Kitty Hawk - 1903 - What Happened

Kitty Hawk – 1903 – What Happened ? 

by Joe Bullmer 

The Wright brothers, Orville and Wilbur. The common story of first manned motorized flight is based on their claims of what happened near Kitty Hawk, NC, on December 17, 1903. -Ed.

     The traditional story of the Wright brothers’ accomplishments at Kitty Hawk in 1903 seems to be well established. But actually there were only three sources of information, the Wrights' statements, their photography, and the statements of a couple of witnesses. It turns out that careful examination of these statements and photographs raise substantial questions concerning what happened there in 1903.

A photograph claimed to be of the first manned, motorized flight in history. Promoted and signed by Orville Wright. -Ed.

The Narratives

     When the Wright brothers brought their first powered aircraft to Kitty Hawk in the fall of 1903 they had a few specific goals in mind.  These goals were revealed in the first public statement made by the Wrights which was released to the Associated Press on January 5th, 1904, less than three weeks after the 1903 tests. 

One of the papers that printed the Wrights' press release version of the 1903 Kitty Hawk events

The statement read in part:

  “The flights were made directly against the wind.  Each time the machine started from the level ground by its own power alone with no assistance from gravity, or any other motive source whatever....Consequently the first flight was short.  The succeeding flights rapidly increased in length and at the fourth trial a flight of fifty-nine seconds was made, in which time the machine flew a little more than a half mile through the air, and a distance of 852 ft. over the ground.”

Obviously at this point the significant flight was considered to be Wilbur’s last attempt, the fourth of the day. 

    One goal was for the machine to achieve flight “by its own power alone with no assistance from gravity, or any other motive source whatever.”  (Mentioning gravity ruled out Wilbur’s attempt on the 14^th, which used a steeply downhill-sloping launch rail to compensate for light winds in an attempt to gain takeoff speed.)  According to Orville’s 1913 article in Flying magazine, the United States Weather Bureau at Kitty Hawk quoted the sustained winds at the time of the first attempt on the 17^th to be 27 miles per hour, diminishing slightly to 24 miles per hour during the last attempt, with gusts even higher.  These headwinds represented over 80% to 90% of the necessary flying speed of the airplane.  So, on the 17^th, even though wind is not apparent in photography as is a sloping hill, these winds more than replaced gravity.  Although not a “motive source” in the propulsive sense, had the sustained wind speed been just a few miles per hour greater or gusting, it would have “motivated” the aircraft to lift off of the ground straight up - without even using the engine.  In fact, later in the day the wind did just that, lifting the unoccupied aircraft off the ground, rolling it over, and destroying it.

     (Aircraft typically take off into any wind, so some might point out that the effect of the headwind could be interpreted to have merely shortened the takeoff run.  So without that wind, but with sufficient track and time, the aircraft might have reached flying speed on its own.  But although seemingly feasible, the acceleration rate demonstrated by the aircraft indicates that without any wind, the Wrights’ 1903 takeoff runs would have taken at least 12 seconds and been more than 450 feet long with the majority of that distance being done at more than the running speed of a human but under the minimum control speed of the aircraft.  Thus the vehicle as configured could not have maintained lateral balance during such a run and consequently could not have reached takeoff speed.  In any case, this discussion is concerned with what actually happened, not hypothetical alternatives using different equipment.)

    Another interesting twist in the press release is that, while the effect of the strong headwind is totally discounted as regards its ability to lift the vehicle off of the ground, it is included to make the statement that the vehicle flew “a half mile through the air.” So already the Wrights were excluding the effects of headwinds when convenient, but including them when convenient.

    Wilbur’s last flight on December 17^th was the only one they claimed to have actually measured and was the one said to have flown 852 feet from the takeoff point.  The other three attempts, only referred to as “short” in the press release, were not measured and were discounted as insignificant.  The Wrights estimated these first three attempts to have been between 120 and 200 feet in length. 

