The tail rotor is needed to "anchor" the engine. If you clamp the shaft of a motor, the motor would spin in the opposite direction. Infact most ceiling fans have a fixed shaft and the motor spinning in the opposite direction. Most other applications of the electric motor has the motor bolted down and the shaft spinning. In a helicopter, how do you "bolt" down the engine? To the airframe? The whole airframe will spin in the opposite direction. That is why you need a tail rotor to provide a counter moment to keep the aircraft from spinning. You can avoid tail rotor if you have two main rotors like in a chinook, or two counter rotating main rotors. You could create a small jet using the gasturbine's exhaust and use it instead of the tail rotor.
Why does it not generate lift in all directions? The Lift is always perpendicular to the blade/wing surface that is true. But the magnitude of the Lift depends on the angle of attack. So when the blade is in a position where you don't want lift, you can change the angle of attack and make it zero. You do it while you are swimming. Imagine the breast stroke. To move forward you have the palm pushing water back. Then you move your arms and bring it forward, but keep the palm cutting through the water without creating any force by pushing water forward. Same thing but you need to do it using a mechanism to keep the angle of attack the precisely right.
Similar thing happened to me with hotels.com. Washington DC. Hotel desk claims that the reservation does not show up in the computer. But they had identical room available. 10$ cheaper to boot!. Took the room, figured the hotel is scamming hotels.com out of the commission it had to pay. The hotel charged me twice for the same room. Once through the hotels.com reservation and once again through the "new" walk-in booking. Had one charge annulled. I have a hunch they do it regularly hoping the double charge will be overlooked by busy business travelers. Made a mental note never to stay in that hotel again if I go to DC.
The problem is not the laws. It is essentially Best Buy claiming that there is no proof that the box they sold had these tiles. It is possible that this guy took the drive, put some tiles in and claim this is what was inside the box. On the other hand, a scam artist like that would not create a hue and cry and issue stop payment order to American Express. The store should have used some judgment. Most stores actually track the purchase/return history of every credit card used in their store. Recently Walmart puts people who return merchandise too often in a watch list and restrict their "no-questions asked return policy."
My guess of what happened: Someone orders the drive, gets it, removes it repacks it with tiles. If this guy has access to shrink wrap machine, he reseals the package and gets full refund. Store thinks the package has not even been opened and restocks it and sends out again to this honest customer.
Given the numbers and bar codes and the tracking they do, BB should be able to find out who ordered and returned the drive and pursue that scammer. To prevent the recurrence, BB should use shrink wrap with its logo and other counterfeit proof shrink wrap.
They do have the same issue. In a helocopter, the advancing and retreating blades are on the right and the left.
In this it is on the top and bottom. That is all.
Yes, helicopters do it too. The advancing blade meets the air at aircraft velocity PLUS velocity due to the spinning of the blades. The retreating blade meets the air at rotational velocity Minus aircraft forward speed. Thus to produce the same lift, it has to have a higher angle of attack. This is done by the cyclic pitch control. Depending on the total lift needed the angle of
attack has to be increased for all the blades by equal amount. That is called the total pitch. It does make the hub mechanism of the helicopter blades very complex.
Yes, my comment was quite lame. But the thought I had when I started typing was marginally better.
I was about to say, "Yes, it would run linux because by that time atleast 9 Year of the Linux would have come and gone". But, so many slips between the cup and the lip.
In a fixed wing aircraft the engines develop enough thrust to overcome the drag. Typical Lift to drag ratio is between 10 and 12 for commercial jets. Some sail planes and gliders have achieved L/D ratio of 30 and 40. In any hovering aircraft, be it helicopter or vectored thrust machines like the Harrier, or the stupid plane V22, the engines must develop enough thrust to overcome the weight. (Weight = Lift). Thus they develop between 10 and 12 time more thrust and thus they consume that much more fuel. That can not be avoided.
Changing the angle of attack of each foil in the wing for this aircraft is no doubt complex, but
even helicopters have this quite complex cyclic pitch/total pitch changing mechanisms. Given the advancement in materials and electrical actuators, it is possible that the time has come for a
horizontal axis rotating wing aircraft.
May be this craft will transition from hover to flight with
locked wings more easily and more stably than that boondongle from Fort Worth, V22 Osprey. Thus
for the long haul you get the speed and efficiency of the fixed wing aircraft. But you get hover
ability too. The price you pay is to haul a larger powerplant all the while. But still it might beat V22.
