Editing Wright brothers (section)

===Adding power===
In addition to developing the lift equation, the brothers also developed the equation for drag. It is of the same form as the lift equation, except the [[coefficient of drag]] replaces the [[lift coefficient|coefficient of lift]], computing drag instead of lift. They used this equation to answer the question, "Is there enough power in the engine to produce a [[thrust]] adequate to overcome the drag of the total frame&nbsp;...," in the words of Combs. The Wrights then "...&nbsp;measured the pull in pounds on various parts of their aircraft, including the pull on each of the wings of the biplane in level position in known wind velocities ... They also devised a formula for [[power-to-weight ratio]] and propeller efficiency that would answer whether or not they could supply to the propellers the power necessary to deliver the thrust to maintain flight ... they even computed the thrust of their propellers to within 1&nbsp;percent of the thrust actually delivered&nbsp;..."<ref name=hc/>{{rp|181–186,367–375}}

[[File:Wright brothers engine 17.jpg|thumb|upright|A Wright engine, serial number&nbsp;17, {{circa|1910}}, on display at the [[New England Air Museum]]]]
In 1903 the brothers built the powered ''[[Wright Flyer]]'', using their preferred material for construction, [[spruce]],<ref>{{cite web|url=http://www.nasm.si.edu/exhibitions/gal100/wright1903.html|title=Exhibitions|date=April 28, 2016|access-date=November 7, 2011|archive-date=December 25, 2018|archive-url=https://web.archive.org/web/20181225123954/https://airandspace.si.edu/exhibitions|url-status=dead}}</ref> a strong and lightweight wood, and Pride of the West [[muslin]] for surface coverings. They also designed and carved their own wooden propellers, and had a purpose-built gasoline engine fabricated in their bicycle shop. They thought propeller design would be a simple matter and intended to adapt data from shipbuilding. However, their library research disclosed no established formulae for either marine or air propellers, and they found themselves with no sure starting point. They discussed and argued the question, sometimes heatedly, until they concluded that an aeronautical propeller is essentially a wing rotating in the vertical plane.<ref name=Crouch-1989/>{{rp|pages=242–243}} On that basis, they used data from more wind tunnel tests to design their propellers. The finished blades were just over eight feet long, made of three laminations of glued spruce. The Wrights decided on twin "[[Pusher configuration|pusher]]" propellers (counter-rotating to cancel torque), which would act on a greater quantity of air than a single relatively slow propeller and not disturb airflow over the leading edge of the wings.

Wilbur made a March 1903 entry in his notebook indicating the prototype propeller was 66% efficient. Modern wind tunnel tests on reproduction 1903 propellers show they were more than 75% efficient under the conditions of the first flights, "a remarkable feat", and actually had a peak efficiency of 82%.<ref>
{{cite magazine
 | last1 = Ash      | first1 = Robert L.
 | last2 = Britcher | first2 = Colin P.
 | last3 = Hyde     | first3 = Kenneth W.
 | date  = December 2003
 | title = 100&nbsp;years of flight
 | at = supplement, Prop-Wrights
 | magazine = Mechanical Engineering
 |url=http://www.memagazine.org/supparch/flight03/propwr/propwr.html
 |url-status=dead
 |archive-url=https://web.archive.org/web/20040705082042/http://www.memagazine.org/supparch/flight03/propwr/propwr.html
 |archive-date=July 5, 2004 }}
</ref> The Wrights wrote to several engine manufacturers, but none could meet their need for a sufficiently light-weight powerplant. They turned to their shop mechanic, [[Charlie Taylor (mechanic)|Charlie Taylor]], who built an engine in just six weeks in close consultation with the brothers.<ref name=Crouch-1989/>{{rp|page=245}}

[[File:Wright First Flight 1903Dec17 (full restore 115).jpg|thumb|left|250px|The first flight of the ''[[Wright Flyer]]'', December 17, 1903, Orville piloting, Wilbur running at wingtip]]
To keep the weight down the [[engine block]] was cast from aluminum, a rare practice at the time. The Wright/Taylor engine had a primitive version of a [[carburetor]], and had no [[fuel pump]]. Gasoline was [[gravitation|gravity]]-fed from the fuel tank mounted on a wing strut into a chamber next to the cylinders where it was mixed with air: The [[fuel-air ratio|fuel-air mixture]] was then vaporized by heat from the crankcase, forcing it into the cylinders.<ref>{{cite web |series=Inventing a Flying Machine |title=Engine |publisher=[[The Smithsonian Institution]] |url=https://airandspace.si.edu/exhibitions/wright-brothers/online/fly/1903/engine.cfm |access-date=March 7, 2014 |archive-date=April 8, 2014 |archive-url=https://web.archive.org/web/20140408224406/https://airandspace.si.edu/exhibitions/wright-brothers/online/fly/1903/engine.cfm |url-status=dead }}</ref>

The propeller [[roller chain|drive chains]], resembling those of bicycles, were supplied by a manufacturer of heavy-duty automobile chains.<ref>Howard 1988, pp. 108–109.</ref> The ''Flyer'' cost less than a thousand dollars, in contrast to more than $50,000 in government funds given to [[Samuel Pierpont Langley|Samuel Langley]] for his man-carrying [[Langley Aerodrome|Great Aerodrome]].<ref>Tobin 2004, p. 192.</ref> In 1903 $1,000 was {{Inflation|US|1000|1903|r=-3|fmt=eq}}. The ''Wright Flyer'' had a wingspan of {{convert|40.3|ft|m|abbr=on}}, weighed {{convert|605|lb|kg|abbr=on}},<ref>{{cite web |title=''Wright Flyer&nbsp;I'' |website=Wright-Brothers.org |url=http://www.wright-brothers.org/Information_Desk/Just_the_Facts/Airplanes/Flyer_I.htm |access-date=January 31, 2013}}</ref> and had a {{convert|12|hp|kW}}, {{convert|180|lb|kg|abbr=on}} engine.<ref>Tobin 2004, p. 159.</ref>

On June 24, 1903, Wilbur made a second presentation in Chicago to the Western Society of Engineers. He gave details about their 1902 experiments and glider flights, but avoided any mention of their plans for powered flight.<ref name=hc/>{{rp|186–187}}