In 1911, in Juvisy in Essonne, construction of a 4th biplane started but with monocoque metal fuselage on wheels with shock absorbers, the hull joining the front cell to the aft stabilizer adjustable, a rear stabilizer in two parts to allow the development of the rudder with a crutch for ground braking. Combination of ailerons with controls on joystick, 60 hp E.N.V motor, Regy tractor propeller, foot rudder control, upper plane span of 8 meters, and lower plane 7 meters.

Louis Verdier carried out the development and flight tests in presence of an officer from the military aeronautical laboratory of Chalais-Meudon in view of the use of this two-seater by the army.

In view of the results obtained, including the solidity of the aircraft, well built, good flight behavior, possibility of landing on very short terrain due to the solidity of its landing gear, a very soft suspension and good braking at
ground, the Guyot-Verdier airplane registered before January 1, 1911 in the 1st major military aviation competition in Reims in la Marne, which began on October 1, 1911.

42 manufacturers take part in this competition, registering around 70 machines. Unfortunately, the Guyot-Verdier aircraft does not meet the qualifications, the required conditions are too stringent.

On Sunday, October 29, 1911, Louis made a demonstration flight of in front of 4000 to 6000 spectators, in the field Berthonnerie Air Force (2 km from La Souterraine), flying for 35 minutes, completing a 35 km circuit where it reaches an altitude of 500 meters. He is carried in triumph in the streets of the city and a wine of honor is offered.

Then follow other flights and aerial celebrations, in November 1911, January 12, 1912, April 28, 1912 in Azérables in Creuse.

In 1912, Louis received his pilot’s license n° 526, from the aeronautical sports commission.

In 1913, Louis Verdier wrote:
“Despite all these facts and qualities as well as many steps taken by our gentlemen, Deputies and Senators of Creuse and Haute-Vienne, the La Souterraine aviation factory has never obtained any order of a military service from the French State, nor any financial aid, all this aviation equipment has been studied, built and developed to no avail, for it was not the few parties and exhibitions that were able to cover all these study and construction costs for these aircraft prototypes. I give up building and flying these planes, I leave the provinces and return to the Paris region”

Louis entered the Sanchez-Beza Establishments as a pilot, then as a test pilot and engine developer at the Salmson aviation factories in Billancourt and, with mechanics, replaces engines on seaplanes in Saint-Raphaël (Var), Bizerte (Tunisia), Marseille (Bouches-du-Rhône), Toulon (Var).

Henri Guyot and Louis Verdier undertake, still at La Souterraine, the construction of a third biplane, two-seater, at Chauvière, 80 horsepower engine and pusher propeller, unequal span wings.

The front cell and the rear fixed plane are joined by V-shaped ash spars and to reduce resistance in flight, the masts and metal parts are profiled. The span of the upper plane is 17.50 meters and the span of the lower plane 15 meters, bearing surfaces with beak entry into the air profiled to avoid resistance to the advancement of the aircraft, the engine mounted on a fuselage which is fixed on the lower plane of the aircraft which constitutes the cockpit. The cell is mounted on skid with 4 shock absorbers metal fixed on two wheels on each runner. The wheels are mounted on balloon tires with bead rims, brakes on wheels and brake stand on the ground.

The first official flight, piloted by Louis, took place on April 24, 1910 at Le Dorat on the flat racecourse. It was completely fenced which facilitated the control of entries because the event was paying. It’s a rectangle of 50 meters by 60 meters, the aircraft can take off in all directions.

Louis passed his A.C.F. (Aéro-Club de France) on July 1, 1911 on this Guyot-Verdier aircraft. His pilot’s license civil bears the n° 538. The license n°1 was obtained in 1909 by Louis Blériot.

The 1909 Guyot-Cellier tandem biplane was designed and built by Guyot and Cellier in France. It is not known if it flew.