     In a November 2nd, 1906 letter to Octave Chanute written three years after the powered Kitty Hawk tests, discussing Santos-Dumont’s trials in France, Wilbur expressed the belief that any flight of less than a tenth of a kilometer, 328 feet, was only a “jump” and “nothing” of significance.  (Both Chanute and Wilbur were clearly referring to distance over the ground since that was all that had been reported about the Santos-Dumont flights.)  Wilbur’s point here was that, with a sufficiently strong takeoff run, a vehicle could “jump” up into the air and continue forward for up to a few hundred feet using the momentum gained on the ground, all the while slowing down and proving “nothing” regarding its ability to develop enough thrust to overcome its aerodynamic drag and sustain itself in the air.  Moreover, unless it was airborne long enough to have flown fairly level for a while during this flight, it would have shown, using Wilbur’s word, “nothing” regarding its ability to generate enough lift to sustain its weight in the air. 

     It is interesting to follow the evolution of subsequent statements describing the 1903 Kitty Hawk events.  The first major article by the Wrights concerning their work appeared in The Century magazine’s September 1908 issue almost five years later.  Although billed as authored by both Orville and Wilbur, Wilbur was in Europe at the time it was written.  His contribution appears to be limited to a letter encouraging Orville to hurry to publish an article stating their accomplishments and another mentioning some erroneous articles about them written by others.  In this article, Orville’s description of his first attempt of 1903 was:

   “The first flight lasted only 12 seconds…[but] was, nevertheless, the first in the history of the world in which a machine carrying a man had raised itself by its own power into the air in free flight, had sailed forward on a level course without reduction of speed, and had finally landed without being wrecked.”

     Again we see the reference to having “raised itself by its own power” without any mention of the headwind that supplied 90% of the airspeed and 80% of the required lift on that attempt.*  But this sentence also includes an absolute falsehood: that the aircraft “sailed forward on a level course”.  In another article written five years later, Orville himself described his first attempt as “exceedingly erratic”.  They also described it as oscillating severely between up and down paths with the pitch control flapping back and fourth between its limits, the second oscillation forcing a dive into the sand.  In other words, the aircraft was totally out of control for the entire event.¹  (In engineering terms, it was more of a constant exchange of kinetic and potential energy rather than a situation of lift balancing out weight.) 

     The sentence ends with a reference to the vehicle not having been wrecked.  This could have the effect of negating Wilbur’s last flight, since on that one the whole front structure was busted up upon landing.  (Actually, on Orville’s first attempt, a landing skid and engine control were damaged upon impact with the sand and had to be repaired before the second trial could be attempted.) 

     So here already is an evolution of the story toward the significant flight being Orville’s first attempt.  Elsewhere in the article, the other three attempts of the 17^th were mentioned almost in passing, although the 852-foot distance claimed for the fourth trial was noted.

     There is apparently no existing record of Wilbur’s reaction upon seeing this account.  However, after his death in 1912, the campaign to consider Orville’s first attempt, along with its appealing photograph, to actually have been the first successful flight became persistent and permanent.  In an article in the December 1913 issue of Flying magazine, Orville wrote of his first attempt:

  “This flight lasted only 12 seconds, but it was nevertheless the first time in the history of the world in which a machine carrying a man had raised itself by its own power into the air in full flight, had sailed forward without reduction of speed, and had finally landed at a point as high as that from which it started.”

     It was elsewhere in this article that Orville described this attempt as “exceedingly erratic” and basically out of control throughout, hardly what could be considered “full flight”.  He described their second attempt as “much like the first,” and the third as being “turned up sidewise in an alarming manner” prompting Orville to overcontrol, sticking the high wing back down and into the sand.  And again, the high wind enabling takeoffs was not mentioned.  

This photograph is described as the third flight of the Wrights on December 17, 1903.

     Since the aircraft used most of the available launch ramp on each of these trials even with headwinds supplying at least 80% to 90% of the necessary airspeed for takeoffs,** it is obvious that without those headwinds there couldn’t have been any flights at all by the Wright brothers in 1903.  Their aircraft did not “take off by its own power alone.”  Furthermore, according to the Wrights’ own criteria, the first three attempts on 17 December, 1903, were not in control and were not of sufficient length (328 feet) to qualify as flights. In the words Wilbur used three years later to discuss Santos-Dumont’s very similar trials, they were just “jumps” amounting to “nothing”. 

     It was also elsewhere in this article that Orville added an estimated 12 seconds of wind speed (420 feet) to the estimated distance of his first attempt to come up with a new distance of 540 feet “through the air.”  This contradicts their original criterion for success -  distance over the ground - and of course ignores the fact that without that wind, the flight distance would have been zero.  In any case, Orville outlived Wilbur by 36 years, and by ignoring their original criterion, and with the aid of biographers and historians eager to include the “first flight” photo in their stories, Orville was able to make his case stick for having accomplished their first successful flight.

