Editing Wright brothers (section)

==Flights==
===Toward flight===
[[File:Park Ranker Wright Brothers Memorial.JPG|thumb|Park Ranger Tom White demonstrates a replica of the Wright brothers' 1899 box kite at the [[Wright Brothers National Memorial]].]]
On July 27, 1899, the brothers put [[wing warping]] to the test by building and flying a biplane kite with a {{convert|5|ft|m|adj=on}} wingspan, and a curved wing with a {{convert|1|ft|m|adj=on}} [[chord (aeronautics)|chord]]. When the wings were warped, or twisted, the trailing edge that was warped down produced more lift than the opposite wing, causing a rolling motion. The warping was controlled by four lines between kite and crossed sticks held by the kite flyer.  In return, the kite was under lateral control.<ref name="hc">{{cite book |last1=Combs |first1=Harry |title=Kill Devil Hill: Discovering the Secret of the Wright Brothers |date=1979 |publisher=TernStyle Press, Ltd. |location=Englewood |isbn=0940053020 |pages=68–71}}</ref>

In 1900 the brothers went to [[Kitty Hawk, North Carolina|Kitty Hawk]], North Carolina, to begin their manned gliding experiments. In his reply to Wilbur's first letter, Octave Chanute had suggested the mid-Atlantic coast for its regular breezes and soft sandy landing surface. Wilbur also requested and examined U.S. [[National Weather Service|Weather Bureau]] data, and decided on Kitty Hawk<ref>{{cite web|url= https://babel.hathitrust.org/cgi/ssd?id=mdp.39015003322461;seq=87;num=23 |title=The papers of Wilbur and Orville Wright, including the Chanute-Wright letters and other papers of Octave Chanute. Marvin W. McFarland, editor., v.1. – Text-only – Full View |date=September 13, 1900|publisher=McGraw-Hill / HathiTrust Digital Library|access-date= March 19, 2017|quote=I chose Kitty Hawk because it seemed the place which most closely met the re-quired conditions. In order to obtain sup-port from the air it is necessary, with wings of reasonable size, to move through it at the rate of fifteen or twenty miles per hour. ... If the wind blows with proper speed, support can be obtained without movement with reference to the ground. It is safer to practice in a wind, provided this is not too much broken up into eddies and sudden gusts by hills, trees, &c.}}</ref><ref>{{citation |title=The papers of Wilbur and Orville Wright, including the Chanute-Wright letters and other papers of Octave Chanute. (Book view) |page=23 |date=September 13, 1900|publisher=McGraw-Hill |hdl = 2027/mdp.39015003322461}}</ref> after receiving information from the government meteorologist stationed there.<ref name="WDL"/><ref>{{cite web|url= https://www.loc.gov/collections/wilbur-and-orville-wright-papers/articles-and-essays/collection-highlights/kitty-hawk/ |title=Letter from J. J. Dosher, Weather Bureau, to Wilbur Wright, August 16, 1900 Kitty Hawk |publisher=[[Library of Congress]] – Wilbur and Orville Wright Papers|access-date=March 19, 2017}}</ref>

Kitty Hawk, although remote, was closer to Dayton than other places Chanute had suggested, including California and Florida. The spot also gave them privacy from reporters, who had turned the 1896 Chanute experiments at Lake Michigan into something of a circus. Chanute visited them in camp each season from 1901 to 1903 and saw gliding experiments, but not the powered flights.

===Gliders===
{{Main|Wright Glider}}
[[File:Chanute-Herring 1896 hang glider.jpg|thumb|Chanute's hang glider of 1896. The pilot may be [[Augustus Moore Herring|Augustus Herring.]]]]
The {{Not a typo|Wrights based}} the design of their kite and full-size gliders on work done in the 1890s by other aviation pioneers. They adopted the basic design of the Chanute-Herring biplane hang glider ("double-decker" as the Wrights called it), which flew well in the 1896 experiments near Chicago, and used aeronautical data on [[lift (force)|lift]] that [[Otto Lilienthal]] had published. The Wrights designed the wings with [[camber (aerodynamics)|camber]], a curvature of the top surface.

The brothers did not discover this principle, but took advantage of it. The better lift of a cambered surface compared to a flat one was first discussed scientifically by [[George Cayley|Sir George Cayley]]. Lilienthal, whose work the Wrights carefully studied, used cambered wings in his gliders, proving in flight the advantage over flat surfaces.
The wooden uprights between the wings of the Wright glider were braced by wires in their own version of Chanute's modified [[Pratt truss]], a bridge-building design he used for his biplane glider (initially built as a triplane). The Wrights mounted the horizontal [[elevator (aircraft)|elevator]] in front of the wings rather than behind, apparently believing this feature would help to avoid, or protect them from, a nosedive and crash like the one that killed Lilienthal.<ref name=Jakab-1997/>{{rp|page=73}} Wilbur incorrectly believed a tail was not necessary,<ref>{{cite web |last=Wright |first=Wilbur |date=September 18, 1901 |title=Some aeronautical experiments |publisher=Western Society of Engineers |via=MS State U. Libraries |url=http://invention.psychology.msstate.edu/inventors/i/Wrights/library/Aeronautical.html |access-date=July 14, 2010}}</ref> and their first two gliders did not have one.

