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autopilot
By William
Scheck
The two grandstands
between Pont Bezons and Pont Argenteuil were packed with spectators, on
hand to see the Concours de la Securité en Aéroplane (Airplane Safety
Competition) being held on the banks of the Seine River. On that glorious
sunny June 18, 1914, there were 57 specially equipped planes competing,
with Lawrence Sperry listed last on the program. Entries featured such
improvements in aircraft technology as magnetos, self-starters,
carburettors and other innovations. Sperry's entry was the sole
participant equipped with a gyroscopic stabilizer apparatus, designed to
improve stability and control.
Sperry's device was mounted on a single-engine Curtiss C-2 biplane with a
hydroplane fuselage. Flying with Sperry was his newly hired French
mechanic and assistant, Emil Cachin. Considering that Sperry spoke almost
no French and Cachin was equally ignorant of English, they seemed an
unlikely team -- but they had hit it off with each other from the start.
Sperry and Cachin had managed to become sufficiently conversant with each
other's language to bandy about phrases such as stabilisateur gyroscopique
and generator electrique with true Gallic flair. Now their opportunity to
demonstrate the feasibility of the Sperry gyroscopic stabilizer was at
hand.
Lawrence's father, Elmer A. Sperry, a renowned American inventor,
accompanied by his wife, Zula, was on hand to see the results, along with
the members of the Ligue Nationale Aérienne de France. With the rest of
the hushed crowd, they waited to see if what was generally thought to be
an impractical gadget might actually work in an airplane.
The elder Sperry had earned a worldwide reputation for his development of
the gyrocompass, which had been installed on more than 30 American
warships. A massive device that was practical only for marine use at that
time, his invention was still gaining in popularity and becoming standard
equipment on vessels then entering service. The gyrocompass was immune
from deviation and variation problems, which hitherto had been difficult
to overcome, particularly in large steel warships. The massive
compensating devices required by conventional magnetic compasses were
eliminated by Sperry's breakthrough. Since then his son, Lawrence, had
developed a lightweight adaptation of the gyroscope that could be coupled
to control surfaces to maintain the flight axes of aircraft.
The firemen's band of the villages of Bezons and Argenteuil, spotting the
aircraft of "l'Americain" approaching, bravely struck up "The Star
Spangled Banner." The Curtiss C-2 flew down the river, and directly in
front of the judge's stand Sperry engaged his stabilizer device,
disentangled himself from the shoulder yoke that controlled the C-2's
ailerons and passed in review with both his arms held high. The aircraft
continued on a straight and steady course, with the pilot obviously not
handling the controls. The crowd was on its feet, cheering, and shouting:
"Remarquable!" "Extraordinaire!" and "Formidable!" Sperry had stunned the
skeptics with his "no hands" flying.
But Sperry wanted to show them what else his device was capable of. During
the second pass, Cachin climbed out on the starboard wing and moved about
7 feet away from the fuselage. Sperry's hands were still off the controls.
As Cachin moved out on the wing, the aircraft momentarily banked due to
the shift of weight, but the gyroscope-equipped stabilizer immediately
took over and corrected the attitudinal change, after which the Curtiss
continued smoothly down the river. This time the crowd was unrestrained in
its appreciation and the firemen's band delivered its supreme compliment
-- a vigorous rendition of "La Marseillaise."
Sperry elected to make one more pass -- his tour de force. As they passed
the reviewing stand, there was Cachin on one wing and Sperry on the other,
with the pilot's seat empty. This was a demonstration beyond the already
exuberant audience's expectations. There was the aircraft, flying serenely
along with both its pilot and mechanic out on the wings, airily waving to
the spectators. The judge, René Quinton, was almost speechless. His
comment mirrored the feelings of the crowd: "Mais, c'est inoui!" ("But
that's unheard of!").
The military observers on hand were simply stunned by Sperry's
performance. And when Commandant Joseph Barrès of the French army air
corps prevailed upon Lawrence Sperry for a ride, he not only saw a
demonstration of the aircraft's stability during straight and level flight
but also witnessed Sperry's device performing an unassisted takeoff and
landing.
