Go Fly a Kite!

[IanC]

wind is a shitty renewable resource in most parts of the world, at least at the surface.

but go up 250, 500 or 1000 meters and it is much more reliable because it is not only more constant but more powerful as well. how to get at that energy? kites.

two main types. power produced aloft and transmitted down through a conductive tether, or power produced by the pull on the tether itself.

I must admit that the idea sounds crazy at first glance. then I started thinking about speed and control when you are sailing, or skiing behind a powerboat. a lot of the limitations of wind disappear when you can control the orientation. the range of usable windspeeds dramatically increases. another benefit is that most of the structure is on the ground and the kites themselves would be cheap.

anyways, I found it interesting. for more info check out High Altitude Wind Power Reviewed .

also check out this way of organizing the efficiency of various sources of energy. ERoEI for Beginners

 

[waltky]

Uncle Ferd says...

... mebbe dey could put a zeppelin up inna air...

... an' send `lectricity down via the tether?

 

[IanC]

Uncle Ferd says...

... mebbe dey could put a zeppelin up inna air...

... an' send `lectricity down via the tether?

uncle Ferd has the makings of a first class bungling bureaucrat. strip the idea of its strengths and add to its drawbacks. well done!

 

[IanC]

the two types of kites work in slightly different ways. one is an air foil that carries generators aloft and sends power down the tether(s). it cuts into the wind in a figure eight which increases the wind speed to the rotors. the other flies the same figure eight but it is the pull on the tether that generates the power on the ground. after the power stroke of the tether is done it dives down, reeling in the tether, and starts over again. anyone who has slalom waterskied knows how easy it is to control speed by how deeply you cut. in three dimensions you never have to cutback and build up speed again, but you can certainly use your speed to put slack in the rope.

a zeppelin would hold the generators aloft but not allow for adjusting the speed. it would also have a problem in high wind. the good part would be that it was more portable.

 

[Crick]

wind is a shitty renewable resource in most parts of the world, at least at the surface.

but go up 250, 500 or 1000 meters and it is much more reliable because it is not only more constant but more powerful as well. how to get at that energy? kites.

two main types. power produced aloft and transmitted down through a conductive tether, or power produced by the pull on the tether itself.

I must admit that the idea sounds crazy at first glance. then I started thinking about speed and control when you are sailing, or skiing behind a powerboat. a lot of the limitations of wind disappear when you can control the orientation. the range of usable windspeeds dramatically increases. another benefit is that most of the structure is on the ground and the kites themselves would be cheap.

anyways, I found it interesting. for more info check out High Altitude Wind Power Reviewed .

also check out this way of organizing the efficiency of various sources of energy. ERoEI for Beginners

Cool. I was impressed by the return on investment figures for the KiteGen although I thought a jumbo-jet sized Makani glider would be way more cool.

 

[waltky]

This has been around before but the skill this guy has with the kites is worth seeing again.

The guy flying the 3 kites is in his 80s and he's from Canada.

He comes to the Washington State International Kite Festival every year.

His skin is like leather as he normally flies with his shirt off.

He is deaf, so when he flies, we hold our hands up and wave them for applause.

He flies 2 with his hands and the 3rd one is attached to his waist.

You must watch to the end to see the amazing landing of that last kite.

And make sure your volume is turned up because the music is wonderful and totally reflects the soaring of the kites.

 

[IanC]

Yup, he's great. Seen him lots of times.

 

[waltky]

How do he keep from gettin'...

... the lines all tangled up?

 

[IanC]

How do he keep from gettin'...

... the lines all tangled up?

He learned as a kid, dancing the May Pole.

 

[waltky]

Granny likes to dance around the Maypole...

... till the menfolk scoop her up...

... but as she's gotten older, it takes longer...

... last year she had to wait till August.

 

[polarbear]

wind is a shitty renewable resource in most parts of the world, at least at the surface.

but go up 250, 500 or 1000 meters and it is much more reliable because it is not only more constant but more powerful as well. how to get at that energy? kites.

two main types. power produced aloft and transmitted down through a conductive tether, or power produced by the pull on the tether itself.