According to some Wright biographers, Wilbur probably did all the gliding until 1902, perhaps to exercise his authority as older brother and to protect Orville from harm as he did not want to have to explain to their father, Bishop Wright, if Orville got injured.<ref>Howard 1988, p. 52.</ref><ref name=Crouch-2003/>{{rp|page=198}}
{| class="wikitable"
|+ Glider vital statistics<ref>{{Cite web|title=Just the Facts|url=https://www.wright-brothers.org/Information_Desk/Just_the_Facts/Just_the_Facts_Intro/Just_the_Facts_Intro.htm|access-date=2023-02-12|website=Wright Brothers Aeroplane Company|author1= Joe McDaniel| display-authors=etal }}</ref>
! !! Wingspan!!Wing area!! Chord !! Camber !!Aspect ratio!!Length  !!Weight
|-
| '''1900''' ||{{convert|17|ft|6|in|m|abbr=on}}|| {{convert|165|sqft|m2|0|abbr=on}}  || {{convert|5|ft|m|0|abbr=on}} ||1/20|| 3.5:1
 ||{{convert|11|ft|6|in|m|abbr=on}}||{{convert|52|lb|kg|abbr=on}}
|-
|'''1901'''|| {{convert|22|ft|m|0|abbr=on}} ||{{convert|290|sqft|m2|0|abbr=on}} ||{{convert|7|ft|m|abbr=on}}||1/12*,1/19||3:1||{{convert|14|ft|m|abbr=on}} ||{{convert|98|lb|kg|abbr=on}}
|-
|'''1902'''||{{convert|32|ft|1|in|m|abbr=on}}||{{convert|305|sqft|m2|0|abbr=on}}||{{convert|5|ft|m|abbr=on}}||1/20–1/24||6.5:1||{{convert|17|ft|m|abbr=on}} ||{{convert|112|lb|kg|abbr=on}}
|}
<nowiki>* (This airfoil caused severe stability problems; the Wrights modified the camber on-site.)</nowiki>

====1900====
[[File:WrightBrothers1900Glider.jpg|thumb|The 1900 glider. No photo was taken with a pilot aboard.]]
The brothers flew the glider for only a few days in the early autumn of 1900 at Kitty Hawk. In the first tests, probably on October 3, Wilbur was aboard while the glider flew as a kite not far above the ground with men below holding tether ropes.<ref name=Crouch-2003/>{{rp|pages=188–189}} Most of the kite tests were unpiloted, with sandbags or chains and even a local boy as ballast.<ref>{{cite web |url=http://www.wright-brothers.org/History_Wing/History_of_the_Airplane/Century_Before/Road_to_Kitty_Hawk/Road_to_Kitty_Hawk.htm |title=The road to Kitty Hawk |website=wright-brothers.org |access-date=January 12, 2016}}, "The Wrights send 10-year-old Tom Tate, William's nephew up on the glider as they fly it like a kite."</ref>

They tested wing-warping using control ropes from the ground. The glider was also tested unmanned while suspended from a small homemade tower. Wilbur, but not Orville, made about a dozen free glides on only a single day, October 20. For those tests the brothers trekked four miles (6{{nbsp}}km) south to the [[Kill Devil Hills]], a group of sand dunes up to {{convert|100|ft|m|-1}} high (where they made camp in each of the next three years). Although the glider's lift was less than expected, the brothers were encouraged because the craft's front elevator worked well and they had no accidents. However, the small number of free glides meant they were not able to give wing-warping a true test.

The pilot lay flat on the lower wing, as planned, to reduce aerodynamic drag. As a glide ended, the pilot was supposed to lower himself to a vertical position through an opening in the wing and land on his feet with his arms wrapped over the framework. Within a few glides, however, they discovered the pilot could remain prone on the wing, headfirst, without undue danger when landing. They made all their flights in that position for the next five years.

====1901====
{{multiple image
| align = right
| direction = vertical
| width =
| image1 = Wright1901GliderBottom.jpg
| width1 = 230
| caption1 = Orville with the [[1901 Wright Glider|1901 glider]], its nose pointed skyward; it had no tail.
| image2 = Wright 1901 glider landing.jpg
| width2 = 230
| caption2 = Wilbur just after landing the 1901 glider. Glider skid marks are visible behind it, and marks from a previous landing are seen in front; Kill Devil Hills, North Carolina.
}}
Before returning to Kitty Hawk in the summer of 1901, Wilbur published two articles, "The Angle of Incidence" in ''The Aeronautical Journal'', and "The Horizontal Position During Gliding Flight" in ''Illustrierte Aeronautische Mitteilungen''.  The brothers brought all of the material they thought was needed to be self-sufficient at Kitty Hawk.  Besides living in tents once again, they built a combination workshop and hangar.  Measuring {{convert|25|ft|m}} long by {{convert|16|ft|m}} wide, the ends opened upward for easy glider access.<ref name=hc/>{{rp|129–130}}

Hoping to improve lift, they built the 1901 glider with a much larger wing area and made dozens of flights in July and August for distances of {{convert|50|to|400|ft|m|abbr=on}}.<ref>{{Cite web|title=1901 Wright Glider|url=https://www.wright-brothers.org/Information_Desk/Just_the_Facts/Kites_&_Gliders/1901_Glider.htm|access-date=2023-02-12|website=Wright Brothers Aeroplane Company| author1 =Joe McDaniel }}</ref> The glider stalled a few times, but the parachute effect of the forward elevator allowed Wilbur to make a safe flat landing, instead of a nose-dive. These incidents wedded the Wrights even more strongly to the ''[[Canard (aeronautics)|canard]]'' design, which they did not give up until 1910. The glider, however, delivered two major disappointments. It produced only about one-third the lift calculated and sometimes pointed opposite the intended direction of a turn – a problem later known as [[adverse yaw]] – when Wilbur used the wing-warping control. On the trip home a deeply dejected Wilbur remarked to Orville that man would not fly in a thousand years.<ref>Kelly 2002, p. 42</ref>

