Sorting through Gustave Whitehead's many projects and machines can become a confusing blur of misinformation, lack of information, and errors. During an interview with the New York Evening Telegram published on November 19, 1901, Whitehead stated that he was then building a "new machine" which "'will be the twentieth I have made,' Whitehead said as he mused in his work to-day, and talked about the invention that promises to make him famous for all time. 'Eighteen of them were failures, through some small fault that I could not fathom at the time, but the last one I made rewarded my years of effort and accomplished what I have so long been trying to solve.'"
That would make the machine of May 1901 the Whitehead No. 19 machine, not No. 21, and would make the one he was constructing in late 1901 his No. 20 machine. However, complicating matters, some four years earlier Whitehead told reporters that as of October 1897 he had then built 42 flying machines. Even more confusing, he was reported in the New York Herald of June 16, 1901, as saying he had by then built "fifty-six flying machines" and that his "present perfected invention is his fifty-seventh…" Accepting that number would make No. 21 his No. 57.
A press release dated January 28, 1902, from the St. Louis, Missouri, Lousiana Purchase Exposition, states Whitehead "… calls it the Aeroplane Flying Machine and he has now reached number 21 in his series of machines." It's clear from the context of the release that Whitehead had planned to exhibit his "old" machine at the exposition. He is quoted from a letter he sent to the exposition, as saying "This machine on June 3, 1901, with an operator on board, flew one and one-half miles. It has done so on several times since with safety. This is the first machine of its kind that has ever risen in the air with a human being on board in an upward course."
The differing total numbers reflect not merely different categories of devices, including kites and such, but are apparently the result of simple overstatement or outright fabrication. Whatever the truth of those varying numbers of machines built, this machine would become known as the "No. 21" ("Weißkopf Nr.21").
The source of the basic design of No. 21 can be found in Le Comte Ferdinand Charles Honore Phillipe d'Esterno's proposal for a flying machine, that appeared in his 1864 pamphlet "Du Vol des Oiseaux" ("On The Flight Of Birds"). He offered his "... seven laws of flapping flight and the eight laws of soaring flight" the results of years of observing birds. Of particular note are Count d'Esterno's three requirements for flight, 1) "equilibrium", 2) "guidance" and 3) "impulsion." In that pamphlet, d'Esterno made the statement, "Gliding seems to be a characteristic of heavy birds; therefore, the odds are not stacked against humans doing the same in a fair wind."
D'Esterno's design was bird-like, not surprising since he believed a flying machine ought to imitate the motions of birds in order to fly. The tips and rear edges of the wings would be flapped, while the front central area of the wings would be fixed. A large horizontal tail surface was mounted on a universal joint and could be moved, at will, by the machine's operator. The operator also shifted their body in the machine's movable seat, to change the center of gravity and thus to control the machine while in flight. It's fairly certain that d'Esterno never began construction of his machine, but he did give considerable thought to how it would be controlled and how it should be built.
D'esterno's estimated total weight for the machine, including an operator, was about 330 pounds, supported by a total wing surface area of about 215 sq. ft. The wings were to each be 15 ft. 6 in. in span and were to have a maximum chord of 7 ft.
For power, d'Esterno thought the moving air would provide the power, and so no engine or other devices were suggested. His was an influential design, made more well known by its inclusion in Octave Chanute's 1894 Progress In Flying Machines (p.97). D'Esterno's thoughts and fundamental design were clearly the origin of No. 21's design, from the overall configuration to the shifting body weight control system.
As noted in other articles on this web site, 'Gus' Whitehead had ready access to d'Esterno's design in Octave Chanute's 1894 Progress In Flying Machines, which he took (along with Aeronautical Annuals for 1895, '96 and '97 and Proceedings of the International Conference on Aerial Navigation published 1894) from the Buffalo Public Library and never returned.
It would not be true to say Whitehead had closely copied d'Esterno's design. The broad elements of d'Esterno's machine are certainly present in Whitehead's No. 21, as are several details, such as shifting body weight for control (even though it would probably be marginally effective on No. 21), the use of a large horizontal tail which can be moved in pitch by an operator as needed, and a hull-fuselage, akin to a bird's body. The foldable wings, in planform and design, are strongly remniscent of the Lilienthal "Normal-Segelapparat" (normal soaring apparatus) glider's wings.