I must admit that the idea sounds crazy at first glance. then I started thinking about speed and control when you are sailing, or skiing behind a powerboat. a lot of the limitations of wind disappear when you can control the orientation. the range of usable windspeeds dramatically increases. another benefit is that most of the structure is on the ground and the kites themselves would be cheap.

anyways, I found it interesting. for more info check out High Altitude Wind Power Reviewed .

also check out this way of organizing the efficiency of various sources of energy. ERoEI for Beginners

It`s another idea that won`t work in the real world where all the other factors that the "idea man" overlooked come to bear full force.
I assume you know how to draw a force vector diagram, so you must be aware that when you sail at an angle across the wind at an increased speed the force oriented in the direction of travel is less than what it would be if the direction of travel is the same as the wind direction.
Granted at a higher elevation the wind speed is also higher but with this "kite-gen"

the force that wind can provide has to provide lift equals to the total weight of this structure plus the tether & cables. From what`s left of this force you can subtract the aerodynamic drag and the residual force is all you got left over to generate power.
And just as soon as you attempt to do that, when the prop-blade angle of attack would give you enough torque to generate power the drag will increase to the point where this "gen-kite" would generate power it will get pushed on an arc to the ground. The arc has the radius of the tether length...the same way a float&hook on a fishing line will arc towards the shore of a fast flowing river.
To generate power you need the product of torque and rpm not just rpm and if you ever had to dead stick a prop-plane you would know how much the drag the prop has if it has not been feathered. You go down like a rock in a steep dive to maintain airspeed or stall the wings if you refuse to dive to keep the speed..and then you REALLY dive!!
No this will never beat a wind turbine tower. They are high enough to be above the so called ground-roll and the decreased wind speed is compensated for by the larger blades.
P.S.:With the "idea-man" I was not referring to you but to the guy or group-think greenies that came up with this stupid idea

 

[mamooth]

Wind power trivia: Why do all large modern wind turbines have 3 blades? Obviously, there's an engineering sweet spot at 3. Let's break the question down further.

Why not use more than 3 blades?

Answer: Turbulence and efficiency.

While 4 or more blades of the same size gives more power than 3, it's not much more. More blades means more turbulence created, so each additional blade gives diminishing returns. More blades would be more weight, so they'd have to be smaller, as the hub can only support so much weight. 3 larger blades gives more power than 4 or more smaller blades.

Why not use 2 blades?

Answer. Bending moment and vibration.

Wind is stronger up higher. Blades up high will be catching more wind, and have more force applied to them. On a two-blade turbine, the bottom blade is at it's lowest when the top blade is highest, which maximizes bending moment at the hub. That would require a beefier and more expensive hub. 3 blades, when one blade is max up or down, the other two blades are more off to the side, which lessens bending moment.

The turbine as a whole needs to be able to shift orientation quickly when wind shifts direction. To give the torque to twist the tower, some blades need to be out sideways. With a 2-blade turbine, blades are sometimes both aligned with the tower, and sometimes both out full sideways. That means slow response and bad vibration. With 3-blades, there are always blades out sideways.

Also, people think that 3-blade turbines are prettier, and aesthetics does matter.

 

[Manonthestreet]

We need flying solar panels too....so on cloudy days they still produce peak power.

 

[polarbear]

Wind power trivia: Why do all large modern wind turbines have 3 blades? Obviously, there's an engineering sweet spot at 3. Let's break the question down further.

Why not use more than 3 blades?

Answer: Turbulence and efficiency.

While 4 or more blades of the same size gives more power than 3, it's not much more. More blades means more turbulence created, so each additional blade gives diminishing returns. More blades would be more weight, so they'd have to be smaller, as the hub can only support so much weight. 3 larger blades gives more power than 4 or more smaller blades.

Why not use 2 blades?

Answer. Bending moment and vibration.

Wind is stronger up higher. Blades up high will be catching more wind, and have more force applied to them. On a two-blade turbine, the bottom blade is at it's lowest when the top blade is highest, which maximizes bending moment at the hub. That would require a beefier and more expensive hub. 3 blades, when one blade is max up or down, the other two blades are more off to the side, which lessens bending moment.

The turbine as a whole needs to be able to shift orientation quickly when wind shifts direction. To give the torque to twist the tower, some blades need to be out sideways. With a 2-blade turbine, blades are sometimes both aligned with the tower, and sometimes both out full sideways. That means slow response and bad vibration. With 3-blades, there are always blades out sideways.

Also, people think that 3-blade turbines are prettier, and aesthetics does matter.

Why not use more than 3 blades?
More blades means more turbulence created, so each additional blade gives diminishing returns.
That is not the reason why 3 blades are used.
At max rpm, which is 16 rpm for a Siemens 2.3-108 the turbulence from one blade is well downwind by the time the next blade is in that angular position.
The Sikorsky S-64 Skycrane uses 6 blades at much higher rpm which according to you makes each blade less efficient. Granted it`s not a wind turbine during normal operation, but the 6 blade rotor is used as a windmill if the Helicopter has to auto-rotate in an emergency.
Large wind turbines use 3 blades because it is the most cost effective engineering solution in terms of power yield over dollars.
First there is the cost to make a blade like that:

And the pitch control for each blade is not exactly cheap either.

Last,not least the blade turbulence is mostly near the blade tips with dino tails to get a noise reduction. The dino tails reduce this turbulence and that was done to comply with local noise bylaws, not because blade turbulence of a blade interfered with the efficiency of the other blades.