The poor lift of the gliders led the Wrights to question the accuracy of Lilienthal's data, as well as the "[[John Smeaton|Smeaton]] coefficient" of air pressure, a value which had been in use for over 100 years and was part of the accepted equation for lift.
::{|  class="wikitable"
|+ The lift equation
|<math>L = k\;S\;V^2\;C_L</math>
L = lift in pounds<br />
k = coefficient of air pressure (Smeaton coefficient)<br />
S = total area of lifting surface in square feet<br />
V = velocity (headwind plus ground speed) in miles per hour<br />
C<sub>L</sub> = coefficient of lift (varies with wing shape)
|}
The Wrights used this equation to calculate the amount of lift that a wing would produce. Over the years a wide variety of values had been measured for the Smeaton coefficient; Chanute identified up to 50 of them. Wilbur knew that Langley, for example, had used a lower number than the traditional one. Intent on confirming the correct Smeaton value, Wilbur performed his own calculations using measurements collected during kite and free flights of the 1901 glider. His results correctly showed that the coefficient was very close to 0.0033 (similar to the number Langley used), not the traditional 0.0054, which would significantly exaggerate predicted lift.<ref name=Crouch-1989/>{{rp|pages=220–221}}
[[File:WB Wind Tunnel.jpg|thumb|Replica of the Wright brothers' [[wind tunnel]] at the Virginia Air and Space Center]]
The brothers decided to find out if Lilienthal's data for lift coefficients were correct. They devised an experimental apparatus which consisted of a freely rotating bicycle wheel mounted horizontally in front of the handlebars of a bicycle. The brothers took turns pedaling the bicycle vigorously, creating air flow over the horizontal wheel. Attached vertically to the wheel were an airfoil and a flat plate mounted 90° away. As air passed by the airfoil, the lift it generated, if unopposed, would cause the wheel to rotate.

The flat plate was oriented so its drag would push the wheel in the opposite direction of the airfoil. The airfoil and flat plate were made in specific sizes such that, according to Lilienthal's measurements, the lift generated by the airfoil would exactly counterbalance the drag generated by the flat plate and the wheel would not turn. However, when the brothers tested the device, the wheel ''did'' turn. The experiment confirmed their suspicion that either the standard Smeaton coefficient or Lilienthal's coefficients of lift and drag – or all of them – were in error.<ref name="KittyHawkBox">
{{cite web |url=http://www.wright-brothers.org/History_Wing/Wright_Story/Inventing_the_Airplane/Kitty_Hawk_in_a_Box/Kitty_Hawk_in_a_Box.htm |title=Kitty Hawk in a box |series=Wright Brothers Aeroplane Company |website=wright-brothers.org |access-date=April 11, 2014}}</ref><ref name=Crouch-1989/>{{rp|pages=221–222}}

They then built a six-foot (1.8&nbsp;m) wind tunnel in their shop, and between October and December&nbsp;1901 conducted systematic tests on dozens of miniature wings.<ref name=Dodson>{{Cite web
| publisher= US Naval Academy 
|title=An Historical and Applied Aerodynamic Study of the Wright Brothers' Wind Tunnel Test Program and Application to Successful Manned Flight
| last=Dodson| type = technical report
|first=M.G.|url=http://archive.rubicon-foundation.org/3585|access-date=2023-02-12|archive-date=September 5, 2011|archive-url=https://web.archive.org/web/20110905162319/http://archive.rubicon-foundation.org/3585|url-status=usurped
| year=2005}}</ref> The "balances" they devised and mounted inside the tunnel to hold the wings looked crude, made of bicycle spokes and scrap metal, but were "as critical to the ultimate success of the Wright brothers as were the gliders."<ref name=Crouch-1989/>{{rp|page=225}} The devices allowed the brothers to balance lift against drag and accurately calculate the performance of each wing. They could also see which wings worked well as they looked through the viewing window in the top of the tunnel. The tests yielded a trove of valuable data never before known and showed that the poor lift of the 1900 and 1901 gliders was entirely due to an incorrect Smeaton value, and that Lilienthal's published data were fairly accurate for the tests he had done.<ref name="KittyHawkBox"/><ref name=Crouch-1989/>{{rp|page=226}}

Before the detailed wind tunnel tests, Wilbur traveled to [[Chicago]] at Chanute's invitation to give a lecture to the [[Western Society of Engineers]] on September 18, 1901. He presented a thorough report about the 1900–1901 glider experiments and complemented his talk with a [[Magic lantern|lantern]] slide show of photographs. Wilbur's speech was the first public account of the brothers' experiments.<ref>{{cite web |last=Wright |first=Wilbur |title=Aeronautical Experiments |url=http://invention.psychology.msstate.edu/i/Wrights/library/Aeronautical.html}}</ref> A report was published in the ''Journal'' of the society, which was then separately published as an offprint titled ''Some Aeronautical Experiments'' in a 300&nbsp;copy printing.<ref>{{cite magazine |magazine=Journal of the Western Society of Engineers |title=Some Aeronautical Experiments |via=Book and Magazine Collector |date=February 2006 |number=265 |page=15}}</ref>