The Pictures

 

    For over a century now, the clear, well-framed photo of Orville’s first attempt on December 17^th, 1903, (second photo above) with the aircraft a couple feet above the end of the launch rail and Wilbur running alongside, has been hailed as the photo showing the very beginning of flight, the moment of takeoff on the first successful manned, controlled, powered flight.  The concept of having such a photograph is very appealing.  To some, it provides proof of the Wrights’ claims.  It also gives us a little sense of having been present for the first successful powered flight.  However, as we just saw, at that time even the Wrights did not consider it as such.

   So then what exactly is the photographic proof of the Wrights’ accomplishment in 1903?  There are three photographs considered to have been of the 1903 aircraft in flight: one of the first attempt, one of the third, and one of the fourth.  As we have seen, the pictures of the first and third trials do not in fact portray an aircraft in “full flight,” under control and going an acceptable minimum distance, and thus do not provide evidence of what the Wrights considered a successful flight.²  Recognizing this, some have latched on to the photo said by Orville to portray the fourth attempt as being the only one that actually provides solid evidence of a successful flight in 1903.  However, careful examination of this photograph leads to a different conclusion.

Photo described by Orville Wright as the end of the fourth flight, December 17, 1903.

      The picture is a slightly blurry photograph taken from well to the left of, and behind, the launch rail, showing the rail on the right side of the plate and on the left, off at some distance, the aircraft.  (The Library of Congress file number is LC-W86-38.)

This author, an intelligence analyst and aircraft design and performance engineer for 31 years, has made an interpretation and mensuration analysis of the photo using a print made directly from the photographic plate, a proportional enlargement of that photo, and also an excellent large, although cropped, two-page print of it appearing in Crouch and Jakab’s book The Wright Brothers.  The results are as follows:

     The biplane aircraft exhibits mild anhedral (drooping of the tips) on both wings.  There is a dark strip on the ground below the lower wing that may be a shadow from the wing or simply a dark strip on the ground.  It is unclear from this whether the aircraft is on the ground or a foot or two above it.  The aircraft appears to be headed away from the track and camera since the clearly visible upper blades of the pusher propellers obscure portions of the trailing edges of the upper wing.  Their camera’s shutter speed was such that moving propellers are not visible in any Wright photos. Consequently, the sharply visible propeller blades must have been stopped and the engine not running when the photo was taken.³

A blowup of the plane and the "three blobs" on the wing of the plane from the photo described as the fourth flight.

     There are three dark “blobs” appearing between the biplane wings at the center of the vehicle.  The blobs appear as three distinct objects whose heights are about 60% of the distance between the lower and upper wings.  Thus, the objects average a little over three feet in height. Together, they total seven feet in width from the left edge of the leftmost to the right edge of the rightmost.  They obscure the farthest portion of the bottom wing but not the nearest portion, the nearest or trailing edge of the lower wing being visible throughout the span.  Also, there are no continuations of the dark objects below the lower wing.  Thus, all three objects appear to be on the lower wing, not in front of or behind it. 

     The 1903 aircraft had dual vertical rudders mounted behind the wings, so consideration was made as to whether the objects could have been one large three- and one-half-foot-high by seven-foot-wide dark object appearing to be sectioned into three segments by the two white rudders.  However, the spaces between the objects are not of uniform width.  Also, the spaces do not appear white like the fabric on the wings, but rather are the tone of the background beyond the aircraft.  Thus, the spaces between the dark objects appear to be open gaps and not rudders.  The less-than-two-inch-thick rudders would not be visible in this photo if trimmed toward the camera anyway.

