Intro to Aircraft Systems Essay Example for Free

Intro to Aircraft Systems Essay All single rotor helicopters need some way to counteract the torque that is created by the rotor blades spinning around the mast. The most common anti-torque system used on helicopters is the Tail Rotor System. The Tail Rotor System is a relatively small rotor and transmission attached at the end of the tail boom that is driven from a shaft coming from the main engine and transmission (ASA, Helicopter Flying Handbook 1-5). Another anti-thrust system used less frequently is the Fenestron system. It is driven in a similar way to the standard tail rotor system but instead of two rotor blades at the end of the boom there is a series of rotating blades that are enclosed in a protective shroud, thus adding a degree in safety by protecting the tail rotor blades from ground contact (ASA, Helicopter Flying Handbook 4-7). The anti-torque system I want to discuss in greater detail is called the â€Å"NOTAR† system. The NOTAR system is dramatically different in design as it does not require another rotor at the end of the tail boom to create thrust and in losing that tail rotor this system has a number of advantages, added safety being one of the crucial benefits. The NOTAR system uses the natural characteristics of aerodynamics along with thrust from pressurized air exiting the tail boom to provide the thrust needed to counter the torque being produced by the main rotor (ASA, Helicopter Flying Handbook 4-7). It does this using the following components that are built into the design of the helicopter: air intake, fan, tail boom the can contain and control airflow, tail thruster cone, and two vertical stabilizers at the end of the tail boom. The first component of this system is the air intake, or a large opening on top of the rear fuselage. This intake is covered by a fine mesh screen designed to keep foreign objects from getting sucked into the system (Wagtendonk 190). The intake pulls air into the second component of this system: an enclosed variable-pitch composite blade fan. This fan’s purpose is to create a low pressure and high volume of ambient air that is sent into the tail boom, pressurizing it in the process. The fan blades are variable-pitch meaning their pitch, or pitch angle, can be increased or decreased creating more or less volume of air that is being introduced into the tail boom (Wagtendonk 190). The fan is located just behind the main transmission where the tail boom connects to the fuselage and is driven directly by the main rotor gearbox, this ensures that the fan is always providing directional control including when in auto rotation (Wagtendonk 190). The tail boom is the third and very crucial component of the NOTAR system. It looks similar to a standard tail boom but has a bigger circumference, is made from composite material and is completely hollow on the inside. The tail boom is designed with two parallel slots that run the length of the right side that allow the fan air (low pressure) to flow out and downwards (Wagtendonk 190). This movement of airflow energizes, or speeds up, the boundary layer of downwash flow that is created by the main rotor. This is called the Coanda effect (Wagtendonk 190). This essentially makes the tail boom a wing in relationship to the airflow created by the main rotor- low pressure on the right side and high pressure on the left side creating lift/thrust in the opposite direction of the torque from the main rotor. The Coanda effect is most effective when the helicopter is at a hover and can produce up to 60% of the needed anti-torque force. When forward speed is gained or in windy conditions the main rotor downwash begins to angle away from the tail boom reducing the Coanda effect (ASA Helicopter Flying Handbook 4-7). At the end of the tail boom we have another component to this system that provides the remaining force needed to produce enough anti-torque: the rotating direct jet thruster cone. The direct jet thruster is basically a nozzle at the end of the tail boom that directs the flow of the pressurized fan driven air. When the airflow reaches the nozzle, it first hits baffles located inside the rotating nozzle, which helps direct the airflow out the rectangular opening on the cone (Wagtendonk 191). The pilot can control the orientation of the cone by making pedal inputs- pressing the left pedal points the opening on the cone to the left side creating more anti-torque while right pedal turns the cone to the right reducing the anti-torque thrust (Wagtendonk 191). The final component to the NOTAR system is the twin vertical