To conclude, the 3 blade design is the engineering sweet spot because it is the most cost effective solution in terms of yield/benefit/production over $$$ spent.
But that`s the kind of math liberals refrain from unless they wanted to prove the fact that they should be abolished

 

[mamooth]

At max rpm, which is 16 rpm for a Siemens 2.3-108 the turbulence from one blade is well downwind by the time the next blade is in that angular position.

Nope. Turbulence is still there 1.3 seconds later, and it definitely matters.

The Sikorsky S-64 Skycrane uses 6 blades at much higher rpm which according to you makes each blade less efficient. Granted it`s not a wind turbine during normal operation, but the 6 blade rotor is used as a windmill if the Helicopter has to auto-rotate in an emergency.

Not relevant, as helicopter rotors aren't designed for efficiency during an auto-rotation hard/crash landing.

And not really related to turbines, but helo turbulence is serious right below the blades, which limits how fast helos can descend. If they descend too fast, they enter vortex ring state. The blades cut turbulence instead of clean air, so the helo loses lift and drops like a rock. That's why you see hovering helos only descending very slowly, while helos moving quickly forward can descend more rapidly, as they're moving out of their own turbulence.

Large wind turbines use 3 blades because it is the most cost effective engineering solution in terms of power yield over dollars.

That's true, but it's the most cost effective engineering because turbulence cuts efficiency as more blades are added. If that wasn't the case, a fourth blade and fifth blade would be just as efficient as the first three, and the cost analysis would say to add them.

But that`s the kind of math liberals refrain from unless they wanted to prove the fact that they should be abolished

No. You're not very good at the math. Your math says 5-bladed windmills would be more cost efficient. They're not.

You do see some 5-bladed windmills, but they're like smaller 2-meter sorts of turbines, used for things like powering a remote weather station, and other cases where getting the most power into a small area is the driving factor, as opposed to cost efficiency.

 

[polarbear]

At max rpm, which is 16 rpm for a Siemens 2.3-108 the turbulence from one blade is well downwind by the time the next blade is in that angular position.

Nope. Turbulence is still there 1.3 seconds later, and it definitely matters.

The Sikorsky S-64 Skycrane uses 6 blades at much higher rpm which according to you makes each blade less efficient. Granted it`s not a wind turbine during normal operation, but the 6 blade rotor is used as a windmill if the Helicopter has to auto-rotate in an emergency.

Not relevant, as helicopter rotors aren't designed for efficiency during an auto-rotation hard/crash landing.

And not really related to turbines, but helo turbulence is serious right below the blades, which limits how fast helos can descend. If they descend too fast, they enter vortex ring state. The blades cut turbulence instead of clean air, so the helo loses lift and drops like a rock. That's why you see hovering helos only descending very slowly, while helos moving quickly forward can descend more rapidly, as they're moving out of their own turbulence.

Large wind turbines use 3 blades because it is the most cost effective engineering solution in terms of power yield over dollars.

That's true, but it's the most cost effective engineering because turbulence cuts efficiency as more blades are added. If that wasn't the case, a fourth blade and fifth blade would be just as efficient as the first three, and the cost analysis would say to add them.

But that`s the kind of math liberals refrain from unless they wanted to prove the fact that they should be abolished

No. You're not very good at the math. Your math says 5-bladed windmills would be more cost efficient. They're not.

You do see some 5-bladed windmills, but they're like smaller 2-meter sorts of turbines, used for things like powering a remote weather station, and other cases where getting the most power into a small area is the driving factor, as opposed to cost efficiency.

No. You're not very good at the math. Your math says 5-bladed windmills would be more cost efficient. They're not.
I said no such thing, I did say this:
Large wind turbines use 3 blades because it is the most cost effective engineering solution in terms of power yield over dollars.
And the pitch control for each blade is not exactly cheap either.
To conclude, the 3 blade design is the engineering sweet spot because it is the most cost effective solution in terms of yield/benefit/production over $$$ spent.
That makes you a liar
And now lets see about your "math"
Nope. Turbulence is still there 1.3 seconds later, and it definitely matters.
Unbelievable how stupid and/or dishonest a person like you will stoop to a level so low that it defies what homo sapiens is supposed to be.
You took the red-line 16 rpm limit to get your 1.3 seconds and try to tell us that the "turbulence is still there". Where is "there"?
Even at the slowest wind speed the lower cut-in limit which is 3 to 4 meters/sec the tip vortices will be1.3 x 3 to 4 meters down-wind by the time the rotor does 1/3 of a revolution.
And at the red-line speed that you picked which can be reached at a wind speed of 25 meters per second they will be 1.3 X 25 meters down wind

That`s why cheats and dumb cheats like you just don`t have what it takes outside your liberal sanctuaries

 

[mamooth]

That makes you a liar

Your math still sucks, no matter how many insults you scream.

