Merged DDWFTTW in a “Real” Wind

[humber]

Are you saying you did not say the exact words "the perfect judging body"

You will never find me saying that NALSA were anything like the perfect body.
I was not posting when the trial took place, so that makes you a cast iron liar.

 

[windgrins]

Thanks for the Bauer Link!

To show energy conservation and steady state you can use a power balance calculation. Power is the time derivate of work, so you need to show that power_input < useable_power_output power_input > useable_power_output for any time point that is of interest. You can do this in any inertial frame. But conveniently you would choose an inertial frame, where one of the interacting (and thus potentially accelerating) objects is at rest at the analyzed time point (the object's instantaneous inertial rest frame).

As an example you can look at the DDWFTTW analyses which usually use the instantaneous inertial rest frame of the cart:

Drela, Mark. "Dead-Downwind Faster Than The Wind (DFTTW) Analysis".
http://www.boatdesign.net/forums/at...w-directly-downwind-faster-than-wind-ddw2.pdf

Gaunaa, Mac; Øye, Stig; Mikkelsen, Robert (2009). "Theory and Design of Flow Driven Vehicles Using Rotors for Energy Conversion". Marseille, France: Proceedings EWEC 2009.
http://orbit.dtu.dk/getResource?recordId=241183&objectId=2&versionId=1

Bauer, Andrew (1969). "Faster Than The Wind". Marina del Rey, California: First AIAA. Symposium on Sailing.
http://projects.m-qp-m.us/donkeypus...aster-Than-The-Wind-The-Ancient-Interface.pdf

I may have missed it earlier but this is the first I've seen of the Bauer paper. Thanks for the Link.

WindGrins

 

[jduffy77]

You will never find me saying that NALSA were anything like the perfect body.
I was not posting when the trial took place, so that makes you a cast iron liar.

I have not said you were posting when the trial took place. I have the exact dates of all your posts in the database.

What are you saying? Are you saying you did not say the exact words "the perfect judging body" or are you saying that you did not state over and over again things like "Nalsa will never test the cart", "Nalsa will not be taken in by this hoax", "Nalsa will not ratify the record", etc, etc, etc?

I am trying to make clear, I interpreted quotes like these and many others to mean that you trusted in NALSA to agree with you. The perfect judging body was not meant as a word for word quote nor did I place it in quotes in my original post. Are you saying you did not say what I have placed in quotes here?

 

[Llyricist]

Really don't care if you do. What you don't present will gain you nothing.

You don't get it. Your chart is good enough for my case.

 

[humber]

You don't get it. Your chart is good enough for my case.

So you say. You don't have the math.

 

[humber]

I have not said you were posting when the trial took place. I have the exact dates of all your posts in the database.

What are you saying? Are you saying you did not say the exact words "the perfect judging body" or are you saying that you did not state over and over again things like "Nalsa will never test the cart", "Nalsa will not be taken in by this hoax", "Nalsa will not ratify the record", etc, etc, etc?

I am trying to make clear, I interpreted quotes like these and many others to mean that you trusted in NALSA to agree with you. The perfect judging body was not meant as a word for word quote nor did I place it in quotes in my original post. Are you saying you did not say what I have placed in quotes here?

I can ignore you. I don't care if The Pope tested that cart, the data from NALSA, Spork's claims in the submission, Steve Smith's emails, the photo from Llyricist, the Javaprop model, the electrical model with support from Drela's papers, says I don't have to.

 

[tobermoryphil]

So you say. You don't have the math.

Still waiting for any maths from you, Humber, in particular for your magic pylon fairings that somehow provide forward thrust!

 

[humber]

Still waiting for any maths from you, Humber, in particular for your magic pylon fairings that somehow provide forward thrust!

The wind plotted over that photo is all that is needed. What a blunder to post that gem.

 

[windgrins]

"Ugly Facts"

I can ignore you. I don't care if The Pope tested that cart, the data from NALSA, Spork's claims in the submission, Steve Smith's emails, the photo from Llyricist, the Javaprop model, the electrical model with support from Drela's papers, says I don't have to.

Yes, let's not let any ugly little facts get in the way of our fancy theory!

Multiple Mathematical models which support concept-Drela, Bauer...
Multiple independent Treadmill Tests
Multiple independent testers
Multiple small carts tested
BUFC and BB cart videos
Certified World Record by respected sanctioning body witnessed by multiple independent and knowledgeable observers.

This reminds me a bit of the "Bumblebee's can't fly" kerfuffle! Perhaps they should be renamed "HumberBees" given their propensity to do the impossible!

Regards,

WindGrins



Regards,

WindGrins

 

[humber]

Yes, let's not let any ugly little facts get in the way of our fancy theory!

Multiple Mathematical models which support concept-Drela, Bauer...

There is no connection between those two papers, and less with Spork's claims. I put Drela's in Matlab. Nice charts.