Still, the particular conjunction of various designs found in the Whitehead No. 21's design is Gustave Whitehead's.
The No. 21 monoplane was begun in Pittsburgh, Pennsylvania, during November of 1899. Many years later, Charles Galomboshe, Whitehead's friend, recalled helping carve the white pine propellers for No. 21. The first mention in newsprint of this flying machine is found in December 1899. By January, Whitehead was unemployed, and by June Whitehead and another friend were bicycling to Boston, where Whitehead hoped to be re-hired by the Boston Aeronautical Society. The two ended up in Bridgeport and settled there, in August of 1900. (See Article # 5 "Weisskopf/Whitehead Arrives in Bridgeport")
Work on the hull of No. 21 took place during the nights of November of 1900, under candle and lantern light in the cellar beneath 241-½ Pine St. No. 21 was completed in late April of 1901 in the yard and the small shop next the Whitehead home which also served as the place No. 21 was kept. As noted in another article on this web site, what looks like "Keep Out DANGER" was painted on the shop door.
On May 3, 1901, within days of being finished, Whitehead, "Andrew Cellie" and Daniel Varoni were at a field, under a Full Moon, testing the device using sandbags as ballast. (See Article # 8 "Out Fairfield Way…")This writer believes the photo to the left is of No. 21 while on exhibition at Atlantic City, New Jersey, during September of 1901
Whitehead's No. 21 reportedly went up, without anyone aboard, propellers turning, after being towed down a slope. At the end of a second test (still without an "operator" aboard), the machine's propeller supports were damaged when a tree was struck. The damage was repaired by late May, when Stanley Y. Beach took the photos that appeared in the June 8, 1901, Scientific American.
The most well known and most cited of the "flights" Whitehead claimed to have made, is the one on August 14, 1901, under a dark moonless sky, as dawn was just breaking. This is covered, in detail, in other articles on this web site. (See Articles # 1, # 2, & # 3 for discussions of the August 14, 1901, matter)
Among the many people who contacted Whitehead after stories of his "flight" on August 14th appeared in print, was Harry D. Le Cato, of Philadelphia, who wanted Whitehead to exhibit No. 21 at Atlantic City and to make demonstration flights along the beach. Whitehead signed a 6-month agreement with Le Cato in late August and on September 3, 1901, No. 21 was placed on paid exhibition at Young's Pier, Ninth St., in Atlantic City, New Jersey, where it apparently stayed on view for some weeks. There apparently was very limited publicity about the exhibition of No. 21, and very little coverage in newspapers. Whitehead was quoted as saying "…as soon as practicable I will make an attempt to fly for miles along the beach." but that did not happen.
While No. 21 was on exhibit at Young's Pier, it attracted the interest of Smithsonian Secretary Samuel P. Langley's aeronautical engineer, Charles M. Manly. He sent a letter on September 20, 1901, to Frederick Webb Hodge of the Smithsonian, who was then staying in Atlantic City, asking that Hodge discreetly examine the machine and report back, "If it will not be too much trouble, and you can find time…" Manly stated that "My opinion is the man is a fraud insofar as he claims to have flown in the machine, since I understand the whole construction is so flimsy that I seriously doubt whether the framework would hold together with an engine mounted in it and developing the 20 horsepower which Whitehead claims to have." Hodge might have reported to Manly in person, or not reported or any response might have been lost, since no record exists of Hodge's reply.
One wag stated that No. 21 had been engaged to draw the public because the "sea serpent" hadn't put in an appearance.
In a newspaper interview dated September 1, 1901, Whitehead mentioned that he had demonstrated his No. 21 to Le Cato…"I am not at all afraid of the result because I have already shown what the machine can do. Mr. Le Cato came out here yesterday on behalf of some patentists and capitalists and I showed him the automobile in operation. I got into the Condor, as I call my machine, and after I had got some speed along the ground, and when I had got up about 50 feet I started forward with the aid of my propellers, which, by the way, are very much the propellers on your ferry boats. When I had gone about half a mile Mr. Le Cato signalled that he was satisfied and I came down as easily as I went up."
There is at least one reference from Whitehead of a test flight in early June 1901 using No.21. On January 10, 1902, Whitehead wrote to the Lousiana Purchase Exposition, seeking to enter the contest for aerial machines, "This machine on June 3, 1901, with an operator on board, flew one and one-half miles. It has done so on several times since with safety."
