I remember in WC III when Angel gets her heart ripped out by the Kilrathi. I was convinced that this happened because I didn't succeed at the mission. I must have replayed it tens of times trying to save her. That was a game defining moment, and it's still stuck in my head today.
I'm certain that the Trash can was an excellent idea when it first came out (except for putting your disk in the trash in order to eject it. WTF???) That's why MS improved it into the Recycling Bin. It's time for Apple to fix two horrendous mistakes, and one minor one.
1) Can't permanently delete directly from Finder. I can SHIFT-del in Win, and it gets rid of the file instantly and forever. That's quite nice for large files such as movies that you want off your system right away. With Mac, I have to rm -Rf everything if I want it to go away instantly.
2) Can't selectively delete files from Trash. I should be able to delete what I want, when I want. I don't care WHY Apple made the Trash motif, I care HOW I want to use it. And I want to use it like Windows. I know a lot of people say that that's not how Mac was developed, but I don't care. Adding my wished-for functionality doesn't change a thing for Mac, just like adding a three-button mouse doesn't prevent developers from trying to make everything all work with just one. (Although one button being completely inferior to three buttons sure prevented them from doing it.)
The best argument I've seen for changing this behavior is what happens when you're on your boss's computer and need to free up some space on your USB key in order to get a file of the computer. Do you empty the trash, possibly deleting his important files? What if he's not there to ask? If you don't know about rm -Rf (most people don't), you have to waste lots of time now either making a new directory and temporarily storing his data there while you empty the trash (As much as we don't want to admit it, most users won't think of this one), or wandering from computer to computer until you find someone who can empty it for you (more likely of two for non-technical users). (To be fair, the most likely solution for non-technical users is just to empyt the Trash without even thinking about the possible consequences. Whoops.)
3) Can't automatically put a file in the Trash back where it came from. Yeah, it's minor, but again, Windows does it right, no ifs, ands, or buts.
Yes, I know that there are aftermarket tools that will do all this for me, but I shouldn't have to pay or install someone else's possibly buggy software that changes LOTS of things when I only want one thing that I have come to accept as completely normal in the Windows and Linux worlds.
They could, but, to dredge up the ol' car analogy, GM doesn't get to tell you what brand of gas you put in your car, even though some gas sometimes is not good. Likewise, Dell cannot tell you what brand of batteries to use in its laptops, and printer manufactures cannot say whose ink cartridges you can use in their printers. It's not that hard to design a system that works with el cheapo power bricks. (And having seen the quality of my aftermarket Nintendo DS charger, I think that those DSs are pretty robust.)
There are too many chargers and plugs, you're absolutely correct. This problem will probably get worse and worse until a gov't has to step in and regulate the power plugs. More and more businesses are building proprietary plugs for simple 5V, 9V, 12V, and 19.6V adapters. Witness Dell with the needle thing center electrode and octogonal shell, and Nintendo with it's odd trapezoidal plug. It's quite obvious that they're doing this because of buyer lock-in, and not for anything approaching the real needs of the product.
DIN, ANSI, and all the other standards bodies have long ago defined reasonable specs for these plugs, which brought prices down because of manufacturing en masse. Now that it's so cheap to custom make these plastic bits, businesses are looking at it on the long term and realizing that buyer lock-in provides them with more money than they'll save by chosing the cheap standardized connector.
The problem is, how to go about this? Gov't regs for technology are Bad (TM) things, and certainly prevent innovation. However, Dell is hardly innovating with a plug that is *more* likely to be broken or bent. Maybe one or two good class-action suits would scare them back into line so that they only develop a new DC connector when there's real innovation in it. Like DC connectors with seperate grounds or magnetic power plugs on laptops. (Apple does this, although I have no idea if they were the first or not)
I had mod-points, but this was already at 5, so I think I'll just chime in instead. This is a GREAT idea. No need to write a long rant, or call them stupid, or anything other than call their attention to the fact that they are in the international public eye. I just sent the following email:
=================== I'm certain that you will receive much more eloquent and thought out responses, so I will keep this short. Your policy is insane. Not in the sense of "raving mad", but in the French sense, of "not healthy". Come to Europe and spend some time here looking at playgrounds. Playgrounds where kids can hurt themselves and even die. And yet don't.