Multiple independent Treadmill Tests

No. The TM is dead.

Multiple independent testers

One NALSA representative, and a gaggle of commercially interested parties.

Multiple small carts tested

One. Spork's. The wind test video shows the prop turning CW, CCW, and then stalling completely. I Ratant's shows abject failure.

BUFC and BB cart videos
Certified World Record by respected sanctioning body witnessed by multiple independent and knowledgeable observers.

A crock.

This reminds me a bit of the "Bumblebee's can't fly" kerfuffle!

And old and blunted saw.

 

[tobermoryphil]

I think the 1 kW, and consequent 111 N, is just what's required to spin the propeller. Then, in addition, there's rolling resistance of 53 N and air resistance of 10 N, for a total of 174 N.

OK, lets take these figures, even though I feel the rolling resistance is high.
Assuming Spork's chain transmission is 93% efficient, a reasonable figure, from the 1 KW, we get power input to the prop of 930 W.
So using Javaprop, for 930 W input, 5 m dia prop, 300 mm dia spinner, 175 rpm, 2 m/sec airspeed, E193 airfoil with Rn of 300,000, we get a thrust of....

207 N, against the retarding forces of 174 N.

So 33N to accelerate the cart.

Over to you, Messers Propfloss and Dumber.

 

[windgrins]

No, No way!

OK, lets take these figures, even though I feel the rolling resistance is high.
Assuming Spork's chain transmission is 93% efficient, a reasonable figure, from the 1 KW, we get power input to the prop of 930 W.
So using Javaprop, for 930 W input, 5 m dia prop, 300 mm dia spinner, 175 rpm, 2 m/sec airspeed, E193 airfoil with Rn of 300,000, we get a thrust of....

207 N, against the retarding forces of 174 N.

So 33N to accelerate the cart.

Over to you, Messers Propfloss and Dumber.

Tober,

You know this can't be correct because this would allow the cart to work! That can't be right since The H-team deems it impossible!

WindGrins

 

[humber]

OK, lets take these figures, even though I feel the rolling resistance is high.
Assuming Spork's chain transmission is 93% efficient, a reasonable figure, from the 1 KW, we get power input to the prop of 930 W.
So using Javaprop, for 930 W input, 5 m dia prop, 300 mm dia spinner, 175 rpm, 2 m/sec airspeed, E193 airfoil with Rn of 300,000, we get a thrust of....

207 N, against the retarding forces of 174 N.

So 33N to accelerate the cart.

Over to you, Mr Propfloss.

Submission says some nonsense in "mph lbs" which converts to 774W, an efficiency of 61.4% and airspeed of 5mph =2.2m/s, rising with speed.
Javaprop says something totally different.

Chart says a constant net force of 32N. Power ~ 400W, Rpm ~75 at 28mph. Power rises with the cube of AV, and Spork's use of 175rpm, was an underhanded trick, that is based on Javaprop's airspeed, where as the prop speed is related to ground speed by the magical gears.


Chart says constant 32N, power is 300W, and a wind that changes by 100 degrees.
Video says prop power at 15rpm is 3W.

 

[jduffy77]

Tober,

You know this can't be correct because this would allow the cart to work! That can't be right since The H-team deems it impossible!

WindGrins

Actually one H agrees with the force calcs (humber agrees with nothing, ever, even things he agrees with). Remember its his energy calcs he then uses to justify his conclusion (by not adding the work at the prop):

At this point the less informed among the cart crowd will say I have just shown the cart works, because the thrust is 250 N and the drag is 174 N, right? No, forces alone are not the whole story as we need to consider energy and power. The thrust force is what would be there IF and only IF, there is sufficient energy in the system to develop and sustain that thrust.

 

[fttw]

Does profpangloss not work on Sundays? I'm waiting to hear from him with his straightforward analysis in the earth-stationary frame.

 

[humber]

Actually one H agrees with the force calcs (humber agrees with nothing, ever, even things he agrees with). Remember its his energy calcs he then uses to justify his conclusion (by not adding the work at the prop):

No he doesn't.

 

[jduffy77]

No he doesn't.

Ummm, yes he does. I just included a quote of his.

 

[humber]

Tober,

You know this can't be correct because this would allow the cart to work! That can't be right since The H-team deems it impossible!

WindGrins

There is not one consistent line of data. Nothing agrees with the data, and JB's marvelous claim of 2800N

 

[humber]

Ummm, yes he does. I just included a quote of his.

No, he doesn't. And you will have to agree with the conclusion too? right? Or is is only what you think you can cherry-pick from the data he took to use against you? See how that works?

 

[tobermoryphil]

Video says prop power at 15rpm is 3W.

Is it only you that the video whispers these figures to, 'cos it didn't say anything to me!

And if you can estimate the power required from just watching a prop being turned by hand in a video, you have supernatural powers, enough to surely to put in a claim for the JREF $1,000,000!