50 years DG aircraft – Success story in aviation!

“Aviation is our passion!”
Holger Back and Sebastian Tschorn, Managing Directors of DG Aviation, agree and have turned their passion into a profession. Both look back on a history of success in aviation. This review was created in cooperation with Wilhelm Dirks.

1973: The beginning of DG

Wilhelm Dirks studied at the Technical University of Darmstadt and was involved in the Darmstadt Academic Flying Group throughout his studies. There he constructed his first glider, the D-38 for the standard class, largely independently and managed to complete the D-38 and carry out the basic flight tests while still a student with the help of the other Akaflieger and, above all, the workshop manager K.H. (Mc.) Hinz.

At Whitsun 1973, during a competition, he was approached by the Bruchsal building contractor Gerhard Glaser, who had landed with him on the same field. Gerhard had been annoyed by the repeated delays in the delivery of his LS1 and therefore wanted to set up his own sailplane production so that there would finally be more competition in a market dominated at the time by only 4 manufacturers of fiberglass sailplanes. He was just looking for a competent designer. That very day, the two of them decided to look into the possibility of working together, even though Wilhelm already had a scholarship for a doctoral thesis. During his first visit to Gerhard’s company site in the Untergrombach district of Bruchsal, the decision was made to found Glaser-Dirks Flugzeugbau GmbH. So Dr. Dirks came to nothing, but there was one more designer who was to help shape the German gliding scene for decades to come.

Wilhelm contributed his knowledge as a designer, but also his experience in working with the then still new material fiberglass, which was extremely important for the start of a new production, because at that time there were no craftsmen who could work with this material.
Wilhelm therefore also had to train all the new employees in order to make glider production possible at all. He also had to pass the examination for an LBA examiner’s license in order to be able to legally build the prototype and all others.
The first DG was not to be called DG-1 but DG-100. The DG-100 corresponded to the D-38 in terms of aerodynamics and flight characteristics, but was immediately developed for construction in negative molds.

Compared to the D-38, however, there were significant improvements which all subsequent DG single-seaters also feature and which are not to be found in the competitor products of that time and in some cases also today, such as the fuselage with the large canopy, the large 5″ main wheel in a closed wheel housing without a tubular steel frame to absorb the forces and the standard tail wheel.Special mention should be made of the safety cockpit with firmly glued-in seat pan and optimally attached seat belts, things that were only verified decades later by research projects using crash tests and found their way into the building regulations.

 

1973 – A SUCCESS STORY STARTS
During his university studies, Wilhelm Dirks constructed a glider, the D-38. Shortly thereafter, a partnership was formed with the building contractor Gerhard Glaser at the company site Untergrombach and the Glaser-Dirks Flugzeugbau GmbH was founded. Dirks became a successful designer, who helped shape the German gliding scene for many decades.

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By the beginning of 1974, the prototype was ready so that the DG-100 could be assembled outdoors in front of the garages for the first time and load tests could then be carried out on all components. After the successful tests, the prototype was completed.

The first flight took place on May 10, 1974 with Wilhelm in the cockpit in Bruchsal, i.e. less than a year after the start of the project.This was a record time, which is unimaginable today and which DG has never achieved again.

1974 to 1989 DG-100

Production was soon able to move into the new halls. Here is a view of the final assembly.The first 6 DG-100s were completed by the end of 1974.

Initially, 103 DG-100s were built in Untergrombach, 16 of which were DG-100Gs with damped instead of pendulum tailplanes, which were delivered as an option from 1976, before production was switched to the next development, the DG-200 racing class aircraft, in 1977.

Dr. Floriancic, a Swiss but Slovenian-born glider pilot whose company was also active in Bruchsal, told us in 1976 on the occasion of a test flight that the Slovenian manufacturer ELAN, known for its ski and boat construction, was interested in manufacturing gliders and was looking for a licensor. He arranged the contact.

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After a presentation of the DG-100 in June 1977 at the Lesce/Bled airfield, which is close to the ELAN company, and corresponding negotiations, ELAN selected the DG-100.
This resulted in a partnership lasting many years, from which the DG-300 and DG-500 were to emerge.

