Rotary Engine Essay Example

Rotary Engine Essay Example Rotary Engine Essay Rotary Engine Essay Svetlozar Simeonov 09/25/11 Wankel Rotary Engine – Huge Power in a Small Box According to Philip’s Encyclopedia Wankel rotary engine or just Wankel engine is â€Å"Internal combustion engine with rotors instead of pistons. † That not so popular engine is actually about two times lighter than a four cylinder piston engine, the one that we all have in our cars, for the same power output. It also has four times less moving parts. Much simpler, much lighter, much smaller it has numerous advantages over a conventional piston engine. One of the most simple and clear explanation of how the Wankel engine works oppose to piston engine comes from Time magazine: â€Å"Instead of converting up-and-down piston motion into wheel-driving circular energy through a series of complex linkages- the way a standard engine works- the Wankel rotors spin continuously and thus provide the proper torque to move a cars wheels directly. † (Time Aug 14 1972). It has four times less moving parts versus four cylinder engine. Therefore, Wankel engines â€Å"are smaller, peppier and potentially cheaper to build than conventional reciprocating models, and have only six major points of wear, v. 00 in a conventional engine† (Time Aug 14 1972). The Wankel engine was reviled in 1956 by its engineer Felix Wankel (The Columbia Encyclopedia – internal-combustion engine). The first mass production car powered by Wankel engine was released in 1967 by the Japanese manufacture Mazda. It was a reference design, twin –rotor 9 82cc, outputting 110 hp. That made the 2000 pounds Cosmo model pretty zippy. Mazda quickly introduced 2 more models in 1970 and with prices significantly lower than its competition Mazda’s success rapidly increased. Seeing the growing interest, 2 of the largest automobile manufactures in the world– General Motors and Mercedes-Benz – purchased license to produce vehicle with this technology. General Motors even had a Corvette on the way, when the 1973 oil crisis changed everything over. The Wankel engine at the time was less fuel efficient, so the sales suddenly dropped down so low that Mazda was a step away from bankrupt. They changed their strategy and rotary cars became a special line, instead of mainstream. Then and now, Mazda is the only manufacture to truly stand by this technology. It improved it radically in terms of output and fuel efficiency. Their last generation engine, called Renesis, used since 2003 in RX-8, has the same output like the previous generation 250hps, red line topping at 10 000 rpms. However, it is naturally aspirated, where the previous one was twin-turbo charged. The Renesis is also 25% more efficient. Sadly it wasn’t enough, and the RX-8 was discontinued in August 2011, with no successor announced. With the slow pace of its evolution, I hope we can see the next generation at the end of this decade. Mazda and the Wankel engine have won many awards and races. The most prestige one is the success in 1991 in the annual â€Å"24 hours of Le Mans†, leaving behind drivers and teams with traditions like Mercedes, Jaguar and the frequent winner Porsche. The four-rotor engine outputting 700 hp lead the team first to the finish, regardless their start position – 55. As William Welch states, in his recent publication in USA Today, â€Å"the only Japanese car and only non-piston engined car to win the grueling French race† (William M. Welch, USA Today 08/23/2011). â€Å"Sanctioning bodies outlawed the engine after the win at Le Mans† and close the history of Wankel powered cars at this scramble (William M. Welch, USA Today 08/23/2011). That win however, confirmed the Wankel reputation of power and durability. Even though the Renesis was a big step forward, it was still a step behind the longer lived piston engine in terms of fuel economy. That was its only drawback, but enough to turn a lot of people away. Not so many had the chance to experience the fun side of this fast revving motor. Fossil fuels, like gasoline, are fated to become extremely rear and expensive and it looks like Mazda engineers are getting prepared for this scenario. In interview for Reuters news agency from 2007 Mazda executive Nobuhiro Hayama revealed their new strategy: â€Å"Researchers at Japanese carmaker Mazda think cars will in future run on water component – hydrogen. †¦the advantage hydrogen fuel was that it could be used in internal combustion engines. However †¦ there is a risk of abnormal combustion. This could be solved by using rotary engines† (Tokyo Reuters Oct 22 2007). That means that a slightly modified RX-8 could reborn and satisfy the need of cheaper run and exciting pull, equipped with â€Å"two fuel tanks, though† (Tokyo Reuters Oct 22 2007). We would expect the price to remain the same, since no direct modification to the engine is needed, and the car has paid of its investments already. It looks like a bright future for the Wankel. Removed paragraphs Taking in consideration the minimum moving parts of the Wankel engine, the aerocraft industry quickly realized its lifesaving advantage. In case of internal engine damage the engine would not fail right away. It will continue delivering power that will decrease with time. Its weight and size made it preferable for many small plane manufactures. It let the engineers improve aero dynamics of the plane nose, due to the smaller engine. The first complete Wankel engine was reviled in 1956 by its engineer Felix Wankel (The Columbia Encyclopedia – internal-combustion engine). Since then, the engine received many improvements. The main contributor is the Japanese manufacture Mazda that started a line of sport cars with Wankel engines in mid-1960. The first model, named Cosmo, had a good success and two more models were released in 1970. Seeing the potential in this relatively new technology, a few more automobile manufactures build their own sport car prototypes including Mercedes-Benz and General Motors. The second had a prototype of the legendary Corvette. As every invention, this one also has disadvantage – fuel efficiency. Hit by the first oil crisis in 1973, all manufactures except Mazda canceled their plans for a production Wankel powered car. Even more Mazda almost bankrupted, since they completely had abandoned reciprocating (piston) engines. Today Mazda is the only one to mass produce Wankel engine cars, and it has made huge, but slow progress in this field. The last generation named RX-8 had achieved better output with lower fuel consumption – huge step forward from the previous RX-7.

