FVA 20 - Standard glider
“The FVA-20 - what lasts long…”, so began an article in the “aerokurier”, issue l/1980, which appeared in view of the successful maiden flight of the FVA-20 on November 28, 1979. 12 years of construction and almost 10000 hours of work since autumn 1973 alone were forgotten when the still unpainted “20” took off in Merzbrück in bright sunshine. Hardly any of the “spiritual fathers” of this aircraft were still in Aachen for the maiden flight.
With the decision to build a standard class aircraft, the design was already roughly outlined: 15m wingspan, no lift-increasing flaps and a minimum fuselage height of 0.8m.
For the wing, the rectangular trapezoidal shape was chosen, which offered significant manufacturing advantages. The minimum wing loading of 26.8kg/m² promises satisfactory flight performance even in European weather conditions. T-tail, retractable landing gear and the proven Schempp-Hirth airbrakes on the upper and lower wing surfaces were features retained from the outset. Fuselage construction began as early as 1967, but the half-finished fuselage sat in a corner of the workshop for a long time without anything happening. The positive construction method in the so-called half-sandwich style had been chosen. Here, balsa wood served as support material for the GRP shell. The fin was built in the same way, the tailplane as a full sandwich in a negative mold. Contizell served as the support material.
The wings were originally to be manufactured in a positive mold similar to the fuselage. However, it turned out that this construction method made it difficult to achieve the required high profile fidelity. It was therefore decided to use the negative construction method. The spar was designed as a box spar, and roving fabric in the form of narrow strips was used for the spar chords.
Since the FVA-20 was the first time in FVA history that a plastic aircraft had been built, the designers and builders initially lacked experience with the new material. It is very likely that the failed breakage test of October 11, 1973, was due to this fact, among others. However, the FVA did not allow itself to be discouraged by setbacks and continued to work consistently. Among many other designers, Uwe Solies, who was project manager of the FVA-20 for many years and spent many a night in front of the drawing board in the factory jam, stood out in particular.
Since 1973, one could read every year anew in the annual report that “we expect the first flight in the course of the coming flight season”. In addition to a gross underestimation of the workload, especially of the “details”, the following situation is also responsible for this: In contrast to earlier FVA aircraft designs, which were produced with all available manpower in an almost incomprehensibly short time from the design to the first flight, it was not possible in the seventies to deal so intensively with just the one project: Maintenance of the aircraft fleet, design and construction of several transport trailers for the newly acquired gliders, and work on the development of the automatic flap system at times took up most of the work capacity. This work, considered an intermezzo in relation to the FVA-20, was manageable in time and brought some financial and psychological benefit to the FVA. In addition, the construction work for the FVA-20 was in the hands of a few active people, so that the mass of those willing to work were occupied with other tasks in the meantime.
When construction of the wings was finally to begin, it was found that the negative molds, which had already been in the workshop for several years, had settled considerably, so that the required surface quality and profile fidelity could not be achieved. Thus, in the winter of 1975/76, the molds were first restored to the necessary condition, which proved to be a very lengthy process. In March 1976, wing construction could finally begin by laminating the upper and lower shells of both wings in the form of mass inserts.
The “innards” were inserted into these shells and then, in an exciting action, the respective upper and lower shells were joined together. Unfortunately, the profile fidelity in the wing nose area now left much to be desired, so there was no shortage of work the following winter.
In 1978/79, the work was then continued very intensively, almost under moral pressure, with the long-awaited goal in mind. But again and again problems arose in the so-called details, which caused further delays. For example, the installation of control organs, operating levers and the operation of the retractable landing gear caused some problems.
In the course of the general advancement in glider construction, some important detail improvements had also been incorporated into the design of the FVA-20. For example, the stick was designed as a parallelogram stick similar to the design of Eugen Hänie, a pioneering glider designer in many respects. The wings are also assembled in the Hänle manner. The wings are pulled together with the aid of an assembly lever.
In the fall of 1979, the time of completion became clearly apparent, and on November 28, the time had finally come. The positive weather report gave the final impetus, and the FVA-20 was looked over to Merzbrück early in the morning. The registration plates and a lettering “FVA-20” designed the evening before were provisionally pasted on the still unpainted aircraft. The pilot selected for the maiden flight, Joachim Ewald (Cassius), had personally picked up the provisional airworthiness certificate from the Luftfahrt-Bundesamt on November 27, 1979, so that nothing now stood in the way of the maiden flight from a legal point of view. At 10:20 a.m. the FVA-20 took off behind our tow plane “Remorqueur” to the happy and satisfied applause of those present. Joachim Ewald released at an altitude of 2200 m and on the following gliding flight in the calm November air the major part of an excellent documentary film was made, set to music, which was premiered with great pleasure on the occasion of the St. Nicholas party on 1.12.1979. The FVA-20 made a total of three flights that day and was then immediately returned to the workshop, where many small things still had to be done until the aircraft could begin actual flight testing in March 1980, painted and finally ready to fly.