Awarded first prize in the competition, Sperry received 50,000 francs
($10,000) and became famous overnight. The handsome young American's face
adorned the front pages of newspapers in Paris, London and Berlin. The New
York Times was more muted in its reception, however. A report covering the
competition appeared on page 6. In the Times of June 22, Sperry's
invention was mentioned on the editorial page in these deprecatory terms:
"Of stability commonly understood, no heavier than air flight vehicles
will ever have even as much as that dreadfully fragile monster, the
dirigible." So much for the technical expertise of The New York Times
staff in the summer of 1914.
Lawrence B. Sperry was born in Chicago on December 22, 1892, Elmer and
Zula's third son. That same year the Sperry name was well represented at
the Chicago Columbian Exposition. At the time, Elmer was the chief
executive officer of the Elmer A. Sperry Company, with more than 70
patents either granted or pending. Among his developments were the Sperry
Electric Street Car as well as the first arc lights (developed when he was
only 19), which graced both the Chicago Board of Trade and Tribune
buildings. As an inventor, Elmer Sperry was generally regarded as being
almost on a level with Thomas Edison. The Sperry clan relocated to
Brooklyn, N.Y., and bought a house in the solid middle-class neighbourhood
of Flatbush.
Lawrence was an energetic youth, and by age 10 he had acquired a bicycle
and a newspaper route. The events at Kitty Hawk, N.C., that made the front
pages in December 1903 left a strong impression on him. The ingenuity of
the Wright brothers spurred young Lawrence to open a bicycle, roller skate
and doorbell repair shop in the basement of the family house. It was an
instant success, and in short order he expanded his operations to include
motorcycle repair. From an early age, he displayed a natural yen for
mechanical devices, despite a lack of formal training.
The Sperrys usually travelled to Bellport, Long Island, each year for a
summer of seaside tranquillity. This absence by the rest of the family was
the opportunity for Lawrence and his brother, Elmer Jr., to make their big
move in 1909. Lawrence had studied a Voisin biplane that he had seen at an
airshow at Mineola, on Long Island, and had made meticulous notes on its
dimensions and construction. Now, with the town house empty except for
servants, the Sperry brothers started building a glider in the basement.
First the boys built the steam box they needed to bend wood to the
required shapes. They also set up a jig on the floor, where the pliant
wood could be clamped until dry. The furnace in the basement furnished
steam for the production of the aircraft components.
The boys' glider plans went out the window when an interested customer, a
Mr. Wilcox, asked Lawrence what he planned to use as an engine. An engine?
That sounded intriguing. A 5-cylinder Anzani radial engine was available
at a cost of $800. The Anzani could claim demonstrated reliability. It had
been the power plant of the aircraft in which Louis Blériot in 1909 became
the first man to fly the English Channel. The Sperry brothers had only
$300 in their till, but Wilcox was willing to put up the balance so their
plane could have an engine. Repayment was to come from the proceeds of a
soon-to-come barnstorming career by 16-year-old Lawrence -- who had not
yet even made it into the air.
If nothing else, Lawrence was daring. When the plane's wings turned out to
be too large to fit through the doors of his parents' house, he proceeded
to remove two large, handsome bay windows from the house so they could
carry the semi-assembled aircraft out into the yard. Sperry Sr., upon
discovering the alterations, made a reasonable decision -- that the first
earnings from young Lawrence's new flying career would be allocated to pay
for repairs to the house.
With the engine not yet on hand, Lawrence thought it might be prudent to
begin flying his plane as a glider so that he could get some practice.
After talking his way into using the nearby Sheepshead Bay Race Track,
which had fallen on hard times, Lawrence towed the aircraft to the new
proving ground with a Panhard automobile he had acquired. After assembly,
the glider was hitched to the Panhard, and with Elmer Jr. at the wheel,
the maiden flight began. The plane had reached a height of 150 feet when
the tow rope broke. The glider, with Lawrence at the controls, proved
fairly tractable in the air, although he did have a hard landing and
received a few scrapes and bruises. The glider needed only minimal
repairs. After that initial hop, Lawrence was consumed by the flying bug.