     The distance to the aircraft from the track can be calculated from blowups of the fourth flight photo using basic trigonometric and geometric photogrammetric mensuration techniques.  The details of this analysis appear in another paper by this author titled Mensuration of the Fourth Flight.  The result is a distance from the launch end of the rail to the aircraft of 277 feet with a confidence of plus or minus 17 feet.  This is less than one-third of the 852-foot distance claimed by the Wrights.  Combining all possible judgments and errors in the direction of increasing the resulting distance, it was not possible to obtain a number approaching one-half of the claimed distance.***

  The magazine World War I Aero – The Journal of the Early Aeroplane published an article in 2002 claiming that their analysis of the photo determined the aircraft to be approximately 250 feet from the end of the launch rail, but that it was still flying and must have gone another 600 feet.  The Library of Congress caption for the photo states that the aircraft has landed, but also claims that the plane did indeed fly for the 852 feet claimed by the Wrights.  Neither mentioned the stopped propellers or the three tall objects on the lower wing.****

Photo claimed by Orville Wright to be the "fourth flight," Dec. 17, 1903, blown up and emphasizing the stopped propeller.

     Another set of measurements is equally perplexing.  The heights of the three dark objects on the lower wing appear to be about 60% of the height separation of the biplane wings.  Measurement of the height of the prone pilot and horizontally disposed engine in the other photos of the 1903 aircraft show the height of those two objects to be only about 20% of the wing separation.  On the other hand, the heights of two seated occupants and the vertical engine in photographs of the 1908/1909 version of the Wright Flyer average nearly 65% of the wing separation distance. 

     A passenger was taken aloft on numerous flights of the two-seat aircraft during trials at Kitty Hawk in 1908.  Since two occupants plus the nearby engine and tall radiator of that vehicle could appear as three dark “blobs” from a distance, it is tempting to consider that the “fourth flight” photo is actually of the two seat version of the aircraft taken at some point during its testing at Kitty Hawk in 1908.  The collection of plates provided to the Library of Congress by the Wright family includes only one [LC-W86-78(P&P)] identified as being of the aircraft at Kitty Hawk in 1908 (below).  It shows the unoccupied vehicle sitting on the starting end of a downward-sloping launch ramp. 

The only photograph taken by the Wrights identified as the Wright aircraft at Kitty Hawk, 1908.

     A photographer for Collier’s magazine, James H. Hare, took unauthorized photos (examples below) of the 1908 flights at Kitty Hawk from a discrete distance.  But it seems that the 1903 “fourth flight” photo would not be one of Hare’s since the photo is a plate in the Library of Congress’s Wright collection.  The James Hare collection, including his 1908 photos from Kitty Hawk, is housed at the University of Texas at Austin.  It includes no such photo.

 

Photograph of the Wright Flyer in the air by Jimmy Hare, a journalist, in 1908. Kitty Hawk

 

A fuzzy blow up of the Flyer in one of the photographs taken by Jimmie Hare in 1908. Note that the wings appear neither anhedral nor dihedral, according to the author.

      A couple other things about the 1908 photography are puzzling.  Why would the Wrights’ only photo identified as the 1908 aircraft at Kitty Hawk show slight dihedral when the Wrights claimed anhedral was the appropriate configuration for Kitty Hawk flying?  (Neither dihedral nor anhedral are detectable in Hare’s distant photos.)  Actually, the span-wise curvature of Wright Flyer wings could be changed either by adjusting the lengths of truss wires, replacing them, or merely switching them.  In fact, while at Kitty Hawk the 1900 glider’s wings were changed from dihedral to straight and the 1901 machine’s wings were changed from straight to anhedral.  But even more intriguing, why would the Wrights, avid photographers, have gone through the trouble of bringing their photographic equipment to Kitty Hawk in 1908, setting it up, and then have taken only one picture of their airplane sitting on the ground and none from the numerous flight tests over the entire month and a half they were there?  After all, they took over a dozen photos of their aircraft in 1903, including eight taken during just a few hours of testing.

     So the “fourth flight” photo poses an enigma for a number of reasons:

1. The wing anhedral, although adjustable, is compatible with the 1903 aircraft, yet the three tall dark objects on the lower wing are consistent with the 1908 version of the Flyers rather than two much smaller objects that would be expected on the 1903 aircraft.
2. Careful mensurations of the photo all show the aircraft to be less than a third as far from the launch rail as the distance claimed for the fourth flight.  (This is consistent with a visual impression.  The airplane certainly does not appear to be nearly three football fields, a sixth of a mile, beyond the launch rail.)
3. The propellers are clearly stopped and the aircraft is on or within just a couple feet off the ground.  If this is a photo of a flight attempt, it was taken very near, or more likely after, the end of it.     
4. The photo claimed to be of the 1903 fourth attempt was not released until after the 1908 Kitty Hawk testing.
5. The fourth flight plate resides in the Wright collection at the Library of Congress, not in the Hare collection in Texas.
6. Why does only one aircraft photo taken by the Wrights exist from the month-and-a-half long 1908 test session involving numerous flights?