Respect to the views and opinion of the old people was a good survival strategy. Back in the hunter gatherer days, these people were the storehouse of knowledge. They remember which roots and berries the tribe survived during the last famine etc. So even if they were not pulling their weight in the hunts, others gave them a cut of the leg of the zebra or a woolly mastodon. But now a days, now that we have the internet to serve as the storehouse of knowledge (and much more), yeah, we really need to think what to do with the old people. First I would like to cut their social security off. I mean, come on. How can we go for lower taxes and less onerous government if these old fogeys keep going to the elections and keep voting for either a tax-and-spend Democrats or borrow-and-spend Republicans?
It could be true that U.S. educational system is turning out more science and engg grads that what the market wants. But that is probably not because we have suddenly turning out good quality engineers by the bucketfuls. It is just that the market is not demanding that many good quality engg grads now, because of out sourcing. When you get good quality engineers at fraction of the salary in India, Ireland, Israel and other countries, the demand slackens.
It takes a while for the information feed back to the corporate honchos to percolate through. Engineer salaries alone can't be compared. For example in India, to support one engineer, you probably need 0.1 cook, 0.1 diesel mechanic, 0.05 secretaries, 0.333 peons/errand boys... Most of what you get from the existing infrastructure in USA, like reliable
grid electricity, commuting infrastructure, lunch provides, etc are all provided by the companies themselves. It is possible that at the present levels of productivity and infrastructure cost, it could be profitable to out source. But dollar is falling against euro, rupee etc. The salaries overseas are increasing at a faster rate. The breakeven point is quite close and the trend towards outsourcing is going to reverse. At that point, it is doubtful if we will have enough qualified engg grads.
It is kind of explainable, given that most MSFT managers grew up in the era where WYSIWYG was the greatest thing since the sliced bread. They have always believed in GUI and never liked CLI much. So the tradition continues, less emphasis on anything script oriented and CLI oriented. Their idea of great script is a vbscript with its own GUI. We might not like it, but that kind of explains part of MSFT's way of working/thinking.
Lacking support for ftp, ssh etc are some vague attempt to create "value" to the non portable skill set developed by the windows admins. If the sys admins develop these skills and could easily run either linux or windows, then the switching cost for corporations to switch from windows to linux will decrease. Since the maximum revenue MSFT can extract from its existing installed base is capped by what it would cost its customers to switch to an alternative system, this is a very rational business strategy to keep them following a straight and narrow road to Redmond. And let us not blame just MSFT for this attitude. It is the customers who should realize the value of reducing their switching costs and demand better support for ftp, ssh and other linux side expertise they have in house. If customers don't demand it, why would a profit centered corporation deliver it?
He is using a couple of bicycle wheels to increase the rpm to drive a truck alternator it looks like. Simple mechanism, easily maintained by the bicycle mechanics of an Indian village. This might find more applications too. Like charging their cell phones. A large part of rural India is still not on the national electric grid. Even the grid goes down sometimes in the rural areas. Most villages have this oil press powered by bullocks walking in a circular path (about 30 feet in diameter) dragging a yoke connected to a central pivot. They take a minute to finish a circuit. RPM=1. The gearing ratio from the picture appears to be 1: 60. (10x6). Not enough in my opinion to drive a standard truck alternator. Their efficiency peaks at around 1800 RPM. (I did a windmill for my undergrad project and I needed to gear it up to 1800 RPM to drive a truck alternator). Need to add another wheel set, not difficult to do.
Almost all the carts in India are drawn by bullocks (castrated bulls). Bullocks are used for irrigation, pressing oil out of seeds etc. They are trained to walk back and forth to draw water out of wells and to walk in circles to press oil. It is an eerie sight to drive on the rural roads in India late at night. The villagers cart their stuff to the nearest market towns, sell, watch a movie, get drunk and sleep in their carts. These bullocks are trained to walk home unaided. So you would come across this caravan of six or eight bullock carts, all obediently following the traffic rules (left side of the road) and plodding along. If you catch them going in opposite direction their eyes gleam eerily reflecting the headlamp. Always thought it would be a very simple thing to silently climb on to the leading cart, override the autopilot and drive the caravan to a secluded spot and rob the villagers. But somehow such crimes don't happen in rural India. (Other kinds of crimes do happen, don't want to paint too rosy a picture.)
It would be a trivial thing to gear up an oil press and drive a tiny generator to power a few laptops.
In a remarkable development, all the seven islands of the Seven Sister's Atoll, seceded from their common government and declared themselves independent sovereign nations. UN approved their nationhood in an emergency session. All of them, (population 7, 21, 3, 23, 7, 5, and 0.5 respectively) have immediately applied for the P membership of ISO. The population count of less than 1 raised a few eyebrows. It turned out to be the National Geographic photographer who camps there every summer. It is widely speculated in slashdot that all of the will soon vote to approve OOXML.