stabilizers that are attached on each end of the horizontal stabilizer. These stabilizers provide most of the anti-torque once the helicopter is in forward flight (ASA Helicopter Flying Handbook 4-7). Unlike the standard helicopter vertical stabilizer the left stabilizer actually moves and acts like a rudder, moving in unison with the rotation of the direct jet thruster (Wagtendonk 192). The right stabilizer is more like a â€Å"yaw damper† and is hooked up to a Yaw Stability Augmentation System (YSAS) (Stephens, â€Å"NOTAR: More Than What It Appears To Be†). The YSAS consists of a small electro-mechanical actuator that moves the right stabilizer based off of information coming from a yaw rate gyro and lateral accelerometer that is installed in the cockpit (Stephens, NOTAR: More Than What It Appears To Be†). There are some distinct advantages of the NOTAR system over the more conventional tail rotor and Fenestron anti-torque systems. One obvious advantage when comparing the NOTAR system to any other helicopter in flight is the amount of noise level reduced due to the lack of another added rotor (Abdollahi 6). In fact the MD 900 (which uses NOTAR) boasts the lowest noise levels of comparable helicopters (Abdollahi 6). Another advantage the NOTAR system has over the conventional tail rotor design is added safety. With no tail rotor, the NOTAR system eliminates the hazards of tail rotor strike, foreign object damage, and eliminates hazards involving people walking into the tail rotor (Wagtendonk 189). Also, the ability to control the heading in crosswind conditions is improved, and tail rotor blade stalls are eliminated (Wagtendonk 189). Though the NOTAR system is not widely used in the helicopter industry it is proven to be a highly effective, safer, anti-torque system. Its simple design using the natural characteristics of aerodynamics adds to its advantages, as does the additional safely gained regarding passengers and the pilot by eliminating the need for a tail rotor.

Population…A Problem That Most of the World Simply Disregards Essay

Population†¦A Problem That Most of the World Simply Disregards There are over Six Billion people inhabiting the planet earth today and that number is growing. â€Å"In the six seconds it takes you to read this sentence, eighteen more people will be added† (Ehrlich 9). The total population of the World, projected on October 23, 2001 at 6:28:09 pm GMT was 6,181,600,089 people (U.S. Bureau of the Census). Each hour there are 11,000 more mouths to feed; each year more than 95 million. Nevertheless, the world has hundreds of billions fewer tons of topsoil and hundreds of trillions fewer gallons of groundwater with which to grow food crops than it had in 1968. Millions of people every year are dying because they are not getting enough food. You see the advertisements, and television programs showing the starving children in Africa and other developing nations: their pleading eyes with helplessness. National Geographic shows the images of tropical forests on fire, beaches strewn with garbage and sewage, and refugee camps filled with hungry people unable to produce enough food because there aren’t enough resources to support the world’s growing number of people. These problem do not only exist in far away countries†¦drive in any large city, you will be overwhelmed with the number of drivers filling the freeways, grid locked any time of day. Visit downtown and see the hundreds of homeless people on street corners, and lined up around the block in front of the shelters for a warm meal. Our news is filled with the nation’s crime, violence, and drug abuse. Global warming is old news, but it is killing us, our ocean level is rising, and our crops are going dry. We are cautioned about the AIDS epidemic because it is everywhere,... ...t needs to understand the problem at hand, and recognize its far-reaching consequences. Works Cited Bouvier, Leon. â€Å"The Census Bureau’s 1989 Projections of Future U.S. Population: Which Scenario Is Reasonable?† CIS Backgrounder. October 1989: 59-65. Breland, H. â€Å"Family Configuration and Intellectual Development.† Journal of individual Psychology. vol. 31, pp.86-96, 1977. Ehrlich, Paul R., and Anne H. Ehrlich. The Population Explosion. New York: Simon & Schuster, 1990. Menk, Thomas. â€Å"Eco-Refugees Warning.† New Scientist, 10 June 1999: 33-35. Running, Stephen F. â€Å"What If the Supreme Court Changed Its Mind?† Stanford Lawyer. Fall 1988: 15-29. Swerdlow, Joel L. â€Å"Changing America.† National Geographic. Sept. 2001: 42-61. U.S. Bureau of the Census. World POP Clock Projection. 23 October 2001 .

