Merged DDWFTTW in a “Real” Wind

[Llyricist]

humber has no idea how propellers work.

 

[D'rok]

Thanks for the welcome and sage advice!

Actually, I've been following this saga on and off for the past two years. Mostly lurking, but every once in a while I have something to say. Like for example:

If Humber makes a post which no one reads, is it still a troll?"

You guys have got to stop feeding this... this... (I don't know what he it is). Wait, yes I do, it is a troll! It thrives on the attention!.

My guess is that Humber knows perfectly well how the cart works. Either that, or it just doesn't care.

Thing about feeding trolls is that there is net benefit to lurkers. Just from following this saga and reading all the careful explanations from rational people, I feel like I have a layperson's grasp on the basics of a bunch of subjects of which I would otherwise be completely ignorant (Relative motion/frames of reference, levers, aerodynamics, etc).

Of course, by now the returns are approaching zero.

 

[A.T.]

That confused me for a while, so I did a little mind experiment to try to figure out where the energy comes from.

At first I thought of the cart as being like a parachute floating in the wind. If that were the case, it seems impossible (and it is) for any energy to be extracted from the wind to make the parachute move faster than the wind.

Then, I pictured having an elastic cord hanging from the parachute.

If the parachute is free to drift with the wind, the cord would hang limp.

But ... if someone standing on the ground were to hold onto the other end of the elastic cord, it would stretch. In a steady wind it would stay stretched. When the cord is anchored, the wind provides a steady source of energy.

In the case of the cart, the friction of the wheels on the ground is the equivalent of the person holding the elastic cord. The wheels take energy from the "elastic cord" and use it to turn the prop. The wind continues to supply energy so that the wheels can continue to turn the prop.

Here is a slightly simpler model that shows how the interaction with the ground is crucial for DDWFTTW.

 

[GlennB]

When above WS, the cart is traveling faster than the wind.
Hence the term "faster than the wind".
It will strike the air that is slower than it, and accelerate it.

Very good humber!

You're quite close to understanding this at last. Now just keep thinking about what you just wrote .....

 

[humber]

Thanks for the welcome and sage advice!

Actually, I've been following this saga on and off for the past two years. Mostly lurking, but every once in a while I have something to say. Like for example:

If Humber makes a post which no one reads, is it still a troll?"

You guys have got to stop feeding this... this... (I don't know what he it is). Wait, yes I do, it is a troll! It thrives on the attention!.

My guess is that Humber knows perfectly well how the cart works. Either that, or it just doesn't care.

No, it's you. Why are you so busy defending a claim that you say is rock-solid and has a record to prove it?
You can't stand the idea that opposition may mean you may be wrong. Lurking in the back of your mind, is that Spork is a rather crass and innumerate buffoon, who calls all his opponents, such as Charles Platt, Prof Allain, Prof Whiteman, Prof Camp and Nobel Laureate Dan Kammen "idiots", and there may just be something wrong about that.
That a manager for a Sport's media company, knows more.

And before you respond, Drela's paper is speculative, and is in fact an internet note that appeared while he was posting at the Boating Forum.
It is not peer-reviewed, and the power analysis is only 25% complete.
Literally. It has a note saying which parts are outstanding.
His arguments contradict his own papers on motor/prop electrical models.
But, well....any port in a storm.

The only other, is Mac Guanna, who is a lecturer. He has written some sponsored papers - again not peer-reviwed. They rely on reducing losses to impractical levels, such as zero.
The connection is that he knows Drela, and they have discussed the matter.

 

[humber]

Here is a slightly simpler model that shows how the interaction with the ground is crucial for DDWFTTW.

[qimg]http://img163.imageshack.us/img163/720/dwfttwstick200x250.gif[/qimg]

Why stop there? Here's a gallery of fine physics models.
http://www.google.nl/images?hl=nl&q...Gs74sgaJpfGMAw&ved=0CE4QsAQ&biw=1920&bih=1015

 

[humber]

Thing about feeding trolls is that there is net benefit to lurkers. Just from following this saga and reading all the careful explanations from rational people, I feel like I have a layperson's grasp on the basics of a bunch of subjects of which I would otherwise be completely ignorant (Relative motion/frames of reference, levers, aerodynamics, etc).

Of course, by now the returns are approaching zero.