People, and especially children, are hardy and resilient beings. Falling down and getting hurt is part of life-- it teaches getting up again. If you insulate children from "failure" on every level, how do you expect them to understand the value of success? ===================
P.S. European playgrounds are SOOOOOOOOOOOO much cooler than anything I had in America growing up. Here in Luxembourg they've got these cool things that go round and round when you run on them (like merry-go-rounds on crack), >10m slides, pirate ships, functioning archimedes pumps, the works.
My reaction is mixed. I use RTAI in my lab, and this doesn't seem to say anything whatsoever about the technologies used in the claimed real-time kernel. In fact, from the article I don't really know if it's real real-time, or "harder but still soft" real-time. Either way, it's great that the kernel is finally seriously integrating real-time, as it's a step in the right direction for getting real-time software to work quickly and painlessly on office distros such as Ubuntu.
Anyone know if this is just the ADEOS micro-kernel patch being distributed as part of the vanilla kernel? If not, is it compatible with RTAI, Xenomai, Fusion, and RTLinux?
To be specific, Bigelow Aerospace bought NASA's TransHab program. Apparently it's all siting out in a warehouse somewhere in Las Vegas. So it's no surprise that their technology compares favorably with NASA's-- it's based on it. (I know this only because I had a long conversation yesterday with a friend who works there, designing their robots and integrating the avionics package.)
My first reaction to this is, "Great! Now I can finish that project I've been wanting to do all this time." See, I've been living in a European country where there are far too many people who drive to work. It almost reminds me of America. I had wanted to use digital photography and analysis to take pictures of everyone's license plate, identify the cars with only one person in them during rush hour, and then send these guilty parties a nicely worded letter informing them of the ecological destruction they're haphazardly causing and a list of alternatives, such as buses and car-pooling.
(See, the climate, and the ecology, and the air polution is much too important to consider that people have a right to a private life when they drive. Individuals should be held as accountable for polluting the air as they are for polluting a stream or the ground. (Note: this is not to read that everyone who drives a car should be pulled out of their car and shot (Except for SUV drivers who should be.) (Just kidding. SUV drivers don't deserve such a quick death. )(Not that I'm advocating violence)(Except against SUV drivers), just that we need to consider the effects of pollution as a general destruction of the public good. Tragedy of the Commons, and all that.). But I digress.)
My second reaction is that, yes, this is going to happen, and there's not a damned thing we can do about it, aside from from change the laws. And then how? How can I differentiate between what's good usage and what's bad? In France, it's illegal to have a database with personal information in it except under certain circumstances. When a few years back I made a small wireless network in my dormitory and then charged fellow students a small fee for access, I was told that my spreadsheet with 1) Name, 2) Room #, and 3) MAC Address was technically illegal. It's going to be very difficult-- perhaps impossible-- to balance an individual's right to do something Good (TM) against a business's desire to do something Evil (TM). How do we draw the line between a small spreadsheet to keep accounting straight and a large database to track, monitor, survey, and sell, sell, sell?
At the least, we should start menacing all these corporations now. "You want to collect information on me? Ooooooookay, but if you get hacked, we're going to ask for $10,000 per person in indemnification. Non-negotiable. What? You don't want that financial risk and exposure? Okay, just delete all those files and the problem will go away."
I say we just keep on using legos in scientific projects and prove to them how valuable legos are.
I've never had an easier time prototyping a model, and the finished instrument table, make out of aluminum and stainless steel to a very high precision, shows the value of legos in the prototyping process.
