PZL Bielsko SZD-9

SZD-9 Bocian
Type:	School glider
Design country:	Poland
Manufacturer:	PZL Bielsko
First flight:	March 10, 1952
Commissioning:	1953
Production time:	1952-1988
Number of pieces:	635

The PZL Bielsko SZD-9 Bocian ( German  Storch ) is a two-seat Polish school glider. The middle decker was made in a wood / steel tube composite construction. The Bocian is suitable for all types of glider training including simple aerobatics . To this day, the SZD-9 Bocian is still used for training in some countries, for example in Poland and Germany . The abbreviation SZD ( Szybowcowy Zakład Doświadczalny ) roughly means glider development company . The gliding index is 76.

history

The SZD-9 was designed by Justyn Sandauer, Marian Wasilewski and Roman Zatwardzicki. The first flight of the prototype took place on March 10, 1952 with Adam Zientka. In the course of the following years several versions and further developments were created. A total of 635 SZD-9s were built, 360 of which were exported to 32 countries.

The following versions were produced:

• SZD-9 - first prototype, license plate SP–1217
• SZD-9-2 - second prototype with some changes, first flight on July 16, 1952, registration SP–1218
• SZD-9 to 1A - first, improved production version, first flight on March 13, 1953 (11 with SZD-9-2)
• SZD-9 to 1B - second production version with enlarged tailplane, first flight on July 29, 1953 (11)
• SZD-9 to 1C - third production version with many changes, including the geometry of the wings and the tail unit changed First flight on February 9, 1954 (40)
• SZD-9 to 1D - fourth production version with few changes, including a larger main wheel, first flight on April 27, 1958 (206)
• SZD-9 to 1E - last production version, first flight on December 9, 1966 actually a new type of aircraft; this version is based on the SZD-33 , the development of which was discontinued in favor of the 1E (366).

A few more projects based on the SZD-9 emerged, but they did not leave the drawing board stage: In 1958, Piotr Mynarski and Wladyslaw Okarmus developed a version with increased aspect ratio , increased wingspan to 18.50 m and reduced fuselage cross-section under the name SZD-23 Bocian II and a negative sweep of −3 °, which should achieve a glide ratio of 28.3 at 85 km / h. In 1965 Tadeusz Labuc worked out a project named SZD-33 Bocian 3 with a span reduced to 17 m, which was initially rejected and, from 1967 to 1968, revised as SZD-34 Bocian 3 , a glide ratio of 30.6 was possible. When it was ultimately not implemented, Józef Niespal used it as a starting point for the SZD-35 Bekas .

The price for an airplane in the 1970s was 30,000 GDR marks. In the 1980s, the manufacturer's price for a general overhaul was 40,000 GDR marks.

construction

View from below

The aircraft is very tail-heavy on the ground. The fixed handles in front of the horizontal stabilizer therefore require two people to lift the stern if possible. All rudders and the airbrakes are moved by cables. The main landing gear is sprung with a rubber ring. The central fuselage is a tubular steel construction with plywood cladding. The passenger / flight instructor sits in the center of gravity of the aircraft. There is generous storage space on both sides in the wing noses, in which the battery for the non-standard radio device was installed. The seats are equipped with 4 or 5 point belts. The front canopy opens to the right, the rear part can be pushed back. An emergency release of the front hood can also be triggered from the rear seat. After the front canopy has been thrown off, the rear canopy, which can otherwise be opened in flight, is no longer possible for aerodynamic reasons.

To make it easier to get on via the rather high side walls, steps are integrated into these steps, which are equipped with flaps that close automatically on the inside. The rudder pedals can be adjusted in three stages before take-off by the pilot. The fresh air supply is located on the bow of the fuselage and can be regulated via an opening flap. The airflow hits the canopy, which can lead to condensation. Alternatively, the rear hood can be clicked into place so that a gap remains open between the two hoods.

The rear passenger / flight instructor can have their own instrument panel. However, this was only ordered from the manufacturer in exceptional cases, as the flight instructor can partially recognize the instruments of the pilot seated in front due to his elevated seating position. The standard instrument panel contained an airspeed indicator (up to 400 km / h), an altimeter , coarse and fine variometer , a compass with a dragonfly and a turn indicator that is operated with two flat batteries .

The aircraft has a very good-natured flight behavior, is very stable in flight, shows excessive flight conditions clearly and can easily be brought back under control from abnormal flight situations. The Bocian had solid flight performance for its construction period, but the focus was not on maximum flight performance, but on school operations. At least four people are required to set up and dismantle.

Compared to other two-seaters of this time such as the ASK 13 , the Bocian requires more complex maintenance and has a shorter maximum operating time (7000 hours).

Flight characteristics

The Bocian has extremely good-natured flight characteristics and climbs very well in thermals. The rudder is a little underdimensioned, so that full deflections are often necessary. It is an excellent way to show the tailspin for training purposes, but it is unlikely to go into a tailspin without intent. The well-sprung landing gear survives hard landings. The brake flap effect is average.

Technical specifications

A bocian in flight

Parameter	Data
crew	1 or 2
Passengers	1
length	8.20 m
span	18.10 m
height	1.80 m
Wing area	20 m²
Wing extension	16.2
Glide ratio	26.4 at 80 km / h
Slightest sinking	0.82 m / s at 68 km / h
payload	approx. 170 kg
Takeoff mass	Max. 540 kg
Wing loading	27.0 kg / m²
Minimum payload	65 kg
Top speed	200 km / h
Minimum speed	60 km / h

literature

• Kazimierz Wojciech Chudzinski: Polish gliders . tape 1: 1945-1970 . Verlag für Technik und Handwerk, Baden-Baden 2014, ISBN 978-3-88180-454-7 .

Web links

Commons : SZD-9 Bocian  - collection of images, videos and audio files

• Website of the protector "SZD Jezow / Henryk Mynarski"
• Bocian in Piotr Piechowski's database
• RC-Modeling & Polish Sailplanes - Extensive information about Polish gliders
• Bocian at the Schleissheim airfield

Individual evidence

1. ↑ Bulletin No. BE-033/9/2019
2. ↑ ^{a b} SZD-9 Bocian, flight manual