Merged DDWFTTW in a “Real” Wind

[humber]

By comparing the real life results with the theoretical results using those figures.

Not measured, so not empirical. Guessed.

What modifications?

You tell me. I am not going to design the prop, but use the data that represents the prop on the cart. Do you have a file. Then there can be no problems.

The geometry data was in this post:
http://www.internationalskeptics.com/forums/showpost.php?p=7155132&postcount=4927

Which you said was NOT javaprop, because it was not metric. The other is the same chord data but metric, correct?

What earlier data? If I guess right, you have your history confused again, I said that the data spork posted was not from javaprop, not that it wasn't correct.

Then why make the distinction?

I just gave everything you need to make it yourself. And I even just threw in a link that you could have found on your own, you figure it out if you are such an expert.
The geometry includes the nominal pitch btw,.... jeez.

Not interested in providing any design input. The prop exists, and that is the prop that is of interest. Not something else.
Are you saying that you do not have a complete file of that data, that may be imported into Javaprop, or that you won't supply it?
For someone so sure, you are being reluctant.

Nope, this started as you disputing that the pitch made a difference. Now you seem to be changing the subject.

No, I will demonstrate that pitch will make no difference, because the failure will be complete. Pitch won't save it, and it was never an issue, and was not fitted to the cart on the first run.

You can do the analysis using any speed, Cd, crr, weight, dt efficiency, or prop you want, it will give different net forces at different pitches regardless.

Net force will not be met, and neither will power.

As I said, they aren't used for the thrust or power calculations. They are just necessary in Java to run an analysis with the propeller object.

Won't make any significant difference. Thrust is certainly influenced by air density.

Wrong, temp 11 miles away was 27 degrees C, altimeter 29.82 inches, elevation 2838 ft.

Not a few meters above the open floor of the lake bed, is it? Humidity?
Not relevant unless you are claiming Goldilocks will only work when the porridge is just right.

Nope. You are already changing things, so agreeing with anything with you would be useless.

The profile data is yours.
http://www.internationalskeptics.com/forums/showpost.php?p=7209254&postcount=7308

 

[Llyricist]

Look, I gave you everything you need to reproduce the results, and more than you need to find that pitch makes a difference. You are just loading a bunch of red herrings and excuses at this point to avoid finding out that you were wrong about that point.

 

[humber]

Look, I gave you everything you need to reproduce the results, and more than you need to find that pitch makes a difference. You are just loading a bunch of red herrings and excuses at this point to avoid finding out that you were wrong about that point.

The pitch will make no difference. It will fail with the nominal pitch. The pitch ruse was yours.
Do you have the javaprop file?

 

[Llyricist]

The pitch will make no difference. The pitch ruse was yours.

Aahh so you prefer to just assert, rather than find out... got it..

Oh yeah, you never actually DO anything, you always just make bald assertions that are, almost without exception, at odds with reality.

Do you have the javaprop file?

Yep, and you can have it too, if you just follow the simple instructions to re create it.

 

[humber]

Aahh so you prefer to just assert, rather than find out... got it..

Oh yeah, you never actually DO anything, you always just make bald assertions that are, almost without exception, at odds with reality.

Not interested. The cart will fail in principle. The performance at the trial is not related to that principle.

Yep, and you can have it too, if you just follow the simple instructions to re create it.

So you are hoping for what? If you are so sure, you will be quite willing to provide the exact data. Otherwise, I will simply ignore what you have, and then leave you
to refute what I have.

 

[Llyricist]

Not interested. The cart will fail in principle. The performance at the trial is not related to that principle.

Once again proving the point to which you are responding.

So you are hoping for what? If you are so sure, you will be quite willing to provide the exact data. Otherwise, I will simply ignore what you have, and then leave you
to refute what I have.

I did provide the exact data. Holy moly.

And go right ahead and do whatever. The only embarrassment will be your own.

