Filip Mihail

The Stable-plane
The creator of this flight apparatus, Filip Mihail, an aviation technician, was born in Cernica in 1896 in a poor farmer family. After graduating an apprentice school, he was hired as a worker in the Aeronautical Storeyard in Cotroceni (a Bucharest district), where he became specialized in maintenance operations, in designing and building aeroplanes. During World War I, being part of the ‘Army Aviation Reserve Division’, Filip Mihail was remarked due to his ability and skills he proved in repairing various types of planes. After the war was over, he worked for a while in the Aeronautical Storeyard and in the IAR Braşov; later on he left for France where he specialized working in several factories; his preoccupations went to building of a new aeroplane type.

On April 4, 1923, he obtained the Invention Patent No. 555924 issued by the French Ministry of Trade and Industry for a monoplane gyro-aircraft, based on the documentation he had submitted on August 19, 1922 in Paris. The monoplane gyro-aircraft was named ‘Peace’ (La Paix) and its construction was taking over a series of constructive elements found in Vlaicu’s and Vuia’s planes: the ‘parasol’ (sun-protected) wing made of a metal frame covered by textiles, the ‘gondola’-type cockpit, the landing gear and the transmission system between the engine and the propeller. The elevator rudders were cancelled, their role being taken over by the wint sweep modification system in flight; as a flight principle this vehicle was very close to the ‘Vuia 1’ which was lacking in elevator rudder and which, in fact, was a real flying wing.

This vehicle later named ‘stable-plane’ due it its in-flight stability, may be included in the so-called ‘flying wings’ category, the construction of which attracted the interest of many inventors at that time. Concerning the design and construction of certain vehicles of the same type, attempts had already been made by German, French and English aircraft constructors who had achieved some tailless gliders between 1919-1920.

Although he obtained one of the first patents for a single-engine flight vehicle of ‘flying wing’ type, Filip Mihail didn’t enjoy the support of his time authorities. He had to work hard for 12 years (1923-1935) to see his dream come true due to his own efforts and to some private contributions. Back in his country, on June 8, 1927, Filip Mihail obtains the patent No. 14115 for a new airplane type. From the attached report one may conclude that it is about an improved version of the patented project in Paris. The author named this vehicle ‘Avieta stabiloplan’ (stable plane) F. Mihail-type III.



Based on the aerodynamic calculations performed by Dipl. Eng. Cristea Constantin in a care workshop belonging to an ex-aviation foreman, Ion Peleanu, an improved version of this invention name by Filip Mihail ‘Stable-plane’ Type IV is achieved. The new vehicle is provided with a wing skidding system against the fuselage, modifying thus the pressure center position related to the aeroplane centre of gravity – so the aeroplane could be vase-lift of in dive. Despite the indifference showed by the authorities, this aeroplane flew, for the first time, on November 11, 1933 without any publicity. According to the ‘Romanian Aeronautical Magazine', No. 11-12, dated December 1934, the vehicle performed its first official flight on April 22, 1934. Later on it was submitted to the approval tests obtaining thus the Airworthiness Certificate No. 71 dated December 4, 1934 and being registered as YR-ACV. Mr Levy (the pilot who was performing the flight) achieved all kinds of flights – level flight and turns. Meanwhile, attracted by the strangeness of the vehicle shape, three military ‘Potez’ combat aircraft approached. Mr Filip Mahail’s small aeroplane was flying by far faster as compared to the ‘Potez’ aircraft. On June 1, 1934, the same pilot, Lucien Levy, performed a non-stop flight; Bucharest - Braşov - Bucharest, crossing the Carpathians at 3,000 m altitude – this vehicle demonstrating particularly high technical qualities and performances.
Despite all the successes obtained by the ‘Stable-plane’ Type IV on the occasion of all aviation contests it took part between 1934-1935, in the autumn of 1935 the authorities prohibited the flight of this Romanian conception vehicle.



In 1937, dispirited by the authorities hostility, Filip Mihail (although without a pilot license) tried to fly with his vehicle. Due to a minor incident because of an air-pocket, he lost control of the apparatus which crashed down. After this accident the creator remained with a permanent invalidity. He died in 1962, leaving the plans of his aircrafts to the Romanian Academy.