Err... some of us do understand it a bit. I'm a mechanical engineer. Heck, I *never* post on/. because most of the time you guys are talking about things I couldn't even begin to formulate an intelligent thougt on.
That's what I like about/. Those who know and tend to get heard, and it's usually pretty clear to me who is full of crap and who isn't on technical issues. However, your point still stands, we're (the educated crowd) pretty skeptical of anything that promises the moon, especially when there's a rash of too-good-to-be-true stories that are all coming out of the same source/poster. Someone else did a pretty good survey of the illustrious/.er who brought us this crackpot idea and the others like it. I'm too lazy to find it, you'll have to get it yourself if you feel like it.
What's even worse than people who don't read the article? People who do, take the time to criticize it and respond to/.ers' follow-up comments, and then are criticized by those who read it, don't understand it, and decide to show their ignorance. Energy's not free, there are no miracle technologies, and any kind of generation such as this has already been highly perfected and will be proceeding in incremental steps, not revolutionary ones. The biggest revolution in wind power will be finding a way to distribute it on a large scale.
And NO wind tower is going to be able to withstand a hurricane while it's turning. Sorry, the slightest of engineering educations would teach that the gusts alone would rip it to shreds. There are no materials that can resist these sorts of forces. Not even buildings fare well, and they're a lot more solid than windmills. I think many HAWTs, which are far more sturdy than the VAWTs, give up the ghost in 60-70mph winds.
I thought I might call it bunk maybe 'cause...
I'm working on a PhD in the field? Not that makes me an expert or anything, since I'm actually working on the distributed grid side of things, but it does certainly mean that I've had a little more experience than the average person. And this is quite clearly bunk. Not only looking at the ancillary information, such as the source (opensourceenergy.com, puh-lease), but at his claims, with the all encompassing "We can't show photos because of... er... patents!".
Ah... but my information is easily found on many websites, as even the most cursory glance at wikipedia will show you. Clicking on the links that I provided would have set you off down the path to enlightenment.
Ahh... I see the confusion now. I wasn't clear enough. What I meant to say was that VAWTs used for power generation are most often times found in the eggbeater configuration. In fact, they can be found in many, many, many configurations, such as the proposed Savonius VAWT, although the Savonius are only used when power generation levels are very low and low cost and maintenance are more important than power output. For instance, powering a weather station in the middle of nowhere. It takes no energy, but it needs to be self-sufficient and cheap, and that means that the difficulty of starting Darrius windmills from a dead standstill makes the Savonius windmill a better choice.
My apologies for not being more clear the first time.
Ah, yes, but he said "power", and not lift. The power *does* increase with the cube of the velocity because the kinetic energy increases with the square of velocity and the amount of mass increases linearly with velocity. So if you want to look at 1/2*m*v^2, the kinetic energy of a given control volume, you simply have to substitute mass for k*v to see that it's C*v^3, where C=1/2*k and k is some constant.
I had theorized earlier that this might have been because a tailflap might not have had enough force to spin round the tower, as bearing technology back then was certainly not advanced enough to manouver all that weight at the touch of a feather.
Whereas a small turbine could have been drastically reduced by gears so that even light winds can have the desired, albeit slow, effect.
Of course, this is all just suposition, as I have never seen-- although I admit never having gone looking for-- a description of this kind of invention.
Nope, or at least not that I can find. HAWTs (Horizontal Axis Wind Turbines) are the big propeller turbines you see all over. VAWTs (Vertical Axis Wind Turbines) are the eggbeater contraptions that are rare but seem to be more efficient, once you take out all material/longevity considerations. You can find out all about them on wikipedia.org, if you'd like a little more background.
The blades of vertical rotors will always have a position in which they move against the wind, which causes drag or tricky aerodynamics at best.