     We are left with the perplexing conclusion that, in view of the above, we don’t really have incontrovertible photographic proof of a flight by the Wright brothers in 1903 that meets the criteria they themselves established for a successful flight.³  The two photos of the first and third attempts, while striking, don’t depict controlled flights of sufficient distance.  The only other photo, claimed to be of the fourth trial, presents a troubling dilemma.  It is definitely a picture of an airplane less than 300 feet from the launch rail with its propellers and engine stopped, and either on the ground or very near it; in other words, at the end of any flight attempt.  So our only choices appear to be that either it is a picture of the fourth flight trial and the aircraft went less than a few hundred feet, or the aircraft may have gone substantially farther, as claimed, for the fourth attempt - but that’s not a picture of it.  The downward curved wings could be interpreted to support the first conclusion; the three large objects on the lower wing support the second.  The distance analysis and stopped propellers could support either.

     But if the photo is not of the end of an 852-foot flight, what is it?  Did they carry the 750-pound machine out 270 feet and take a picture of it?  Or could they have stopped while carrying it back from a longer flight and three people sat on the wing while someone, for some reason, took a picture of that from back behind the launch rail?  In either case, why?

     And finally, it’s worth reiterating that anyone that considers Orville’s first attempt to be the first successful controlled, manned, powered flight has to overlook at least four facts.  First, that at least 90 percent of the necessary takeoff speed of the vehicle was supplied by the invisible wind, not the engine. Second, this attempt came nowhere near meeting the Wrights’ expressed minimum distance requirement.  Third, they must overlook Orville’s statements about the attempt being “exceedingly erratic” and his inability to keep the forward elevator from slamming back and forth between its limits during this attempt, resulting in the uncontrolled porpoising of the aircraft into the ground.  And finally, of course, they have to overlook the fact that available records indicate that for at least five years the Wrights themselves did not claim this attempt to be their first successful flight.⁴   

So What Happened ?

 

     In spite of all this, the Wrights may have briefly achieved some degree of control over part of a manned powered flight in 1903.  But this conclusion would have to be based on the following: the photo claimed to be of the fourth flight of 852 feet but showing a distance from the launch rail of less than 300 feet; the Wrights’ claim that the aircraft flew under control and fairly smoothly for a portion of that flight; and some of the testimonies of witnesses which, while one or two could be considered to be somewhat corroborating, also contain obvious errors and contradictions, both among themselves and with the Wright brothers’ statements.

     John Daniels and Adam Etheridge, Life Savers and witnesses, gave the most extensive statements many years later, both saying that they assisted the Wrights in carrying the 1903 airplane up a hill to its launch point. The Wrights claimed, however, and the photos seem to show, that the launch rail was on fairly level ground.  Daniels mentions only two flights and claimed the last flight went at least a half mile.  He didn’t even remember taking the famous photo of the “first flight.”  Orville apparently told him he did.*****  Much of the confusion no doubt stems from nearly all of the “witness’s” statements having been taken decades after the events. In fact, some of Daniels' recollections seem to have been heavily influenced or even created by Orville Wright in the intervening years. In any case, their statements, in total, contradict the Wrights' accounts more often than they corroborate them.

     Perhaps the strongest indicator of some success in 1903 is the initial limited flying ability the Wrights claimed for their next machine at Huffman Prairie in 1904.  It seems unlikely that the 1903 tests could have all been complete failures and the next extremely similar vehicle a limited success, at least at straight-line flight when launched with a strong headwind or from a powerful catapult.

The Wrights' catapult was needed to assist their engine in taking off. This photo appears to be in France.

Epilogue 

 

     The Wrights’ catapult brings up an interesting point.  The brothers were sticklers for semantics, particularly as pertained to flying vehicles.  This was indeed the crux of their patent litigation arguments.  However, applying their penchant for linguistic accuracy to their own statements leads to a surprising conclusion. 

     As we have seen, in their press release of January 1904 they stated

“Each time the machine started from the level ground by its own power alone with no assistance from gravity, or any other motive source whatever.”

