Jun 18, 2011

Aeronautical engineering since 1903 until nowadays

Aeronautical engineering since 1903 until nowadays
William H. Pickering, James A. van Allen, and Wernher von Braun, the engineers behind the Explorer 1, show off a model of the satellite in January, 1958, shortly before it was launched into space. (NASA) 
In the first century of crewed flight, this began in December, 1903; the application of the new science of aerodynamics was translated into flying machines by people who understood engineering and problem solving. The industry that grew from this small beginning made amazing strides in the first century of air travel. It is an industry built around visionary engineers and pilots.
Aeronautical engineering had its true beginning before Orville and Wilbur Wright but the two brothers were the pioneers in the techniques, processes, and system testing that were at the heart of the engineering design and development of aircraft and spacecraft.
The conceptualization of an aircraft begins with the identification of something useful to be accomplished by an air machine. The process begins with sketches of an air vehicle to fulfill the performance expectations for the aircraft. In the first two decades of aircraft design and operations, many concepts were proposed, but by the end of World War I, the basics of successful aircraft design were established. Future refinements would come through better tools, materials, and concepts.

At the beginning of the second century of crewed flight, the process involves digitally created drawings that are sent to machines that make the basic parts, which are then assembled, tested, and prepared for flight test.
Twentieth century aircraft engineering refinements moved at a speed unseen in any previous period of the industrial world. The motivation and excitement of flying higher, faster, and with larger payloads seemed to drive innovation and to demand engineering solutions.
By the end of World War II, the aviation industry was fully established as a significant contributor to the economic and military strength of the United States. European aerospace also produced leaders in this field. Companies were built on the talents of engineers and the skills of craftsman. Engineering disciplines expanded, and in the late 1950’s, aeronautical engineering became aerospace engineering.
In most aircraft manufacturing firms, the engineering department was second in size only to the production groups.

Typically, in the middle of the twentieth century, modern aerospace companies spread their products between commercial enterprises and government contracts. The bread and butter contracts came from the federal government until the end of the Cold War. Commercial applications of engineering ideas were spun off from aircraft and missiles that had been developed for the military. However, by 1990, the industry was in decline.
Following the Gulf War in 1991, the downsizing of the air arms of the military accelerated

The demand for large numbers of new and different military aircraft came under such scrutiny that few of the new programs survived. On the commercial side of the industry, the engineering of new and better transports and aircraft destined for the air carrier markets stopped in favor of building on existing concepts to build bigger aircraft with bigger engines.
Airspeed, comfort, and passenger loading ceased to be major requirements and took a back seat to economically viable air transport.

Research and Development:
There are three significant eras in the expansion of the aerospace industry. These coincide with technology improvements as well as political changes that affected the industry.
The first period started with the Wright brothers’ successful efforts at powered flight and ended with the advent of the jet engine. The next period began when jet engines were being put into all new aircraft designs, and this period saw rapid advances in aircraft performance.
The last period began with the introduction of digital computer controls for the aircraft. This development made it possible to design and build incredibly safe and reliable aerospace systems.
Out of World War II came large bombers and cargo aircraft.
When jet engines were added to these aircraft they held promise for faster and higher, hence more efficient and comfortable, air transportation for the public. The first such jet transport built for the British Overseas Airway Corporation (BOAC, which became British Airways) was the Comet. However, the understanding of structural issues arising from rapid changes in pressure on certain parts of the aircraft, along with manufacturing techniques from the 1940’s, resulted in an unsafe aircraft. After two exploded in flight due to structural failure and one burst during ground pressure testing, the world of aeronautical engineering became aware of fatigue failures and the need to design fail-safe structures.

At the time, the U.S. Air Force had Boeing designing and building a jet tanker using technology similar to that applied to its highly successful swept-wing B-47 jet bomber program.
What came out of that work was the most successful aircraft transport design in history. The Boeing 707 model was the forerunner of all of today’s large jet transports.