Actually, the blades are always moving agains a relative wind. What's tricky about the aerodynamics is that the relative wind constantly changes as you go round the circle. The solution to this is to spin faster, so that the wind component which changes (the real wind itself) is small in comparison to the wind component which doesn't (the relative wind produced tangentially to the spinning blade).
Of course, as you spin faster, you get more centripital forces, and if you go too fast, everything fall down go boom.
Actually, having the propeller mounted in a duct does wonders for the efficiency. It also adds weight. WEIGHT. Think about how much metal it would take to fill up the area carved out by a 100m prop as it spins round and round. I don't have the numbers handy, but I bet it'd cost more in steel and installation than I earn in a year!
I have to wonder though whether one of these is really as efficent as a propeller-type windmill, given that a propeller type one can alter its blade pitch and keep the rotational speed relatively constant in different wind speeds. Is there a way to do that with a Savonius design? It doesn't seem like the airfoils are really anything that you could easily change in flight.
From my readings, and as a pilot, I can hazard a guess that this is because of the enormous complexity both in manufacturing and in maintenance of having a variable pitch prop. The money that you save (earn) through increased efficiency might be gobbled up the first time you have to higher a technician to climb to the top of a 200m tower and fix a faulty blade. Don't know if this is the only reason, but it's certainly a major one.
I'm not sure if it's true, but I once heard an interesting factoid about Dutch-style propeller windmills, and how they were among the first mechanical devices to implement a "feedback loop"; you have a tail rotor mounted perpendicular to the main rotor, which drives the mechanism that orients the windmill. If the wind isn't blowing at the mill directly from the front, it causes the small rotor to turn, turning the mill into the wind. When the mill is pointing in the right direction, there's no wind on the small rotor, so it stops. Pretty brilliant, for the 17th or 18th century.
Never heard that before, but it sounds pretty cool and feasible. It makes sense if you consider that bearings would have been pretty difficult back then, and thus you might not be able to rely on a little tail flap a la weather vane for orienting the mill.
A lot of it has to do with materials. VAWTs suffer from two notable stresses that are inexistant on HAWTs. 1) centripital forces and 2) vibration.
1) These things spin *quickly*. Far faster than the windspeed. Now, that's not so much a problem in a propeller blade because all the mass is on the inside and the blade happens to be strongest here, too. But on a VAWT, all the mass is on the outside, meaning that there is a significant amount of energy stored as they spin round and round. This pull can quickly destroy the windmill, and apparently has caused a couple deaths (Or so I have read in the windmill forums. Caveat reader.).
2) Because of the way the VAWTs spin, the mill is subject to pulsing as the blades change their angle of attack and speed with respect to the wind. Of course, this is reduced by having more blades which are thinner, (the ideal propeller being made out of an infinite number of infinitely thin blades) but the materials have limits and it seems that 2, 3, and 4 blades are all we can reasonably do. So the pulsing motion fatigues the support and can lead to failure.
HAWTs don't suffer from these problems, although they do have other problems-- such as torque applied by gyroscopic precession, torque applied by higher windspeeds at the top of the mill than at the bottom, orientation into the wind-- but they don't seem to be as difficult to overcome as the VAWT ones.
This design isn't new. It's bunk. As he describes it, it's a Savonius windmill, which is nothing if not inefficient.
Although your comments about microgrids are very apt. And since what we truly need in this world are microgrids (encourage conservation of energy, reduce fossil fuel use, provide energy to Africa), I'm very excited about wind's possibilities in this arena.
(Which is why I just started a PhD. in solar and wind microgeneration cells.)
Slashdot Mirror
I remember in WC III when Angel gets her heart ripped out by the Kilrathi. I was convinced that this happened because I didn't succeed at the mission. I must have replayed it tens of times trying to save her. That was a game defining moment, and it's still stuck in my head today.
I'm certain that the Trash can was an excellent idea when it first came out (except for putting your disk in the trash in order to eject it. WTF???) That's why MS improved it into the Recycling Bin. It's time for Apple to fix two horrendous mistakes, and one minor one.