Green Revolution Essay

Interaction between humans and the environment has always had a great importance in the development of humankind; according to Marx, what differentiates humans from other animals is the fact that humans can transform their surroundings to suit their needs, through labor. The Green Revolution is not the exception to that. In times of need the human being manipulated its environment to be suitable for its development, however, the question lingers, how efficient was it, how positive? The Green Revolution, from 1945 to the present, was motivated by the need to increase the production of food to supply for the increasing demand as population grew, to promote national self-sustainability in terms of food. However, during that period the effect of the Revolution have been detrimental to the environment and society: they have damaged agricultural diversity and heritage, damaged the lands, and put at risk food security; also, they have widened the gap between the very rich and the very poor, monopolizing the food industry. The Green Revolution originated after an urgent need to promote food security with a growing trend in global population, as a way to promote self-sustainability and independence. As it is clear in the report given by the Food and Agriculture Organization (DOC 2), in the period ranging from around 1929 (great depression) and 1945 (end of World War II) the global food supply index was below the world population. What this means is that there was literally not enough food being produced world wide to feed the world population. This struggle of human kind to stay afloat in supplying the minimum needs for survival meant that a change needed to occur. The answer, as Dr. Norman Borlaug stated in his Nobel Lecture (DOC 4) was not simply planting more in the developing nations, since the lands in those areas were â€Å"tired, worn out, depleted of plant nutrients†¦Ã¢â‚¬  Clearly, what the document refers is that a new, more effective way of growing food had to be developed. In fact, Dr. Borlaug states that the priority of the developments of the green revolution concentrated in the millions that were lurked by hunger, a large problematic that clearly was under the spotlight. As a proof that the world was prioritizing the deficient food supply is the statement given by President Harry Truman (DOC 3). President Truman was the leader of the most powerful nation in the world at the time, the one with the largest technological developments, and his word was the one that would set the course of the world. This particular speech is vital, since it is the inaugural speech, where he was to set the priorities of the government and address the world with what the United States had as a course for the future. In this speech, he clearly refers to the shocking figure that â€Å"more than half the people of the world are living in conditions approaching misery† and says that the United States will help provide â€Å"technical knowledge†¦ to produce more food† In the speech President Truman refers often to liberty, thus meaning that self-sustainability will provide freedom. This speech is the perfect example, the jewel of the trend that the world was seeing with regard to prioritizing food. The mention of â€Å"technical knowledge† is vital in the construction of the green revolution as a response to the lack of food, with technological developments in the agricultural field. Some have said that the Green Revolution has been a success in improving the food industry, and improving living conditions for everyone; nevertheless the numbers today reflect a mediocre success. Indian minister for food and agriculture (1964-1967) states in an interview (DOC 5) that the farmers of the state of Punjab competed to use the technology that was introduced by the green revolution the best. It is stated with a positive connotation, as to refer to the great feats of Punjab. This seems very positive, however, the most likely reason for this to have occurred is the fact that multinational corporations were kicking them out of the market and they were forced into utilizing the technology that those same corporations were imposing on them. If this were true, which it most likely is, as it has happened in many places around the world, it would discredit the great success that the Green Revolution supposedly is. Furthermore, the claim is that the Green Revolution has brought prosperity, however, to whom, to the ones that were rich already? A perfect example of this negative impact of the Green Revolution is the conversation between Mrs. Dula and the United Nations official (DOC 6), which gives a not very realistic perspective of the impact of the green Revolution and is concentrated exclusively in the sector of the very rich. This document is indeed quite revealing, as the speaker is an aristocratic woman of Mexico, probably a housewife who sees the world through the optic of his husband, a man who earns a salary if the revolution which he works for is successful; in fact, she is most likely part of one of the clubs she talks about herself. The occasion of this statement is a simple conversation with a UN official, probably at some sort of a social event, where the high class is all joined together, with perfectly slanted people who are not really analyzing the global impact of the Green Revolution. This document gives a crystal clear proof of how much the Green Revolution has made the â€Å"rich Mexican farmers† richer probably at the expense of making the poor laborers, poorer, however, this document presents only one, very bright point of view to sell the revolution. With regards to India once again, socially, they sell the idea of improvement, like in the report of the State of Punjab (DOC 9) where it