The Wrights' "Fourth Flight" - Mensuration

Mensuration  of  the  “Fourth  Flight”

by Joe Bullmer 

( Figure 1)  Photograph identified by Orville Wright as the end of the fourth flight Dec 17, 1903

Measurements

          On December 17th, 1903,  the Wright brothers claimed they made four attempts at manned, powered flight near Kitty Hawk, North Carolina. Piloting was alternated between the brothers with Orville making the first attempt. The first three were basically out of control throughout, none exceeding 200 feet in distance. However, the fourth attempt, the second by Wilbur, was claimed to have gone 852 feet with its mid portion under fairly smooth control. 

         A photograph which Orville Wright asserted in writing was taken after the fourth attempt, shows the launch rail and the aircraft off at a distance. (See Figure 1 above.) Some have questioned whether the aircraft actually appears to be 852 feet, a sixth of a mile, beyond the end of the launch rail. Consequently, an analysis of the photo was done using magnification devices and common geometric and trigonometric mensuration techniques on large scale proportionally accurate prints of this and other relevant Wright photographic plates.

         One of the first things evident in this analysis, particularly on blowups of the photo in question, is that the propellers, and thus the engine of the aircraft, are stopped. Apparently this had not been noted prior to this examination. Also, the aircraft is on or very near the ground.  If indeed this is a photo of a flight, it was definitely taken after the end of it. (Figure 2)

      

(Figure 2) "Fourth Flight" photo blown up, showing one of the stopped propellers highlighted.

     The first step in any mensuration analysis is to identify known dimensions. The launch rail appearing on the right of the photo was known to be 60 feet in length.  The airplane off in the distance had a wing span of 40 feet and four inches with a separation between the biplane wings of 74 inches.  (Due to the small size of the image and its rounded wing tips, for mensuration purposes the wing span used here was 40 feet, an approximation of less than 1%.)  Comparison of the ratios of wing tip separations to span showed the aircraft to be headed within a few degrees of directly away from the camera, its wings essentially crosswise to the camera. (parallel to the optical plane).

         Major unknowns in the subject photo are the focal length of the camera, the distance from the camera to the launch rail, the rail’s angle to the camera, and the size of and distance to the sawhorse appearing in the photo.  Focal length of a camera can often be used to calculate accurate distances to objects of known size. However the bellows type camera used by the Wrights has a variable focal length dependent upon the lens used, so since no record of it was found it was considered unknown for this analysis.  Also, since the camera’s tripod had adjustable legs, it’s height above the ground is not precisely known.

     In mensuration of this type, it is desirable, if possible, to perform independent analyses using horizontal and vertical dimensions for verification or refinement of results.

    Horizontal Mensuration 

         The camera was mounted on a tripod about four feet in height and obviously pointed somewhat downward as evidenced by the optical axis being below the far horizon in the uncropped version of the photograph appearing as Figure 3.

 

(Figure 3)  Uncropped photograph that Orville Wright identified in writing as the end of the 852 feet fourth flight

   

         Subtended angles of objects in the photo as well as the angles between objects were measured from a reference point at the bottom center of a large proportional blowup of the image.These angles were then graphically referenced back ten feet to an assumed camera position.  The distance from the reference point at the bottom of the photo back to the camera position was estimated considering camera format, pointing angle, and footprint sizes appearing at the bottom of the photo.  It will be shown later that, due largely to compensating factors, the exact distance between the camera and reference point is not critical to calculation of the distance from the end of the launch rail to the aircraft. 
  

         Ignoring less than two degrees of parallax, the triangle described by the 60-foot rail and lines from its ends to the camera resulted very nearly in an isosceles triangle lying on the ground.  Bisecting the 26º vertex of this triangle yielded two right triangles 30 feet on their short sides with angles opposite those sides at the camera of 26º/2 = 13º.  (Figure 4)

Figure 4

   Then 30/tan13º = 30/.231 = 130 feet for the distance from the camera to the center of the launch rail.  But the concern here was with the distance of the aircraft from the launch end of the rail, so that end was 130/cos13º = 130/.974 = 133 feet from the camera. The bisector of the 26º angle (the center of the rail) was 28º from a line through the optical axis.  
  

