Merged DDWFTTW in a “Real” Wind

[profpangloss]

A: The 98+% is achieved for real, not just in theory (everyone here knows exactly how you meant that.)

Everyone here knows exactly how I meant that? I know how I meant it, and my statement was correct in every possible way. Do you know what paranoia is? You might want to look into that.

B: According to your "theory" of correctness, this statement would also have been just as valid. "... theoretical efficiencies of over 10%".

You're the only one who believes your story.

JB

What story? Man, you really, really ought to look into that paranoia thing. Seriously. And rather than reading into things too far, in order to decipher secret meanings, how about staying on topic? Do you think a laboratory controlled test of a short chain that was special made to fit the sprokets with perfect alignment and optimum tension, run by computer controlled motors, so well matched that it did not even require lubrication, says anything at all about an ordinary, five meter(plus) long chain, in an outdoor environment with sand and dirt, twisted between two sprockets that are at right angles to each other, kept in place with home-made chain tensioners, no possible hope of optimum alignment or tension, a chain that has a history (yes I can read) of breaking and bending sprockets out of whack, THAT chain, is somehow comparable to the chain in the lab? Do you think THAT chain drive was/is 90% efficient? Try a little honesty here, instead of trying to find hidden meanings in my posts.

 

[profpangloss]

No, this means that their are no readily accessible formulas or programs that bother to calculate thrust for the condition of air moving back to front through a propeller.

I wonder why that is? But no matter, there ARE thrust formulas and they can be modified for any case. Its just mathematics. More on this later, I promise.

What purpose does it serve to calculate for a condition that the cart will never be in, if the numbers show the cart cannot even reach wind speed?

 

[Subduction Zone]

It sounds like profpangloss is projecting a bit here. He is accusing everyone capable of doing physics of having paranoia. I guess we are all out to get him.

Meanwhile he continues his very Haroldish avoidance of a chance to learn how the treadmill works.

 

[Llyricist]

With a 90% drive train efficiency, fresh BMX tires, Cd of .365, the prop operating at 89% efficiency with a theoretical max of 93%. I'm getting:

26 horsepower at the shaft, 569 ft lbs torque, and 228.8 lbs of thrust, and a 10 newton net acceleration force.

 

[Subduction Zone]

I wonder why that is? But no matter, there ARE thrust formulas and they can be modified for any case. Its just mathematics. More on this later, I promise.

What purpose does it serve to calculate for a condition that the cart will never be in, if the numbers show the cart cannot even reach wind speed?

Wrong again ppg. The reason that you don't have prebuilt software that will calculate thrust in these conditions is that there is not much demand for it. It might seem to you that spork has thousands of minions building carts but there aren't nearly that number. So besides an education in physics do you need an education in economics too?

 

[profpangloss]

With a 90% drive train efficiency, fresh BMX tires, Cd of .365, the prop operating at 89% efficiency with a theoretical max of 93%. I'm getting:

26 horsepower at the shaft, 569 ft lbs torque, and 228.8 lbs of thrust, and a 10 newton net acceleration force.

How about showing your calculations instead of just your result?

 

[Llyricist]

I wonder why that is? But no matter, there ARE thrust formulas and they can be modified for any case. Its just mathematics. More on this later, I promise.

What purpose does it serve to calculate for a condition that the cart will never be in, if the numbers show the cart cannot even reach wind speed?

because it does not matter how it gets up to wind speed, the claim never had anything to do with that until they found out that it actually could get there on its own in real life tests.

 

[profpangloss]

Edited by Tricky: 

Edited for rule 11.

 

[Subduction Zone]

With a 90% drive train efficiency, fresh BMX tires, Cd of .365, the prop operating at 89% efficiency with a theoretical max of 93%. I'm getting:

26 horsepower at the shaft, 569 ft lbs torque, and 228.8 lbs of thrust, and a 10 newton net acceleration force.

You must be doing that calculation wrong, too bad Harold isn't here to show you how to subtract the thrust from your answer, or if not that he can subtract the force from the wheels twice for you At any rate I am sure that he could get another answer than you did.

 

[profpangloss]

because it does not matter how it gets up to wind speed, the claim never had anything to do with that until they found out that it actually could get there on its own in real life tests.

IF it actually gets there in real life, then you should be able to show the math how it does that.

 

[Llyricist]

How about showing your calculations instead of just your result?

Because I already gave the relevant numbers for anyone that cares to check for themselves. And it would be too much to wade through for those that just want the results.

 

[Llyricist]

You must be doing that calculation wrong, too bad Harold isn't here to show you how to subtract the thrust from your answer, or if not that he can subtract the force from the wheels twice for you At any rate I am sure that he could get another answer than you did.

Actually, he's been doing the power and force calculation correctly lately, he's doing the energy bookkeeping by double counting and and changing signs.

 

[Subduction Zone]

Edited by Tricky: 

Edited for response to modded post.

 

[Llyricist]

IF it actually gets there in real life, then you should be able to show the math how it does that.

I prefer to show the real life result, since I don't have access to the necessary formulas to show the math.

http://www.youtube.com/watch?v=7SYvg40NHtc

 

[Subduction Zone]

Actually, he's been doing the power and force calculation correctly lately, he's doing the energy bookkeeping by double counting and and changing signs.

I haven't seen him run through an entire force analysis lately. But the errors he makes in the energy analysis sound the same as his errors in his earlier force analysis. Harold does have the ability to do the math. But since he has convinced himself of the answer ahead of time he will always find a way that corrupts the math in a manner that he can live with.

 

[profpangloss]

I prefer to show the real life result, since I don't have access to the necessary formulas to show the math.

http://www.youtube.com/watch?v=7SYvg40NHtc

But you said you were getting certain results, may I quote:

With a 90% drive train efficiency, fresh BMX tires, Cd of .365, the prop operating at 89% efficiency with a theoretical max of 93%. I'm getting:

26 horsepower at the shaft, 569 ft lbs torque, and 228.8 lbs of thrust, and a 10 newton net acceleration force.

Now you say you don't have access to the formulas? More Internet wooo?

 

[Llyricist]

Actually, he's been doing the power and force calculation correctly lately, he's doing the energy bookkeeping by double counting and and changing signs.

And by correctly, I mean in the mathematical sense. He still uses ridiculously high rr and drag numbers. while at the same time using using ridiculously high efficiency for the prop.

 

[Llyricist]

But you said you were getting certain results, may I quote:

With a 90% drive train efficiency, fresh BMX tires, Cd of .365, the prop operating at 89% efficiency with a theoretical max of 93%. I'm getting:

26 horsepower at the shaft, 569 ft lbs torque, and 228.8 lbs of thrust, and a 10 newton net acceleration force.

Now you say you don't have access to the formulas? More Internet wooo?

We were talking about the situation below wind speed, that calculation was for 3.11 times the wind speed, a situation for which I do have access to the math.

 

[3point14]

IF it actually gets there in real life, then you should be able to show the math how it does that.

how about a video of it actually doing it. Surely reality trumps mathematics?

 

[profpangloss]

how about a video of it actually doing it. Surely reality trumps mathematics?

Would you like to see a video of a UFO? Bigfoot? Ghosts? An elephant flying? I can direct you to the links, but I'm sure you can find them on your own.

This is physics, or so it is claimed, and mathematics rules. Where's the math?