The Wrong Wright Story 2
Peter Jakab's Visions of a Flying Machine
Part II of a critique by Joe Bullmer
 |
| Left: Peter L. Jakab of the Smithsonian Institution; Right: Jakab's book Visions of a Flying Machine |
Introduction to the Wrong Wright Story series:
This is the second in a series of critical reviews of four books and a television documentary about the Wright brothers’ creation of an airplane. The books include a biography authorized by Orville Wright, and three more by senior officials of the Smithsonian’s National Air and Space Museum. This article refers to the paperback reissue of Visions ofa Flying Machine by Associate Director Peter Jakab, published in 1990 by the Smithsonian Press, ISBN 1-56098-748-0.
These books were chosen because they have been used as source material for dozens of other publications containing discussions of the Wright brothers’ work and accomplishments. The NOVA documentary Wright Brothers' Flying Machineis perhaps the most prominent of approximately a dozen produced since 2003 portraying the invention of the airplane.
These five accounts all contain numerous fabrications and false statements that contradict the Wright brothers’ original records, the records of other aviation researchers who preceded the Wrights, and even aviation science. Unfortunately, other authors have relied on these books as bases from which to launch into discussions of the Wrights’ work. As a result, nearly every source of information on the Wright brothers’ work is contaminated with some of these same falsehoods and errors.
This series of articles represents an attempt by this author to establish “truthinaviationhistory” concerning the work of the Wright brothers. With this goal in mind, any technically qualified rebuttal to these critiques, or criticism of The WRight Story, would be welcomed.
Visions of a Flying Machine: Overview
It may seem unlikely that a book with such an extensive list of contributors in its Acknowledgements section as Visions would contain so many errors. However, only three contributors are credited with technical qualifications. One of these made similar errors in his books, which subsequent articles in this series will reveal. The others have published only limited writings on the Wright brothers, indicating only limited research.
A couple years of researching thousands of pages of original records of the Wrights and their predecessors resulted in my publishing a book in 2009 titled The WRight Story. Reliable primary and secondary sources were consulted for historical events preceding the Wrights and those after 1905. However, only original Wright material was consulted for all descriptions of their work resulting in a successful airplane by October of 1905. Surviving authors and producers of the works discussed in these reviews were contacted in an effort to discuss and resolve differences, but none have expressed interest in pursuing a dialogue.
A first reading of the book being discussed in this article revealed over 160 exaggerations or errors. Just addressing the 43 listed here precluded citing complete sources for each comment. However, eliminating more would be an injustice to portraying the nature of the book.
Chapter 1: "Why Wilbur and Orville?"
Page 15: The author claims “The majority of the critical elements in the airplane were original to the Wrights.” Actually, Wilbur admitted that the truss biplane structure was copied from the Chanute/Herring glider, their successful post-1902 wing camber and aspect ratios were essentially those used by numerous predecessors, and wing warping had already been used and patented by at least three experimenters. Cambered twisted propellers had also been recommended by a few predecessors, and even the forward elevator was a feature of Maxim’s 1894 machine. The only feature “original to the Wrights”, opposable wing warping with a mechanically coordinated rudder, had to be abandoned by them in 1905 in order to make turns.
 |
| The Chanute/Herring glider |
Page 16: Here he repeats, writing that “Much of what the Wrights accomplished was highly original.” These comments are the first examples of the author's frequent contradictions, since page 217 says that “with the exception of the propellers, there was nothing fundamentally original about the way in which (sic) 1903 machine was designed”. In a sort of double reverse, the next paragraph on 217 says “they invented a fundamentally new technology.”
Chapter 2: "Aeronautics before the Airplane"
Page 33: The author claims that “Using [Otto Lilienthal’s] data and tables, an experimenter could easily calculate the size wing required to support a given weight at a particular velocity.” Then on pages 143 to 149 he talks about how bad he thinks Lilienthal’s data was. This is another unresolved contradiction in the book.