       Mensuration was carried out using these values, namely 40 foot wings separated by 74 inches and a 60 foot launch rail canted at 28º from the optical plane, the launch end of which was 133 feet on the ground from the camera.
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    In a large print of the fourth attempt photo, the launch rail measured 3.75 inches and the wing span .99.  Two thirds of the 60 foot rail equates to the aircraft’s 40 foot wingspan, so the rail measurement was reduced by two thirds to 2.5 inches to represent the aircraft’s wingspan.This measurement was rotated to be perpendicular to the optical axis of the camera (parallel to the optical plane and the aircraft's wings) by dividing it by the cosine28º which is .883.  Thus forty feet of the rail rotated to perpendicular to the optical axis became 2.5/.883 = 2.83 inches.  (Figure 5)

Figure 5

     Objects twice as far look half as big, so the ratio of their measurement scales is proportional to their distances from the camera.  On the blowup the aircraft’s 40 foot wings measured .99 inches and 40 feet of the rail rotated crossways to the camera was  found to be 2.83 inches.  Their scale ratio is then 2.83/.99 = 2.86. The aircraft was thus 2.86 times farther from the camera than was the end of the rail, or 2.86x133 = 380 feet from the camera.

     Unfortunately since the rail end and the aircraft are not on a straight line from the camera their distances could not simply be subtracted to arrive at the distance of the aircraft from the rail.  Consequently a double triangulation had to be used. 

     The camera, rail launch end, and aircraft center formed a triangle whose angle at the camera was 32º with the distance from the camera to the rail's launch end having been found to be 133 feet.  (Figure 6)

Figure 6

     A line was drawn from the rail end perpendicular to the line going from the camera to the aircraft. Thus two right triangles were formed, one with its acute angles at the camera and rail end, and an adjacent one with its acute angles at the rail end and the aircraft.  Both triangles shared the line from the rail end running perpendicular to the camera-to-aircraft line.The length of the shared line was sin32ºx133 = .53x133 = 70.5 feet.

     The length of the line from the camera to the perpendicular line was cos32ºx133 = .848x133 = 113 feet.  Subtracting this from the distance from the camera to the aircraft gave 380 – 113 = 267 feet from the perpendicular line to the aircraft.  Then the angle of the triangle at the aircraft equaled the arctan70.5/267 = 15⅓º.  The hypotenuse of this right triangle was 267/cos15⅓º = 267/.964 = 277 feet which is then the distance of the aircraft from the launch end of the rail.

      A possible uncertainty in this analysis was the distance of the point on the ground shown at the bottom center of the photo from the camera, so the entire analysis was repeated with the distance set at zero.  Since there are a number of offsetting factors in the procedure (primarily angles offsetting distances) the result for distance of the aircraft from the launch end of the rail in this case was 275 feet, a change of less than 1%.  Thus the calculated distance of the aircraft from the rail is essentially independent of the distance assumed from the camera to the reference point at the bottom center of the photo.   

    

Vertical Mensuration

     There are two objects in the fourth flight photograph other than the airplane that show vertical dimensions, the launch rail and a sawhorse.  Unfortunately, the rail height is two orders of magnitude smaller than its length used in the horizontal analysis.  Analyses similar to the horizontal analysis just described but comparing rail heights to aircraft wing vertical separation revealed that an error of one one-hundredth of an inch in measuring the rail height on the blowup of the fourth attempt resulted in an error in calculating the distance from the rail to the aircraft of over 80 feet or about 30%.  The height of the rail near the launch end in the blowup varies from .04 to .06 inches depending upon exactly where it is measured.  Thus it was evident that rail height could not yield a solution comparable in accuracy to that obtained in the horizontal analysis.

