The 1969 Blackbird wind turbine sailing craft concept

[ridgerunner]

19 hours ago, VictorMedvil said:

... So unless you wanna power your car with a skyscraper I would stay away from wind powered vehicles, why can't you guys forgo crackpottery and come up with a nuclear powered car or something. ...

No one has claimed that there is a practical use for a DDWFTTW vehicle and no one should. It is  essentially useless as a practical mode of transportation. What it *IS* very good at is tweaking brains, especially well educated brains!

It does work and it does NOT violate any laws of physics, including the conservation of energy you cited. Note that the rotor blades are NOT acting as turbine blades - they are acting as propeller blades and they are driven by extracting power from the ground via a braking force at the wheels. As it turns out, the forward pointing thrust force generated by the propeller, (which is accelerating air rearwards), can be greater than the rearward pointing ground force acting on the bottom of the wheels. This net forward pointing force can be used to overcome all the frictional losses in the system and accelerate the vehicle to a speed significantly above wind speed.

One brain-tweakingly unintuitive aspect of this vehicle is that when the vehicle operates at precisely wind speed, from the frame of reference of the cart, the air is stopped and has zero kinetic energy and the propeller is actually adding energy to the air speeding it up. But at the exact same time, an observer on the ground witnessing the same cart roll by will observe that the air behind the propeller is moving slower than the surrounding wind and the propeller is thus slowing down the air in this reference frame. Strange but true!

Read the papers I attached to my second post and come back and tell me where Dr. Drela made any mistakes.

Cheers from Central Utah!

Edited December 13, 2021 by ridgerunner

[OceanBreeze]

7 hours ago, ridgerunner said:

No one has claimed that there is a practical use for a DDWFTTW vehicle and no one should. It is  essentially useless as a practical mode of transportation. What it *IS* very good at is tweaking brains, especially well educated brains!

It does work and it does NOT violate any laws of physics, including the conservation of energy you cited. Note that the rotor blades are NOT acting as turbine blades - they are acting as propeller blades and they are driven by extracting power from the ground via a braking force at the wheels. As it turns out, the forward pointing thrust force generated by the propeller, (which is accelerating air rearwards), can be greater than the rearward pointing ground force acting on the bottom of the wheels. This net forward pointing force can be used to overcome all the frictional losses in the system and accelerate the vehicle to a speed significantly above wind speed.

One brain-tweakingly unintuitive aspect of this vehicle is that when the vehicle operates at precisely wind speed, from the frame of reference of the cart, the air is stopped and has zero kinetic energy and the propeller is actually adding energy to the air speeding it up. But at the exact same time, an observer on the ground witnessing the same cart roll by will observe that the air behind the propeller is moving slower than the surrounding wind and the propeller is thus slowing down the air in this reference frame. Strange but true!

Read the papers I attached to my second post and come back and tell me where Dr. Drela made any mistakes.

Cheers from Central Utah!

"One brain-tweakingly unintuitive aspect of this vehicle is that when the vehicle operates at precisely wind speed, from the frame of reference of the cart, the air is stopped and has zero kinetic energy and the propeller is actually adding energy to the air speeding it up. But at the exact same time, an observer on the ground witnessing the same cart roll by will observe that the air behind the propeller is moving slower than the surrounding wind and the propeller is thus slowing down the air in this reference frame. Strange but true!"

 

 

That’s worse than just “strange” it is ridiculous! In the first frame you mentioned, the car cannot work as it is supposedly wind-powered. As you said, the air (wind) in this frame has zero kinetic energy and cannot power the car. That should be the end of this story. If it does not work in one frame, it does not work in any frame.

Certainly, I understand the concept of frame-dependent energy, and in the second frame, the observer standing on the ground has plenty of wind energy, but the car still has none so it cannot be slowing down the air as it has no energy to do that work on the wind. Oh, I know! You are going to claim there is ground energy because the car is moving, right? And that is why this is a crank claim.

I had a look at Drela’s papers. They are smoke and mirrors and obviously written to obfuscate rather than to explain anything. You may as well have given me The Papyrus of Ani. I am not going to waste my time on it. If Drela wanted to explain this thing he could have done it much simpler, but if he had, people would see it can’t work, so he made his non-peer-reviewed and unpublished-anywhere-that-matters, “paper” as convoluted as humanly possible.