Chapter 3: "'You Must Mount a Machine'"
Page 46: The author writes, “[Lilienthal] failed to see that [weight shifting] was a dead end as far as a large, powered aircraft was concerned.” Actually Lilienthal did not “fail to see that.” On page 284 of the current edition of his book Birdflight as the Basis of Aviation, Lilienthal pointed out that although wings twice as big would be more optimum for gliding, he felt he couldn’t safely handle gliders larger than about 160 square feet with just weight shifting. In the 1896 edition of James Means’ TheAeronautical Annual, Lilienthal reported that he was well aware aerodynamic methods would be necessary to control larger aircraft. In fact, he was collaborating with other German experimenters on the design of such controls and had begun experimenting with them. Some claim it was actually a failure of one of these devices, rather than a piloting mistake, that resulted in his fatal crash.
 |
| Left: Lilienthal's Birdflight as the Basis of Aviation; Right: Chanute's Progress in Flying Machines. |
Page 48: Here the Wrights are given credit for being the first to realize that control was the most important problem to solve. But in his 1894 book Progress in Flying Machines, the Wrights’ principal research source, Chanute stated that experimenters should direct their attention to gliding or “soaring” flight, and that the “maintenance of equilibrium….was by far the most important aspect of flight yet to be solved”. Nonetheless, in the book under discussion, this author goes on to say that “The Wrights’ recognition of the centrality of control…was…the premier conceptual leap that set them apart from their predecessors and their contemporaries.” He apparently has no idea that they read it in Octave Chanute’s book.
In the next paragraph, Alphonse Penaud is given credit for developing dihedral for roll stability during the 1870s. Yet again a lack of research is evident. Sir George Cayley invented dihedral and reported on it in the November, 1809 issue of Nicholson’s Journal of Natural Philosophy, Chemistry, and the Arts.
Page 49: The careless claim is made that “proponents of inherent stability gave no thought whatsoever to controlling or steering their machines.” adding “Many reasoned that if simple straight-line flight was achieved, control could be easily dealt with later.” This completely misses the fact that that is precisely the approach the Wright brothers took, concentrating solely on achieving straight line flight until 1904, then beginning attempts at maneuvering and turning, finally accomplishing these by October, 1905. They stated this many times, even in their patent, wherein on page three, lines 78 to 87, they explained that their moveable coordinated rudder was invented to maintain straight and level flight.
Page 50: In the second paragraph a severe lack of knowledge of aircraft design is exhibited by the author. He states “The Wrights were the first to see that control was [for airplanes] the very essence of maintaining equilibrium.” Actually, until recently all airplanes have been designed such that, once trimmed, they maintain equilibrium completely by their aerodynamic design without any control movements whatsoever. This was true of airplanes immediately following the Wright Flyers, and is largely what caused the Wrights to eventually totally change their designs not long before going out of business.
Later in the paragraph the author's lack of knowledge is confirmed by saying “…just as a cyclist must make constant control movements to stay on two wheels, the airplane pilot must exercise similar authority over his craft to stay in the air.” Anyone who has ever flown in an airplane, or even seen a film of a pilot flying one, should know this is not true. Even more astounding is the number of “aviation historians” that have confidently parroted these absurd statements in their books and TV appearances.
Page 51: The Wrights’ experience of riding bicycles is given credit for the idea of banking an airplane in order to turn. This is another fallacy that has been picked up by countless authors and “aviation historians.” It’s quite likely that some cavemen, over 100,000 years ago, noticed that birds always bank when they turn.
Page 58: Here and on the next page indecision is expressed as to whether or not the Wrights copied the trussed biplane design of the Chanute/Herring glider of 1896. Again, lack of research glares out. The Wrights both said they did! In a December 21st, 1909 letter Wilbur wrote, “We have repeatedly acknowledged our indebtedness to the Chanute double-decker for our ideas regarding the best way of obtaining the strongest and lightest sustaining surfaces [wings].” Explaining their design in his sworn deposition for the 1920 Montgomery case, Orville testified that “it was apparent that the wings of a Chanute double-deck type [of glider] could be warped.”
 |
| Octave Chanute and his 1896 "double-decker" (as the Wrights called it) |
Chapter 4: "Learning the Art of Airplane Design"
In this chapter, the book’s author, a history and arts major, attempts to explain key aerodynamic and stability and control aspects of aircraft design. Only major errors are discussed here. There are many others.