1) Can't permanently delete directly from Finder. I can SHIFT-del in Win, and it gets rid of the file instantly and forever. That's quite nice for large files such as movies that you want off your system right away. With Mac, I have to rm -Rf everything if I want it to go away instantly.
2) Can't selectively delete files from Trash. I should be able to delete what I want, when I want. I don't care WHY Apple made the Trash motif, I care HOW I want to use it. And I want to use it like Windows. I know a lot of people say that that's not how Mac was developed, but I don't care. Adding my wished-for functionality doesn't change a thing for Mac, just like adding a three-button mouse doesn't prevent developers from trying to make everything all work with just one. (Although one button being completely inferior to three buttons sure prevented them from doing it.)
The best argument I've seen for changing this behavior is what happens when you're on your boss's computer and need to free up some space on your USB key in order to get a file of the computer. Do you empty the trash, possibly deleting his important files? What if he's not there to ask? If you don't know about rm -Rf (most people don't), you have to waste lots of time now either making a new directory and temporarily storing his data there while you empty the trash (As much as we don't want to admit it, most users won't think of this one), or wandering from computer to computer until you find someone who can empty it for you (more likely of two for non-technical users). (To be fair, the most likely solution for non-technical users is just to empyt the Trash without even thinking about the possible consequences. Whoops.)
3) Can't automatically put a file in the Trash back where it came from. Yeah, it's minor, but again, Windows does it right, no ifs, ands, or buts.
Yes, I know that there are aftermarket tools that will do all this for me, but I shouldn't have to pay or install someone else's possibly buggy software that changes LOTS of things when I only want one thing that I have come to accept as completely normal in the Windows and Linux worlds.
They could, but, to dredge up the ol' car analogy, GM doesn't get to tell you what brand of gas you put in your car, even though some gas sometimes is not good. Likewise, Dell cannot tell you what brand of batteries to use in its laptops, and printer manufactures cannot say whose ink cartridges you can use in their printers. It's not that hard to design a system that works with el cheapo power bricks. (And having seen the quality of my aftermarket Nintendo DS charger, I think that those DSs are pretty robust.)
There are too many chargers and plugs, you're absolutely correct. This problem will probably get worse and worse until a gov't has to step in and regulate the power plugs. More and more businesses are building proprietary plugs for simple 5V, 9V, 12V, and 19.6V adapters. Witness Dell with the needle thing center electrode and octogonal shell, and Nintendo with it's odd trapezoidal plug. It's quite obvious that they're doing this because of buyer lock-in, and not for anything approaching the real needs of the product.
DIN, ANSI, and all the other standards bodies have long ago defined reasonable specs for these plugs, which brought prices down because of manufacturing en masse. Now that it's so cheap to custom make these plastic bits, businesses are looking at it on the long term and realizing that buyer lock-in provides them with more money than they'll save by chosing the cheap standardized connector.
The problem is, how to go about this? Gov't regs for technology are Bad (TM) things, and certainly prevent innovation. However, Dell is hardly innovating with a plug that is *more* likely to be broken or bent. Maybe one or two good class-action suits would scare them back into line so that they only develop a new DC connector when there's real innovation in it. Like DC connectors with seperate grounds or magnetic power plugs on laptops. (Apple does this, although I have no idea if they were the first or not)
I had mod-points, but this was already at 5, so I think I'll just chime in instead. This is a GREAT idea. No need to write a long rant, or call them stupid, or anything other than call their attention to the fact that they are in the international public eye. I just sent the following email:
===================
I'm certain that you will receive much more eloquent and thought out
responses, so I will keep this short. Your policy is insane. Not in
the sense of "raving mad", but in the French sense, of "not healthy".
Come to Europe and spend some time here looking at playgrounds.
Playgrounds where kids can hurt themselves and even die. And yet
don't.
People, and especially children, are hardy and resilient beings.
