Merged DDWFTTW in a “Real” Wind

[Subduction Zone]

At 9m/s the cart's KE is 1/2*195kg*9^2 = 7897J
From the trial, a = 0.11ms-2, so one second later it is 1/2*195kg*9.11^2 = 8091J
An increase of 194J. The input form the wheels is 1440J/sec, so the cart's overall efficiency would be 194/1440 = 13.5%, if that were at all possible.

After looking at this analysis I can't wait to see humber have a go at analyzing a car on the road. I think that we have to add "efficiency" to the many many concepts that humber does not understand.

 

[humber]

Actually, at that particular speed and power, it is not. but it would be closer to the maximum theoretical (0 loss) of 64.5% than the 12.5% I used.



The formulas I have been using (from here) are actually proving very close to the Java Prop results, as long as Push up way closer to the max theoretical efficiency from them.

"I found the Reverend's sermon to be quite enlightening"

 

[Llyricist]

How long ago was it that I predicted profpangloss' next step was to make a ridiculous "proof" where he double counts, changes signs and other errors to prove that the cart does not work?

Thank you Harold for showing your true colors, or is that Christoph here?

Frankly, I thought he might try a little harder to be slightly less transparent, by perhaps just asking where the energy came from or something, rather than going straight into ripping off his mask.

 

[humber]

Frankly, I thought he might try a little harder to be slightly less transparent, by perhaps just asking where the energy came from or something, rather than going straight into ripping off his mask.

And there is no way you can fit the trial result into any theory, no matter how you try and massage the numbers. You have been taken in.

 

[humber]

After looking at this analysis I can't wait to see humber have a go at analyzing a car on the road. I think that we have to add "efficiency" to the many many concepts that humber does not understand.

You mean one the completely escaped your notice.

 

[ThinAirDesigns]

How long ago was it that I predicted profpangloss' next step was to make a ridiculous "proof" where he double counts, changes signs and other errors to prove that the cart does not work?

Thank you Harold for showing your true colors, or is that Christoph here?

It's the flawed arguments of ChristopherM actually. Screen names vary, but argument remains the same.

JB

 

[humber]

It's the flawed arguments of ChristopherM actually. Screen names vary, but argument remains the same.

JB

And the submission report has Spork's appeal to PM in black and white, while the same trial contradicts it.

 

[profpangloss]

Okay.




Not true. Thrust of 160 Newtons at a speed of 9 m/s provides 1,440 Watts of power. That implies nothing about what the cart needs to run at 9 m/s or to generate that thrust or anything else.

That's a rather fundamental distinction for what you're trying to demonstrate, so it's probably best if you were to start over from there.

Respectfully,
Myriad

Oh really? So tell me why a Cessna needs a fuel tank? Or is it to collect all of the energy provided to the aircraft by the propeller thrust? I'd say you have things a bit backwards, but I suspect you already know that!

 

[jduffy77]

And the submission report has Spork's appeal to PM in black and white, while the same trial contradicts it.

Humber we need a translation here. It sounds like you are outright lying again but it might just be gibberish. Could you elaborate?

 

[3point14]

Seriously, are you serious? This is what your faith in DDWFTTW rests on, and there are people out there who actually believe in this? There are people out there who look at this so-called “math” and don’t fall over themselves laughing?
OK, I’m going to make this short as possible and just use nice round numbers to bring a bit of enlightenment to the masses.
Thrust is 160 Newtons and the cart is supposed to move at 9 m/s, so it requires 1,440 Joules/sec, that is 1,440 Watts of Power.
You started out with 750 Watts at the wheels, only the Good Lord knows where it came, from (ground power) but I know the only place it could have come from is the cart’s very own kinetic energy, assuming it is somehow already moving at 9 m/s without explanation of how it got there. So, at 295 kg it would have 12 kilo joules of ke, right? Now you steal maybe 850 of that to get your 750 watts at the wheels ( nothing is 100% efficient, you know) Scorecard reads, minus 100, gone to heat and unrecoverable. (bye bye). Next, you send that up the long twisted chain held in place with pieces of skateboard, and 600 Watts arrives at the propeller shaft, so you lost another 150 Joules. (not looking good is it?) Now the propeller gets into the act, and with 52% efficiency (your number, not mine) it puts 312 watts of power into working on the air. Ah, lets make that 350 watts just to give this thing a fighting chance. Scorecard reads minus 500 watts. That is minus 500 Joules per second of precious kinetic energy and you know what that means don’t you? The cart is slowing down. What do propose as a solution to this quagmire? In order to push with that thrust of 160 N and move at 9 m/s, the cart needs 1,440 watts of power. After burning off 500 watts, it has 350 watts at the propeller to do some magic on the air. Now think about where we are here: the cart wants 1,440 watts to do what you claim, but it has already lost 500 watts trying. Now it needs 1, 940 watts to do what you claim and it has a grand total of 350 watts to do it with. BLEAK, VERY BLEAK.
What can the cart do to get out of this big hole it has dug for itself? It can slow down some of that wind that is out there somewhere, but going slower than the cart. OK let it do that! 160 N of thrust and 350 watts, with F = ma, a simple back of the envelope calc says it slows down at most 72 kg of air by 2.2 m/s (72 x 2.2 ~ 160, close enough for this nonsense). That wind will lose some energy during the slow down of 2.2 m/s, with respect to the ground it loses about 1000 joules per second, that is 1000 watts absolute Maximum. IF that ALL went to the cart, the cart would have 1,350 watts when it needs 1,940 watts. But as we all know, no process is 100% efficient and there is no way all of that wind energy goes into the cart but it doesn’t matter anyway as the cart is dead meat, slowing down and it will not stop slowing down until it is well below the wind speed.
Still some believers out there?

