Wrights Develop Automatic Stabilizer

by Dr. Richard Stimson

in Wright Activities Before and After 1903

By 1905 the Wrights had developed a practical airplane that for the first time could be controlled by a pilot. Having achieved that goal, they decided to develop an automatic stabilizer that could fly the airplane straight without a pilot’s intervention.

They were successful in their effort and were awarded the prestigious Collier Trophy by the Aero Club of America for their device on January 5, 1914. The prize recognized the most significant contribution to aeronautics made during the year of 1913.

Unfortunately for the Wrights, Lawrence Sperry publicly unveiled a more technologically advanced device in France six months later on June 18, 1914.

The Wrights began their work on the device in secrecy sometime after 1905. Their concept was to develop an adaptive system with feedback. A change in direction of heading, automatically applies power to adjust the airplane controls in yaw, roll and pitch as appropriate, and brings the airplane back to its original heading.

The 30-pound device consisted of a pendulum and vertical vane that were connected to a power source which drove servomotors. Whenever the pendulum swung out of vertical the wing warping control was activated to restore yaw and roll balance.

Similarly the horizontal vane sensed pitch stability and activated the elevator control.

The original power source was compressed air, then it was replaced with a battery, and in the final version, a small windmill set in motion by wind was used.

The pilot could adjust the vane at any angle desired for use in climbing or descending. It could also be switched on or off by the pilot as desired.

They applied for a patent on February 8, 1908 although the device was still in development and not been flight tested yet because of desire to maintain secrecy.

The Wrights worked on the device intermittently, as time would allow. In the fall of 1911 they had progressed to the point where they decided to test it out on a new glider at Kitty Hawk. However a number of reporters also showed up, so in order to maintain secrecy on the new device, they flew the glider without using the automatic control feature.

Their patent (#1,075,555) was granted October 14, 1913 although they still had not flight-tested it.

The Wrights didn’t seem to be in any hurry in using the device until Glenn Curtiss had won the Collier Trophy two years in a row during 1911 and 1912. Curtiss had won the trophy for his development of flying boats.

Orville decided Curtiss wasn’t going to win again in 1913. He decided he would use the Automatic Stabilizer to win the prize with.

In the fall of 1913, Orville installed the stabilizer on a special Wright Model E airplane that utilized a single pusher propeller. He kept the details of the stabilizer secret even from the Wright Company. He purposely waited until the last day of the year to fly for the prize.

He invited the Aero Club’s judges to Huffman Prairie to see a demonstration of his new device on a cold snowy day, December 31st.

He turned up his coat collar, put on a pair of goggles and took off. He made a total of 17 flights.

His most spectacular flight consisted of 7 full circles of the field with both hands held in the air. The automatic stabilizer kept the same angle of bank and almost the same altitude. He wowed the judges and was awarded the prize on February 5, 1914.

The stabilizer was then offered as an option for use with the sale of Wright 1910-1911 Model B flyers.

However, it saw little use, because on June 18, 1914, a young Lawrence Sperry, as part of a great safety competition, unveiled a totally new type of stabilizer to the world. The safety competition was jointly sponsored by the Aero-Club de France and the French War Department.

In his demonstration flight, Sperry took off from the Seine in a Curtiss C-2, climbed to altitude and flew back down the river. At the appropriate moment, his mechanic, Emile Cachin, crawled 7 feet out on the wing as Sperry lifted his hands from the controls and stood up in the cockpit. The plane sped by the judges as the crowd went wild.

What Sperry had done was adapt a balancing mechanism invented by his father, Elmer, for counteracting the rolling of ships, to an airplane. The device employed two gyroscopes that performed the function of the pendulum and vanes in the Wrights’ device.

The invention was a new technology that would create expanded opportunities for application in the future. It certainly has done that and is used in today’s satellites and space flights.

The rapid obsolescence of the automatic stabilizer was symbolic of what was also happening to the Wright airplanes. The awarding of the Collier trophy to the Wrights signaled the end of an era in which the Wrights had invented and nurtured the airplane to a reality. In so doing they set a standard of excellence for others to follow in their footsteps.

References: The Bishops Boys by Tom Crouch; Wilbur and Orville by Fred Howard

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