Surprisingly, Whitehead makes no clear mention of the supposed (noted and notorious) August 14, 1901, "flight" in his letter of January 1902, and there's no mention of the supposed "flight" made on June 3, 1901 - neither is the supposed "flight" of late August made for Le Cato. Two newspaper articles, one in the June 8th New York Sun, and one in the June 10th Washington, D.C., Times, comment only on the May 3rd test, and make no reference to a "flight" on June 3rd.
So, the one "flight" Whitehead cites is not mentioned elsewhere, and the three other "flights" which are cited in newspaper accounts are not detailed in his letter to the exposition, which is odd. Saying, as he did, that "It has done so on several times since with safety." diminishes the event of August 14, 1901, as well as the other two supposed "flights," while highlighting a "flight" mentioned nowhere else. —That seems very strange.—
The No. 21 monoplane had a short lifespan, only a little over six months, from late April until mid-November, 1901. As early as late August 1901, he was calling his No. 21 "rough and cumbersome." By the time No. 21 was on exhibition to a paying public at Young's Pier off Ninth St., on the boardwalk at Atlantic City, 'Gus' was describing this machine as his "old one" and by November 19, 1901, Whitehead had abandoned it as (in his words) "junk." Whitehead was quoted in the Evening Telegram article saying, of No. 21 “There is the machine that I flew in. You can go out and look at it. It is abandoned now as junk for the new one I am making will be much lighter and stronger and will contain better material. The old one taught me my lesson, and that was enough for it to do.”
Whitehead's newly found investor and partner, Herman Linde, made an agreement in October 1901, that Whitehead would construct s flying machine and Linde would provide the funds.
Three months later, though, in his January 1902 letter to the Lousiana Purchase Exposition he said he'd be bringing his No. 21 to St. Louis, to compete for prizes. The No. 21 monoplane was the only machine Whitehead had to offer the exposition, since the "new" machine was incomplete.
A new shop was built in October and November of 1901, and staffed with machinists (former Wilmot & Hobbs employees) to build the next of Whitehead's machine, the No.22. After paying for the construction of a new shop for Whitehead (on the southside of Cherry Street, between Hancock and Bostwick Avenues - just across Cherry from Wilmot & Hobbs), Linde and Whitehead had a serious falling out. This was only a little over two months from when Linde opened an account at a lumber company on which Whitehead could draw funds.
By the spring of 1902, their relationship had ended over two things - the amount of money being spent and what Linde saw as Whitehead's insistence on building another "boat." Linde locked Whitehead out of the new shop, a lumber company took "Whitehead & Linde" to court for an un-paid bill, Linde said Whitehead had cost him at least $1,000 (one report said the total was $6,000), and that he, Linde, thought he'd been 'victimized' by Whitehead. (See Article # 6, to be posted, "Wandering Diogenes - Truth & Gustave Whitehead," for more information on the Whitehead-Linde Affair)
Since No. 22 was not completed, Whitehead with only his "old" "rough" "cumbersome" "junk" No. 21 to take to St. Louis. Junius Harworth recalled, 48 years later, that he and Whitehead had discussed how to freight No. 21 to St. Louis, and, Harworth recalled, they "studied plans to sail up the Hudson, the Great Lakes and on down the Miss.river." Ultimately, Whitehead didn't attempt to fly or even display his No. 21 at the exposition, although he did exhibit one of his engines at the exposition. — Some sloppy researchers have stated that a Whitehead engine was used in Tom Baldwin's California Arrow dirigible at the 1904 Louisiana Purchase Exposition. The engine used in the California Arrow was a Curtiss motorcycle engine, not a Whitehead engine —
After Whitehead's letter of January 10, 1902, to the exposition, there appears to be no more mention made of No. 21, however, there are a number of stories about young Junius Harworth, and other youths, making hops with it and in it, and towing it as a glider. For his part, Whitehead seems to have abandoned the machine after the first couple of months of 1902.
While Whitehead's next machine, his No. 22, is beyond the scope of this article, there are very interesting events associated with No. 22, and considerable controversy.