 

[Subduction Zone]

Llyricist, for humber any data that showed that the cart went faster than the wind is manipulated data by definition. He cannot prove it mathematically but he "knows" that the cart does not work. Therefore anything that does show that it works is by definition manipulated and bogus. I am still waiting for his mathematical proof that the cart does not work. I hope it is up to the same standards as Harold's

 

[humber]

Once again proving the point to which you are responding.

I will use the Propdesigner information. That will be OK. There will be no margin that can save the cart.
The trial data is junk.
So far, the TM is dead, the little cart has been demonstrated to be a failure, and then the theory will be buried using this data.
The trial data will then fall on the errors and manipulation already manifest.

I did provide the exact data. Holy moly.
And go right ahead and do whatever. The only embarrassment will be your own.

Like the "exact" rolling and aero data, but no mention of the tyre type, weight, over each wheel...etc.

No matter, it will fail anyway, and I will use the data from Continental tyres. That will be adequate.

The other stuff about modifying the NAC airfoil is just talk to lend and impression. It will make no more difference if the prop were a stick.

 

[humber]

Llyricist, for humber any data that showed that the cart went faster than the wind is manipulated data by definition. He cannot prove it mathematically but he "knows" that the cart does not work. Therefore anything that does show that it works is by definition manipulated and bogus. I am still waiting for his mathematical proof that the cart does not work. I hope it is up to the same standards as Harold's

Profpangloss knows that the cart will not meet its power requirements, and by a big margin.

 

[Llyricist]

I will use the Propdesigner information.

Even though I linked you to spork's post that includes the angle info., brilliant.

Snipped same o PRATTs

Like the "exact" rolling and aero data, but no mention of the tyre type, weight, over each wheel...etc.

^ LMAO, like I said, the only embarrassment ^

No matter, it will fail anyway, and I will use the data from Continental tyres. That will be adequate.

So you are going to use data that is specifically NOT actual, instead of numbers that are consistent with the facts.

The other stuff about modifying the NAC airfoil is just talk to lend and impression.

LMAO, The guy is so accustomed to perpetrating double talk he just assumes everyone else does it.

 

[Subduction Zone]

Profpangloss knows that the cart will not meet its power requirements, and by a big margin.

Nope, ppg always makes the same mistake. He forgets about the contribution of the wind to the power of the cart.

At least Harold has seen the light and no longer tries to do force analysis. His mistakes were just too hard to hide when he made that approach.

 

[CORed]

Not interested. The cart will fail in principle. The performance at the trial is not related to that principle.



So you are hoping for what? If you are so sure, you will be quite willing to provide the exact data. Otherwise, I will simply ignore what you have, and then leave you
to refute what I have.

It will almost certainly be self-refuting.

 

[humber]

Even though I linked you to spork's post that includes the angle info., brilliant.





^ LMAO, like I said, the only embarrassment ^


So you are going to use data that is specifically NOT actual, instead of numbers that are consistent with the facts.

It will do. You will be left to try and massage your numbers into the result and fail. The reason is lost on you.
You don't have the tyre data. You adjusted it to fit the wind data, like all the other numbers. I told you that is what you had done.

And you can't use the cosine of the wind, because it's not ddw then, is it? Cos 0 =1. Otherwise you are agreeing it is driven by the wind deviation.
The cart will not produce enough prop power to drive the wheel, to produce the prop power....

 

[Llyricist]

And you can't use the cosine of the wind, because it's not ddw then, is it? Cos 0 =1. Otherwise you are agreeing it is driven by the wind deviation.

Wow, did you really have to edit to add that bit of absurdity?

Yes, when the deviation is 0, I multiply the wind speed by 1, meaning that the cart has the lowest possible airspeed to have to generate thrust in, and lower drag to fight against.

Any other angle and the airspeed goes up relative to ground speed, the prop has to generate thrust with a higher airspeed at the same omega, and there is more drag to fight against. But it doesn't degrade the performance very much in the first 20 degrees as it still has the benefit of 92% of the wind's speed at that point. But after that it falls off much more rapidly.

That's how the cart actually works. The less the difference between its longitudinal airspeed and its ground speed, the worse it works. And if the difference is 0, it can't work no matter what. In fact, there is a minimum difference below which it can't work.

