Merged DDWFTTW in a “Real” Wind

[I Ratant]

Looks faked to me. Where is the fencing wire?
...

.
The logs are chained through the slots in the wheels.
But I expect the cable attached to the front bumper assisted.

 

[CORed]

Looks faked to me. Where is the fencing wire?



Of course. It's a sail. The wheels only seem to work as claimed.

Sort of like how the cotton reel only seems to move faster than the hand.

 

[Andrew Wiggin]

How, exactly?

By some sooper seekrit mechanism that he has yet to actually explain.

 

[A.T.]

Accelerating wind? Is it accelerating in a useful direction? Are there cleverly-shaped airfoil parts on BB which can exploit these sudden gusts? Can you point them out and briefly explain their operation? Thanks.

Let me explain the word matching algorithm:

Humber read that an airfoil turns the airflow to create a lift force.

Humber therefore thinks that any turning of the airflow, even when not caused by the airfoil, creates a lift force at the airfoil.

Humber's logic: There is "turning" in both sentences

 

[humber]

The record will fall to the next contestant with a bucket.

 

[Jack by the hedge]

Do you think a metre or so above the hub,windspeed is likely to be 2.8x as high as at the hub?

It could be a lot more. This profile is possible

[latex] \ v_w(h) = v_{10} \cdot \left( \frac {h} {h_{10}} \right)^ a [/latex]

where:

[latex] \ v_w(h) = velocity of the wind at height, h [m/s][/latex]
[latex] \ v_{10} = velocity of the wind at height, h10 = 10 meters [m/s][/latex]
[latex] \ a = Hellman exponent [/latex] = maybe 0.15.

Hmm. Well, I read that BB is a little under 25' tall with a 17' diameter prop.

So the hub is about 5m above the ground and the tip of the prop reaches somewhere close to 7.6m (the height reached by most of the blade's surface is less, but let's consider the maximum).

So your equation says the wind speed at the hub might be;
v_hub = v₁₀ * (5/10)^0.15 = 0.901 * v₁₀
And the wind speed at the highest point ever reached by the very tip of the turning prop;
v_tip = v₁₀ * (7.6/10)^0.15 = 0.960 * v₁₀

So that's (0.960/0.901) times or, if you prefer, 6½% higher windspeed at the very highest point any part of the prop ever reaches than is measured at the hub. It's a bit less than the 180% higher in my actual question.

So although your initial comment was "it could be a lot more" the concise answer was emphatically "no".

 

[humber]

Let me explain the word matching algorithm:

Humber read that an airfoil turns the airflow to create a lift force.

The resultant acceleration of the air, produces lift.

Humber therefore thinks that any turning of the airflow, even when not caused by the airfoil, creates a lift force at the airfoil.

The result acceleration of cart, produces lift.

Humber's logic: There is "turning" in both sentences

AT's raison d'etre : There's "humber" in each sentence.

 

[Jack by the hedge]

Accelerating wind? Is it accelerating in a useful direction?

Yes. F=ma.

These two things are not the same.

Please briefly explain what specific variation in wind movement you believe BB can exploit to produce forward thrust which would accelerate it to 2.8x average windspeed. Please also indicate what structure on BB converts this variation into forward thrust and by what mechanism.

Thanks again.

 

[humber]

Hmm. Well, I read that BB is a little under 25' tall with a 17' diameter prop.

So the hub is about 5m above the ground and the tip of the prop reaches somewhere close to 7.6m (the height reached by most of the blade's surface is less, but let's consider the maximum).

So your equation says the wind speed at the hub might be;
v_hub = v₁₀ * (5/10)^0.15 = 0.901 * v₁₀
And the wind speed at the highest point ever reached by the very tip of the turning prop;
v_tip = v₁₀ * (7.6/10)^0.15 = 0.960 * v₁₀

So that's (0.960/0.901) times or, if you prefer, 6½% higher windspeed at the very highest point any part of the prop ever reaches than is measured at the hub. It's a bit less than the 180% higher in my actual question.

So although your initial comment was "it could be a lot more" the concise answer was emphatically "no".

That refers to wind measured at 10m. Now correct for that.
(And you need to take the integral)

Consider then the wind sheer over the heated desert floor.
Then consult records to find out how large that may be.
You will then be able to tell NALSA, they are wrong about their assumption
about the correlation of windspeed and direction changes.

And when that is done, consider why you believe a cart can go ddwfttw, though that is theoretically impossible, but don't think that indirect gains not formerly considered by you, may make it possible.

 

[humber]

These two things are not the same.

Please briefly explain what specific variation in wind movement you believe BB can exploit to produce forward thrust which would accelerate it to 2.8x average windspeed. Please also indicate what structure on BB converts this variation into forward thrust and by what mechanism.

Thanks again.

1) Not a fan of Galileo now?
2) F=ma
3)And I don't need to prove anything other than the cart is not ddw.
4) You have to prove that the so-called theory is the only way the cart can get >WS
Not much of a task. Pushed to 40% of the speed, a = 0.1m/s, Vavge = 8.8mph.
Wind travels >2.5 times the distance of the cart in the same time.