====1902====
[[File:WrightGlidersSideBySide.jpg|right|thumb|At left, 1901 glider flown by Wilbur (left) and Orville. At right, 1902 glider flown by Wilbur (right) and Dan Tate, their helper. Dramatic improvement in performance is apparent. The 1901 glider flies at a steep [[angle of attack]] due to poor lift and high drag. In contrast, the 1902 glider flies at a much flatter angle and holds up its tether lines almost vertically, clearly demonstrating a much better [[lift-to-drag ratio]].<ref>[http://airandspace.si.edu/exhibitions/wright-brothers/online/fly/1902/perfecting.cfm "Perfecting the Control System"], Inventing a Flying Machine, The Wright Brothers and the Invention of the Aerial Age, [[The Smithsonian Institution]], [[National Air and Space Museum]]. Retrieved April 6, 2014.</ref>]]

Lilienthal had made "whirling arm" tests on only a few wing shapes, and the Wrights mistakenly assumed the data would apply to their wings, which had a different shape. The Wrights took a huge step forward and made basic wind tunnel tests on 200 [[scale-model]] wings of many shapes and [[airfoil]] curves, followed by detailed tests on 38 of them. An important discovery was the benefit of longer narrower wings: in aeronautical terms, wings with a larger [[aspect ratio]] (wingspan divided by [[Chord (aircraft)|chord]] – the wing's front-to-back dimension). Such shapes offered much better [[lift-to-drag ratio]] than the stubbier wings the brothers had tried so far. With this knowledge, and a more accurate Smeaton number, the Wrights designed their 1902 glider.

The wind tunnel tests, made from October to December 1901, were described by biographer Fred Howard as "the most crucial and fruitful aeronautical experiments ever conducted in so short a time with so few materials and at so little expense".<ref>Howard 1988, p. 72.</ref> In their September 1908 ''Century Magazine'' article, the Wrights explained, "The calculations on which all flying machines had been based were unreliable, and ... every experiment was simply groping in the dark ... We cast it all aside and decided to rely entirely upon our own investigations."<ref>{{cite magazine |last1=Wright |first1=Orville |last2=Wright |first2=Wilbur |collaboration=Wright Brothers Aeroplane Company |date=September 1908 |title=The Wright Brothers aeroplane |magazine=Century Magazine |url=https://www.wright-brothers.org/History_Wing/Wright_Story/Showing_the_World/Tragedy_at_Fort_Myer/Wright_Brothers_Aeroplane.htm |via=Wright-Brothers.org |access-date=March 7, 2021}}</ref>

The 1902 glider wing had a flatter airfoil, with the [[camber (aerodynamics)|camber]] reduced to a ratio of 1-in-24, in contrast to the previous thicker wing. The larger aspect ratio was achieved by increasing the wingspan and shortening the chord. The glider also had a new structural feature: A fixed, rear vertical rudder, which the brothers hoped would eliminate turning problems. However, the 1902 glider encountered trouble in crosswinds and steep banked turns, when it sometimes spiraled into the ground – a phenomenon the brothers called "well digging".  According to [[Harry B. Combs|Combs]], "They knew that when the earlier 1901 glider banked, it would begin to slide sideways through the air, and if the side motion was left uncorrected, or took place too quickly, the glider would go into an uncontrolled pivoting motion. Now, with vertical fins added to correct this, the glider again went into a pivoting motion, but in the opposite direction, with the nose swinging downward."<ref name=hc/>{{rp|149,158–168}}

[[File:1902 WrightBrosGlider.jpg|left|thumb|upright|Wilbur Wright pilots the [[1902 Wright Glider|1902 glider]] over the Kill Devil Hills, October 10, 1902. The single rear rudder is steerable; it replaced the original fixed double rudder.]]

Orville apparently visualized that the fixed rudder resisted the effect of corrective wing-warping when attempting to level off from a turn. He wrote in his diary that on the night of October 2, "I studied out a new vertical rudder". The brothers then decided to make the rear rudder movable to solve the problem.<ref>Anderson 2004, p. 134.</ref> They hinged the rudder and connected it to the pilot's warping "cradle", so a single movement by the pilot simultaneously controlled wing-warping and rudder deflection. The apparatus made the trailing edge of the rudder turn away from whichever end of the wings had more drag (and lift) due to warping. The opposing pressure produced by turning the rudder enabled corrective wing-warping to reliably restore level flight after a turn or a wind disturbance. Furthermore, when the glider banked into a turn, rudder pressure overcame the effect of differential drag and pointed the nose of the aircraft in the direction of the turn, eliminating adverse yaw.

In short, the Wrights discovered the true purpose of the movable vertical rudder. Its role was not to change the direction of flight, as a rudder does in sailing, but rather, to aim or align the aircraft correctly during banking turns and when leveling off from turns and wind disturbances.<ref>Culick, Fred E.C. [http://www.wrightflyer.org/wp-content/uploads/2012/10/Flight-Mechanics-In-Modern-Terms.pdf "What the Wright brothers did and did not understand about flight mechanics – in modern terms."] Pasadena, California: ''American Institute of Aeronautics and Astronautics: California Institute of Technology'', Paper AIAA-2001-3385, 37th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit, July 8–11, 2001. Retrieved: February 20, 2017.</ref> The actual turn – the change in direction – was done with roll control using wing-warping. The principles remained the same when [[ailerons]] superseded wing-warping.

