# Engineering

March 31, 2017/ Free Online/ 0 comments

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A successful engineering design must follow its own process. There are 5 steps in the engineering design process, the first step is ???Needs assessment???, second is ???Problem formulation???, the third named ???Abstraction and synthesis???, the fourth called ???Analysis??? and the last is ???Implementation???. In this reaction, I will show you why the Wright Brother can design the Manned Flignt successfully.

In 1900, the Wrights designed and constructed a 52-pound glider with a wing-span of 17.5 feet and a camber of only 1/23(recall that lift is essentially proportional to camber), this is the first Needs assessment. They flew this first glider as a kite, and then, they used some equation and various data and knew that the amount of lift that would be applied to their gilder. According to these calulations, the glider should have been able to lift 192 pounds in a 25-mile-per-hour airstream with a 3?°angle of attack ?. That is the second part of the engineering design: Problem formulation. This step tell us that we need to consider a problem as a formulation, though the formulation and many kinds of data, we can improve our design. So the Wright brothers figured out from the formular that they must control pitch, roll and yaw.

The third part is ???Abstraction and synthesis???, is tells us that we should have the ability which can solve the problem from other part of the design. For example, the Wright recognized that a human pilot would need to control a heavier-than-air craft about all three axes of rotation: roll, pitch, and yaw. So the Wright brothers installed a flat horizontal surface on the front of their glider to act as an elevator. By properly raising or lowering this elevator, the pilot could control rotation about the pitch axis rather than simply allowing the angle of angle of attack to be determined by the relative movement of the CL. Next, the Wrights discovered a way to control rotation about the roll axis. Rather than simplyshifting their bodies to maintain balance about this axis, the Wrights began to use wings that could be warped or twisted to varying degrees by the pilot through a system of pulleys and cables. Such warping allowed one to adjust the relative angles of attack of each wing and thus the corresponding lift forces applied to these wings. But ufortunately, successful roration about the roll axis can lead to a corresponding roration about the yaw axis and a hazardous phenomenon known as siderslipping, a danger that soon became apparent to the Wrights during their next series of flights in 1901.

The third step named Analysis. In this step, we must have the ability in analyzing, it means when we face a big difficulty, we cannot give up just because it is too difficult. Everything has its solution, so what we need to do when we face a difficulty is analyze. All possible alternative solutions have to be analyzed to determine their potential. At this point the engineer will again condense the possible solutions. Using mathematical and key engineering principles, the engineer analyzes the potential performance of the solution to determine if the solution is physically possible. During this analyzing process engineers review the laws of nature and determine whether the product is economically practical by using common sense. Let me give you an example, Wilbur and Orville returned to the Kitty Hawk region in 1901 bearing a new glider, one with a wingspan of 22 feet and a camber ratio of 1:12, Even with the expanded wingspan and camber, the amount of lift generated was still inadequate. The Wrights had to find the reason or abandon their great adventure. They flew each wing of the glider separately as a kite in order to carefully observe and evaluate its behavior. Wilbur noticed that in winds of high velocity, the wing was pushed downward because the CL moved behind the center of gravity and toward the trailing edge of the wing. This reversal at high speeds of the CL??™s generally forward movement was totally unexpected. To counteract this effect, the Wrights decreased the camber to 1:19. The lift did indeed increase with this change, but it continued to remain below expected values. Disappointed but undererred, Wilbur and Orville decided that Lilienthal??™s data would need to be verified by experiment.

Finally, the first glider was completed though the Wright brother??™s hard working. A few years later, the Wrights designed 2 glider as well, and in 1903 the first flyer of humanity was made finally, their dream was came true at last.