 

[Jack by the hedge]

That refers to wind measured at 10m. Now correct for that. If you had read it you would notice that is exactly what I did. Both figures were calculated, using your formula, relative to the figure for 10m.
(And you need to take the integral) Which and why, please? Are you now saying that the formula you presented is incorrect?
Consider then the wind sheer over the heated desert floor.
Then consult records to find out how large that may be.
You will then be able to tell NALSA, they are wrong about their assumption
about the correlation of windspeed and direction changes. One imagines you have already done this. I wonder what NALSA made of your submission.

And when that is done, consider why you believe a cart can go ddwfttw (I believe it works because I can understand how it works, and I have seen evidence of its working) though that is theoretically impossible (impossible when using your incoherent, junk assemblage of physics) but don't think that indirect gains not formerly considered by you, may make it possible.

You have not yet made any serious effort to explain the mechanism by which these "indirect gains" might make it possible to accelerate the BB to 2.8x windspeed. I have given up any hope that you can do so.

 

[Jack by the hedge]

1) Not a fan of Galileo now? Relevance?
2) F=ma "Is it accelerating in a useful direction?"
3)And I don't need to prove anything other than the cart is not ddw. For full credit, remember to show all your working.
4) You have to prove that the so-called theory is the only way the cart can get >WS
Not much of a task. On the contrary - that's not my job. I don't have to do anything. I am content that the way BB works is comprehensible, explained and works. You claim otherwise and I want you to explain how you think it works in a better than handwaving way. Pushed to 40% of the speed, a = 0.1m/s, Vavge = 8.8mph.
Wind travels >2.5 times the distance of the cart in the same time.

Congratulations, you have calculated that the average speed taken over all the time the cart was moving is less than windspeed. Sadly for you, that was not the purpose of the exercise and your calculation is irrelevant.

Perhaps you would like to declare all other land speed records invalid, as they too were travelling much slower outside their measured mile.

 

[A.T.]

The result acceleration of cart, produces lift.

So the acceleration of the cart produces lift that accelerates the cart?

 

[jduffy77]

Congratulations, you have calculated that the average speed taken over all the time the cart was moving is less than windspeed. Sadly for you, that was not the purpose of the exercise and your calculation is irrelevant.

Perhaps you would like to declare all other land speed records invalid, as they too were travelling much slower outside their measured mile.

Conveniently (and hilariously) he never includes the time during which the cart was being towed to the test site.

 

[humber]

Congratulations, you have calculated that the average speed taken over all the time the cart was moving is less than windspeed. Sadly for you, that was not the purpose of the exercise and your calculation is irrelevant.

That is how velocity is measured. Distance over time. The average speed of the cart is 8.8mph. Only the initial push, lasting 10 seconds raises that to about 17.5mph, while the wind has a steady 12mph and takes a much longer path. The reel has taught you nothing about transient and steady-state speeds.

The BB is not a successor to Bauer, but a carbon-copy of Goodman.

1) Goodman's cart follows the road, and not the wind, in the same way the
BB follows a heading, and not the wind. The "pilot" adds only mass.

2) Both exploit several mechanisms to gain KE, including sliding by loss of traction ( see the scuffed tyres).

3) Both film until something happens. That is, both select for transient and favorable wind patterns by waiting until they occur, and recording only those guaranteed-to-happen "successes"

4) Goodman also started again when the cart failed to start from rest.

Etc...Etc...

Perhaps you would like to declare all other land speed records invalid, as they too were travelling much slower outside their measured mile.

I would build a cart that would thrash that pile of junk. Lots of means, but add a bit of technology. Use 4 blades not 2, use Bauer like prop ( wide and flat), add force controlled pitch control, variable transmission and so forth.
And no red text please, JBTH, it does nothing, but to add to the lament.

 

[humber]

Conveniently (and hilariously) he never includes the time during which the cart was being towed to the test site.

It's embarrassing to be told that the mighty iconoclastic cart was pushed to above WS, isn't it?

 

[humber]

So the acceleration of the cart produces lift that accelerates the cart?

See Newton's impact theorem and solve the Taylor power series.
Failing that, draw a cartoon, where the wind is a stick.

 

[Jack by the hedge]

That is how velocity is measured. Distance over time.

And you chose to lump in an irrelevant period of time. Garbage in, garbage out.
By your method of calculation all land speed records would have to be revised to include the run up and slow down time as well as the measured mile. Right?

3) Both film until something happens. That is, both select for transient and favorable wind patterns by waiting until they occur, and recording only those guaranteed-to-happen "successes"

So they potter along, below windspeed, until a sudden gust hurls them up to 2.8x windspeed and then they release the video of that bit. Is that what happened? No? Oh.

I would build a cart that would thrash that pile of junk.

Good luck. You'll be deservedly famous when you do that, as surely as the world remembers who the second guy to break the sound barrier was.

And no red text please.

I felt it saved column inches, but if you don't like it, have it your way.

 

[Jack by the hedge]

It's embarrassing to be told that the mighty iconoclastic cart was pushed to above WS, isn't it?

No. It's a little embarassing to see you still clutching at that straw, though.

 

[EHocking]

No. It's a little embarassing to see you still clutching at that straw, though.

A firm grasp on straw aids construction of strawmen...