The Sperry brothers' shiny new engine arrived the following week and was
installed without delay. As a protective measure, Lawrence had taken steps
to prevent a noseover by installing six bicycle wheels as an enhanced
landing gear. Fuelled up, the engine started, and then, sensing the moment
of truth was at hand, Lawrence opened the throttle. With his recent
experience in the glider coupled with apparently latent talent for flying,
Lawrence reached the respectable altitude of 500 feet. Even more
important, he made a decent landing.
Realizing that a mostly on-the-job education in flying was insufficient,
Lawrence decided to formalize his conquest of the air. After a few more
years of academic study, he enrolled in the aviation school run by Glenn
Curtiss at Hammondsport, N.Y. Sperry learned quickly. On October 15, 1913,
he received Federal Aeronautics Pilot License No. 11 from the Aero Club of
America.
At this time Curtiss was working under the auspices of the U.S. Navy to
develop a hydroplane. In the same shop, Sperry, the youngest licensed
pilot in the United States, was soon developing a new interest, a
gyroscopic stabilizer for aircraft. Sperry's goal was to develop an
apparatus that would enable an airplane to maintain its course and
attitude under all circumstances.
Sperry had been intrigued by the tendency of a motorcycle or bicycle to
remain upright provided it was moving. The Wright brothers, with their
experience in bicycles, had also dabbled in the gyroscopic phenomenon but
had not explored it very deeply. The principles of the gyroscopic effect
were fairly well understood at that time, but as yet there had been no
attempt to utilize the gyroscope's capabilities in an aircraft.
Sperry hit upon the idea that if the three flight axes of an aircraft --
yaw, pitch and roll -- could be harnessed to the stability of a gyroscope,
an automatic control system might be developed. Yaw represented lateral
deviation from the course heading, pitch was the up and down divergence
from level flight, and roll referred to lengthwise rotation around the
axis of flight. The aircraft might wander through the flight axes without
pilot input on the controls, but Sperry reasoned that a spinning gyroscope
could maintain an airplane's original orientation. The youthful inventor
put it all together by linking the control surfaces with three gyroscopes,
allowing flight corrections to be introduced based on the angle of
deviation between the flight direction and the original gyroscopic
settings.
The guidance device would perform mechanically what the pilot performed
instinctively. Sperry's control gyroscopes were designed to maintain a
zero setting for all control surfaces unless corrective action was
required. The transmission of corrective commands to the controls required
a mechanical linkage to the control surfaces. The gyroscopes needed
electrical power to maintain rotational rotor speed as the actuating
medium. Sperry obtained power for the gyroscope motors by mounting a
wind-driven generator on the upper wing, in the slipstream. He had an
additional problem, however.
His stabilizer was mechanically linked to the aircraft control mechanism,
but the aircraft industry was fragmented, and different manufacturers had
different methods of operating control surfaces. Sperry's stabilizer
required four gyroscopes rotating at 7,000 rpm. As one of the gyroscopes
moved in opposition to the movement of the aircraft, linkage to valves
would actuate pistons operated by compressed air and connected by levers
to the control surfaces. In addition, an anemometer that could sense
inadequate airspeed and incipient stall was also linked to the device and
would institute corrective action. The entire device, weighing in at 40
pounds, was compressed into 18 inches by 18 inches by 12 inches -- a small
package for such a sophisticated and complex apparatus.
Sperry had come up with a brilliant solution to the problem of a practical
autopilot. But as always, nature sides with the hidden flaw. Since
aircraft employed unique control systems, pilots had to learn a completely
different cockpit layout for each different type. For example, in Curtiss
planes the ailerons were attached to a yoke that fit over the shoulders of
the pilot and were actuated by his moving his upper body to the left or
right. Another system in many aircraft of that day had the ailerons linked
to the armrests of the pilot's seat. In both the Curtiss and armrest
systems, it was difficult to achieve the mechanical force necessary for
rapid manoeuvres. Some planes used rudder pedals or a rudder bar; others
used an automobile steering wheel to actuate the rudder. Some aircraft had
multiple control sticks, and a few employed even more bizarre methods. It
was clearly impractical for Sperry to design a stabilizer for the unique
control actuation methods employed in different aircraft.