Falling down and getting hurt is part of life-- it teaches getting up
again. If you insulate children from "failure" on every level, how do
you expect them to understand the value of success?
===================
P.S. European playgrounds are SOOOOOOOOOOOO much cooler than anything I had in America growing up. Here in Luxembourg they've got these cool things that go round and round when you run on them (like merry-go-rounds on crack), >10m slides, pirate ships, functioning archimedes pumps, the works.
My reaction is mixed. I use RTAI in my lab, and this doesn't seem to say anything whatsoever about the technologies used in the claimed real-time kernel. In fact, from the article I don't really know if it's real real-time, or "harder but still soft" real-time. Either way, it's great that the kernel is finally seriously integrating real-time, as it's a step in the right direction for getting real-time software to work quickly and painlessly on office distros such as Ubuntu.
Anyone know if this is just the ADEOS micro-kernel patch being distributed as part of the vanilla kernel? If not, is it compatible with RTAI, Xenomai, Fusion, and RTLinux?
To be specific, Bigelow Aerospace bought NASA's TransHab program. Apparently it's all siting out in a warehouse somewhere in Las Vegas. So it's no surprise that their technology compares favorably with NASA's-- it's based on it. (I know this only because I had a long conversation yesterday with a friend who works there, designing their robots and integrating the avionics package.)
My first reaction to this is, "Great! Now I can finish that project I've been wanting to do all this time." See, I've been living in a European country where there are far too many people who drive to work. It almost reminds me of America. I had wanted to use digital photography and analysis to take pictures of everyone's license plate, identify the cars with only one person in them during rush hour, and then send these guilty parties a nicely worded letter informing them of the ecological destruction they're haphazardly causing and a list of alternatives, such as buses and car-pooling.
(See, the climate, and the ecology, and the air polution is much too important to consider that people have a right to a private life when they drive. Individuals should be held as accountable for polluting the air as they are for polluting a stream or the ground. (Note: this is not to read that everyone who drives a car should be pulled out of their car and shot (Except for SUV drivers who should be.) (Just kidding. SUV drivers don't deserve such a quick death. )(Not that I'm advocating violence)(Except against SUV drivers), just that we need to consider the effects of pollution as a general destruction of the public good. Tragedy of the Commons, and all that.). But I digress.)
My second reaction is that, yes, this is going to happen, and there's not a damned thing we can do about it, aside from from change the laws. And then how? How can I differentiate between what's good usage and what's bad? In France, it's illegal to have a database with personal information in it except under certain circumstances. When a few years back I made a small wireless network in my dormitory and then charged fellow students a small fee for access, I was told that my spreadsheet with 1) Name, 2) Room #, and 3) MAC Address was technically illegal. It's going to be very difficult-- perhaps impossible-- to balance an individual's right to do something Good (TM) against a business's desire to do something Evil (TM). How do we draw the line between a small spreadsheet to keep accounting straight and a large database to track, monitor, survey, and sell, sell, sell?
At the least, we should start menacing all these corporations now. "You want to collect information on me? Ooooooookay, but if you get hacked, we're going to ask for $10,000 per person in indemnification. Non-negotiable. What? You don't want that financial risk and exposure? Okay, just delete all those files and the problem will go away."
Two things to notice:
1) His (windows) desktop uses the default XP background. Odd that the world's richest man doesn't change his background picture.
2) The (real) desktop looks as if it were made out of particle board.
Maybe Gates is more down to earth than we'd thought?
This was my masters project. Ball and Plate system
I say we just keep on using legos in scientific projects and prove to them how valuable legos are.
I've never had an easier time prototyping a model, and the finished instrument table, make out of aluminum and stainless steel to a very high precision, shows the value of legos in the prototyping process.
Is there someplace where we can vote to deny the teaching of Kansas? Intelligent design of the United States could never have made such a state.
I shudder to think about how many times I made that mistake today. Oh, well, at least I get an E for effort.