I agree with one thing you said A total piece of crap

Can you do this with numbers and units on ones side, numbers and units on the other and '=' signs in the middle please, otherwise it's just tl:dr.

 

[jduffy77]

Oh really? So tell me why a Cessna needs a fuel tank? Or is it to collect all of the energy provided to the aircraft by the propeller thrust? I'd say you have things a bit backwards, but I suspect you already know that!

You completely ignored Myriad's point and asked a nonsensical question instead but I suspect you already know that!

FYI, a Cessna would not need a fuel tank if it were modified to look like the BB and a rigid properly geared connection established between a properly pitched propeller and you did not care if it only went ddw and you did not want it to leave the ground.

 

[profpangloss]

I said it was pushed up to that speed in one of the first sentences..

Yes of course, push that sucker because it won't go anywhere any other way!

The cart's KE has nothing to do with where the energy comes from. And you are just making up a loss here..

That's the only energy there is, unless of course you believe in that magical mystical ground energy? You don't really do you?

I'm not going to bother with the rest, I'm just going to do the energy balance correctly..

I have already done it correctly. There is no ground power, it does not exist, forget it. The friction with the ground takes kinetic energy out of the cart. I delineated all the losses exactly as you specified them. The cart is leaking energy all over the place, and the wind does not have enough to give it even with the propeller trying to spin using the cart's own kinetic energy. The entire idea is ridiculous.

 

[profpangloss]

Can you do this with numbers and units on ones side, numbers and units on the other and '=' signs in the middle please, otherwise it's just tl:dr.

You probably should not read it. It is full of facts, and will destroy your imaginary model of the universe. Best you give it a skip.

 

[3point14]

You probably should not read it. It is full of facts, and will destroy your imaginary model of the universe. Best you give it a skip.

So what you're saying is that you don't want to educate me as to the mistake as you see it, you just want to provide the information in as confusing a format as possible, obfuscate your point and then be sarcastic?

Fair enough, but it does seem to demonstrate that rather than have a reasoned debate in which you clearly say what you mean, you'd rather snipe from the sidelines and not present your information in the manner that has been traditional for years and that everyone is used to.

I thought that the whole point of your argument was to:

...destroy your imaginary model of the universe...

So now, when presented with the opportunity, you baulk?

 

[humber]

Humber we need a translation here. It sounds like you are outright lying again but it might just be gibberish. Could you elaborate?

Well you can ask Spork to plot the figures from Propcalc over the range of speeds found in the trial, and then compare that with the Harrypothesis of the Submission Report, or does he simply take you for granted, and you willingly accept that?

From that submission, which makes no use of Propcalc at all:
Vcart = Speed of cart wrt ground
VP = Headwind ( difference of V_cart and the wind speed)
n = efficiency (0.85 on three occasions, so 0.85^3 = 0.61)
F_thrust = Prop thrust
F_wheel = Wheel drag.


F_thrust = Vp/Vcart*F_wheel*n

No way to make F_thrust - Fwheel a constant, save to lower n.

 

[jduffy77]

Can you do this with numbers and units on ones side, numbers and units on the other and '=' signs in the middle please, otherwise it's just tl:dr.

That you will never see. He cannot hide his silly errors in bad prose that way. What kind of a riddle would this make:

$30 (initial payment) = $25 (to clerk) + $2 (to bellhop) + $3 (refund)

instead of:
$27 (final payment) - $2 (to bellhop) = $25 (to clerk)

HyevPrangGloss hides in his prose something which looks silly in equation form:

$27 (final payment) + $2 (to bellhop) = $29 (to clerk)

There is no reason to add the $2 and $27 as the $2 is contained within the $27 already. Thus the addition is meaningless. But he always does it anyway.

 

[humber]

You completely ignored Myriad's point and asked a nonsensical question instead but I suspect you already know that!

FYI, a Cessna would not need a fuel tank if it were modified to look like the BB and a rigid properly geared connection established between a properly pitched propeller and you did not care if it only went ddw and you did not want it to leave the ground.

Cessna's do have a fuel tank, but don't gear the prop to the wheel. There are good reasons for both.

 

[humber]

That you will never see. He cannot hide his silly errors in bad prose that way. What kind of a riddle would this make:

$30 (initial payment) = $25 (to clerk) + $2 (to bellhop) + $3 (refund)

instead of:
$27 (final payment) - $2 (to bellhop) = $25 (to clerk)

HyevPrangGloss hides in his prose something which looks silly in equation form:

$27 (final payment) + $2 (to bellhop) = $29 (to clerk)

There is no reason to add the $2 and $27 as the $2 is contained within the $27 already. Thus the addition is meaningless. But he always does it anyway.

It was the bellhop's idea to put the wishing well in the hotel lobby.
ETA:
Rather than appealing to an old saw, why don't you show EXACTLY where Profpangloss does as you claim?

 

[Llyricist]

Cessna's do have a fuel tank, but don't gear the prop to the wheel. There are good reasons for both.

And that reason is implicit in jduffy's post. A Cessna is not designed to go faster than the wind DDW, powered only by the wind on the ground.

 

[jduffy77]

Cessna's do have a fuel tank, but don't gear the prop to the wheel. There are good reasons for both.

Without exaggeration I think this is the first post I have ever read of Humber's which is entirely correct and contains no lies or gibberish.