Booga, Booga. Look out for the snake in the Garden of Eden who knows enough not to buy the flim-flam that Spork sold to you,.



This says your mentor has given you the shaft.

STEADY STATE is important!
The red line is the BB, but another cart has less mass, so accelerates faster, meaning that at the point of measurement it is faster, but may have a lower terminal (steady-state) speed, yet steals the record from the BB.
That is a major flaw in the entire procedure.
But, it works the other way too. If the BB gains from some short term wind pattern, you may find it can't sustain that over time. In that case, the yellow cart is legitimate, but the BB is not.
The deal was steady-state ddw, not "whatever"

 

[Llyricist]

Thanks for the welcome and sage advice!

Actually, I've been following this saga on and off for the past two years. Mostly lurking, but every once in a while I have something to say. Like for example:

If Humber makes a post which no one reads, is it still a troll?"

You guys have got to stop feeding this... this... (I don't know what he it is). Wait, yes I do, it is a troll! It thrives on the attention!.

My guess is that Humber knows perfectly well how the cart works. Either that, or it just doesn't care.

I for one, feed it to elicit the occasional coherent declarative statement that is hilariously wrong.

Such as:
"even the wind wasn't DDW"

 

[Jack by the hedge]

When above WS, the cart is traveling faster than the wind.
Hence the term "faster than the wind"
It will strike the air that is slower than it, and accelerate it. There goes some of the cart's momentum. The best you could hope to do - in a cartoon world - is to recover what is lost from the cart to that air. But even that cartoon does not allow for acceleration. The cart leaves a trail of accelerated air, and a vortex street in its wake. It does not gain from drag.

Once again humber "proves" that propeller-driven aircraft cannot work, because the headwind acting on the propeller must slow the craft down instead of speeding it up.

 

[CORed]

humber has no idea how propellers anything works.

ftfy

 

[Jack by the hedge]

The cart faces the same problem. The claim is actually contradicted by Spork's own calculation. He has the drag force above WS as an opposing force, and subtracts it to get the net force. See the submission report. He uses Rayleigh's drag formula.

Now you are saying that when that same air hits the prop, it drives the cart. It adds to the net force.
It is little wonder that with that sort of loony-tunes theory as a basis, that the trials were not similarity tainted.

The air through which an aeroplane flies creates drag. But now those crazy plane builders are saying that when that same air hits the prop, it drives the plane. It adds to the net force.
It is little wonder that with that sort of loony-tunes theory as a basis, no propeller driven aircraft has ever flown steady-state, without being pushed by one of those little airport tractors or waggling its rudder to extract momentum from side winds or something. It's all perfectly simple.

 

[Dr.Sid]

I love this problem ..

 

[GlennB]

I love this problem ..

Yeah But it nearly led to a relationship breakdown between me and a close friend who would not go and read the blogs and analyses from the experts. Because he knew it wasn't possible. Catch was that he's the engineer while I specialised in creepy-crawlies, blood+guts etc. So he kept taunting me about how many more perpetual motion machines I'd found on the internet

 

[CORed]

So, basically, humber has created an impregnable but imaginary tree-fort where his demands for evidence can never be met. In this case a 100% stable wind in terms of direction and speed. This way he can not only protect his ego but actually magnify it.

Seen it so many times in the CT forums. What a tosser.

Actually, the 100% stable wind in direction and speed was met with the treadmill tests. The treadmill tests established beyond any reasonable doubt, that the propeller cart words for achieving DDWFTTW. Humber, however, refused to accept the equivalence of the treadmill tests to tests in the wind, which is obvious to anybody with a rudimentary understanding of physics.

Now that the large scale, passenger carrying cart has been shown to work in the "real" wind, he complains that the speed and direction of the wind changed. Guess what? "Real" winds in the open air do that. Finding a natural wind that doesn't gust and swirl is just about impossible. So yes, humber has pretty well made it impossible to prove to his satisfaction that the cart works. I have no doubt that if somebody did find a natural wind that was constant in speed and direction, and successfully test a DDWFTTW cart in it, that humber would invent reasons that the test was invalid.

It's rather amazing the amount of effort humber has devoted to attempting to refute the idea. He has demonstrated a phenomenal ignorance of basic physics on several internet forums, attempting to use an erroneous understanding of theory to show that something that has been clearly and repeatedly shown to work experimentally couldn't possibly work.

 

[CORed]

I love this problem ..