[[File:1902 Wright glider turns.jpeg|right|thumb|Wilbur makes a turn using wing-warping and the movable rudder, October 24, 1902.]]
With their new method, the Wrights achieved true control in turns for the first time on October 9, a major milestone. From September 20 until the last weeks of October, they flew over a thousand flights.  The longest duration was up to 26 seconds, and the longest distance more than {{convert|600|ft|m}}.  Having demonstrated lift, control, and stability, the brothers now turned their focus to the problem of power.<ref name=hc/>{{rp|161,171–175}}

Thus did [[flight dynamics|three-axis control]] evolve: wing-warping for roll (lateral motion), forward elevator for pitch (up and down) and rear rudder for yaw (side to side). On March 23, 1903, the Wrights applied for their famous patent for a "Flying Machine", based on their successful 1902 glider. Some aviation historians believe that applying the system of three-axis flight control on the 1902 glider was equal to, or even more significant, than the addition of power to the 1903 Flyer. Peter Jakab of the Smithsonian asserts that perfection of the 1902 glider essentially represents invention of the airplane.<ref>Langewiesche 1972, p. 163.</ref><ref name=Jakab-1997/>{{rp|pages=183–184}}

===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}}

===First powered flight===

{{multiple image
| align = right
| direction = vertical
| width =
| image1 = 19031228 Machine That Flies - The Newark Daily Advocate.jpg
| width1 = 350
| caption1 = Within weeks of the first powered flight, this Ohio newspaper described "what the Wright brothers' invention has accomplished" – after years of glider tests, four successful flights in a powered flier that has "no balloon attachments of any kind, but is supported in the air by a pair of aerocurves, or wings", placing "[[Alberto Santos-Dumont|Santos-Dumont]] and [[Patrie (airship)|Lebaudys]], with their dirigible balloons ... in eclipse".<ref name=NewarkDailyAdvocate_19031228>{{cite news |title=Machine that flies / What the Wright brothers' invention has accomplished |date=December 28, 1903 |newspaper=The Newark Daily Advocate |location=Newark, Ohio, U.S. |page=7 |url=https://newspaperarchive.com/newark-advocate-dec-28-1903-p-7/}}</ref>
| image2 = 19060107 Another attempt to solve aerial navigation problem - Wright Brothers - The New York Times.jpg
| width2 = 350
| caption2 = This 1906 article describes how the Wrights' experiments were conducted in "strict secrecy for several years", with "not more than a dozen persons" being in on the secret.<ref name=NYTimes_19060107/> One insider stated that the brothers had "not sought for spectacular success", and instead described their "progressive accumulation of experiences", including gradual progression from gliders to powered flight, and from straight flights to circuits requiring turning the aeroplane.<ref name=NYTimes_19060107/> The account reported "some slight success in flying through the air at the end of the Summer of 1903".<ref name=NYTimes_19060107/> The Wrights were said to have solved flight control issues to achieve controlled turns on a one&nbsp;mile circuit on September 20, 1904, followed by five minute flights in the ensuing weeks, and a 24&nbsp;mile, 38&nbsp;minute flight in summer 1905.<ref name=NYTimes_19060107>{{cite news |title=Another attempt to solve aerial navigation problem |url=https://newspaperarchive.com/new-york-times-jan-07-1906-p-12/ |newspaper=[[The New York Times]] |date=January 7, 1906 |page=2 }} (page&nbsp;2 of the ''[[New York Times]]'' "Magazine" section)</ref>
}}
In camp at [[Kill Devil Hills]], the Wrights endured weeks of delays caused by broken propeller shafts during engine tests. After the shafts were replaced (requiring two trips back to Dayton), Wilbur won a [[coin flipping|coin toss]] and made a three-second flight attempt on December 14, 1903, stalling after takeoff and causing minor damage to the ''Flyer''. Because December 13, 1903, was a [[Sunday]], the brothers did not make any attempts that day, even though the weather was good, so their first powered test flight happened on the 121st&nbsp;anniversary of the first hot air balloon test flight that the [[Montgolfier brothers#Early experiments|Montgolfier brothers]] had made on December 14, 1782. In a message to their family, Wilbur referred to the trial as having "only partial success", stating "the power is ample, and but for a trifling error due to lack of experience with this machine and this method of starting, the machine would undoubtedly have flown beautifully."<ref>Kelly 2002, pp. 112–113.</ref>