Err... some of us do understand it a bit. I'm a mechanical engineer. Heck, I *never* post on /. because most of the time you guys are talking about things I couldn't even begin to formulate an intelligent thougt on.
/. Those who know and tend to get heard, and it's usually pretty clear to me who is full of crap and who isn't on technical issues. However, your point still stands, we're (the educated crowd) pretty skeptical of anything that promises the moon, especially when there's a rash of too-good-to-be-true stories that are all coming out of the same source/poster. Someone else did a pretty good survey of the illustrious /.er who brought us this crackpot idea and the others like it. I'm too lazy to find it, you'll have to get it yourself if you feel like it.
That's what I like about
What's even worse than people who don't read the article? People who do, take the time to criticize it and respond to /.ers' follow-up comments, and then are criticized by those who read it, don't understand it, and decide to show their ignorance. Energy's not free, there are no miracle technologies, and any kind of generation such as this has already been highly perfected and will be proceeding in incremental steps, not revolutionary ones. The biggest revolution in wind power will be finding a way to distribute it on a large scale.
And NO wind tower is going to be able to withstand a hurricane while it's turning. Sorry, the slightest of engineering educations would teach that the gusts alone would rip it to shreds. There are no materials that can resist these sorts of forces. Not even buildings fare well, and they're a lot more solid than windmills. I think many HAWTs, which are far more sturdy than the VAWTs, give up the ghost in 60-70mph winds.
I thought I might call it bunk maybe 'cause...
I'm working on a PhD in the field? Not that makes me an expert or anything, since I'm actually working on the distributed grid side of things, but it does certainly mean that I've had a little more experience than the average person. And this is quite clearly bunk. Not only looking at the ancillary information, such as the source (opensourceenergy.com, puh-lease), but at his claims, with the all encompassing "We can't show photos because of... er... patents!".
Ah... but my information is easily found on many websites, as even the most cursory glance at wikipedia will show you. Clicking on the links that I provided would have set you off down the path to enlightenment.
Or is your mouse button broken today?
Ahh... I see the confusion now. I wasn't clear enough. What I meant to say was that VAWTs used for power generation are most often times found in the eggbeater configuration. In fact, they can be found in many, many, many configurations, such as the proposed Savonius VAWT, although the Savonius are only used when power generation levels are very low and low cost and maintenance are more important than power output. For instance, powering a weather station in the middle of nowhere. It takes no energy, but it needs to be self-sufficient and cheap, and that means that the difficulty of starting Darrius windmills from a dead standstill makes the Savonius windmill a better choice.
My apologies for not being more clear the first time.
Ah, yes, but he said "power", and not lift. The power *does* increase with the cube of the velocity because the kinetic energy increases with the square of velocity and the amount of mass increases linearly with velocity. So if you want to look at 1/2*m*v^2, the kinetic energy of a given control volume, you simply have to substitute mass for k*v to see that it's C*v^3, where C=1/2*k and k is some constant.
I had theorized earlier that this might have been because a tailflap might not have had enough force to spin round the tower, as bearing technology back then was certainly not advanced enough to manouver all that weight at the touch of a feather.
Whereas a small turbine could have been drastically reduced by gears so that even light winds can have the desired, albeit slow, effect.
Of course, this is all just suposition, as I have never seen-- although I admit never having gone looking for-- a description of this kind of invention.
A Savonius windmill generally means a windmill that uses drag from air to turn the blades, and thus can never spin any faster than windspeed.
This is in comparison to Darrius windmills which use aerodynamic lift to spin the turbine.
An advantage of Savonius windmills is that they are self-starting, whereas Darrius windmills aren't (although there have been a few designs that are).
I think you may have your "H"s and "V"s mixed up.