He may as well have saved himself a lot of trouble and just wrote “The car works. It works because I say so and my name is Mark Drela. I am a great aerodynamicist and you must believe me. Did I mention my name is Mark Drela? No, my paper is not peer reviewed, why should it be? I have no peers. I am Mark Drela, and don’t you forget it!!!!!”

There are many great aerodynamicists in this world and most of them have grown up and stopped playing with propeller toys that have no use whatsoever. They are developing things like the AH-64 Apache helicopter, the world’s most advanced helicopter; and the Lockheed Martin F-35 fighter. Those aero engineers are no slouches! I doubt if any one of them gives a damn about this silly toy.

I am a marine engineer and I work with some very advanced equipment also. I deleted my posts and dropped out of this thread before because it is a silly claim (see, it is right where it belongs). Now I am dropping out again. If you believers want to talk about this amongst yourselves and reinforce each other’s beliefs, you can do so here in Silly Claims. I have no time for this nonsense but do call me if you get around to the balloon experiment. That, I want to see!

Meanwhile, just be sure to not break any of the furniture here and attack this forum, or your thread will disappear faster than the wind. Have a nice day!

 

 

[AnssiH]

On 12/12/2021 at 7:43 AM, VictorMedvil said:

Final Verdict: You are never going to create energy it doesn't matter how you "Gear' it or anything of that nature, energy in a closed system is constant being the Wind and Vehicle , this entire concept is crackpot that somehow you can make "Extra" energy from any known method. The vehicle will have the amount of energy that the wind yields to it which is many orders of magnitude less than the energy of a gallon of gasoline.

"The law of conservation of energy states that energy can neither be created nor destroyed - only converted from one form of energy to another. This means that a system always has the same amount of energy, unless it's added from the outside."

There is no debating it, the wind plus vehicle system will always have the same amount of energy at a given velocity of the wind, which is governed by Newtonian mechanics in  the equations already written down by me, the only thing you could do is make the propeller much larger and it would capture more energy from the wind by increasing it's surface area having more wind/air molecules hit it, which is why sailboat sails are so large to capture more energy from the air/wind to make a gallon of gasoline's level of energy they would have to be 1000+ meters^2 depending on the mass of the vehicle being moved by the air/wind.

Victor, buddy. You wrote the equation of a sail. I told you back then, but you ignored it.

I know you are capable of understanding the difference of a propeller and a sail, but you want to avoid thinking by the same blunder everyone who get this wrong avoid thinking.
You've been told many times it's no different from Monty Hall problem in that regard. Yet you spend all your energy into avoiding thinking.

No one is saying the law of conservation of energy is violated. In fact it's easy to prove it's not. Are you interested of understanding why? Or are you just confident that your intuition is correct without examination? I'm perfectly willing to walk you through it so that you learn something here.

Science, remember.

Cheers,

-Anssi

[AnssiH]

On 12/12/2021 at 1:28 PM, OceanBreeze said:

Yes, I am a scientist and believe strongly in the scientific method, that is why I propose this experiment.

Then why are you so hell-bent on avoiding a rational analysis?

I'll copy-paste here my simple demonstration from our PM that should reveal the operating principle of the vehicle for anyone who cares to think about it:

---

Let the wind and car velocity be 10 m/s in the reference frame of the ground. Thus, vehicle air speed is 0.

We spend 1 Newton at the wheel for power generation. This gives us 10 watts:

P = Fv
P_harvested_by_wheel = F * ground_velocity = 1 N * 10 m/s = 10 Nm/s = 10 Watts

Now the question is, how much propeller thrust can be produced with 10 W given that the propeller is sitting in air speed of 0. If the answer is more than 1 N, then the vehicle must accelerate beyond wind speed. If it's less, then the vehicle must be losing speed.

Equation 4 in Martin's article:

P_engine = Thrust * (air_speed + dv/2)

Where dv is the air speed difference caused by propeller blades. NOT the vehicle acceleration. What number dv is depends on our propeller design (the larger the propeller, the smaller the dv for same thrust).

Note how this differs from the usual P = Fv. The propeller thrust depends on air speed and the last term is like it is because propeller is not just pushing against air like a sail.

Air speed in our circumstance is 0. For efficiency reasons we choose a propeller design where dv is low (say, 1 m/s) and the propeller is large. Thus;

Thrust = P_harvested_by_wheel / 0.5dv
Thrust = 10 Nm/s / 0.5 m/s
Thrust = 20 N

So for 1 N braking loss at wheel, the propeller thrust is 20 N minus efficiency losses.