Following repairs, the Wrights finally took to the air on December 17, 1903, making two flights each from level ground<ref>{{cite book |last1=Andrews |first1=Allen |title=The Flying Machine: Its Evolution Through the Ages |date=1977 |publisher=Putnam |isbn=9780399119675 |page=94}}</ref> into a freezing headwind gusting to {{convert|27|mph|km/h}}. The first flight, by Orville at 10:35&nbsp;am, of {{convert|120|ft|m}} in 12&nbsp;seconds, at a speed of only {{convert|6.8|mph|km/h}} over the ground, was recorded in a [[:File:First flight2.jpg|famous photograph]].<ref name="WDL">{{cite web |title = Telegram from Orville Wright in Kitty Hawk, North Carolina, to his father announcing four successful flights, December 17, 1903 |website = [[World Digital Library]] |date = December 17, 1903 |url=http://www.wdl.org/en/item/11372/ |access-date = July 21, 2013}}</ref> The next two flights covered approximately {{convert|175|and|200|ft|m}}, by Wilbur and Orville respectively. Their altitude was about {{convert|10|ft|m}} above the ground.<ref name="wb-first-five-flights">{{cite journal |first=Carroll F. |last=Gray |date=August 2002 |title=The first five flights, the slope and winds of Big Kill Devil Hill – the first flight reconsidered |journal=WW1 AERO the Journal of the Early Aeroplane |issue=177 |url=http://www.thewrightbrothers.org/fivefirstflights.html |via=TheWrightBrothers.org |access-date=September 21, 2010 |url-status=live |archive-url=https://web.archive.org/web/20150423162519/http://www.thewrightbrothers.org/fivefirstflights.html |archive-date=April 23, 2015}}</ref> The following is Orville Wright's account of the final flight of the day:<ref>Kelly 1943, pp. 101–102.</ref>
{{Blockquote|text=Wilbur started the fourth and last flight at just about 12&nbsp;o'clock. The first few hundred feet were up and down, as before, but by the time three hundred ft had been covered, the machine was under much better control. The course for the next four or five hundred feet had but little undulation. However, when out about eight hundred feet the machine began pitching again, and, in one of its darts downward, struck the ground. The distance over the ground was measured to be 852&nbsp;feet; the time of the flight was 59&nbsp;seconds. The frame supporting the front rudder was badly broken, but the main part of the machine was not injured at all. We estimated that the machine could be put in condition for flight again in about a day or two.}}

[[File:Wright diary1.jpg|left|thumb|Orville's notebook entry of December 17, 1903]]
Five people witnessed the flights: Adam Etheridge, [[John T. Daniels]] (who snapped the famous "first flight" photo using Orville's pre-positioned camera), and Will Dough, all of the U.S. government coastal lifesaving crew; area businessman W.C. Brinkley; and Johnny Moore, a teenaged boy who lived in the area.
After the men hauled the ''Flyer'' back from its fourth flight, a powerful gust of wind flipped it over several times, despite the crew's attempt to hold it down. Severely damaged, the ''Wright Flyer'' never flew again.<ref>Howard 1988, p. 139.</ref> The brothers shipped the airplane home, and years later Orville restored it, lending it to several U.S. locations for display, then to the [[Science Museum, London|Science Museum]] in London (see Smithsonian dispute below), before it was finally installed in 1948 in [[the Smithsonian Institution]], its current residence.

The Wrights sent a telegram about the flights to their father, requesting that he "inform press".<ref name="WDL"/> However, the ''Dayton Journal'' refused to publish the story, saying the flights were too short to be important. Meanwhile, against the brothers' wishes, a telegraph operator leaked their message to a Virginia newspaper, which concocted a highly inaccurate news article that was reprinted the next day in several newspapers elsewhere, including Dayton.<ref name=Crouch-1989/>{{rp|pages=271–272}}<ref>{{cite web |url=http://www.wright-brothers.org/History_Wing/Wright_Story/Inventing_the_Airplane/December_17_1903/Virginia_Pilot_Story.htm |title=''Virginian-Pilot'' story |series=In their own words |website=Wright-Brothers.org |access-date=January 29, 2013}}</ref>

The Wrights issued their own factual statement to the press in January.<ref name=Crouch-1989/>{{rp|page=274}} Nevertheless, the flights did not create public excitement – if people even knew about them – and the news soon faded.{{citation needed|date=April 2014}} In Paris, however, Aero Club of France members, already stimulated by Chanute's reports of Wright gliding successes, took the news more seriously and increased their efforts to catch up to the brothers.<ref>{{cite book |first=C.H. |last=Gibbs-Smith |author-link=Charles Harvard Gibbs-Smith |title=The Rebirth of European Aviation |year=1974 |pages=64–9 |isbn=978-0112901808 |location=London, UK |publisher=HMSO}}</ref>

An analysis in 1985 by Professor Fred E.C. Culick and Henry R. Jex demonstrated that the 1903 ''Wright Flyer'' was so unstable as to be almost unmanageable by anyone but the Wrights, who had trained themselves in the 1902 glider.<ref>{{cite book |last1=Abzug |first1=Malcolm J. |first2=E. Eugene |last2=Larrabee |title=Airplane Stability and Control: A history of the technologies that made aviation possible |date=September 23, 2002 |edition=2nd |publisher= (cambridge.org) |isbn=97805218-0992-4 |url=http://assets.cambridge.org/97805218/09924/sample/9780521809924ws.pdf |access-date=September 21, 2010}}{{full citation needed|date=April 2021}}</ref> In a recreation attempt on the event's 100th&nbsp;anniversary on December 17, 2003, Kevin Kochersberger, piloting an exact replica, failed in his effort to match the success that the Wright brothers had achieved with their piloting skill.<ref>{{cite AV media |url=https://www.youtube.com/watch?v=S3b1avsSw3g&t=136 | archive-url=https://ghostarchive.org/varchive/youtube/20211028/S3b1avsSw3g| archive-date=October 28, 2021|via=YouTube |title=Attempt to recreate Wright brothers flight fails |publisher=AP Archive |medium=video}}{{cbignore}}</ref>

===Establishing legitimacy===
[[File:1904WrightFlyer.jpg|thumb|Orville in flight over [[Huffman Prairie]] in [[Wright Flyer II]]. Flight&nbsp;85, approximately {{convert|1760|ft|m|0}} in {{frac|40|1|5}}&nbsp;seconds, November 16, 1904]]
In 1904 the Wrights built the [[Wright Flyer II]]. They decided to avoid the expense of travel and bringing supplies to the Outer Banks and set up an airfield at [[Huffman Prairie]], a cow pasture eight miles (13{{nbsp}}km) northeast of Dayton. The Wrights referred to the airfield as Simms Station in their flying school brochure. They received permission to use the field rent-free from owner and bank president Torrance Huffman.