Page 65: At the bottom of the page he writes, “Although the record shows little specific discussion of these issues by the Wrights before 1901, it is clear….that they had at least a basic understanding of the reversal of the center of pressure before building their first full-size machine.” (Although he cites two references in the Notes section of his book for this statement, examination of the references reveals no justification for such a statement.)
On the next page he reverts to his favorite theme of Wright perfection, saying “Just as their initial instincts…regarding control moved them well ahead of their contemporaries, so too did their beginning assumptions concerning aerodynamics.”
Actually, both brothers recorded statements directly admitting that their canards (forward elevators) were the result of their erroneous concept of the movement of the center of pressure on a wing. During his speech in Chicago in 1901 Wilbur stated, “Our peculiar plan of control by forward surfaces instead of tails was based on the assumption that the center of pressure would continue to move farther and farther forward as the angle [of attack] became less”, an assumption that proved to be false. In his legal deposition of 1920, Orville recalled their perplexity thus: “Our elevator was placed in front of the surfaces [wings] with the idea of producing inherent stability fore and aft, which it should have done had the travel of the center of pressure been forward [with decreasing angle of attack] as we had been led to believe.”
The author admits that he couldn’t find much about the Wrights’ knowledge of center of pressure movements before 1901. The reason is that they didn’t know how it moved until the summer of 1901 when Chanute’s cohorts Edward Huffaker and Dr. George Spratt demonstrated it to them through wing balance tests at Kitty Hawk. Wright statements reveal that the reversal of movement of the center of pressure came as quite a surprise to them. Evidently they had only seen data on flat surfaces and neglected to check cambered ones.
This is a good spot to address the constantly repeated claims throughout the book that the Wright’s “intuition” or “instinct” about aerodynamics enabled them to “visualize” air flow correctly in their minds without actually seeing it. This ability is credited for their development of their 1900 and 1901 wing shapes which he repeatedly claims were very good. He later contradicts these statements by blaming Otto Lilienthal’s data for these two vehicles having totally inadequate lift.
In fact, these vehicles could barely fly, and the Wrights’ wind tunnel showed them they had to change wing camber and aspect ratio to something very similar to Lilienthal’s (and numerous other predecessors) which solved their lifting problems. In a November 24th, 1901 (i can't find this letter) letter to Octave Chanute, Wilbur admitted that “It is very evident that a table based on one aspect [ratio] and [wing section] profile is worthless for a surface of different aspect and curvature. This no doubt explains why we have had so much trouble figuring all our machines from Lilienthal’s table.”
Other examples of the Wrights’ “instinct” for aerodynamics failing them, but not noted in this book, were not seeing
- How cambered wings generate lift.
- That an airplane needs tails to be easily controllable.
- How wing warping would work in free flight.
- That a fixed vertical tail wouldn't stop their warp-induced spins.
- That stability and insensitivity to crosswinds were opposing goals.
Page 66: We are informed that when the center of pressure and center of gravity coincide, an airplane is at equilibrium. Instantaneously, yes. But practically, equilibrium implies stability at that point, i.e., the airplane should want to stay there. That requirement is something that eluded the Wrights, and evidently also the author of the book being discussed.
Page 67: Here he states that Horatio F. Phillips’ 1884 airfoil shapes set the precedent for the Wrights’ early airfoils. One can only conclude that he has never seen Phillips’ airfoils because some of them look quite modern, and all had maximum cambers at least a third of the way back, as opposed to those of the Wrights in which maximum camber was located immediately behind the leading edges.
 |
| Horatio F. Phillips' patented airfoil shapes |
The author goes on to incorrectly discuss camber as if it was only “the [maximum] depth of the curvature” as opposed to the entire curvature of the wing from leading to trailing edges, including the critical location of maximum camber.
