somehow recall the record!?

Wasn't Charles Platt the guy that made the ridiculous propeller that looked like it was made out of a bunch of popsicle sticks glued together?

Yes. He made a truly awful cart, and then changed the design so the prop turned the wrong way because he couldn't imagine that it would work as Jack Goodman explained it.

If so, he's definitely an idiot.

Yes, a particularly unpleasant idiot.

 

[humber]

I'm enjoying the fact that he's running around like Ernest T. Bass yelling at anyone he thinks will listen - because his appeals to NALSA are laughed at or ignored. Does he hope the folks on the forums are going to somehow recall the record!?

Once again you let fantasy get in the way of fact. I have never contacted NALSA.
The letters to NASA, were a result of your refusal to accept questions at the talk you gave at Ames Yacht Club. My emails to Steve Smith, were in response to one you received and posted, which made reference to me.

It was you who approached Dr Camp, in the hope of gaining his support. He said that he would "bag the TM"

What you hope is that nobody will take away your record, but is an act of faith and bravado, brought about by your obvious inability to support your claim.

Yes. He made a truly awful cart, and then changed the design so the prop turned the wrong way because he couldn't imagine that it would work as Jack Goodman explained it.

On the contrary, his prop is more efficient than yours, so works better as a turbine and moves towards the fan. I have tried this, comparing several model aircraft props.
The best performer is a blade I took from a 4" desk fan, which cost 5 Euro. Much like this one. http://www.amazon.com/Foshan-Guanmei-Electrical-Velocity-Personal/dp/B000WEIJ7K/ref=pd_sim_dbs_k_1

Yes, a particularly unpleasant idiot.

You are not looking so bright.

My model DC/DC cart exploits the gusty wind. I estimated that it would achieve 1.3WS, but that was on the basis that I would be subjected to controlled measurement. But, if given the freedom that NALSA afforded you, then I can do much better than that. Perhaps a bucket could do it.
That is reason I told you to build a cart "to the max" , meaning with some mass, and a height that could exploit the wind gradient, and so you did.

Faster than the wind has no meaning, except in the wind tunnel conditions you claimed your cart would work. In that case, the wind speed is consistently the mean.
In the real world, one would have to say "faster then the wind"... RMS, Peak, Quasi-peak, etc.
Without the push, the average speed of your cart is 8.5mph. Less than the mean speed of the wind over the same time.

 

[Llyricist]

I also see that he's back to posting links that show pretty much the opposite of what he claims. Such as the wind data (forecasts) for El Mirage that show remarkable consistency hour to hour, and pretty minor gusts, except at night, which is irrelevant.

Of course they show the direction consistency because the are averaged over 60 minutes..... Why he would post data that can't possibly support or refute the NALSA run run data variation is unclear.

Not to mention why he keeps repeating the one thing that is actually correct, that tends to refute all his other claims about the shifting wind somehow driving the cart. That transients (such as the Chase Vehicle hitting a bump, or a sudden wind gust) will cause the weather vane to oscillate back and forth around the actual wind direction. Which is clearly the case in the first half of the test period data.

And why he keeps repeating that NALSA ignores that effect, when they actually called attention to it in the report, referring to it as "vane waggle". Also that effect is exactly what justifies using the regular mean, rather than the RMS. In electronic terms (which is what he claims to understand), what you actually want to know is the DC Bias, not the power level of the oscillations, since the oscillations themselves are spurious in this case.

 

[Jack by the hedge]

...Dan Kammen thinks it is. Dr Camp thinks it is. As do so many more. In fact, it is. The claim would violate the conservation of energy.

No, it would not. Lots of people are wrong about that, as you attest, but it does not violate conservation of energy.

It is said that the cart "extracts" energy from the headwind it sees above WS, so driving it even faster. That is a recipe for perpetual motion

That's not correct

... but in the case of the BB, there is a further snag.

The prop has a ratchet which prevents the prop from driving the wheel. Even if the rotor were to extract that energy, it can't drive the wheel. If the claim then becomes that the prop generates "thrust" or whatever, such that drive to the wheel is unnecessary, then the hypothesis around the gears must be wrong. Lose one way or the other.

You do not understand. The prop does not turn the wheels. The wheels turn the prop. The wind bears on the retreating face of the propeller blades and applies a force which tends to oppose their rotation (which is a loss) and a force which presses the propeller forward. That forward force is transmitted though the mast and pushes the craft forwards, which forces its wheels to turn.

Given that the supporting theory has a hole below the waterline, I think it is safe to say the result is due to poor instrumentation, and the cart is not traveling ddw.

Given that your objection is based on your inablity to grasp the way in which the craft operates, I have to suspect your pronouncements on its instrumentation are similarly unreliable.