They invited reporters to their first flight attempt of the year on May&nbsp;23, on the condition that no photographs be taken. Engine troubles and slack winds prevented any flying, and they could manage only a very short hop a few days later with fewer reporters present. Library of Congress historian Fred Howard noted some speculation that the brothers had intentionally failed to fly in order to cause reporters to lose interest in their experiments. Whether that is true is not known, but after their poor showing local newspapers virtually ignored them for the next year and a half.<ref>Howard 1998, pp. 154–155.</ref>

The Wrights were glad to be free from the distraction of reporters. The absence of newsmen also reduced the chance of competitors learning their methods. After the Kitty Hawk powered flights, the Wrights made a decision to begin withdrawing from the bicycle business so they could concentrate on creating and marketing a practical airplane.<ref name=Crouch-2003/>{{rp|pages=273–274}} This was financially risky, since they were neither wealthy nor government-funded (unlike other experimenters such as [[Clément Ader|Ader]], [[Hiram Stevens Maxim|Maxim]], [[Samuel Pierpont Langley|Langley]], and [[Alberto Santos-Dumont|Santos-Dumont]]). The Wright brothers did not have the luxury of being able to give away their invention: It had to be their livelihood. Thus, their secrecy intensified, encouraged by advice from their patent attorney, [[Harry Aubrey Toulmin Sr.|Henry Toulmin]], not to reveal details of their machine.

[[File:WrightFlyer1904Circling.jpg|thumb|Wilbur flying almost four circles of Huffman Prairie, about {{frac|2|3|4}}&nbsp;miles in 5&nbsp;minutes 4&nbsp;seconds; flight&nbsp;82, November 9, 1904.]]
At Huffman Prairie, lighter winds made takeoffs harder, and they had to use a longer starting rail than the {{convert|60|ft|m|0|adj=on}} rail used at Kitty Hawk. The first flights in 1904 revealed problems with longitudinal stability, solved by adding ballast and lengthening the supports for the elevator.<ref name=Crouch-2003/>{{rp|page=286}} During the spring and summer they suffered many hard landings, often damaging the aircraft and causing minor injuries. On August&nbsp;13, making an unassisted takeoff, Wilbur finally exceeded their best Kitty Hawk effort with a flight of {{convert|1300|ft|m|-1}}.
They then decided to use a weight-powered catapult to make takeoffs easier and tried it for the first time on September&nbsp;7.<ref name="Howard 1998, p. 161">Howard 1998, p. 161</ref>

[[File:WrightBrothersFirstCircleFlightLogBook.gif|thumb|left|Wilbur's logbook showing diagram and data for first circle flight on September 20, 1904]]
On September 20, 1904, Wilbur flew the first complete circle in history by a manned heavier-than-air powered machine, covering {{convert|4080|ft|m|0}} in about a minute and a half.<ref name="Howard 1998, p. 161"/> Their two best flights were November&nbsp;9 by Wilbur and December&nbsp;1 by Orville, each exceeding five minutes and covering nearly three miles in almost four circles.<ref>Howard 1998, pp. 162–163</ref>
By the end of the year the brothers had accumulated about 50 minutes in the air in 105&nbsp;flights over the rather soggy {{convert|85|acre|ha}} pasture, which, remarkably, is virtually unchanged today from its original condition and is now part of [[Dayton Aviation Heritage National Historical Park]], adjacent to [[Wright-Patterson Air Force Base]].

The Wrights scrapped the battered and much-repaired aircraft, but saved the engine, and in 1905 built a new airplane, the ''Flyer&nbsp;III''. Nevertheless, at first this ''Flyer'' offered the same marginal performance as the first two. Its maiden flight was on June&nbsp;23 and the first few flights were no longer than 10&nbsp;seconds.<ref name="Winchester">Winchester 2005, p. 311.</ref> After Orville suffered a bone-jarring and potentially fatal crash on July&nbsp;14, they rebuilt the ''Flyer'' with the forward elevator and rear rudder both enlarged and placed several feet farther away from the wings. They also installed a separate control for the rear rudder instead of linking it to the wing-warping "cradle" as before.<ref name="auto">A Wright brothers letter [[commons:File:WrightAeroClubLetterPg1.jpg|(page 1]], [[commons:File:WrightAeroClubLetterPg2.jpg|page 2)]] to the Aero Club of America describes the long flights and provides a list of witnesses. (Courtesy Dayton Metro Library.)</ref>

Each of the three axes – pitch, roll, and yaw – now had its own independent control. These modifications greatly improved stability and control, enabling a series of six dramatic "long flights" ranging from 17 to 38&nbsp;minutes and {{convert|11|to|24|mi|km|0}} around the three-quarter mile course over Huffman Prairie between September&nbsp;26 and October&nbsp;5. Wilbur made the last and longest flight, {{convert|24.5|mi|km|1}} in 38&nbsp;minutes and 3&nbsp;seconds, ending with a safe landing when the fuel ran out. The flight was seen by several invited friends, their father Milton, and neighboring farmers.<ref name="auto"/>

[[File:Wright Flyer III above.jpg|thumb|upright|''[[Wright Flyer III]]'' piloted by Orville over Huffman Prairie, October 4, 1905. Flight #46, covering {{frac|20|3|4}}&nbsp;miles in 33&nbsp;minutes 17&nbsp;seconds; the last photographed flight of the year.]]