Both of Orville’s articles from 1908 in The Century and 1913 in Flying include the statement that his first attempt was

“…the first in the history of the world in which a machine carrying a man had raised itself by its own power into the air…”

Obviously, the Wrights considered this to be an important criterion for successful powered flight.  As previously discussed, at Kitty Hawk, over 80% to 90% of their impetus for flight came from the ambient winds.  Without these winds they couldn’t have flown.  In 1904 at Huffman Prairie, even with over 200 feet of launch rail, they found that reliably getting their aircraft into the air was highly problematic due to insufficient winds.  So while there, and at subsequent locations for the next seven years, their aircraft enlisted the assistance for takeoff from either a very strong headwind or the catapult described to them in a letter from Octave Chanute.  The catapult used the pull of gravity on a falling weight of half of a ton or more in order to push their aircraft into the air. 

     None of their early aircraft - the 1903, 1904, 1905, and 1908 Flyers, as well as the subsequent Model A Flyer of 1909 and early 1910 - could initiate flight “by its own power alone”.  The Model B of late 1910 was the first Wright airplane that had wheels, sufficient structure, and enough power to enable it to take off from rough unimproved fields in reasonably calm air without the use of a catapult and launch rail. 

     By 1910, there were many other aircraft around the world that for a few years had been regularly accomplishing unassisted takeoffs, even from bumpy unimproved fields.  Although Wright Flyers could certainly fly once in the air, so could these other aircraft.  Taken together, these considerations lead to the surprising realization that there were many other aircraft that consistently accomplished all of the Wrights’ stated attributes of a successful airplane, including taking off “by its own power alone,” years before the Wrights’ own airplanes did.  If nothing more, this is at least a lesson in being cautious and consistent when applying words to one's self and to others.

   It is only fair to subject the Wrights’ claims and data to the same level of scrutiny to which other competing claims have been subjected.   They employed a catapult to reliably achieve takeoffs at Huffman Prairie, and also for their flights at Ft. Myers, and in Europe.  And without headwinds of at least 24 to 27 miles per hour providing over 80% of the necessary initial lifting force for their aircraft, there wouldn’t have been any flying by the Wrights in 1903 either.  In fact, until the later part of 1910 their aircraft were not capable of initiating flight by their own power alone, a capability the Wrights had repeatedly claimed to be an important attribute of a successful airplane.

Author's Notes

¹ Orville’s first attempt at flight in 1903 is often heralded as the first manned, powered, controlled flight by an airplane.  The vehicle certainly had a motor and he certainly was on board.  But the achievement of control is another matter entirely.

  The vehicle had aerodynamic controls designed into it and they were brought into play constantly in every trial of 1903.  And apparently, they did cause the airplane to react.  In the iconic “first flight” photo, the elevator had inadvertently been put in the full up position and the plane was said to have immediately zoomed up.  They said that the elevator was then quickly, and again inadvertently, put in the full down position and the airplane dove down.  One more cycle of this caused the vehicle to hit the ground, causing minor damage and ending the flight in 12 seconds.  Those extreme control positions, and the resulting reactions of the aircraft, are certainly not what Orville intended.

     That was not a controlled flight.  Controlled flight is only achieved when the pilot can control the aircraft to go in the manner and direction that he wishes it to go.  According to the Wrights’ descriptions, that was only achieved during the mid portion of the last trial of the day.  At all other times, and throughout all of the other attempts, the vehicle was clearly not doing what the pilot intended and was thus out of control.  The “first flight” photo with the elevator in the full up position just after takeoff shows the pilot struggling to achieve control, which he never did.

²  A number of measurements have shown the airplane in the “fourth flight” photo to be less than 300 feet from the launch ramp.  Consequently, the issue of whether the propellers were stopped when this photo was taken is crucial in determining if the aircraft in this photo could have continued on to the 852 foot point.  The only remaining question is, would it have been possible for the Wrights’ camera to have taken a clear sharp picture of spinning blades?