The following description is of the No. 21 Condor monoplane as it existed between late May and November of 1901. Stanley Yale Beach took what are arguably the definitive photographs of the machine one Sunday during May of 1901 (not during winter or early spring, as has sometimes been stated), likely on the 26th, after the damage done on May 3rd had been repaired. (See Article # 8 "Out Fairfield Way…")
HULL-FUSELAGE The No. 21's hull was 16 ft. in length. The hull was box-framed with wooden stringers and vertical frames. The hull was a constant 3 ft. high along the sides which were covered by muslin (some sources say "canvas"), and a strip of wood along the top edge of the hull sandwiched the muslin, securing it to the hull, as well as providing additional structural support.
The "new" machine which Whitehead was building during the last half of 1901 had a hull length of 18 ft., and several sources have confused the two. The No. 21's hull had a maximum interior width of 2' 6" and an overall maximum width of some 3 ft., while the "new" machine had a 4 ft. wide hull (probably the outside width).
The hull on one modern No. 21 has a slope to the hull in profile, which the original No. 21 did not have, the most commonly available three-view drawing of No. 21 also has this error, perhaps stemming from perspective in one of the Scientific American photos of June 1901. One source states that the framing was painted blue. The bottom of the hull was fitted with tongue-in-groove white pine flooring, and was, according to a source, made "water tight."
The hull had four 1 ft. diameter wheels of hardwood mounted underneath. One source says the wheels had a steel rim, others say the wheels were not rimmed, while another source says the wheels were made of laminated wood. The two front wheels were fixed to an axle, while the two rear wheels' axle was pivoted, allowing the operator to steer the machine while it was rolling or running along the ground. The control consisted of a drum around which a cord was wound, the cord's ends were then run along the sides of the hull, using pulleys, to the rear and fixed to each end of the pivoting axle. By turning the drum, using knobs attached to the drum, the machine could be steered.
There is some reason to believe that the classic fish-shape of the hull, broader near the fore end and tapering to the aft when seen from above, was devised by reflecting an 1891 patented Phillips aerofoil curve Whitehead found depicted in Octave Chanute's 1894 Progress In Flying Machines (p.168), one of the three aeronautics books he took from the Buffalo Public Library.
WINGS Bamboo fishing poles (likely Tonkin Cane - Arundinaria amabilis), each 16 ft. long, were used as wing ribs. The wing surface area might have been limited by the availability of lengths of bamboo. On No. 21, the muslin covering was attached using strips of ½ inch wide cloth, which was stitched by hand to the muslin in an "X," the ends of which were then tied above the bamboo pole, thus securing the fabric to the bamboo rods. The outboard ends of the poles were fitted into pockets sewn into the muslin at 10º intervals. The inboard ends of the bamboo poles were fixed into steel tubes, which were, in turn, pivoted to a quarter-circle arced platform, allowing the wings to be folded, as well as unfurled, very similar to the system used by the Lilienthal's, Otto and Gustav, on their "Normal" series of gliding machines.
The wings on No. 21 closely followed the Lilienthal design and by the mid-1890's that design was widely available, in detail. This set of plans appeared in the Aeronautics section (edited by Octave Chanute) of the September 1895 issue of The American Engineer And Railroad Journal.
The attachment of the muslin in the manner described, and the bamboo poles themselves, caused the airflow over the upper surface of the wing to be disturbed, and would have resulted in less lift being generated than theoretically possible. The most common theory of lift at that time held that lift occured on the bottom surface of a wing, so it would have made sense to ensure the bottom surface was smooth, while not being particularly concerned with how smooth the upper surface was.
The term in use at the time for the wings of No. 21 appears to have been "sails." The wings were stayed with wires, tightened with turnbuckles. the wires were not fixed to the tips of the bamboo poles, but were fixed to the poles about 4 ft. from the wings' outer edges. This could have been a serious problem as the ends of the wings were then free to deform and distort under aerodynamic pressures. The wings were set at a significant dihedral to provide a measure of lateral stability.
TAIL The tail surface, which had no camber other than it's natural droop, consisted of five 10 ft. long bamboo poles, with muslin segments attached as on the wings. The tail was not stayed with wires as the wings were - it was free to deform over its entire length. When not in use, the tail could be closed, horizontally, as the bamboo rods were pivoted in the same fashion as were the wings' bamboo poles. A supporting rod would be affixed to the tail when opened, to maintain the tail's shape. A framed triangular box surrounded the forward ends of the tail's poles, and perhaps it was to this box that the cords were attached which permitted the operator top raise and lower the tail, for pitch control. There were no surfaces for yaw control or roll control.