Reporters showed up the next day (only their second appearance at the field since May the previous year), but the brothers declined to fly. The long flights convinced the Wrights they had achieved their goal of creating a flying machine of "practical utility" which they could offer to sell.

The only photos of the flights of 1904–1905 were taken by the brothers. (A few photos were damaged in the [[Great Dayton Flood]] of 1913, but most survived intact.) In 1904 Ohio beekeeping businessman [[Amos Root]], a technology enthusiast, saw a few flights including the first circle. Articles he wrote for his beekeeping magazine were the only published eyewitness reports of the Huffman Prairie flights, except for the unimpressive early hop local newsmen saw. Root offered a report to ''[[Scientific American]]'' magazine, but the editor turned it down. As a result, the news was not widely known outside Ohio, and was often met with skepticism. The Paris edition of the ''[[International Herald Tribune|Herald Tribune]]'' headlined a 1906 article on the Wrights "Flyers or liars?".

In years to come, Dayton newspapers would proudly celebrate the hometown Wright brothers as national heroes, but the local reporters somehow missed one of the most important stories in history as it was happening a few miles from their doorstep. [[James M. Cox|J.M. Cox]],{{efn| ''[[Dayton Daily News]]'' publisher [[James M. Cox]] later became governor of Ohio, and a 1920 Democratic presidential nominee.}} who published the ''[[Dayton Daily News]]'' at that time, expressed the attitude of newspapermen – and the public – in those days when he admitted years later: "Frankly, none of us believed it."<ref>Tobin 2004, p. 211.</ref>

[[File:HeadlineWrightBros.gif|thumb|The ''Dayton Daily News'' reported the October&nbsp;5, 1905, flight on page&nbsp;9, with agriculture and business news.{{refn|Image courtesy Dayton Metro Library. The newspaper article can be read at the commons.<ref>[[commons:File:DaytonNewspaperArticleWrightBros.gif|"Wright Brothers"]]. Dayton Metro Library. Retrieved: September 21, 2010.</ref>}}]]
A few newspapers published articles about the long flights, but no reporters or photographers had been there. The lack of splashy eyewitness press coverage was a major reason for disbelief in Washington, DC, and Europe, and in journals like ''Scientific American'', whose editors doubted the "alleged experiments" and asked how U.S. newspapers, "alert as they are, allowed these sensational performances to escape their notice."<ref>{{Citation|title=The Wright Aeroplane and its Fabled Performance|url=https://invention.psychology.msstate.edu/i/Wrights/library/WrightSiAm1.html|access-date=2023-02-12|work= Scientific American | volume= 94 | number= 2 | page = 40 | date=January 13, 1905
}}</ref>

In October&nbsp;1904, the brothers were visited by the first of many important Europeans they would befriend in coming years, [[John Capper|Colonel J.E. Capper]], later superintendent of the [[Royal Aircraft Establishment|Royal Balloon Factory]]. Capper and his wife were visiting the United States to investigate the aeronautical exhibits at the [[Louisiana Purchase Exposition|St.&nbsp;Louis World Fair]], but had been given a letter of introduction to both Chanute and the Wrights by [[Patrick Young Alexander|Patrick Alexander]]. Capper was very favorably impressed by the Wrights, who showed him photographs of their aircraft in flight.<ref>{{Cite book|last=Gollin|first=Alfred M.|url=https://books.google.com/books?id=xT2rAAAAIAAJ|title=No Longer an Island: Britain and the Wright Brothers, 1902–1909|date=1984|publisher=Stanford University Press|isbn=978-0-8047-1265-1|pages= 66–68}}</ref>

The Wright brothers were certainly complicit in the lack of attention they received. Fearful of competitors stealing their ideas, and still without a patent, they flew on only one more day after October 5. From then on, they refused to fly anywhere unless they had a firm contract to sell their aircraft. They wrote to the U.S. government, then to Britain, France and Germany with an offer to sell a flying machine, but were rebuffed because they insisted on a signed contract before giving a demonstration. They were unwilling even to show their photographs of the airborne Flyer.

The American military, having recently spent $50,000 on the [[Langley Aerodrome]] – a product of the nation's foremost scientist – only to see it plunge twice into the Potomac River "like a handful of mortar", was particularly unreceptive to the claims of two unknown bicycle makers from Ohio.<ref name="wb-smithson-langley">{{cite web |url=http://airandspace.si.edu/research/aero/aircraft/langleyA.htm |title=Langley Aerodrome A |publisher=[[The Smithsonian Institution]] |department=[[National Air and Space Museum]] |access-date=November 21, 2006 |archive-url=https://web.archive.org/web/20071109075536/http://airandspace.si.edu/research/aero/aircraft/langleyA.htm |archive-date=November 9, 2007 |url-status=dead}}</ref> Thus, doubted or scorned, the Wright brothers continued their work in semi-obscurity, while other aviation pioneers like Santos-Dumont, [[Henri Farman]], [[Léon Delagrange]], and American [[Glenn Curtiss]] entered the limelight.