     The Wrights’ 5”x7” glass plate camera was a Gundlach model Korona-V with a Series F pneumatic shutter.  Along with slower speeds, the shutter was capable of speeds of 1/25^th, 1/50^th, and 1/100^th of a second, the fastest available.  Although the engine was capable of 1,200 rpm, the Wrights claimed it recorded only about 1,000 revolutions during the last trial that they said lasted 59 seconds, i.e., an average of 1,000 rpm.  The gear reduction from crankshaft to propellers was close to 4 to 1.  Although meticulous photo logs indicate that the Wrights usually used a shutter speed of 1/25^th of a second, a couple sources, including the Ohio Memory Collection, claim that the Wrights said they had the camera set at 1/50^th of a second for the iconic “first flight” photo.  Since the lighting appears to have been no better during the “fourth flight,” it seems likely that the exposure setting wasn’t changed for that event.  If so, the propeller blades would have swept at least 30 degrees of arc during the exposure.  This is consistent with the barely visible blurs of the spinning props in the photos of the first and third attempts of the 17^th of December.

From view of the Wright Flyer showing the two propellers.

    Measurements of the blades taken from an original 1903 Wright propeller shown on page 81 of The Wright Flyer, an Engineering Perspective, and an excellent frontal view of the 1903 aircraft (Library of Congress number LC-W86-24[P&P]) show the apparent subtended angle of each twisted blade to be 7½ degrees.  The three blades visible in the “fourth flight” photo, although difficult to measure, under six power magnification measure no more than about eight degrees in subtended angle.  If the engine was turning at flying speed and the shutter was set to the value used for all other photos of the airplane in flight, the blades would have shown blurs at least four times as wide as is shown in the photo, if they would have shown at all.

     Considering worst cases, if the engine was turning 1,100 rpm the blades would still have looked over four times as wide.  Or, if for some reason the shutter speed had been reset to 1/100^th of a second, the blades would still have appeared at least 2½ times as wide as they do.  Even under the most extreme circumstances imaginable, with the engine turning only 1,000 rpm and the camera set at 1/100^th of a second (its minimum exposure time), the blades, if visible, would still have looked more than twice as wide as they appear in the photo. 

     The actual case appears to be 1,000 engine rpm and 1/50^th of a second exposure, which would result in a blur approximately four times the width of a blade, about 30 degrees.  The inescapable conclusion is that the aircraft’s propellers (and engine) were stopped less than 300 feet from the launch rail in the photo claimed to be of the fourth flight at Kitty Hawk on December 17^th, 1903.  Apparently, this has not been noted before now.

³  An article by Carroll F. Gray published in the August 2002 issue of World War I Aeronautics – The Journal of the Early Airplane addresses some of these issues. Titled "The First Five Flights," the article discusses the Wrights’ narratives, their distance criterion, the wind, their lack of control, and the distance shown in the “fourth flight” photo.  In all of these aspects it agrees with this analysis.  However, it does not address the three objects in the lower wing, the stopped propellers, and the fact that the aircraft in the photo must have been at or very near the end of its flight when the photo was taken.

⁴   Smithsonian authors and others have referred to the events of 1903 at Kitty Hawk as the first "sustained" flights of a manned, powered, controlled airplane. Since mensuration of the longest flight attempt has shown that the vehicle did not meet the Wrights' own criterion for a minimum, sustained flight and the Wrights did not use that term, it is not used in this article.
  


Editor's Notes:


* The lifting force on an airplane is proportional to the square of the airspeed. Also, the minimum takeoff speed of the 1903 airplane is very close to 30 mph. Therefore, the 27 mph steady headwind speed on the first trial of December 17th represented 90% of the takeoff speed, and - since 0.9 x 0.9 = 0.81 - about 80% of the lifting force at takeoff. Similarly, since the headwind for the fourth trial hours later was 24 mph, or about 80% of the minimum takeoff speed, the lifting force provided by it was 0.8 x 0.8 = 0.64, or about 65% of the required lift.

** See note * above. 

*** An article detailing the calculation of the "Fourth Flight" distance will follow soon.

**** Handwriting analysis has shown that the description on the reverse of the "fourth flight" photo at the Wright Library was written, as were captions of other photos sent to the Library of Congress, by Orville Wright. Orville wrongly states, as we have demonstrated, that the "fourth attempt" picture shows the end of the 852-foot flight.

***** Daniels made no mention of taking a photograph until much later. However, in his first interview, he stated he was supporting the wing of the plane during the first takeoff. He couldn't have done both. It is only logical that he could not have known about the photograph unless Orville had told him.

Updated information of note:: In the next blog post, "Mensuration of the Fourth Flight," Joe Bullmer provides a detailed study of how the "fourth flight photo" was analyzed.