I love it too. When it first appeared on this forum a few years ago, I thought What? No way! When I saw the first videos, of a small cart outdoors, I thought the prop was a wind driven turbine, and of course there is no way that a cart with that design could go downwind faster than the wind.

Then I read a bit more, and discovered that the wheels drive the propeller. Huh? Impossible! Or is it? Then I saw the treadmill tests. With a little change of frame of reference, it suddenly made perfect sense to me. Belt drives wheels, wheels drive prop, prop moves the cart forward. And of course the tread mill moving in stationary air is equivalent to air moving over the ground.

I don't think the design would have occurred to me in a million years, but it's really quite simple. It's not perpetual motion, and it violates no physical principles. But, from the "wind over ground" frame of reference, to me it kind of feels "wrong". But unlike humber, I recognize the "wrong" feeling is a flaw in my intuition, not a flaw in the design of the cart.

 

[humber]

Once again humber "proves" that propeller-driven aircraft cannot work, because the headwind acting on the propeller must slow the craft down instead of speeding it up.

Deary me, JBTH, I have already explained that.
The cart's theory, is why YOU don't want people like Spork, and their cranky "intuitions", to have anything to do with the design or maintenance of an aircraft in which you may one day find yourself a passenger. Trust me.

Aircraft are indeed slowed down by their propellers -s ome are deliberately designed to do that.
http://en.wikipedia.org/wiki/Controllable_pitch_propeller
"the reversible propeller can also create reverse thrust for braking or going backwards without the need of changing the direction of shaft revolutions."
But that is by way of information.

There is drag, but also "lift". The engine applies power to the prop shaft, such that thrust can be generated to overcome the drag and then some.
That is an entirely different proposition, from running the aircraft on the drag it generates by moving through the air that generates the drag.

What about the chart and the two carts? NALSA have created a non-record.

 

[RossFW]

What's even more amusing, on another forum Humber has characterized the shellacking he's getting here as him soundly defeating Spork.

JREF was where the Humber phenomena started. It would be appropriate for a presentation at TAM to cover the theory and proving of DDW, followed by an examination of delusional denial, as has never been better illustrated than here!!

 

[humber]

What's even more amusing, on another forum Humber has characterized the shellacking he's getting here as him soundly defeating Spork.

JREF was where the Humber phenomena started. It would be appropriate for a presentation at TAM to cover the theory and proving of DDW, followed by an examination of delusional denial, as has never been better illustrated than here!!

Spork is whining to the mods and has PM'd all and everyone.
You don't have the courage to ask him to share the raw data, but have the gall to push half-baked aoerdynamic theories, without having that data yourself.

The point of the trial is not to prove general aerodynamic, theory, or whatever you choose to randomly apply of it, but if a specific application works or not. For that, you need data. So once again, have the integrity to ask your mentor or shut up. Flying a plane means you can push the buttons, Captain. And yes, I have worked on the instrumentation for the A380.
You may know of the cabin PC. That too.

 

[D'rok]

What's even more amusing, on another forum Humber has characterized the shellacking he's getting here as him soundly defeating Spork.

JREF was where the Humber phenomena started. It would be appropriate for a presentation at TAM to cover the theory and proving of DDW, followed by an examination of delusional denial, as has never been better illustrated than here!!

That's an excellent idea. Spork would make a great TAM presenter.

 

[CORed]

What's even more amusing, on another forum Humber has characterized the shellacking he's getting here as him soundly defeating Spork.

JREF was where the Humber phenomena started. It would be appropriate for a presentation at TAM to cover the theory and proving of DDW, followed by an examination of delusional denial, as has never been better illustrated than here!!

Well, I spend enough time on the CT forums to have seen the phenomenon of a delusional person declaring victory after being soundly defeated many times. They remind me of the Black Knight in "Monty Python and the Holy Grail". The thing about humber is that he does it in a way that I find quite entertaining. He has pretty good written communication skills, and he seems to have read a lot, but seems to have grossly misunderstood much of what he has read, so he can be relied upon to put something glaringly, and laugh-out-loud funnily wrong in just about every post.

With most delusional or trolling posters (and I'm still not sure which category humber fits into), I get bored after awhile. In fact, it is the rational posters giving up and going away that seems to convince a lot of the delusional that they have won. But with humber, somehow I just keep coming back for more.