DC 38
| School glider SG 38 | |
|---|---|
.jpg)
|
|
| Type: | Glider |
| Design country: | |
| Manufacturer: |
Amateur and industrial construction |
| Commissioning: |
1938 |
| Production time: |
1938-1954 |
| Number of pieces: |
about 9170 |
.svg){kind=small}
The SG 38 school glider is the most popular single flight training aircraft of the 1940s. This glider was developed from 1936 and from 1938 onwards it was manufactured in large numbers in both amateur and industrial construction. The SG 38 was mainly used for training beginners. The abbreviation “SG” does not actually refer to the term school glider , but to “Schneider” in “ Grunau ”. “38” stands for the year 1938 was introduced.
history
The builders of the SG 38 school glider are the aircraft manufacturer and designer Edmund Schneider ( Grunau Baby ), the production manager and test pilot Ludwig Hofmann and the inspector Rehberg from the Schneider aircraft factory in Grunau (today Jeżów Sudecki in Poland). They had probably already developed a prototype of the SG 38 school glider based on the Grunau 9 / ESG 29 (the legendary "skull splitter"), as well as the Zögling 31 and Zögling 35 models, as early as 1936 , and started testing it in Grunau.
After a short time it turned out that this aircraft was particularly suitable for the single-seater training that was common at the time, as it could withstand harder landings. Hardly any glider has been built and flown more often. Thousands of pilots made their first jumps on an SG 38.
15 years of development work on simple gliders led to the most sophisticated school glider for beginners' training in 1938. An increase in performance was achieved by improving a pupil profile; A strong, integrated into the aileron twist made for an extremely docile stall characteristics.
In addition to the approximately 8,750 industrially manufactured gliders, an unknown number of gliders was also created in the following decades in the glider clubs. It was flown in many countries and was the standard training aircraft in the GDR until around 1960. In the 1950s, VEB Nagema Schmiedeberg 68 and VEB Waggonbau Gotha 329 school gliders were built. A total of 420 SG 38s were built in the GDR.
In Great Britain, the company Elliots of Newbury (EoN) produced the SG 38 almost identically as the EoN Primary after the war, while Slingsby fitted a similar fuselage with wings and tail unit of the pre-war training sailor T 7 Kadet . Under the name T 38 Grasshopper, this design was widely used in the pre-military Air Cadets training organization.
The latter versions from the GDR and Great Britain were also approved for towing aircraft in addition to rubber rope and winch launching . Recently this approval was also possible for some (slightly modified) “West German” SG 38s.
construction
Due to the simple structure, the SG 38 is suitable for series production in aircraft yards, but also for building in groups of pilots.
The school glider SG 38 is a steel cable - braced high-decker made of wood. The hull, tombstone and lattice tail are designed as a flat wooden framework. The two-spar wing is divided into two parts and has a slight V-shape. Spliced wire ropes between the tombstone, wings and fuselage give the surface the necessary support and the fuselage structure torsional and flexural rigidity. A central tensioning device at the top of the tombstone enables quick and easy assembly: This eliminates the need for time-consuming measurement and adjustment of individual tensioning cables for each assembly, as was necessary with the previous models. The tail unit, designed as a lattice tail, is attached to the clamping tower with bolts. The control surfaces are linked using numerous wire ropes and pulleys that are attached to the fuselage, the lattice tail and the wings. The upward twisting of the ailerons at the outer end of the rudder serves to restrict the wings, increase lateral stability and prevent damage to the edge of the ground.
For trimming, steel cylinder weights are attached to the fuselage under the control pedals or to the rear tensioning tower for each pilot mass. They enable correct trimming for pilots from around 40 to 90 kg.
The sprung runner is made of ash wood and is connected to the hull via energy-absorbing dampers. Optionally, the open seat can be clad with an easily removable "boat" to increase performance.
Performance measurement
In August 2009 the SG 38 D-8985 was measured by Mario Selss during the Idaflieg summer meeting at the Aalen-Elchingen airfield with the measuring system of the IFF of the TU Braunschweig using the altitude level method. The result was a best glide ratio of 8.3 at around 58 km / h, a lowest sink rate of 1.85 m / s at 53 km / h and a minimum speed of 48 km / h with a normalized flight mass of 197.3 kg. His DAeC index was then set at 22.
The rubber rope start
The rubber rope start was (after the run start) the earliest starting procedure for gliders. It was demonstrated for the first time at the first Rhön gliding competition in 1920 by Aachen students from the Aachen Aviation Science Association (FVA) with the FVA-1 "Schwatze Düvel" . For this purpose, an approximately 2-3 cm thick rubber cord is hung in the middle on a hook on the nose of the aircraft. Normal ropes are attached to the ends of the V-shaped elastic rope and are occupied by four to six people - the so-called "rubber dogs" - by the two starting teams. A short rope is attached to the fuselage of the aircraft, which is held by two to four people (holding team) or attached to a starting trap.