The Industry:
After World War II, the growth in the aviation industry, both commercial and military, saw a proliferation of new prime contractors who were building and selling aircraft.
A prime contractor was defined as the company that was responsible for the concept, design, development, and final introduction of the new aircraft into operational use. In short, a prime contractor was responsible for all aspects of the life cycle of the aircraft. The prime would have subcontractors, perhaps hundreds, with which it did business.
At the start of the 1970’s, and at the height of the Vietnam War, there were many primes in the aerospace business.
The biggest and most successful were Boeing Aircraft, Douglas Aircraft, McDonnell Aircraft, Lockheed Aircraft, Republic Aircraft, General Dynamics, Grumman Aircraft, North American Aviation (North American Rockwell), Northrop Aviation, LTV Aerospace (part of LTV, which used to be Chance Vought), Northrop Aircraft, Bell Airplane and Bell Helicopter, Sikorsky Helicopter, and a handful of general aviation companies, including Cessna, Beech, Piper, and others. At the end of the twentieth century there were only three major aerospace companies left, with all others being absorbed into the remaining companies or having gone out of business. Boeing took over McDonnell Douglas, which used to be McDonnell Aircraft and Douglas Aircraft. Lockheed Martin absorbed General Dynamics Aircraft Division and Martin Marietta.
Northrop and Grumman joined, adding pieces of LTV and others. In addition, Raytheon Corporation, which was a small missiles and electronics outfit in the 1960’s, took over Beech Aircraft and other subsidiary companies.
Cessna and Piper nearly went out of business during the 1970’s and 1980’s, due to changes in liability laws. Chance Vought became Ling TemcoVought in the mid-1960’s and changed its name to LTV Corporation in the 1970’s. It was one of the first prime contractors that attempted product diversification, with markets in steel, appliances, missiles and aircraft; the corporation went bankrupt in 1986.

Future Developments:
Compared to the days of the Wright Flyer and the Curtiss JN-4, aircraft which were very difficult to control and which carried very small payloads, the F-22 automated advanced fighter and the Boeing 777 automated, large twin engine transport are engineering marvels.
At the beginning of the twenty-first century, there are several different paths that may provide the next major step forward in aeronautical engineering.
In June, 1963, President John F. Kennedy, speaking at the commencement of the fifth class to graduate from the United States Air Force Academy, announced that the federal government would seek to develop the world’s first supersonic passenger transport (SST). This never happened, for two reasons. The first was the economic issue.
Such an aircraft, designed using late 1950’s and early 1960’s technology, would be very expensive. Airlines could not justify the costs to operate them. The second issue was environmental.
Warnings and concerns about the pollution or damage to the upper atmosphere from turbojet engines and problems with sonic booms, which are caused by the shock waves from a supersonic aircraft, led to a premature end of the SST. Europe, in a cooperative move between British and French aircraft firms, did pursue a smaller version of the SST, called the Concorde. It operated successfully starting in January, 1976, although it was under a limitation forbidding it from flying supersonically over the United States. Technology improved during the twenty two years the Concorde was operating, and by the late 1990’s, the National Aeronautics and Space Administration (NASA) attempted to resurrect the SST concept. By then, the problems of jet exhaust and its impact upon the upper atmosphere had been nearly resolved.
Ways to reduce the pressure from the sonic booms were being planned.
The program ended in 1999 when, for the second time, the economic issues surrounding operational costs of a large SST overrode advances in the aerospace engineering field.
The next hope for large transport aircraft lies in engineering a craft that will cruise just under Mach 1. Most large aircraft can cruise efficiently at Mach .75 to .9 (the percent of the speed of sound) but if they could fly efficiently at 95 percent of the speed of sound this would mean a 5 to 20 percent increase in true airspeed (35 to 155 miles per hour).
A speed increase of that magnitude would shorten the flight time from New York to Paris by approximately an hour and fifteen minutes. The potential savings in fuel, the increase in the number of aircraft that could fly the same route, and other factors make this an appealing possibility. It is not an easy engineering task, but then, most of the history of aviation has faced such challenging engineering tasks.
The ultimate flight would be one that takes the passenger into low-Earth orbit and flies across both continents and oceans. That aircraft will probably come about once the space program has fully established the safety and reliability of such travel. Aeronautical engineering and the companies that have come to the forefront in both engineering and applied sciences for aerospace purposes will be able to achieve these ideas.

0 التعليقات:

Post a Comment