The Wright brothers identified weight and balance as the basic factors of successful flight. It proved of huge importance later, discovering that the pilots prone position is unsuitable and so it would be better to fly in horizontal position, where the pilot would lie down. (Hallion, 2003, p.187) These discoveries disproved the false findings of Leonardo Da Vinci, Langley and others. As a result of this finding, it was easier for pilots to fly and control an aircraft, also distributing the weight alongside.

Compared to Leonardo Da Vinci’s idea of ‘Ornithopher’, ( some of the aviators followed this false idea until the late 19th century), the brothers used fixed wings on their aircraft and proved that era of flapping wings as an instrument of flying is over.
The wings were later improved, applying findings from a study of aerodynamics. This changed the understanding of wings and made further development possible.
Based on studies of Cayley, Lilienthal and Chanute, the brothers concluded that aerodynamic control rather than weight-shift, was the correct way to control flying machines. (Dale, 1992, p.59)
Because they have been the first aviators to understand and use aerodynamics in practice, by testing different shapes of aerofoil in the wind tunnel in 1901, they developed very unique and perfectly shaped wing (also duck shaped aircraft) giving the ability to lift the aircraft and control it in the air.
According to NASA information, they recognized importance of ratio. Using aspect ratio (the ratio of length of the wing linked to the width) by increasing the length and decreasing the width of the wing, they cut the drag experience by half. The brothers made it clear that the most important aspect needed for successful flight was one of the control.

Another very important technical impact in the aircraft development is that of Wilbur´s propeller. According to Hallion (2003), Wilbur Wright was the first person to recognise that a propeller is nothing more than a twisted wing, where the "lift" force is pointing forward for propulsion (Taking Flight, p.185).

To add justification to the arguments that the Wright brothers were the first votaries in aviation industry, they established an aircraft business which survived both World Wars. Wilbur Wright set the basis for the first aviation school in Pao.
Their successful flights (a couple of years after the first flight) were able to remain in the air for nearly three hours. This particular flight performed by Wilmour Wright on 31st December 1908 took 2 hours and 20 minutes in Auvours, France and made the world endurance record.
Additional versions of Flyer (Flier III.) were manufactured under license in Germany and France and for certain period affected constructors in Britain, France, Germany, Austria and other countries.

The first ‘heavier-than-air’ engine powered aircraft flight, antiquated quite fast and the huge expansion of aircraft development could not be stopped. The Wright brothers gave the world enormous inspiration and findings which without a doubt helped in further fast development. For example: aircraft expansion during the both World Wars, the development of trade and connecting the world in an unbelievable pace. Nothing changed leading position of the Wright brothers in development of civil aviation. Perhaps the best example comes from some quotes by well-known public figures who acknowledge the impact the Wright brothers made on the development of civil aviation.

Bill Gates, CEO of Microsoft Corporations stated: “The Wright Brothers created the single greatest cultural force since the invention of writing. The airplane became the first World Wide Web, bringing people, languages, ideas, and values together.”

When acknowledged the 17th of December as a national day of Wright brothers in United States, The President of the United States George W. Bush (2002) stated: “During more than 100 years from that historic moment since that revolutionary event, mankind has flown across oceans, broken the sound barrier, launched satellites, and landed on the moon. On Wright Brothers Day, we celebrate the vision and determination of these innovators whose remarkable achievements changed the world forever. Through their courage and willingness to take risks, the Wright brothers reflect the true American character.”

National Aviation Day is celebrated on 19th August – on the birthday of Orville Wright.

Conclusions

The main part of this report gives extensive description about why the Wright brothers had the biggest impact on the development of civil aviation. These are the conclusions I have come to:

In comparison with all the previous attempts to fly, the Wright brothers were the first to fly the ´heavier-than-air´ aircraft. They achieved it by bringing together all the components of today’s modern aircraft. They could control the aircraft (take-off, keep it in the air and land with it). Because they invented a light weighted engine (which worked on two slow running propellers driven by chain gear) it finished the use of heavy steam engines and invented an aircraft that could fly.
They had the biggest impact on development of the aircraft engines by recognizing the fact that using the propellers as a part of engine would lift it up easier.
They proved the findings of Leonardo Da Vinci and his followers to be false by using fixed and specially curved wings. This way they proved that if the weight is distributed alongside the aircraft, the machine will be controllable in the air.
Using aerodynamics findings in the correct way and improving them by their own research in this field brought them to understanding the flying machine as an entirety and led them to achieve a successfully flight.
Because all of their findings and inventions succeeded and were used from this time on until today, that the main reason why the Wright brothers had the biggest impact on development of civil aviation.