Aachen FVA 14 Ringfugel
A few years after World War 2 a Department of aircraft was re-established in Aachen, and the FVA could hope for with the right to non-teaching support. It was decided to take on a very unconventional project: the construction of a ring-wing glider.
The aim of this work was to investigate the flight characteristics of such an aircraft. Due to the absence of non-load bearing parts, it was hoped for a minimum structural weight, and reduced induced drag, because of the lack of wing tips. Furthermore, the project seemed to be a suitable object of study, with many questions of aerodynamics, strength and manufacturing. A small model a ring wing was flown successfully .
In the "Little Aachener air sports newspaper in May 1952 an article dealt with the special properties of a ring-wing. There are two main elements that allow this machine to fly: They are the wings that generate lift and the tail that controls the wings and gives them the necessary positional stability. There is the possibility that one acts as a control, a second support surface. The two wings to control one another. In this arrangement, the front face must have the larger effective angle of attack in all flight attitudes. We arrive at the concept of a stable tandem aircraft.
If during this tandem the ends of the front wing sweeps out to the rear and the rear wing exactly so that the ends of both forward pass each other, we get a ring-shaped hydrofoil system. It is not important whether this system is round, oval or triangular.
The aerodynamic characteristics of this annular wing systems are not yet fully explored. However, it is proven that you can build longitudinally stable flying machines based on these systems. It was also unrealistic to suppose as possible that the induced drag on wings ring is lower than for regular wings with the same aspect ratio.
The ring wing disc has the property that the buoyancy force to relatively large angles increases steadily with angle of attack without eruptive pulling and tearing occurs the flow. The maximum lift seems to be at an angle of approximately 30°.
Another remarkable feature of the ring-wing found the . Englishman Tilgham Richards found that the center of pressure of such wings is almost stationary during flight or that you can achieve a moving pressure center, which is practically stable up to an angle of incidence of 18°. In ring wings no case of longitudinal instability is actually known so far, although it has the centre often moved relatively far back.
Construction started in 1952but the first wind tunnel tests are not until 1955 carried out in the wind tunnel of the State School of Mechanical Engineering
The theoretical investigations were concluded very slowly, so that the construction of full-size version was more advanced than the scientific study and calculation of the project that normally time would have allowed. In the wind tunnel tests, it was found that the ring wing compared with normal aircraft also has disadvantages.
The longitudinal stability behavior had a bad habit: In high-speed flight, the aircraft had a tendency to seek out the back attitude with a nose-down moment. Within certain limits, improving the flight characteristics resulted because of a small extension, resulting in significant losses in flight performance. These changes had caused extensive and costly modifications to the almost finished full size version. Under these circumstances, the FVA opted not to complete the full-size version. After another two years, space in the workshop was needed and the FVA14 was broken up.