This is just a bribe to make sure Facebook does not use any portable technology or make it easy for competition to write applications/search on top of Facebook. Like the money it paid to large domain registrars to get them to switch away from Apache.
If the cost increases, they will invest the money and upgrade the network. What is the problem? When MSFT thinks Facebook is worth 15 billion dollars, routers are chump change for them. What is the crisis here? Cost of something is going to go up? Big deal. Oil prices are shooting up. College tuition costs are shooting up. Y ! routing costs?
Come on, there is no comparison! Porn does not nag you to fix the broken windows and leaky faucets.
It does not get head aches. It does not make any demands on the personal hygiene front. You don't have
to share you stash of pot and crack with it. Porn does not get jealous if you get another set.
Come on. Wife's for dummies. Discerning slashdotters know, prOn beats wife hands down.
I remember a group of people waiting for you. Some 32 people in some large farm house or something in California. All wearing some kind of black clothing and Nike shoes. They took your promise to come in 1999 or so and committed suicide but you are coming so late. OK atleast the rest of the believers can now die and meet you.
Slashdot Mirror
Why does it not generate lift in all directions? The Lift is always perpendicular to the blade/wing surface that is true. But the magnitude of the Lift depends on the angle of attack. So when the blade is in a position where you don't want lift, you can change the angle of attack and make it zero. You do it while you are swimming. Imagine the breast stroke. To move forward you have the palm pushing water back. Then you move your arms and bring it forward, but keep the palm cutting through the water without creating any force by pushing water forward. Same thing but you need to do it using a mechanism to keep the angle of attack the precisely right.
After reading all the comments in this story, looks like one could make a killing in the stock market by shorting BB.
Similar thing happened to me with hotels.com. Washington DC. Hotel desk claims that the reservation does not show up in the computer. But they had identical room available. 10$ cheaper to boot!. Took the room, figured the hotel is scamming hotels.com out of the commission it had to pay. The hotel charged me twice for the same room. Once through the hotels.com reservation and once again through the "new" walk-in booking. Had one charge annulled. I have a hunch they do it regularly hoping the double charge will be overlooked by busy business travelers. Made a mental note never to stay in that hotel again if I go to DC.
My guess of what happened: Someone orders the drive, gets it, removes it repacks it with tiles. If this guy has access to shrink wrap machine, he reseals the package and gets full refund. Store thinks the package has not even been opened and restocks it and sends out again to this honest customer.
Given the numbers and bar codes and the tracking they do, BB should be able to find out who ordered and returned the drive and pursue that scammer. To prevent the recurrence, BB should use shrink wrap with its logo and other counterfeit proof shrink wrap.
They do have the same issue. In a helocopter, the advancing and retreating blades are on the right and the left. In this it is on the top and bottom. That is all.
I think we could design a mechanism to lock the rotation out and lock the foils at specific angle of attack to make the whole contraption glide.
Yes, helicopters do it too. The advancing blade meets the air at aircraft velocity PLUS velocity due to the spinning of the blades. The retreating blade meets the air at rotational velocity Minus aircraft forward speed. Thus to produce the same lift, it has to have a higher angle of attack. This is done by the cyclic pitch control. Depending on the total lift needed the angle of attack has to be increased for all the blades by equal amount. That is called the total pitch. It does make the hub mechanism of the helicopter blades very complex.
Yes, my comment was quite lame. But the thought I had when I started typing was marginally better. I was about to say, "Yes, it would run linux because by that time atleast 9 Year of the Linux would have come and gone". But, so many slips between the cup and the lip.
Changing the angle of attack of each foil in the wing for this aircraft is no doubt complex, but even helicopters have this quite complex cyclic pitch/total pitch changing mechanisms. Given the advancement in materials and electrical actuators, it is possible that the time has come for a horizontal axis rotating wing aircraft.
May be this craft will transition from hover to flight with locked wings more easily and more stably than that boondongle from Fort Worth, V22 Osprey. Thus for the long haul you get the speed and efficiency of the fixed wing aircraft. But you get hover ability too. The price you pay is to haul a larger powerplant all the while. But still it might beat V22.
Before anyone asks. Also you can imagine a beowulf cluster of these, as well as welcome the overlords.