The breakthrough for Sperry came through by dint of common sense. The
diversity of control apparatus was finally stabilized thanks to the
universal but reluctant adoption of the Deperdussin system, which has
remained in use to this day. The Societé de Production Armand Deperdussin
was a financially shaky French aircraft producer operating under the
acronym of SPAD, later to achieve fame under a different designation --
Societé Pour l'Aviation et ses Dérivés. Deperdussin had developed the
modern method of using a central control stick to manipulate the elevators
and ailerons, with pedals or a rudder bar controlling the vertical rudder.
Ailerons linked to a wheel have remained in use for large, multi-engine
aircraft, though few fighters other than the Lockheed P-38 Lightning
retained that system by World War II. The simplicity of Deperdussin's
control layout made it immediately popular -- and ideally suited for use
with Sperry's device.
The U.S. Navy, which underwrote Sperry's research, had designated
Lieutenant Patrick Bellinger to assist him and act as a watchdog during
testing. Trials of the gyroscopic stabilizer soon shifted to San Diego,
Calif., to avoid the inclement weather near Lake Keuka at Hammondsport,
where the Curtiss facility was located. Although the California climate
was more benign, Bellinger's confidence in Sperry's device had not
increased. In flight tests with Sperry, Bellinger had a tendency to grab
the controls if the gyroscopic operation seemed slow or reluctant.
During one test, Bellinger conquered his tendency to go for the controls,
but this time he waited too long, and the Curtiss C-2 they were using as a
test-bed flew full tilt into the waters of Spanish Bight. Inexplicably,
this mishap converted Bellinger into a Sperry adherent. Sperry managed to
rescue the stabilizer, and both men suffered only a dunking. In subsequent
trials, Sperry finally solved most of the problems. Rudder position had to
be offset to overcome engine torque. Aileron settings had to compensate
for the location of the centre of gravity in each aircraft. As the work
progressed, Sperry finally reached the ultimate test. With Bellinger
sitting nervously in the cockpit, Sperry clambered out onto the wing. The
device worked as designed and corrected the banking momentarily caused by
the transfer of Sperry's weight to the wing, confirming Bellinger's
newfound confidence.
The Aero Club of France and the French War Department announced an
international airplane safety competition, the Concours de la Securité en
Aéroplane, scheduled for June 1914. Curtiss knew a good public relations
gambit when he saw it and offered to send one of his C-2s, with Sperry to
provide his stabilizer and flying expertise. The competition was a
smashing victory for Sperry.
With the outbreak of World War I weeks later, Sperry's life changed. He
offered to serve in a French frontline squadron as an experienced pilot,
but to his dismay officials turned him down because he lacked a college
degree. Undaunted, he returned to the United States to continue his
research.
So far, Sperry had flown hydroplanes almost exclusively, but he began to
think about creating a dual-purpose aircraft. He reasoned that a flying
boat could carry a retractable landing gear so that it could also operate
from a land base. The result: The Aerial Age Weekly issue of March 29,
1915, featured an article with Sperry demonstrating what was the first
wheeled retractable landing gear in an amphibian.
The Sperry Gyroscope Company, of Brooklyn -- with Elmer Sr. and Lawrence
working in tandem -- soon developed an unpiloted aircraft that could fly
to a target guided by the Sperry gyroscopic device. But that turned out to
be an idea ahead of its time. (The concept would resurface during World
War II.)
Lawrence travelled to Britain and returned in 1916 with a briefcase
crammed full of orders for what is now famous as the automatic pilot. At
age 24, he had become a well-known inventor. In 1916 he was also
commissioned a lieutenant junior grade by the U.S. Navy and assigned as a
flight instructor.
Lawrence Sperry never rested on his laurels. Between 1915 and 1923, he had
23 patents either pending or granted. Among his inventions was
instrumentation that permitted aircraft to be piloted when visibility was
zero. His bank-and-turn indicator and artificial horizon have remained the
basic instruments for every aircraft from the Boeing 747 to the Piper Cub.
He also came up with a variety of other instrumentation, including an
airspeed indicator, a drift indicator and a significant improvement over
the (British) Creaghton-Osborne liquid-filled magnetic compass.