---

Now this is near ideal situation with very large propeller and the moment we are at 0 air speed, but if you imagine this situation in your mind, you should see it's just a leverage system, like this:

 

OH NO, THE VEHICLE IS MOVING FASTER THAN THE POWER TRAIN!!! NEW PHYSICS!!!! 😱🙀

Or maybe not. Maybe wind power is not the same thing as wind speed. Just maybe.

@OceanBreeze your position on my analysis above currently is that it would require 200 watts of power to produce 20 N of thrust if the vehicle ground speed is 10 m/s. You are failing to understand that propellers act on air speed, not on ground speed. I feel like a physics forum moderator should be required to understand basic things like these.

You cited this yourself https://www.mh-aerotools.de/airfoils/propuls4.htm but you seem to not have read it. Propeller power to thrust equation that I used is in there. Try it next time. Spoiler alert - propeller thrust depends on air speed. This is why airplanes move faster in tailwind than headwind. It's not free energy. It's just basic newtonian momentum.

After I pointed out your wrong use if V for the first time, your response was that you were correct, without any examination or rational thought.

Then you insisted again that 200W via P = Fv, again with v being ground speed, at which point I thought maybe you are confused about Newtonian and Aristotlean physics, and think that constant power is required to stay at certain ground speed, or something. 🤷‍♂️ Hard to tell when you just make a silly argument without any explanation.

So I have told you multiple times now that propeller thrust is not dependent on ground speed, it's dependent on air speed, but you keep insisting you are right, and, quote "If you are going to post crackpot nonsense you better get used to some "harsh tones" LOL or toughen up"

What was the definition of crackpot nonsense again?

And @VictorMedvil do let me know, would you or would you not challenge OceanBreeze's idea that propeller thurst depends on ground speed instead of air speed of the vehicle?

Now if you guys feel even a slightest pinch that maybe your immediate knee-jerk intuition might be faulty - just like everyone are warning you it will be - are you interested of actually understanding this or not? It's not hard if you are willing to do a step by step analysis, and then little bit of examination and rational thought will reveal to you that every single argument I've told you this thread is absolutely valid. And then you can commence that self-kicking I also told you about.

Cheers

-Anssi

Edited December 14, 2021 by AnssiH

[AnssiH]

On 12/12/2021 at 1:28 PM, OceanBreeze said:

You can throw all of those analysis in the trash and settle this argument, that has gone on for at least 10 years (I don't know the full history) by doing the experiment I proposed. Just race this car against a neutrally buoyant balloon that is floating in the wind. That would be soooo convincing, I can't believe it has never even occurred to you people. There must be a damn good reason why it has not been done and I am sure the reason is that you know the car will be shown to never reach wind speed.

This balloon thing is so hilarious it's probably now going to become a meme.
Also as I said before, you are not asking it because it would suddenly completely convince you. You are asking it simply because you believe that somehow it could not be done.
Exactly the same thing as saying no one's written a paper, and then when someone has (like this one https://www.researchgate.net/publication/276175512_Analysis_of_Down-Wind_Propeller_Vehicle/link/5551d54d08ae739bdb924310/download ), it's off to the next excuse.

And before you say the next silly knee-jerk thing, let me explain why I'm bringing this up - because even if you saw a balloon video, it would be terribly unscientific of you to suddenly just believe that one. It's much better to understand things. For that, all you need is basically those two equations I posted in my previous post.

You see, logic it either valid, or invalid. If you are interested of rational analysis, you must do logic, and not just persistently mistake your own intuition for science.

Or why do you think it is that everyone who claim this thing works, are those who have actually worked it out in greater detail than "P_in is like a sail, thus P_out must be less. Done"

-Anssi

[AnssiH]

On 12/13/2021 at 10:31 AM, OceanBreeze said:

As you said, the air (wind) in this frame has zero kinetic energy and cannot power the car. That should be the end of this story.

 

See OceanBreeze, this is the kind of stuff that makes me seriously question your basic physics comprehension.

Again, propellers thrust air. They rotate, and air moves, get it? Apply 3rd law of Newton, and you get force.

Did you know that airplanes can take off even on a calm day?

Think a little before you post.

If in doubt, maybe consult some of your friends about it. Most of them can probably explain propellers to you.