says that the Green Revolution has seen with it the â€Å"emergence of middle and rich peasants† a very undesirable euphemism to conceal the actual situation. This document seems to give a perspective of social growth and development, of a population going for education, yet once again, it seems very idealistic in its tone, when in reality India has totally different conditions. With regards to that, India has one of the largest Gini index’s in the world, meaning a huge social inequality, and has one of the smallest middle classes in the world, which has diminished even more throughout the years, meaning that in reality, India may have had a somewhat positive year, but the general trend is of a very pronounced downturn in social progress, all related to the Green Revolution which is destroying the small farmers. The Green Revolution, in truth has brought more ill than it has brought good, in the environmental and social aspects. Regarding environmental harm, the FAO Wheat Yield report (DOC 1) is very good in demonstrating the introduction of massive scale crops that the Green Revolution brings forth with it. The introduction of these crops damages the lands since they are not prone to such production. The graphs show that in both Mexico and India the crop yields were extremely irregular, and as time passed they have become even more, this is due to the fact that they are not proper to those areas and its planting is something totally synthetic and with complete disrespect towards the natural balance. The article by Dr. Vandana Shiva (DOC 8) reveals how much damage the crops, especially Genetically Modified Organisms; do to the land they are planted in. The â€Å"reduced genetic diversity, increased vulnerability to pests, soil erosion, water shortages†¦Ã¢â‚¬  are effect that will leave marked the land for a long time, as Dr. Shiva states, and are a threat to future generations, which will have totally barren land where it will be impossible to plant food. Dr. Shiva also refers to the social problematic that the Green Revolution is planting alongside its seeds. For instance the fight for water to provide irrigation, previously not needed in India, has lead to â€Å"conflict and violence† and as it has become a worldwide trend, the career for water dominance is â€Å"leading to both local and interstate water conflicts. † This clearly shows how disadvantageous the spread of the Green Revolution has been, since it has brought unmeasured changes that have not been made responsibly, but rather abruptly, causing enormous damage. Dr. Shiva is an Indian Physicist, and being from India she probably has had a very direct contact with the Green Revolution, considering that one of its birthplaces was in fact the State of Punjab. In this occasion she is writing for the Ecologist magazine, a publication read by people with primary interest in the environmental issues, including organization leaders and maybe politicians who will probably get concerned, especially due to the tone of annoyance and hatred that she employs in the article. Expanding on social implications, the Guatemalan National Coordinating Committee of Indigenous peasants (DOC 10) gives a different perspective. Although it may sound somewhat as mysticism from indigenous people, saying that they have contaminated the seeds is not a joke, considering the hormones that can be found in GMO plantations. This also acknowledges a vital issue, the loss of diversity and heritage that society is killing with the systematic Green Revolution trends, like the Mayan traditions, which have been present for â€Å"five thousand years. † Furthermore, the social disaster does not stop there, but stumbles over women, which according to the FAO Newsletter (DOC 7) have been forced to change their job. In this case the implications have made woman, traditionally in other roles, have even less opportunities to succeed, as the increased need for cash income made the woman be forced to work. This implies a social catastrophe since it denies the right of woman to equal opportunities, which are stripped off with the Green Revolution, which makes them simply one more laborer forced to work. Additional to the information presented in the documents it would be vital to contain the point of view of a small scale male farmer that has to compete with the multinational corporations, which have been installed after the start of the Green Revolution circa 1945. This would be important since it would show the first hand effects of the monopolies that the Green Revolution has brought, with regards to the social impact it has made, and whether that impact is positive or negative. As discussed throughout the essay, the Green Revolution, which has lasted from 1945 until the present day, was originated with a need to secure food production in a starving world. However its effects were not so positive, since today many starve, and the Green Revolution has damaged the environment and widened the gap between the social classes. The setup of crops that have give no benefit to the places in which they are grown, with complete disregard to the ecological balance that was being destroyed have caused issues ranging from soil erosion to water shortages and crops with pest vulnerability. The Green Revolution has also made the rich farmers richer at the cost of the poor being poorer, since the costs of the new technologies are not easily accessible, but the yields that they provide take the small farmers out of business. In general, although certain governments sponsor the Green Revolution and make it seem positive, it has brought about large changes in the way humans interact with the environment, with a generalized destruction of it to get short-term solutions to the problem of food shortages.