   The other vertical dimension that might be compared to the aircraft’s wing separation is the height of the sawhorse.  But there are a number of problems associated with using the sawhorse.  First off, there were at least two sawhorses used by the Wrights at Kitty Hawk.  One appears in a photo from December 14^th of 1903 and another in a photo from May 11^th, 1908.  In both photos sawhorse heights could be scaled from the separation of adjacent aircraft wing tips.  The one from the 1903 photo measured about 21 inches high and the other 28 inches high.

      To calculate the distance from the camera to the sawhorse in the fourth attempt blowup the sawhorse width must be determined.  In both photos mentioned in the previous paragraph the sawhorses were at oblique angles to the optical axis of the photos, and the obliquity angles could not be determined with any accuracy.  Thus although their heights could be measured, the spread of the sawhorse legs could not accurately be determined from these photos.

     In the fourth attempt photo the sawhorse was almost in line with the optical axis and its leg spread is 0.825 of its height.  This ratio could be applied to the known heights of the sawhorses in the other photos to determine their widths, but this left another uncertainty, namely which sawhorse to use.

     A much greater uncertainty arose from the measurement of the subtended angle of the sawhorse legs from the camera in the fourth flight blowup.  Not only was the horizontal subtended angle small (from two to three degrees) but optical parallax becomes a factor.  The vertical parallax angle to the sawhorse would be nearly six degrees, a non-negligible amount.

     (The importance of parallax can be easily seen by looking down one of the acute angles of a 45º or 30º-60º triangle.  Looking straight down on the triangle the true angles are obvious.  But looking at an acute corner with the triangle nearly edge on to the line of sight it becomes evident that even small changes in viewing angles result in big changes in apparent angles of the corner.  In fact, at only small sight angles to the plane of the triangle its acute corners appear as obtuse angles.)

     Determination of the distance from the camera to the sawhorse was crucial in determining its scale factor relative to the scale factor of the aircraft, and thus the distance to the aircraft.  Multiple analyses revealed that an error in the subtended angle of the legs of the sawhorse of ½ degree resulted in an error in calculation of the aircraft distance from the end of the launch rail of over 70 feet.  Considering possible errors introduced from assuming:

      a.  that both sawhorse proportions are the same,

      b. that the subtended angle of the sawhorse legs from the reference point in the blowup can be determined much more accurately than ½ degree, and

      c.  that six degrees of parallax can be neglected,

it was concluded that any aircraft distance derived from the sawhorse could not lend more accuracy to the result obtained from the horizontal analysis that used the launch rail length.

Result

    

     To explore any possible source of significant error, the horizontal analysis was repeated assuming that the camera was positioned 60 feet farther back relative to the launch rail, i.e., 30 feet behind a line on the ground perpendicular to the rail at its starting end. In this case the distance of of the aircraft from the rail's launching end came out to be 298 feet, an increase of 7 1/2 percent.  Consequently, the horizontal analysis is considered accurate to within about 7%.  Both vertical analyses, although encompassing the horizontal result, showed uncertainties of nearly 30%.  So it was evident that vertical analyses could not improve confidence in the result.  Thus the most confident result of the mensuration was obtained from the horizontal mensuration alone.  Therefore the conclusion of this analysis is that

The distance from the launch end of the rail to the aircraft was found to be 277 feet with a confidence of plus or minus 19 feet.

This is less than one third of the 852 foot distance claimed for the fourth attempt at Kitty Hawk on December 17^th, 1903.  Even the most distant results from the low confidence vertical analyses were well under half of the claimed distance.  In order for this analysis to yield the distance claimed, the rail would have to have been 200 feet long and 450 feet from the camera and this analysis would have to be in error by 210%.  Conversely, if it was 852 feet away from the end of the 60-foot rail, the aircraft's image would have to appear one-third of its present size.

