Merged DDWFTTW in a “Real” Wind

[CORed]

Spork et al never claimed to be first.

Just what about those videos is supposed to refute anything about Spork's cart?

The only thing that the belt sander videos show is that the wheels on the stationary platform are a bit "sticky". I really don't think humber ever realized that the propeller carts were moving opposite the direction of the belt when not restrained. I think he still believes that they were moving with the belt.

 

[Subduction Zone]

humber, we covered the treadmill equivalence to running at wind speed long ago. I guess I will have to remind you. It was during one of your very rare periods where you were fairly lucid. You agreed to go through a series of simple yes/no questions where I showed that they were equivalent. You agreed all the way right to the end when it was too late and all you could do was to run away. Do you want to do it again? I can guarantee you that the answers would be the same.

 

[D'rok]

The only thing that the belt sander videos show is that the wheels on the stationary platform are a bit "sticky". I really don't think humber ever realized that the propeller carts were moving opposite the direction of the belt when not restrained. I think he still believes that they were moving with the belt.

 

[AvalonXQ]

humber, we covered the treadmill equivalence to running at wind speed long ago. I guess I will have to remind you. It was during one of your very rare periods where you were fairly lucid. You agreed to go through a series of simple yes/no questions where I showed that they were equivalent. You agreed all the way right to the end when it was too late and all you could do was to run away. Do you want to do it again? I can guarantee you that the answers would be the same.

Link?

 

[Subduction Zone]

Avalon, I will look for it. But it was so long ago, and humber has been trolling his nonsense for at least 20,000 of his own posts alone that it might take quite a search.

 

[jduffy77]

So, Humber, at 2.8* windspeed you contend that the prop still acts as a sail?

I don't know if you missed the failed upwind cart hilarity at TR but its worth re-reading if you need a laugh. Humber believes the cart would travel much faster without the prop. He says its an opposing turbine.

 

[humber]

I don't know if you missed the failed upwind cart hilarity at TR but its worth re-reading if you need a laugh. Humber believes the cart would travel much faster without the prop. He says its an opposing turbine.

This is a video showing that the rotor on Spork's cart turns CCW when placed before a fan, so like an upwind turbine.
http://www.youtube.com/watch?v=nudBjrOF3LE

That CCW rotation would drive the cart towards the fan, but, the rotor is designed to work at high speed, so is inefficient.
But the direct force on the cart, blows it away from the fan as a sail would. It is slow, because the rotor drives the cart towards the fan, while the direct drag drives away from it. The two forces oppose, but the direct drag is larger,so the cart moves slowly away from the fan. That is why the cart often fails to start when ddw. It's failed a upwind cart, that gets better when the wind is not ddw. ( Turbine power is reduced as cos^3 from the axis.)
The chart shows that the cart is better when not ddw.

This guy's rotor is more efficient, so the cart moves towards the fan.
http://img24.imageshack.us/img24/1811/9ih.mp4
http://img816.imageshack.us/img816/6015/ql0.mp4

 

[jduffy77]

This is a video showing that the rotor on Spork's cart turns CCW when placed before a fan, so like an upwind turbine.

That CCW rotation would drive the cart towards the fan, but, the rotor is designed to work at high speed, so is inefficient.
But the direct force on the cart, blows it away from the fan as a sail would. It is slow, because the rotor drives the cart towards the fan, while the direct drag drives away from it. The two forces oppose, but the direct drag is larger,so the cart moves slowly away from the fan. That is why the cart often fails to start when ddw. It's failed a upwind cart, that gets better when the wind is not ddw. ( Turbine power is reduced as cos^3 from the axis.)
The chart shows that the cart is better when not ddw.

See what I mean? This stuff is priceless.

 

[humber]

See what I mean? This stuff is priceless.

Yes....don't you worry about the evidence, and that it's all been done before, and failed. Since 1882.
Of course, it's the magic gearbox that makes the difference isn't it? When the wheels are not on the
ground, they turn towards the fan, but when on the ground, they turn the other way. Magic.
Spork says the prop "fights" the wheels and the wheels "win". I can find that post, and they are the words he used.

You will not find that claim in Bauer's, Drela's, Guanna's or Ruina's papers. But then, you will also find nothing
else in common, either.
But, Charles Platt, and the maker of the cart in the posted videos, found that gearing did not make the cart
go forwards.
The video of the small cart in the wind, shows the cart moving, without the wheels or prop turning, because one
stalls the other until traction breaks, and the cart slides. It's not my video, so what do you say about that?
It's an upwind turbine, that gets blown downwind. That is embarrassing for you, so I can appreciate that you don't want to
accept it. But it's a bit of a "brain teaser" and not "intuitive", so that may be the reason?