 

[humber]

Wow, did you really have to edit to add that bit of absurdity?

Yes, when the deviation is 0, I multiply the wind speed by 1, meaning that the cart has the lowest possible airspeed to have to generate thrust in, and lower drag to fight against.

Then the cart using the wind deviation to power the cart. The claim is that it works best ddw, remember? Then the airspeed is Vcart - Vwind, so a headwind. That is how it is presented in the submission, and has always been done that way. There is also a "proof" that the prop will not work as well if not ddw.

"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."

Naughty to try and sneak that in.

You didn't think I took any of those calculations seriously did you?

The rest is irrelevant.

ETA
crr of .08
Sure?

EDIT
If the tailwind is directly behind the cart, then its component in the direction of the cart is at a maximum. The apparent wind seen by the cart is Vwind - Vcart, so a minimum
If the wind deviates from that direct path, then the component in the direction of the cart must fall, so the apparent wind will increase. That must be true, because if it deviates by 180 degrees it adds directly to the apparent wind seen by the cart. Deviation can't improve the performance of the cart in that way you describe. The force that drives the cart, is then the lateral lift force, but the drag force has increased, so the L/D ratio is critical to exploiting that deviant wind.

 

[A.T.]

Flying Magazin drinks the Kool Aid:
http://www.flyingmag.com/pilots-places/pilots-adventures-more/technicalities-something-nothing

 

[windgrins]

Reasoned Analysis not very helpful when data is scarce!

You didn't think I took any of those calculations seriously did you?
The rest is irrelevant.

PPG, The above is an example of why I believe you will not be able to come to any valid conclusions on your "power/energy" quest.

I assume that leaving out the power supplied by the wind in your example and having it pointed out, was why my post was disconcerting. It does sort of put that argument in the trash if you don't include it.

No need to answer this, but if you have enough data, you may want to rethink your equations by adding this back in. I believe that if you recompute your energy/power equation by putting in the correct gains from operating in the wind vs a no-wind environment, you will find adequate energy to make the cart accelerate. On the other hand, my critique of the unknown and hypothetical nature of any available, data (since we don't have all relevant empirical measurements of several key pieces of data to make your analysis valid) will probably preclude a justifiable outcome for either of us.

Lastly, if you ignore the fundamental data of a cart accelerating up TM in all the videos because you don't understand IRFs and Galilean transforms, All the data in the world may not help your analysis.

WindGrins

 

[Llyricist]

Then the cart using the wind deviation to power the cart. The claim is that it works best ddw, remember? Then the airspeed is Vcart - Vwind, so a headwind. That is how it is presented in the submission, and has always been done that way. There is also a "proof" that the prop will not work as well if not ddw.

"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."

Naughty to try and sneak that in.

You didn't think I took any of those calculations seriously did you?

The rest is irrelevant.

ETA
crr of .08
Sure?

EDIT
If the tailwind is directly behind the cart, then its component in the direction of the cart is at a maximum. The apparent wind seen by the cart is Vwind - Vcart, so a minimum
If the wind deviates from that direct path, then the component in the direction of the cart must fall, so the apparent wind will increase. That must be true, because if it deviates by 180 degrees it adds directly to the apparent wind seen by the cart. Deviation can't improve the performance of the cart in that way you describe. The force that drives the cart, is then the lateral lift force, but the drag force has increased, so the L/D ratio is critical to exploiting that deviant wind.

Okay, your comprehension of this is so far removed from reality as to be inexplicable.

I just got through saying that adding to the airspeed hurts the cart. And that the wind deviating from DDW adds to the airspeed. And you turn around and claimed I said the opposite. Which of course would be ridiculous. Then you PSed and made the almost correct interpretation of what I said and claimed it contradicted what I said.

Jeeez man.

Or maybe you don't understand what airspeed means?

 

[Llyricist]

ETA
crr of .08
Sure?

Ah you actually caught one, that was a typo or brain freeze, I used .008, not .08.

 

[spork]

Or maybe you don't understand...

I think you're onto something.