Whitehead stated several times that the yaw control was to be effected by the operator shifting their body weight (while standing, as Whitehead claimed to have been when making "flights") and by speeding up one propeller - or, conversely, slowing one propeller down - which would cause the machine to rotate in yaw about its center of gravity, but would not cause a clear change of direction. There is reason to believe that a movable seat on a frame might have been used to aid the operator shifting body weight, but as mentioned, Whitehead claimed to control his machine in flight while standing upright. This system also did not permit banks in the conventional meaning of the word. At least one of the modern versions of No. 21, the German Nr.21B, uses foot pedal controls to cause the tail surface (which is significantly larger than the original No. 21's tail) to lift on its right or left side, for roll control. Roll control and foot pedals were not mentioned as present on No. 21.
PROPELLERS The 6 ft., 12 lb., two-bladed propellers were patterned after the Hiram Maxim Type "J" design, and were typical of the period, wide-bladed at the ends and tapering towards the center. The Type "J" design was the most efficient of the eight that Maxim tested. The projected surface of each propeller blade's surface was 4 sq. ft. No. 21's propellers were made of white pine, and each of the four propeller blades was attached to flat metal strips, which were connected to the propeller shafts. The propellers counter-rotated, the port propeller rotated in a counter-clockwise direction as seen from the operator's point of view, while the starboard propeller rotated in a clockwise direction as seen by the operator. The propellers on No. 21 were not covered with aluminum, although they do appear to have a coating, perhaps aluminized varnish, or the same blue paint as used on No. 21's framing. Whitehead did state at least once that the propeller blades on his "new" machine had a thin aluminum sheet covering, but that was not present on No. 21.
POWERPLANTS Apparently, a few engine-types were used to power No. 21's propellers. The ones which appears to have been used most frequently were operated by compressed air, held in a tank placed in the hull and which was fitted to the hull's shape. The two 2-cylinder compound engines, said to generate a total of 20-horse power and to weigh 35 pounds, had bores of 2-¼" & 3-7/16" and a stroke of 7."
The two 2-cylinder compound engines were very similar to the Locomobile steam engine in use in Locomobile automobiles, then being manufactured in Bridgeport, and Whitehead worked for a time at the Locomobile factory. By varying the flow of compressed air to each engine the propellers could be differentially sped up or slowed down without a need for gearing or a transmission, as the two compound engines operated each propeller independently.
A 1-cylinder engine, said to generate 10-horse power and to weigh 22 pounds, with a bore and stroke of 3-7/16" x 8," was mounted on the floor of No. 21's hull and powered the front pair of wheels. One source states the drive was via a bicycle sprocket and chain arrangement. As No. 21 reached speed, this engine was said to be disengaged by having the flow of compressed air (or externally generated steam) stopped and shifted to the two 2-cylinder compound engines driving the propellers.
There is no clear evidence that the much-publicized Whitehead calcium carbonate/acetylene engine, said to power No. 21, was ever operated successfully.
If steam were used to operate No. 21's three engines, it wasn't from an onboard steam engine. The steam would have been supplied by the heavy Pacific Iron Works fishing boat boiler which Whitehead had held fast to a concrete base, the steam flowing through a rotating line then to No. 21 which was tethered to the rotating arm which held the steam feed line. A circular "runway" some 100 ft. (or 60 ft., accounts vary) in diameter was constructed by Whitehead on Wordin avenue just west of Bostwick. The "track" was 4 or 5 ft. wide and made of concrete shoveled over the ground. The boiler was described as weighing about 700 to 1000 lb., and was 2-½ feet wide, 4 feet long and 3 feet high. This arrangement was similar to the 200 ft. diameter wooden track used by Horatio Frederick Phillips at Harrow, England, in 1893, to test lift of various wing aerofoils (which he termed "sustainers"). (See Essay # 2, to be posted, "'Round & 'Round She Goes" for more on the Whitehead test track)
RIGGING The bowsprit and mast were each 1-½" in diameter, according to one source. They served the same function as the mast and bowsprit of a ship, to secure the rigging and thus to hold the sails in place. The bowsprit on No. 21 held the wings in their fully open position, using wires attached to the leading edge (a bamboo pole) of each wing. Additional wires, atop and below, were attached to a single wire running from each side of the mast up top, and to the rearmost motor and propeller support below, at the bottom edge of the hull.