You claim each additional blade would be just as efficient.

Being the each tower is a fixed cost, that means the most cost-efficient way, by your math, is to squeeze the most blades into each tower.

And yet nobody does that, which shows your math is shit.

Unbelievable how stupid and/or dishonest a person like you will stoop to a level so low that it defies what homo sapiens is supposed to be.
You took the red-line 16 rpm limit to get your 1.3 seconds and try to tell us that the "turbulence is still there". Where is "there"?

Example. Airports. After one of the big jets takes off, they have to wait a full 2 minutes until another aircraft can leave. It's not because of spacing issues. It's because the strong turbulence the first jet creates literally stays around for that long.

Your "turbulence can only last a fraction of a second!" theory is contradicted by the real world. This isn't a discussion. You're just clueless.

That`s why cheats and dumb cheats like you just don`t have what it takes outside your liberal sanctuaries

You have no engineering or scientific common sense. You can run numbers, but as you always completely fail at the big picture, your numbers are meaningless. That's why you always end up so humiliated here, and then have to resort to crying like a snowflake about politics.

 

[polarbear]

That makes you a liar

Your math still sucks, no matter how many insults you scream.

You claim each additional blade would be just as efficient.

Being the each tower is a fixed cost, that means the most cost-efficient way, by your math, is to squeeze the most blades into each tower.

And yet nobody does that, which shows your math is shit.

Unbelievable how stupid and/or dishonest a person like you will stoop to a level so low that it defies what homo sapiens is supposed to be.
You took the red-line 16 rpm limit to get your 1.3 seconds and try to tell us that the "turbulence is still there". Where is "there"?

Example. Airports. After one of the big jets takes off, they have to wait a full 2 minutes until another aircraft can leave. It's not because of spacing issues. It's because the strong turbulence the first jet creates literally stays around for that long.

Your "turbulence can only last a fraction of a second!" theory is contradicted by the real world. This isn't a discussion. You're just clueless.

That`s why cheats and dumb cheats like you just don`t have what it takes outside your liberal sanctuaries

You have no engineering or scientific common sense. You can run numbers, but as you always completely fail at the big picture, your numbers are meaningless. That's why you always end up so humiliated here, and then have to resort to crying like a snowflake about politics.

Okay show me where I said that the turbulence can last only a fraction of a second, snowflake.
I did show you where it is after the 1.3 seconds that you boasted with your kiddie math.
I showed you the distance and a picture because I knew that without a picture you are clueless, but you still are without a clue...amazing.
Now you...who I`m sure have zero pilot training or experience are telling me about wake turbulence.
You have no idea how many times I landed airplanes at airports all over Canada & the US.
About the 2 minutes, there are lots of uncontrolled airports where you don't have to wait 2 minutes after a heavy just departed. As long as you noted where the heavy rotated and get airborne before you get to that point of the runway there is no problem. After that it's up to you to know how to avoid the wake turbulence...and you would have no idea where that would be.
The more I see of your replies on the USMB the more obvious it gets how delusional you are.
No matter how much of the fool you are exposing yourself as here, you do a victory lap like some weird child that plays stick-ball alone in a driveway and adds it's own applause background sound.

 

[Olde Europe]

While 4 or more blades of the same size gives more power than 3, it's not much more. More blades means more turbulence created, so each additional blade gives diminishing returns. More blades would be more weight, so they'd have to be smaller, as the hub can only support so much weight. 3 larger blades gives more power than 4 or more smaller blades.

All well stated. Just to further strengthen the point:

According to Betz's law, a wind turbine can harvest at most 59.3% of the kinetic energy of the wind. Modern turbines (3 blades) reap something in the order of 50%. That serves to show that the added gains with more blades would be minuscule, while adding further strains on the system, predominantly at higher wind speeds, resulting in way higher costs, as you've pointed out.

 

[polarbear]

While 4 or more blades of the same size gives more power than 3, it's not much more. More blades means more turbulence created, so each additional blade gives diminishing returns. More blades would be more weight, so they'd have to be smaller, as the hub can only support so much weight. 3 larger blades gives more power than 4 or more smaller blades.

All well stated. Just to further strengthen the point:

According to Betz's law, a wind turbine can harvest at most 59.3% of the kinetic energy of the wind. Modern turbines (3 blades) reap something in the order of 50%. That serves to show that the added gains with more blades would be minuscule, while adding further strains on the system, predominantly at higher wind speeds, resulting in way higher costs, as you've pointed out.

No that's not what he said. He said that it was a turbulence problem(already with just 3 blades)
I said there is not & showed him why not and now you come along after you made yourself an instant expert because you got wifi and pretend to know something about aerodynamics just like him or her, who knows these days. Either one of you is brain dead the moment your wifi goes down