Average GRE Scores for Top Private Universities

Average GRE Scores for Top Private Universities Most graduate schools have done away with publishing the average GRE scores for their incoming graduate students online and in promotional literature. They dont want hopeful attendees to get the wrong idea that if their scores arent the same as what other students have achieved, then they should not even bother to apply. However, some graduate schools are willing to post average  ranges  of scores for incoming grad students, although most of those scores are arranged by intended major rather than by the schools statistics as a whole. Keep reading to see the average GRE scores as listed for top private universities for a couple of very popular majors (engineering and education) as published by the U.S. News and World Report.   GRE Scores Information If you are perplexed as you run through these scores because you expected to see numbers in the 700s, then you are probably still using the old GRE score system which ended in 2011. As of August 2011, average GRE scores can run anywhere between 130 - 170 in 1-point increments. The old system more people are familiar with, assessed students on a scale from 200 - 800 in 10-point increments. If you took the GRE using the old system and are curious about what your approximate GRE score would be with the new scale, then check out the two concordance tables listed below. Please note, however, that GRE scores are only valid for five years, so July 2016 was the last time students with GRE scores in the prior format were able to use them for admissions into graduate school.   GRE Verbal Concordance TableGRE Quantitative Concordance Table    Massachusetts Institute of Technology (MIT) Engineering:   Quantitative: 167 Stanford University Engineering:   Quantitative: 167 Education Quantitative: 162Verbal: 164 Harvard University Engineering:   Quantitative: 167 Education Quantitative: 161Verbal: 165 California Institute of Technology (CalTech) Engineering:   Quantitative: 168 Duke University Engineering:   Quantitative: 164 University of Chicago Engineering:   Quantitative: NA Northwestern University Engineering:   Quantitative: NA Education Quantitative: 158Verbal: 163 University of Pennsylvania Engineering:   Quantitative: NA Education Quantitative: 159Verbal: 161 Johns Hopkins University Engineering:   Quantitative: 164 Education Quantitative: 161Verbal: 163 Rice University Engineering:   Quantitative: 166 New York University Engineering:   Quantitative: NA Education Quantitative: 154Verbal: 159 University of Notre Dame Engineering:   Quantitative: 160 Vanderbilt University Engineering:   Quantitative: 167 Education Quantitative: 159Verbal: 164 Are My GRE Scores Going To Get Me In? There are quite a few factors that go into your acceptance into one of these top private universities, so dont stress out just yet. Although your GRE scores  are  important, they are not the only things considered by admissions counselors, as Im sure youve heard before. Make sure your application essay is top-notch and that you have secured great recommendations from those professors who knew you best in undergrad. And if you havent worked on bumping up your GPA already, then now is the time to ensure youre getting the best grades you possibly can in case your GRE score isnt exactly what you wanted it to be.