There was one wire to each bamboo pole at about three-quarters the distance from the hull side to the tip of each bamboo pole. A period newspaper account states the bowsprit could be "unstepped" - a nautical term meaning removed from their mounts. In more than one account, the wings ("sails") were said to have been deployed once the machine had reached a proper speed, so some mechanism for tensioning the bowsprit wires running to the leading edge bamboo poles would likely have been used. The simplest means would have been to move the bowsprit into a vertical position while the machine is rolling and running along the ground, the wings folded along the sides, and then put into position "on the fly" - pulling the folded wings forward and into position. One account mentioned a "lever" which the operator could move to put the wings into position.
WEIGHTS The two 2-cylinder compound engines each weighed 35 lb., the 1-cylinder "automobile" engine driving the front wheels weighed 22 lb. The hull-fuselage "body" weight, including wheels, was stated to be 45 lb. The wings and tail were said to weigh, together, 35 lb. Adding those weights together gives a total of 196 pounds (doubling the 12 pounds cited as being per propeller, and assuming the two engines are mounted). Not all weights were mentioned in articles, so wiring, turnbuckles and other fixtures are not included in the individual weights the Scientific American article mentions.
WING LOADING The total No. 21 weight "when equipped for flying" (apparently without an operator) was stated to be 350 pounds (recall that d'Esterno estimated a total weight with an operator of 330 pounds). Adding 165 pounds (Whitehead's weight) for an operator, yields an "all-up" weight of 515 lb. Wing loading at that weight would have been 1.29 lb. per sq.ft. - for wings and tail combined, the loading would be 1.14 lb. per sq. ft., both are in the range of modern hang gliders.
THRUST - "PULL" The "dead pull" was measured at 365 lb. "Pull" (thrust) was measured in those days by securing a line to a machine and attaching it to a butcher's meat scale, which could register hundreds of pounds, then attaching the scale to some fixed or heavy object.
1) POSTED: Junius Harworth's 3-view drawing of No. 21 "from memory" - January 18, 1936 - the views have significant errors and are posted here for their historical value; previously unpublished 2) (to be posted) Sikorsky Helicopters engineer Irving Burger produced 3-view drawings of No. 21, in at least four versions, ca. 1967 3) POSTED: Bjorn Karlstrom's 3-view rendering of the "Whitehead N-21" appeared in American Aircraft Modeler magazine, November 1968 (vol. 67-5, p.16); errors are apparent, especially in the shape of the hull-fuselage and the planform of the wings 4) POSTED: This copy of Bjorn Karlstrom's 3-view plan (with Bjorn Karlstrom's signature removed) appeared in "Ich flog vor den Wrights" ("I Flew Before The Wrights") by Albert Wüst, 1999, p. 235; (translation of top) "The Replica of The Originals"; (translation of bottom) "Fig. 88" "Plan drawing from the USA: Weisskopf No. 21"
The earliest known No. 21 replica was built by pioneer aviator and Early Bird Otto Timm, and his brother Wally, for the 1938 William Wellmann Paramount Technicolor feature film "Men With Wings."
Otto Timm first built aircraft in 1911, was Charles Lindbergh's first flight instructor and gave Lindbergh his first airplane ride. The film's "technicians and pilots" opinion (probably Otto Timm speaking) was "The ship hadn't a chance of getting into the air with or without an operator. It was not aerodynamically stable. It lacked proper controlling devices, including a rudder. The inventor did not understand the shifting of the center of pressure and other fundamental problems which the Wright brothers mastered." Otto Timm is directly quoted saying "But, our experiments show that the plane would have crashed within the first few yards of flight - if it rose from the ground at all."
The "Men With Wings" No. 21 was flown on wires - in the film it crashes and bursts into flames soon after take-off from a ramp atop a hill.