Page 68: Again, reality is contradicted here by saying that the Wrights’ early wings, with maximum camber right behind the leading edges were a “marked improvement in aerodynamic efficiency over the….wing used by Lilienthal and others” and “it also provided much more lift than the wings used by contemporary glider experimenters.” (Here again a source in his Notes section of the book is referenced that has nothing to do with his claim.) Contradicting this on pages 154 and 155 the author admits that their 1900 and 1901 wings were terrible and the wind tunnel showed that they had to move maximum camber much farther back and increase aspect ratio (more than doubling it to Lilienthal’s value) to obtain reasonable lift for their 1902 glider.
Page 69: He attempts to explain the “Penaud” method of achieving longitudinal stability but gets it exactly backwards by saying Penaud set his horizontal tails at a positive angle of attack. His explanation of how this would work is incoherent since it can’t work. In fact, Penaud set them at negative angles of attack to balance out the centers of gravity which were placed ahead of the centers of lift to achieve dynamic stability. With this, if the aircraft pitched nose up, Penaud’s negative tails would have a less negative angle to the wind and push down less, allowing the forward center of gravity to pull the nose back down. If the aircraft was pitched nose down, the tails would have a more negative angle, push down harder, and bring the nose of the vehicle back up.
Penaud's "aeronautical machines:" helicopter, planophore, and ornithopter.
And by the way, this author, like most all others, erroneously credits Penaud with originating this method of achieving stability. Sir George Cayley reported on using it for his unmanned gliders in Nicholson’s Journal in 1809.
Later on this page the author reveals the falseness of his assertion on page 65 that the Wrights knew about the reversal of movement of the center of lift (pressure) when they started. He says here that they “designed their forward rudder [canard] as if they were dealing with a wing having the properties of a flat plate,” i.e., no reversal of travel of the center of lift with angle of attack.
Page 70: Here he says “the Wrights’ scheme of a moveable elevator to keep pace with a constantly roving center of pressure was fundamentally sound, and it has been the method for pitch control on virtually every airplane since.” Yet again ignorance of aircraft design, and even flying, is revealed by not knowing that airplanes, once the horizontal stabilizer is trimmed out, do not need any help from an elevator to maintain longitudinal balance. A proper understanding of the “Penaud” technique would have revealed why.
Page 71: The author states that a canard stalls before the main wings because of its smaller size and thus avoids stalling of the wings which he implies is a stabilizing effect. Thus, two mistakes for the price of one. First, nothing stalls because of its size. It would stall first because of lack of camber or higher angle of attack, but not because it was smaller. Also, their canard is what made the airplane unstable and caused it to depart from level flight in the first place. It was therefore destabilizing.
Page 75: It’s asserted here that the Wrights didn’t put a vertical tail on their gliders for the first couple years because “it would complicate matters unnecessarily.” No, they didn’t think one was necessary because they were only trying to fly straight, and their aerodynamic “instinct” didn’t tell them about wing warping creating asymmetric drag which yawed their airplane. That’s why a rudder was required; to maintain the original heading.
In fact, in his speech in Chicago in 1901 Wilbur erroneously stated that “tails, both vertical and horizontal,..…may with safety be eliminated.” He then proceeded to design their next machines with vertical tails.
Page 78: Here the author explains the lift and drag equations as though lift and drag coefficients are the same for all wing shapes. Actually, until November of 1901 the Wrights thought so too.
Page 81: The bizarre tutorial on aerodynamics and airplane design is wound up by again admiring the Wrights’ supposed ability to mentally visualize aerodynamics, which, as previously noted, was often wrong.
Conclusion - Part I:
At this point the first four chapters of the book Visions of a Flying Machine have been discussed. Due to the length of this critique the remainder will be discussed in the second part appearing shortly in truthinaviationhistory. That part of the article will begin the discussion of Chapter 5 with a list of ten seldom noted, but well documented, significant contributions to the Wright effort by Octave Chanute, without which the brothers' achievement of success would have been problematic.
No comments:
Post a Comment