Sportavia MS-75

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The motor glider Sportavia MS-75 was an aircraft development that Sportavia-Pützer had pursued since 1973 .

history

With the Pützer MS-60 , Alfons Pützer realized a motor glider design optimized for the needs of sailing and touring pilots at the beginning of the 1960s , but on its series production Pützer against the background of the beginning collaboration with René Fournier and Antoine d'Assche for the benefit of the Fournier RF-4 and Fournier RF-5 waived. Since René Fournier had cruising in focus when designing these aircraft, the machines proved difficult to market in glider pilot circles. At Sportavia-Pützer, derivatives were then created for this customer group, such as the SFS 31 “Milan” disc or the Fournier RF-5B “Sperber”.

With the beginning of the separation of Fournier and Pützer, Alfons Pützer took up his original MS-60 development again and had the design modernized by Helmut Schrecker in 1973 under the name Sportavia MS-75. After an extensive analysis of the market for two-seater motor gliders, Schrecker designed a completely new low- wing aircraft with a pitch propeller at the tip of the fuselage and two pilot seats arranged side by side. The 72 hp Limbach SL-1700, known from RF aircraft, was used as the drive, which was integrated in the fuselage in front of the cabin. The wings were made of GRP wood sandwich construction , which made fewer demands on the surface quality of the negative form. The retractable landing gear was in the retracted state between the two pilots.

Further development as MS-75-II or MS-II

The original design by Helmut Schrecker was fundamentally revised several times until 1976. A last known design from June 1976 by Alfons Pützer and Erich Ufer is called the MS-II motor glider. This design is based more closely on the original Pützer MS-60. The motor is located behind the cabin and drives two folding propellers arranged on the wing tip edges, as in the MS-60. In order to achieve the necessary ground clearance for the propeller, the original low-wing approach by Schrecker was converted back into a shoulder- wing construction. The resulting disruptive influences on the horizontal stabilizer of the tail unit were eliminated by using a T-tail unit.

For the American market, Ufer and Pützer envisaged alternative engines for the MS-II, which would have enabled the FAA to approve it as a powered aircraft in the USA . Among other things, an 80 PS Sportavia Limbach SL2300D with twin igniter and a 108 PS Lycoming O235 engine were planned. In the purely powered aircraft variant, a shortened wing of 14 m was provided. The maximum take-off weight for the MS-II with O235 engine was 820 kg with a payload of 280 kg.

With the departure of Alfons Pützer and the subsequent decision to discontinue motor glider construction at Sportavia-Pützer, the development of the Sportavia MS-75 ended in early 1977. A prototype was no longer built.

Bank of the Moself

There is another project sketch by Erich Ufer from June 1990, which shows the long-range motor glider "Moself". This 8.50 m long shoulder-wing monoplane also used the folding propellers provided by Pützer for the MS-60 and MS-II on the wing tip edge. However, Ufer planned a separate motor for each propeller. Either 15 m or 22 m spans were provided as wings, which were constructed in three parts with a central wing center section. The outer wings were foldable. The "Moself" had retractable main landing gear and support wheels, as well as a steerable nose wheel. As with the MS-75, a T-tail unit was also planned for the “Moself”.

With two engines, the "Moself" could also be used as a four-seat aircraft. Obviously the banks had already in 1990 the admission issue with the Federal Aviation Authority discussed and recorded in a marginal note that the Office of the approval rejects as a motor glider for a twin-engine airplane. The "Moself" was also not built and seems to represent the last stage of development of the motor glider developments pursued by Ufer and Pützer since 1958, from the MS-60 to the MS-75 and MS-II to the "Moself".

Technical specifications

Parameter MS-75 (1973) MS-II (1976) Moself (1990)
Crew and passengers 2 2 2-4
length 8.00 m 8.00 m 8.50 m
span 18.40 m 15.00 m 15 m / 22 m
height 1.80 m
Wing area 20.00 m² 17.55 m²
Wing extension 16.2 12.8
Glide ratio
Slightest sinking
payload 190 kg 250 kg
Empty mass 490 kg 485 kg
Max. Takeoff mass 680 kg 730 kg
Cruising speed
Top speed
Service ceiling
Range
Engines 1–2 × Limbach SL1700, each 72 PS (53 kW)

See also

literature

Web links

Individual evidence

  1. ^ Paul Zöller: Fournier aircraft. 2017, ISBN 978-3-7460-4864-2
  2. ↑ Sportavia-Pützer, MS-75 motor glider , design documents by Helmut Schrecker, May 1973
  3. ↑ Alfons Pützer homepage
  4. ^ Paul Zöller, Hanns-Jakob Pützer: Pützer aircraft. Dec. 2018, ISBN 978-3-7481-2096-4
  5. ↑ Erich Ufer, project sketch Moself , June 1990