Connecticut high school biology teacher and hang gliding instructor Andrew "Andy" Kosch built No. 21A, beginning on September 1, 1985, funded by a grant from Kaye Williams of Bridgeport, and with assistance from Bill Wargo. Kosch estimated some 4,000 hours of work was involved. The plans drawn by Irving Burger were used as the design reference for the project. Kosch did not want to re-engineer or improve No. 21, and sought to build a very close replica of that machine. For flight testing a modified ultralight aircraft undercarriage was mounted. WINGS 360 sq. ft. (180 sq. ft. each) = 33.45sqm
TAIL 90 sq. ft. = 8.36sqm
POWERPLANTS two 1-cylinder Chotia two-stroke 460cc engines (25 h.p. each - total 50 h.p. to propellers vs. 20 h.p. total to propellers in No. 21), counter-rotating, with reduction gearing yielding 600-700 r.p.m., same r.p.m. as No. 21, although with greater torque PROPELLERS two 6 ft. laminated spruce Maxim Type "J" with solid hub, built by Tennessee Propeller Co.; also, set of 6 ft. laminated spruce Maxim Type "J" propellers with ground adjustable pitch
CONTROLS Pitch Control - by lifting and lowering tail
Roll Control - by wing warping (Not used on the original No. 21)
Yaw Control - by weight shifting
WEIGHT (empty, approx.) = 500 lb. = 226.8kg
(gross weight, approx.) = 700 lb. = 317.5kg
DIMENSIONS Wing Span = 35 ft. = 10.64m
Overall Length = 35 ft. = 10.64m
HFRC-GW-Weißkopf Nr.21B will be posted here)
Horst Philipp received the Nr.21B from HRFC-GW-Weißkopf Nr.21B built by the German Historical Flight Research Committee Gustav Weißkopf - HFRC-GW in September 1993, for testing at Manching, Bavaria, Germany. The testing spanned from December 1993 to February 1998, which included time to make modifications to the Nr.21B. In 1999, he presented a detailed written report of his tests, including towed and powered flights. Overall, his report makes the best of a bad situation, as he assumes, without any evidence, that several necessary and significant modifications would have been made by Whitehead. Also, he says in the mildest possible way, that the 20 hp cited as the power available in No. 21 was insufficient, at least that is this writer's view of his comments. Philipp cites several important and significant changes to the wings, including replacing the first three ribs with strengthened ones, and the rigging of the wings with additional wiring to keep them from deforming, since they buckled under load when using the wire rigging as originally designed. Also the location of the underside wing rigging was moved significantly forward. Philipp made several important comments (these have been chosen by this writer as significant), including... "This change in pressure distribution, together with the fact that the central wing tensioning rope had been installed on the fuselage floor too far aft, had led to static instability and caused the wing to collapse like an umbrella in a storm." "With the first three wing spars strengthened, and the wing tensioning rope fitting moved forward, the wing now withstood an air load test up to 56 kmh." Philipp states that in order to be able to fly No. 21
"Whitehead would have had to perform the following modifications:
- provision of one additional wing forward tensioning rope for each wing
- replacement of bowstring ropes on spars 1 – 5 by a third lower tensioning rope
- installation of one tail supporting rope on each side of the tail tensioner
- repositioning of lower wing tensioning rope fitting forward, level with wing leading edge replacement of wing
spars 1 – 3 with stronger ones
- wing profile cambering" Cutting power to the propellers in order to land, as Whitehead said he did, resulted in stalls "The resulting manoeuvres and landings were, in fact, more or less controlled crashes, and more than a little dramatic." "Wing structure proved to be flexible, as expected, causing aeroelasticity. Unlike rigid wing profiles the lift to drag ratio at constant angle of attack was altered by dynamic pressure, which means the optimum speed range was very small, that is, between 40 kmh and 55 kmh." "The thrust proved to be sufficient for shallow climbs, which soon ended, however, due to the reduction of positive ground effect. "It cannot be completely ruled out on the other hand, as the flying machine possessed a considerable degree of inherent stability, that Whitehead could have survived a few flights in calm air without too much trouble, even without active flight control. Attempts at steering by shifting body weight did not provide any evidence of practical value." "The additional elevator deflection required for trim compensation will lead to an increase in total drag, and therefore to an increase in power required, which will most probably exceed the 20 hp available.
"There is a chance, however, that the efficiency of the large, slow-rotating Whitehead propellers, together with their less intense air blast, will mean smaller installation losses, and therefore save some of the power required.