Implications

     The photo claimed to be of the fourth attempt on December 17^th, 1903, at Kitty Hawk and examined here clearly shows that the propellers were stopped and the aircraft was on, or very near, the ground.  So, based on this analysis, either the aircraft did not go anywhere near 852 feet, or if it did, this is not a picture of it.

     In a November 2^nd, 1906, letter* to Octave Chanute, Wilbur Wright stated their opinion that any flight of less than 100 meters, 328 feet, would just be a "jump" and would prove, using his word, “nothing.” Here he was discussing distances over the ground and considering the requirement to achieve sufficiently stable control to demonstrate the thrust necessary to maintain flying speed and generation of enough lift to sustain the vehicle in the air as opposed to merely making a semi-ballistic hop using the kinetic energy obtained from a ground run.  None of the other attempts earlier that day exceeded 200 feet.  Consequently, this analysis indicates that, if held to their own criterion for success, the Wrights' photography provides no evidence of a successful powered flight in 1903.

Addendum

      To justify his first attempt on December 17^th as being a success, Orville claimed that without the strong headwind he would have flown over 500 feet.  Some might find it tempting to use this rationale to legitimize their claim for distance on the fourth attempt.  However, to Orville an even more important and often repeated claim was that their aircraft took off using “its own power alone with no assistance from gravity or any other motive source whatever.”

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     In fact the strong headwinds on the 17^th supplied 80% of the lift required for his and their subsequent takeoffs.  Without those strong headwinds there would have been no flying at all by the Wrights in 1903.  Their aircraft was almost flying sitting still.  So either it flew a great deal farther through the air but could come nowhere near lifting off of the ground on its own, or the plane left the ground on its own but did not demonstrate sustained flight.  It can’t be claimed that the wind had nothing to do with its ability to achieve flight but everything to do with it demonstrating successful flight distances.  Historians can’t have it both ways, and neither could Orville Wright.

     The result of this analysis also calls into question the claimed 59 second duration of the fourth attempt.  Dividing 59 seconds into 277 feet yields an average ground speed of only 4.7 feet per second, or about three miles per hour.  The official government records of the sustained wind speeds at Kitty Hawk on December 17^th as recounted by Orville Wright were 24 miles per hour at the time of their fourth trial and 27 miles per hour during the first attempt.  So the average airspeed for a 59-second, 277-foot fourth attempt would have been 27 miles per hour, the same as the minimum wind speed at the time of their first trial.  In other words, if on that day the wind was so strong that they needed 59 seconds on the fourth attempt to cover 277 feet, then with the stronger wind on their first attempt giving the same airspeed, their vehicle would have taken off on its first trial with no ground run at all and would have made no forward progress whatsoever. Obviously, a 59 second flight time is not compatible with the flight distance calculated herein.

     Assuming an average airspeed for their vehicle of 35 miles per hour on their fourth attempt, and a corresponding ground speed of 11 miles per hour (16 feet per second), it would have taken about 17 seconds to cover 277 feet. If the airspeed was 30 miles per hour, the flight time would have been 31.5 seconds. Headwind gusts would have increased these flight times slightly.

(Figure 7)  Photograph clearly showing three objects on lower wing. Again, this is the photo claimed by Orville Wright and historians to document the fourth flight, December 17, 1903. (blown up and cropped) **

     This analysis can offer no further insight into the significant discrepancies between the times and distances claimed for the fourth flight attempt at Kitty Hawk on December 17th, 1903 and those calculated herein from the photograph claimed to show the end of the fourth attempt.  It also does not address the three dark objects on the lower wing of the aircraft. (Figure 7 above.)

 *  This article is a companion piece to the previous study in this blog by Joe Bullmer titled: Kitty Hawk - 1903 - What Happened?  
Enjoy!

Copyright 2019 - Joe Bullmer
 

Aeronautical engineer, historian, and author, Joe Bullmer

"The WRight Story" available at Amazon.com.

**Note: Photos and their captions provided for the most part by the editor of "Truth in Aviation History."

   

   

    

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.