Next your mind will wander off to thinking that the propeller cannot receive any real torque when at wind speed. Let me know if you can't work out the answer, and I'm more than glad to do it step by step. But please you have to stop the infantile crank accusations, because the deeper you go the more embarrassing it will be when you realize how badly mistaken you were.

-Anssi

[OceanBreeze]

15 hours ago, AnssiH said:

This balloon thing is so hilarious it's probably now going to become a meme.
Also as I said before, you are not asking it because it would suddenly completely convince you. You are asking it simply because you believe that somehow it could not be done.

Exactly the same thing as saying no one's written a paper, and then when someone has (like this one https://www.researchgate.net/publication/276175512_Analysis_of_Down-Wind_Propeller_Vehicle/link/5551d54d08ae739bdb924310/download ), it's off to the next excuse.
 

I know the balloon experiment will fail, just as I know the “International Journal of Scientific and Research Publications” (who published that "paper") is clearly a predatory journal. Check out the list yourself. The fact that you cite this as support just confirms your crackpot status.

No respected peer-reviewed journal has ever touched this, and you know it. It is crackpot nonsense!

[OceanBreeze]

15 hours ago, AnssiH said:

See OceanBreeze, this is the kind of stuff that makes me seriously question your basic physics comprehension.

Again, propellers thrust air. They rotate, and air moves, get it? Apply 3rd law of Newton, and you get force.

Did you know that airplanes can take off even on a calm day?

Think a little before you post.

If in doubt, maybe consult some of your friends about it. Most of them can probably explain propellers to you.

Next your mind will wander off to thinking that the propeller cannot receive any real torque when at wind speed. Let me know if you can't work out the answer, and I'm more than glad to do it step by step. But please you have to stop the infantile crank accusations, because the deeper you go the more embarrassing it will be when you realize how badly mistaken you were.

-Anssi

Yes, propellers rotate and produce thrust and they require a source of energy to do that. That is why propeller airplanes have engines, or have you never noticed that?

There is no engine on this as it is a wind-powered vehicle.

As ridge runner noted, and I quoted him, when the car is at wind speed, “the air (wind) in this frame has zero kinetic energy and cannot power the car”

Do you have a problem understanding that? Without wind power, the propeller cannot produce thrust!

The car cannot work in this frame and if you understand that, it cannot work in any frame. All observers in any frame must agree on this, there cannot be a different result in any other frame. They don’t have to agree on the velocity or even the source of energy but they must agree on acceleration. If the car cannot work in the frame where it has no wind energy, it slows down with negative acceleration. All observers must agree on that acceleration.

Your little fairy tale has an unhappy ending for you and all the rest of your clan of believers.

Don’t address any more of your crackpot posts to me, don’t try and waste any more of my time on this. I am not interested in your “toy story”

 Your persistence indicates you are unhinged at the fact that you can't convince everyone about your belief. A sure sign of mental illness.

 

[AnssiH]

8 hours ago, OceanBreeze said:

I know the balloon experiment will fail, just as I know the “International Journal of Scientific and Research Publications” (who published that "paper") is clearly a predatory journal. Check out the list yourself. The fact that you cite this as support just confirms your crackpot status.

Like I said, off to the next excuse without any examination of the actual argument.

While in general I support the sentiment of tracking various predatory practices of publishers, I don't personally judge the validity of an argument based on external metrics like that. I just base them on whether they are logically valid. As in, actually work it out until I understand what is being said. When I don't have the competence to work it out, I try to withhold opinion. (Also I have not examined the criteria of that site, but sounds interesting and could be a topic of another whole discussion)

The point is, you use that word "science" a lot, but you don't seem to know what it means. Which one applies more to "science":

A: Having unwavering confidence to one's own intuition so that no rational analysis is necessary.

or

B: Performing actual rational analysis of the logic of an argument.

In general you are following the usual pattern of people who are not that good at rational analysis themselves, where you put all of your energy into finding excuses to avoid thinking. You spit out that same tired belief which you have never really examined in any detail, and say you don't want to hear more. Again, science, have you heard of it?

Would you like to try and actually prove me wrong, and walk through some steps to analyze whether your belief is valid or not? Do it for science?

8 hours ago, OceanBreeze said:

Yes, propellers rotate and produce thrust and they require a source of energy to do that. That is why propeller airplanes have engines, or have you never noticed that?

There is no engine on this as it is a wind-powered vehicle.