 

[GlennB]

For linear acceleration v=at, but the average speed over t is v/2, but for
for constant velocity, the average is v.

So, obviously, the time spend accelerating influences the peak but non-constant speed, unless a = 0, and it does not.

So lets's see .... assuming my car has a top speed of 90mph:

I've accelerated to 89.99 mph after rolling to 10mph before even starting the engine. You're saying that only 79.99 mph of that is down to the engine, so my instantaneous and average measure of petrol consumption is proportional to X-10 mph even though the 'roll' was 20 yards while the drive is 5 miles?

I accelerate the extra 0.01 mph, at which point all of the car's speed - and therefore petrol consumption - is down to the engine? That was a terribly costly gain of 0.01mph afaics.

Is this some new law of physics? "Humber's Law of Conservation of Free Speed"?

 

[dafydd]

Not for humber, but can you do it for laffs for the rest of us who missed it?

I didn't miss it,it's worth a repeat.

 

[catsmate]

I never cease to be astounded at the reality-denying lengths some people will go to simply to avoid admitting that they were wrong.

Have you seen this thread?

 

[humber]

So lets's see .... assuming my car has a top speed of 90mph:

I've accelerated to 89.99 mph after rolling to 10mph before even starting the engine. You're saying that only 79.99 mph of that is down to the engine, so my instantaneous and average measure of petrol consumption is proportional to X-10 mph even though the 'roll' was 20 yards while the drive is 5 miles?

Where is the engine in the cart? But...

The total time from the starting line to the record point is 105s.

Assume the cart starts from a standstill, and accelerates at a constant 0.1ms-2 - that is the value derived from the chart and is almost constant.

The speed after 105s will be v=at = 0.1ms-2*105s = 10.5ms-1.

But, the cart is pushed to over 10mph (4.4ms-1), and that takes 15s, leaving 90s until the record point. The final speed will then be u + at = 4.4ms-1 + 0.1ms-2*90 = 13.4ms-1
It gains from the push, because it never reaches constant speed, and the run length determines where the record time is set.

In fact, it benefits a bit more, because after the pushing stops, the acceleration falls to much less than 0.1ms-2 for about 10s before the wind changes, and it accelerates at 0.1ms-2. This mighty cart travels only 0.41 miles in 105s. The average speed is less than 13mph. Exclude the push, and it's 8.5mph. A farce.
It's so "counter-intuitive" to find out that you have been sold a donkey that claims to be a racehorse.

ETA: And who is in denial?

 

[D'rok]

Have you seen this thread?

Got about two pages in and then had to rage quit.

 

[humber]

Gentlemen, you have been had. Take a look at the wind pattern, and how it dives sharply South just after the record point. What would have happened if the start had been delayed by say, 15 seconds? What was the wind like before the start? The cart takes advantage of short term patterns in the wind. If it fails, try again. NALSA allow the contestant to pick the best run.
Ivanpah is known to have such patterns, and the run was known to be too short for the cart to reach steady-state. Spork knew that before the trial.

 

[humber]

I think I will start my own class of cart record. The "whatever" class. I can employ bad instrumentation. I get to play with the data and ignore all failures. I can pick and choose the day and location, and I determined what "ddw" is. I don't care how it gets above WS; I may even tow it, and release it before the end of the run. As long as it accelerates a bit
( or instrument limits say so) I can claim a record. Oh wait, Spork beat me to it.

 

[Jack by the hedge]

Gentlemen, you have been had. Take a look at the wind pattern, and how it dives sharply South just after the record point.

What's the significance of what the wind does after the record point?

 

[humber]

What's the significance of what the wind does after the record point?

It means that the wind changes a lot, and the result can be totally different, just because the start is perhaps 10 seconds earlier or later.
The winds at Ivanpah have lengthy records, and they show that the wind is variable. NIST use an averaging time of 10 minutes, because short term winds are not indicative.

In a 30 minute period, there may be periods of higher gusts, but the average over that period will be much lower. The cart can select for those higher periods by waiting. If it fails, it gets another go. There is no control.
To remedy that, the cart should be forced to start at regular periods and all the results including failures, averaged. To do otherwise is "publication bias"

NALSA is not a regulatory body, nor an accredited testing facility, but a yacht club, and it shows.

 

[Jack by the hedge]

I don't quite follow you - are you saying that the test measured the cart's speed during a period of 10 seconds and compared it to the windspeed averaged over 30 minutes?

 

[Subduction Zone]

Yes, in the humberverse not only does the cart know how it got to speed, if it was pushed by hand it can achieve a higher top speed than if it got there by the wind blowing, but it knows what the wind will do in the future as well