Nope, or at least not that I can find. HAWTs (Horizontal Axis Wind Turbines) are the big propeller turbines you see all over. VAWTs (Vertical Axis Wind Turbines) are the eggbeater contraptions that are rare but seem to be more efficient, once you take out all material/longevity considerations. You can find out all about them on wikipedia.org, if you'd like a little more background.
The blades of vertical rotors will always have a position in which they move against the wind, which causes drag or tricky aerodynamics at best.
Actually, the blades are always moving agains a relative wind. What's tricky about the aerodynamics is that the relative wind constantly changes as you go round the circle. The solution to this is to spin faster, so that the wind component which changes (the real wind itself) is small in comparison to the wind component which doesn't (the relative wind produced tangentially to the spinning blade).
Of course, as you spin faster, you get more centripital forces, and if you go too fast, everything fall down go boom.
Actually, having the propeller mounted in a duct does wonders for the efficiency. It also adds weight. WEIGHT. Think about how much metal it would take to fill up the area carved out by a 100m prop as it spins round and round. I don't have the numbers handy, but I bet it'd cost more in steel and installation than I earn in a year!
I have to wonder though whether one of these is really as efficent as a propeller-type windmill, given that a propeller type one can alter its blade pitch and keep the rotational speed relatively constant in different wind speeds. Is there a way to do that with a Savonius design? It doesn't seem like the airfoils are really anything that you could easily change in flight.
From my readings, and as a pilot, I can hazard a guess that this is because of the enormous complexity both in manufacturing and in maintenance of having a variable pitch prop. The money that you save (earn) through increased efficiency might be gobbled up the first time you have to higher a technician to climb to the top of a 200m tower and fix a faulty blade. Don't know if this is the only reason, but it's certainly a major one.
I'm not sure if it's true, but I once heard an interesting factoid about Dutch-style propeller windmills, and how they were among the first mechanical devices to implement a "feedback loop"; you have a tail rotor mounted perpendicular to the main rotor, which drives the mechanism that orients the windmill. If the wind isn't blowing at the mill directly from the front, it causes the small rotor to turn, turning the mill into the wind. When the mill is pointing in the right direction, there's no wind on the small rotor, so it stops. Pretty brilliant, for the 17th or 18th century.
Never heard that before, but it sounds pretty cool and feasible. It makes sense if you consider that bearings would have been pretty difficult back then, and thus you might not be able to rely on a little tail flap a la weather vane for orienting the mill.
A lot of it has to do with materials. VAWTs suffer from two notable stresses that are inexistant on HAWTs. 1) centripital forces and 2) vibration.
1) These things spin *quickly*. Far faster than the windspeed. Now, that's not so much a problem in a propeller blade because all the mass is on the inside and the blade happens to be strongest here, too. But on a VAWT, all the mass is on the outside, meaning that there is a significant amount of energy stored as they spin round and round. This pull can quickly destroy the windmill, and apparently has caused a couple deaths (Or so I have read in the windmill forums. Caveat reader.).
2) Because of the way the VAWTs spin, the mill is subject to pulsing as the blades change their angle of attack and speed with respect to the wind. Of course, this is reduced by having more blades which are thinner, (the ideal propeller being made out of an infinite number of infinitely thin blades) but the materials have limits and it seems that 2, 3, and 4 blades are all we can reasonably do. So the pulsing motion fatigues the support and can lead to failure.
HAWTs don't suffer from these problems, although they do have other problems-- such as torque applied by gyroscopic precession, torque applied by higher windspeeds at the top of the mill than at the bottom, orientation into the wind-- but they don't seem to be as difficult to overcome as the VAWT ones.
This design isn't new. It's bunk. As he describes it, it's a Savonius windmill, which is nothing if not inefficient.
Although your comments about microgrids are very apt. And since what we truly need in this world are microgrids (encourage conservation of energy, reduce fossil fuel use, provide energy to Africa), I'm very excited about wind's possibilities in this arena.
(Which is why I just started a PhD. in solar and wind microgeneration cells.)