The Many Meanings of the Spanish Ya

Already, right now, still, enough — these are just four of the dozens of possible translations of the Spanish ya. Ya, which is usually an adverb but sometimes a conjunction, is one of those words whose meaning depends almost entirely on the context. Sometimes it doesnt have much of a translatable meaning, becoming a filler word something like pues, adding a slight amount of emotional content to a sentence (although the exact nature of the emotional content may be difficult to determine out of the context). Key Takeaways Ya  is usually an adverb, very common in speech, whose meaning depends almost on the context. It can express both resignation and surprise, both agreement and disbelief.The most common translations of  ya  include now, still, and already.Sometimes,  ya  doesnt need to be translated, as it can function as a filler word or a word that adds a vague emotional content rather than a denotation. Most Common Meanings: Now and Already The most common meanings of ya are now and already. Often, it signifies a slight amount of impatience, although it sometimes can indicate satisfaction or agreement with the person being spoken to. As you might have guessed, its a word youll come across more often in informal conversation than you will in formal writing. When the verb of the sentence is in a past tense, already is usually a good translation: Lo he leà ­do ya. (Ive already read it.)El lunes ya lo habrà © visto. (By Monday I will have already seen it.) ¿Ya compraste tu boleto para la loterà ­a? (Did you already buy your ticket for the lottery?)No se puede romper lo ya que està ¡ roto. (You cant break whats already broken.) When the verb refers to an anticipated action, now is a common meaning. If the context or tone of voice suggests impatience, right now can also be used: Ya està ¡ aquà ­. (Shes here now.)Ya salen. (Theyre leaving now.)Lo quiero ya. (I want it right now.)Tienes que estudiar ya. (You need to study right now.) In some situations, you may be able to use either already or now in translation, such as when expressing surprise. The first sentence above, for example, might have been translated as Shes already here. And the question  ¿Sales ya? could mean either Youre leaving now? or Youre leaving already? When being rude,  ¡Corta ya! could be translated as either Shut up now! or Shut up already! Other Translations for Ya There are dozens of other ways you could interpret ya. Here are examples of other ways you could interpret ya: Still, any more (especially when used in the negative): Ya no trabaja aquà ­. (He doesnt work here any more.) Ya no està ¡n ganando dinero en la situacià ³n actual. (They arent making money any more in the current situation.)To note that a wish has been satisfied:  ¡Ya conseguà ­ el trabajo! (I got the job!) Ya entiendo las diferencias. (Finally I understand the differences.)To indicate frustration:  ¡Basta ya! (Enough is enough!)  ¡Ya està ¡ bien! (Thats plenty!)  ¡Ya era hora! (Its about time!)  ¡Vete ya! (Get yourself out of here!)To indicate emphasis:  ¡Ya lo sà ©! (I already know that!) Es difà ­cil, ya verà ¡s. (Its difficult, youll see.) Ya puedes empezar a estudiar. (You had better start studying.) Él no comià ³, que ya es decir. (He didnt eat, which is saying something.) Ya me gustarà ­a ser inteligente. (Id love to be intelligent.)Later (to indicate something will happen in the indefinite future): Ya ocurrirà ¡. (Itll happen.) Ya lo harà ©. (Ill get it done.) Excelente. Ya hablaremos. (Excellent. Well talk later.)To express agreement or incredulity:  ¡Ya, ya! (Oh, sure!) Ya, y el papa es luterano. (Sure, and the pope is Lutheran.) Ya, pero es difà ­cil. (Yes, but its difficult.)To call attention to something, especially when followed by que: Ya que no està ¡ aquà ­, podemos salir. (Considering that hes not here, we can leave.) Ya que conocemos es fà ¡cil, podemos hacerlo. (Since we know its easy, we can do it.)To offer reassurance: Ya aprobarà ¡s el examen. (Youll pass the test.) Ya sabrà ¡s pronto. (Youll know soon.)To emphasize a connection between different facts: Yo quisiera consultarte sobre este tema, ya que mi perro tiene esta conducta en diferentes situaciones. (I would like to talk to you about this, because my dog acts like this in different situations.) La diamante era muy caro, ya lo comprà ©. (It was very expensive, yet I bought it.)