After the flight is ready for take-off, the flight instructor holds the wing horizontally and gives take-off commands. At the command “Take off!”, The starting teams begin to tighten and take off their end of the rope. At the command “Run!” The starting teams run off and bring the rope to the optimum tension. As soon as this is reached, the flight instructor gives the command “Go!”, Whereupon the holding team lets go of their rope or the starter latch is unlocked by the flight instructor. The plane is accelerated by the rubber rope and takes off. When the "rubber dogs" fly over the rubber rope falls out of the hook.
Ideally, you start on a slope, as the flight would end very quickly at a release height of less than ten meters. On the Wasserkuppe today, with a southerly wind (this is the only way to use the longest slope), a flight time of over a minute can be achieved; in the 1930s, flight times of several hours were achieved by using uphill winds .
Technical specifications
| Parameter | SG 38 (D-7738, No. 269) | SG 38 (D-NNSG, No. 269) |
|---|---|---|
| Manufacturer | VEB Waggonbau Gotha ( GDR ) | |
| Construction year | 1953 | |
| length | 6.283 m | |
| span | 10,414 m | |
| height | 2,430 m | |
| Wing area | 16.00 m² | |
| Setting angle | + 1.5 ° | |
| Wing restriction | 0 ° | |
| Wing extension | 6.78 | |
| profile | modified Zögling 35 profile | |
| Glide ratio | 8.3 at 58 km / h | |
| Slightest sinking | 1.83 m / s at 48 km / h | |
| Max. Payload | 90 kg | |
| Empty mass | 125 kg | 113 kg |
| Max. Takeoff mass | 210 kg | |
| Wing loading | 13.1 kg / m² | |
| Speed range | 40–115 km / h | |
| Winch towing speed | Max. 74 km / h | |
| Aircraft tow speed | Max. 90 km / h | |
| Car towing speed | Max. 60 km / h | |
| permissible load multiple | +3 g | |
| Breaking load multiple | +6 g | |
Preserved copies
There are currently far more than a dozen airworthy gliders in Germany, at least four of them from the GDR era. One of them was built by the youth group of the Baden-Württemberg Air Sports Association. In contrast to the information given above, it has an empty weight of 95 kg, which with a maximum take-off weight of 210 kg enables a payload of 115 kg. With a lower payload, a glide ratio of 10 can be achieved.
- D-7738 / D-NNSG
- The SG 38 with the approval D-7738 was put into service on October 28, 1953 and flew until July 19, 1967 under the approval number 269 at Bronkow airfield. Due to the glue used, the service life of the aircraft was officially limited to 15 years. After staying at the Bronkow and Nardt airfields for decades, the school glider was taken over by members of the Aeroklubs Hoyerswerda e. V. was completely overhauled between 1992 and 1994 under the direction of workshop manager Herbert Hansel. On August 5, 1994, the aircraft was flown in again by the flight instructor Heinz Mehlhose. The painting and the marking (except for the current license plate) are true to the original.
The school glider SG 38, which was previously approved as D-7738, was approved on January 16, 2017 in the category "Air Sports Equipment - UL Glider" with the D-NNSG label. This completed another major overhaul and made the aircraft ready to fly again as an aerial sports device.
- D-8985
- D-8146
- Exhibit in the German Glider Museum on the Wasserkuppe.
- D-7052 airworthy on the Wasserkuppe - can be flown for group events (clubs and individuals) under flight instructor supervision on the historical slopes of the Wasserkuppe. The holder and owner is the ROSC Wasserkuppe / Rhön eV - This aircraft makes up to 650 take-offs per year and is approved for training. The rubber rope start authorization can be obtained here.
- D-7055 airworthy, new building from the 1990s, also at home on the Wasserkuppe - can be used for airfield festivals or corresponding events. This example can be used in both a rubber rope launch and a winch launch. Holder and owner of the ROSC Wasserkuppe / Rhön eV
literature
- Peter F. Selinger: Glider Stories. The gliders and gliders of the German Glider Museum with model flight on the Wasserkuppe . Stiftung Deutsches Segelflugmuseum Wasserkuppe with model flight, Gersfeld / Rhön 2004, ISBN 3-00-011649-4 .
Web links
- Video with aircraft and car towing of SG 38
- Overview of school gliders approved and flying in Germany
- Flight characteristics, upgrading, take-off types, measurements
- SG 38 in the Deutsches Museum in Munich
- School glider in the Flugwerft Schleissheim
- [1]
- Video about flight operations with rubber rope from D-7052 - recorded in June 2019: https://vimeo.com/382826337
Individual evidence
- ^ School glider SG 38 in the Flugwerft Schleißheim
- ↑ a b c Idaflieg survey ( memento from December 23, 2015 in the Internet Archive )
- ↑ Segelfliegen-Magazin Issue 3 (May – June) 2010, ISSN 1612-1740
- ↑ Information on the information board about the aircraft