Respect to the views and opinion of the old people was a good survival strategy. Back in the hunter gatherer days, these people were the storehouse of knowledge. They remember which roots and berries the tribe survived during the last famine etc. So even if they were not pulling their weight in the hunts, others gave them a cut of the leg of the zebra or a woolly mastodon. But now a days, now that we have the internet to serve as the storehouse of knowledge (and much more), yeah, we really need to think what to do with the old people. First I would like to cut their social security off. I mean, come on. How can we go for lower taxes and less onerous government if these old fogeys keep going to the elections and keep voting for either a tax-and-spend Democrats or borrow-and-spend Republicans?
Thank you, America for a quick reply.
Or the work is going out.
It takes a while for the information feed back to the corporate honchos to percolate through. Engineer salaries alone can't be compared. For example in India, to support one engineer, you probably need 0.1 cook, 0.1 diesel mechanic, 0.05 secretaries, 0.333 peons/errand boys ... Most of what you get from the existing infrastructure in USA, like reliable
grid electricity, commuting infrastructure, lunch provides, etc are all provided by the companies themselves. It is possible that at the present levels of productivity and infrastructure cost, it could be profitable to out source. But dollar is falling against euro, rupee etc. The salaries overseas are increasing at a faster rate. The breakeven point is quite close and the trend towards outsourcing is going to reverse. At that point, it is doubtful if we will have enough qualified engg grads.
Lacking support for ftp, ssh etc are some vague attempt to create "value" to the non portable skill set developed by the windows admins. If the sys admins develop these skills and could easily run either linux or windows, then the switching cost for corporations to switch from windows to linux will decrease. Since the maximum revenue MSFT can extract from its existing installed base is capped by what it would cost its customers to switch to an alternative system, this is a very rational business strategy to keep them following a straight and narrow road to Redmond. And let us not blame just MSFT for this attitude. It is the customers who should realize the value of reducing their switching costs and demand better support for ftp, ssh and other linux side expertise they have in house. If customers don't demand it, why would a profit centered corporation deliver it?
Looks like the advantage is, you don't waste your scree space with useless forward/backward buttons, URL strings etc.
He is using a couple of bicycle wheels to increase the rpm to drive a truck alternator it looks like. Simple mechanism, easily maintained by the bicycle mechanics of an Indian village. This might find more applications too. Like charging their cell phones. A large part of rural India is still not on the national electric grid. Even the grid goes down sometimes in the rural areas. Most villages have this oil press powered by bullocks walking in a circular path (about 30 feet in diameter) dragging a yoke connected to a central pivot. They take a minute to finish a circuit. RPM=1. The gearing ratio from the picture appears to be 1: 60. (10x6). Not enough in my opinion to drive a standard truck alternator. Their efficiency peaks at around 1800 RPM. (I did a windmill for my undergrad project and I needed to gear it up to 1800 RPM to drive a truck alternator). Need to add another wheel set, not difficult to do.
It would be a trivial thing to gear up an oil press and drive a tiny generator to power a few laptops.
In a remarkable development, all the seven islands of the Seven Sister's Atoll, seceded from their common government and declared themselves independent sovereign nations. UN approved their nationhood in an emergency session. All of them, (population 7, 21, 3, 23, 7, 5, and 0.5 respectively) have immediately applied for the P membership of ISO. The population count of less than 1 raised a few eyebrows. It turned out to be the National Geographic photographer who camps there every summer. It is widely speculated in slashdot that all of the will soon vote to approve OOXML.
This is just a bribe to make sure Facebook does not use any portable technology or make it easy for competition to write applications/search on top of Facebook. Like the money it paid to large domain registrars to get them to switch away from Apache.
Come on even humans have difficulty telling the emotional state of someone who got botoxed ... How can the software tell?
If the cost increases, they will invest the money and upgrade the network. What is the problem? When MSFT thinks Facebook is worth 15 billion dollars, routers are chump change for them. What is the crisis here? Cost of something is going to go up? Big deal. Oil prices are shooting up. College tuition costs are shooting up. Y ! routing costs?
Come on, there is no comparison! Porn does not nag you to fix the broken windows and leaky faucets. It does not get head aches. It does not make any demands on the personal hygiene front. You don't have to share you stash of pot and crack with it. Porn does not get jealous if you get another set. Come on. Wife's for dummies. Discerning slashdotters know, prOn beats wife hands down.
I don't get it. I am sure millions of slashdotters are scratching their head too. If you have porn, why do you need a wife?
I remember a group of people waiting for you. Some 32 people in some large farm house or something in California. All wearing some kind of black clothing and Nike shoes. They took your promise to come in 1999 or so and committed suicide but you are coming so late. OK atleast the rest of the believers can now die and meet you.