After the United States entered World War I on April 6, 1917, Sperry
continued research on an aerial torpedo that was actually a guided bomb.
Working in concert with automotive inventor Charles Kettering, he produced
a prototype of a pilotless aircraft rigged to fly a preset course to a
designated target. Another member of that research team was 1st Lt. James
Doolittle of the U.S. Army, whose name would become a household word in
the three decades to come. The project, called the "Bug," was not entirely
successful, largely due to the unreliability of the engines used.
The Sperry-Kettering research, however, provided the guidance principles
utilized in Germany's later development of a flying bomb, the
Vergeltungswaffe-1 (V-1 vengeance weapon), in 1944. The Germans solved the
problem of unreliable power plants by using a simple and reliable
pulse-jet engine, which required an absolute minimum of moving parts.
While testing the Bug in March 1918, Sperry -- who was serving as pilot --
crashed, suffering a broken pelvis that immobilized him for three months.
During his recovery he spent time on calculations that would result in a
new and improved parachute. By the time he was released from the hospital,
he knew he had invented a seemingly foolproof seat, or backpack,
parachute. His design would eliminate the problem of a parachute becoming
entangled in aircraft empennage. To test his device, he went to the roof
of the Garden City Hotel, on Long Island, and let his parachute fill and
drag him from the roof. It performed as designed, and he landed safely.
The Sperry parachute soon entered production.
At WWI's end the entire nation turned to civilian diversions, and Sperry
shifted gears as well. As the result of a conversation with Brig. Gen.
Billy Mitchell, assistant chief of the U.S. Air Service, Sperry designed
and built an inexpensive sport plane, the Sperry Messenger, which could
reach 95 miles per hour. It had a 20-foot wingspan and was powered by a
3-cylinder radial engine that delivered 30 miles to the gallon.
Mitchell was so impressed by the design that the Army ordered a dozen for
general service. The Messenger was also well received by civilian aviators
and appeared at airports around the country.
Sperry used a Messenger to commute from his Brooklyn home to the factory
on Long Island. He would routinely land and take off from the parade
grounds on Parkside Avenue, adjacent to Prospect Park, and leave his
aircraft at a convenient police station at the western end of the
impromptu landing field. His home on Marlborough Road and the site of his
initial aircraft production plant were within easy walking distance.
An experienced pilot with more than 4,000 hours of flight time, fully
trained to fly by instruments alone, Sperry had no hesitation in taking
off in any weather conditions. His personal aircraft was always fully
equipped with instrumentation of his design. On December 23, 1923, he took
off from Britain for a quick flight to France, undeterred by the fact that
the Channel was fogbound. Somewhere en route, however, his luck ran out.
Whether due to mechanical failure or inability to navigate over the
Channel, he never reached his destination. The Messenger he had personally
designed was found in the water. Sperry's body was recovered on January
11, 1924.
The Sperry aircraft manufacturing effort did not survive the loss of
Lawrence Sperry. Without his vision and ingenuity, the company could not
cope with the increasing competition of inexpensive surplus World War I
aircraft then being sold in enormous numbers by the government. But the
name Sperry lives on today -- a revered imprimatur among many aircraft
factories that remains part of the nomenclature of aircraft instruments to
this day. The autopilot and stabilization system was also adapted for
marine use. All major passenger ships plying oceans today employ a
Sperry-type stabilizer actuating a winglike device to dampen rolling. A
form of the Sperry autopilot linked to a Sperry gyrocompass is in common
use today on every ship of any size. The illustrious family name is also
maintained today on the nameplates of diverse navigational equipment
produced by the Sperry Marine Corporation, a division of Litton Industries
Incorporated, as well as the Newport News Shipbuilding Corporation of
Virginia.
Given Lawrence Sperry's extraordinary productivity and fertile
imagination, it seems especially tragic that he died so young. When he
went down in the Channel at age 31, he had 23 patents related to aircraft
safety in his name. Surely, had he lived longer, he would have come up
with even more brilliant ideas and inventions to make flying easier, safer
and more readily available to the public. |