"This means that the question of whether the 20 hp were sufficient for flight can not finally be answered." "With regard to the central question of the applicability of flying performance, the subject of drag forms a special case.
"No 21 total drag is influenced above all by trim drag in addition to classical drag elements. In the event that only 20 hp is available for propulsion, this drag element would be decisive as to whether the aircraft can remain airborne."
As a result of testing, Experimental Test Pilot Horst Philipp reached these conclusions "The airframe of the Flying Machine Gustave Whitehead No.21 is capable of flight. The design concept provides inherent in-flight stability. "The thrust required, and which Whitehead claimed he had available, has yet to be demonstrated with the original propulsion system installed. "A positive result would mean that there is a high degree of probability that the eyewitness reports were correct and that Whitehead actually did fly the No 21. "Until such evidence is forthcoming, however, any claim that the Flying Machine No 21 with Whitehead on board did, or did not fly, is premature at this stage and can only be accepted as a personal opinion."
WINGS 37.1 sqm = 399.34 sq ft TAIL 5.6 sqm = 60.277 sq. ft. POWERPLANTS two 1-cylinder Chotia two-stroke 460cc engines (25 h.p. each - total 50 h.p. to propellers vs. 20 h.p. total to propellers in No. 21), counter-rotating PROPELLERS 127cm diameter wooden modern profile CONTROLS Pitch Control - by standard stick lifting and lowering tail
Roll Control - by standard stick "through elastic deformation of wing structure obtained by means of wing wiring" (Not used on the original No. 21)
Yaw Control - by standard foot pedals "obtained through lateral deflection of the tailplane" (Not used on the original No. 21) WEIGHT (empty) = 255.5kg = 561.1 lb.
(takeoff weight) = 334.5kg = 737.45 lb. DIMENSIONS Wing Span = 10.64m = 34.9 ft.
Overall Length = 10.3m = 33.79 ft.
Wing Surface = 37.1sq m = 399.34 sq. ft.
Tail surface: 5.6sq m = 60.28 sq. ft.
Total Supporting Surface of 42.7 sqm = 459.62 sq. ft. (original total of 450 sq. ft.) PERFORMANCE Airspeed = 53kmh = 32.93 m.p.h.
L/D Ratio = approx. 4.6
Climbing Angle = 9º
The modern-day renditions of No. 21 used for flight testing have surface areas close to the published value of 450 sq. ft., yet allocate the surface areas between wings and tail differently.
The Kosch-Whitehead No. 21A machine used 450 sq. ft. total surface area, but had 90 sq. ft. of tail surface and 360 sq. ft. of wing area, 180 sq. ft. for each wing, meaning over 40 sq. ft. were added to the surface area of the tail. The HRFC-GW-Weißkopf Nr.21B built by the German "Historical Flight Research Committee Gustav Weißkopf (Whitehead)" "HFRC-GW" had 400 sq. ft. of wing surface (200 sq. ft. each) and 60 sq. ft. of tail surface area - adding an additional 10 sq. ft. over the original area. The HRFC-GW-Weißkopf Nr.21B relied on modern conventional flight controls, including a stick for control of pitch and yaw, and deformation of the wing by use of pedals for roll control, none of which was present on the original No. 21. The addition of roll control and yaw control are significant differences between the HRFC-GW-Weißkopf Nr.21B and No. 21.
The differences in surface area between the modern versions and the original No. 21 call into serious question the results of tests of modern No. 21-type machines. The total surface area of an aerial machine is a major factor of whether or not that machine will lift off and fly, other factors being lift and angle of incidence of the aerofoil used, total weight, total head resistance and thrust, among other factors.
Additionally, the Nr.21B machine made use of modern 3,200 r.p.m. engines (No. 21's propellers ran at 700 r.p.m.) turning modern "toothpick" propellers, significant departures from the design of the original No. 21 Condor - as well as using control systems not found on No. 21 - that alter the flight characteristics and performance of the machines.
As a result, flight data derived from testing No. 21A and most especially the Nr.21B machine, with its many modifications based on modern understanding of structures and aeronautics, should be considered provisional. The free-flights of No. 21A and the Nr.21B are not evidence that No. 21 made controlled, powered flights.