As ridge runner noted, and I quoted him, when the car is at wind speed, “the air (wind) in this frame has zero kinetic energy and cannot power the car”

Do you have a problem understanding that? Without wind power, the propeller cannot produce thrust!

That's exactly the idea that sounds intuitively valid but on closer examination turns out to be false. Have you noticed how everyone warns you about this? Why might that be? Could it be because intuition is a terrible tool to do science?

Without even admitting your blunder about the propeller thrust being wrong, now your current argument is:
"[As everyone knows] at wind speed air has zero kinetic energy, thus it cannot power the car"

Sounds great, until you break it down to actual logical thoughts:

- The wheel of the vehicle is rotating against ground momentum and producing power.
- We are using that power directly to rotate a propeller.
- Clearly the propeller must be rotating even if we are at 0 air speed.
- Since the propeller is rotating, it must produce thrust against air, even though it feels no wind.

Why is it that your intuition implied there cannot be thrust at wind speed (and led you to make all the silly claims you have so far), even though clearly a propeller also must rotate. What is that amazing new physics that will prevent thrust here? I would say this, if anything, is a crank argument.

Right now the intuitive side of your brain is saying "yeah okay but I KNOW something in here will prevent the thrust because P_in < P_out". Believing that thought without rational analysis is the opposite of doing science. (Hint, your tacit assumptions behind P_in are wrong and I could show you how if you would listen)

 

8 hours ago, OceanBreeze said:

The car cannot work in this frame and if you understand that, it cannot work in any frame. All observers in any frame must agree on this, there cannot be a different result in any other frame. They don’t have to agree on the velocity or even the source of energy but they must agree on acceleration. If the car cannot work in the frame where it has no wind energy, it slows down with negative acceleration. All observers must agree on that acceleration.

I find it fascinating that you are trying to make an argument about reference frame symmetries after completely failing to recognize the same thing on the treadmill versions of the same vehicle. I mean if you think about how that treadmill machine might be producing its thrust (the propeller is undoubtedly rotating, is it not?), you might be able to work the whole thing out.

See, your argument can also be phrased as "if wind has speed X, nothing it powers could possibly move at faster speed".
Why not? Is that not the same as saying "the speed of a powertrain (lego beam / wind) is also the fundamental speed limit of what it powers (lego vehicle / blackbird)". Or do you believe that to also be true?

 

8 hours ago, OceanBreeze said:

Your little fairy tale has an unhappy ending for you and all the rest of your clan of believers.

Don’t address any more of your crackpot posts to me, don’t try and waste any more of my time on this. I am not interested in your “toy story”

 Your persistence indicates you are unhinged at the fact that you can't convince everyone about your belief. A sure sign of mental illness.

These are fascinating comments because they demonstrate also a big difference between the two of us. I'm interested of teaching people things they have not thought about, interesting concepts and ideas, scientific attitude and methods of avoiding irrational thinking. Stuff like that.

Where-as you are just interested of just asserting your self-proclaimed superiority over everyone who might not agree with your pre-conceived notions. That is how you act as a moderator of this site, your goal is to prop up your ego, instead of teaching anyone anything. And that is why you keep trying to escape this situation with a tirade of insults, instead of having to face actual logic, and possibly have someone else teach you something.

I suppose that was the real reason why you spent hours doing the math for the propeller (in the now-deleted post) is because you struggled to find a way to interpret the parameters in a way that would support your argument. That is why your equations and parameters were so hilariously different from what your sources actually said. The only reason you initially thought you were correct was that once you landed on appropriate set of errors that gave you the results you expected (actually a sail), your extreme confirmation bias led you to believe you had done it finally correctly. And you wanted to close the thread before anyone could point out your errors.

Do you not recognize this as completely anti-scientific behavior?

If you feel a pinch, let's play and do the actual steps of working out whether this thing works or not, shall we?

Best,

-Anssi

[Spork]

My god you people are stupid!

[OceanBreeze]

1 hour ago, Spork said:

My god you people are stupid!

A brilliant post from the great genius who is responsible for this nonsense. Just exactly what I would expect!

Stupidity can usually be corrected, but the sort of mental illness you have, lasts a lifetime. And I am sure I am making it worse since I don’t believe one bit of this ddw crap. That must really bother you!

Your persistence indicates you are unhinged at the fact that you can't convince everyone about your belief. A sure sign of mental illness.

This forum has no obligation to continue to host this nonsense, especially now that  you have degraded it with your childish input. Thread CLOSED.