Ultimately, this was also the nucleus of the Slovenian companies that today successfully build fiber composite motor gliders and aircraft.

5 ELAN employees and the specially hired engineer Tone Cerin came to Untergrombach for training and built 2 more DG-100s here.
All molds and the necessary equipment were transported to Slovenia, where production was initially set up in an idyllic former water mill. At the same time, ELAN expanded the production hall for boat production, creating a spacious workplace for glider production.

From 1979 to 1989, 222 DG-100 ELANs and 188 DG-100G ELANs were built.

1977: DG-200

First flight: October 28, 1978. 192 aircraft built. With an adapted fuselage from the DG-100 and a more modern flap profile for the wings, the DG-200 was developed as a racing class aircraft. With the addition of clip-on wings, this aircraft was also intended for the open class.
DG-200/17C: Wings mainly made of carbon fiber (CFRP).

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The technological development of fiber composites continued and the first industrially produced carbon fibers came onto the market. As a kind of technology project, Gerhard and Wilhelm decided to develop the DG-200/17 with wings made mainly of carbon fiber (CFRP) and to build it in series. The first flight of the DG-200/17C took place on April 6, 1980.

22 units were produced. Even though the DG-200 did not necessarily require a lower weight, the DG-200/17C wing would later enable the DG-200 to be motorized as a DG-400 self-launcher.

After 192 units of all series had been produced, DG-200 production ended in 1984 to create capacity for DG-400 production.

1981: DG-400

290 units. New: DG-200/17C airframe with a thickened, reinforced fuselage in the engine area. Unique selling point at the time: it could be rolled with engine power – Glaser-Dirks developed into the world market leader for self-launching motor gliders.

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To make ground handling easier, Wilhelm developed the steerable tail wheel and wingtip wheels that were later still used in the DG-800.

This allowed the DG-400 to be maneuvered almost like a powered aircraft with engine power without outside help, a unique selling point at the time and one of the reasons for the success of the DG-400.

An equally important reason was the very simple engine operation, which did not exist at the time in the few folding engine powered gliders available on the market and which would only be found in some competitor products much later.

In addition to the retraction of the engine by means of an electric spindle drive, the extensive automation of the engine control is decisive.
In order not to lose valuable space in the instrument panel with round instruments for the engine display, Wilhelm designed a flat instrument that displayed all the necessary displays in digital form and also contained all the necessary switches and indicator lights, except for the retract/extend switch, which was mounted on the control stick handle for operation with the index finger. Utz Schicke, a student who was working at Glaser-Dirks at the time and also knew a lot about electronics, offered to develop this device. Wilhelm called it the “digital engine indicator” (DEI) and it can still be found today in further developed versions in all DG motor gliders with combustion engines.

Today, Utz Schicke has his own company and continues to build and develop DEIs for DG and similar devices for other aircraft.

Digital displays were something quite new in 1981 and not yet recognized in aviation. Accordingly, it was difficult to convince the LBA staff to install something like this instead of round instruments. At first this ended in a compromise and a round rev counter had to be installed in addition, but it was accepted that this could be installed in a console on the side of the fuselage.
Through his work on a committee to improve European building regulations, Wilhelm succeeded in establishing digital displays in the building regulations for motor gliders and consequently the round rev counter was allowed to be removed again.

The DG-400 was Glaser-Dirks’ most successful product to date. In the first test flight week alone, 50 options were ordered.

With the DG-400, Glaser-Dirks became the world market leader in self-launching motor gliders. Even less technically experienced glider pilots, who were not confident enough to operate the complicated motor gliders available at the time, had no problems with the DG-400.

After 290 units had been built, production ended in 1993.

1987-2006: DG-500

First flight: March 19, 1987. 261 units. Glaser-Dirks and ELAN jointly developed the DG-500 as a two-seater. DG-500M: self-launching motor glider with flaps, 22 m wingspan, carbon
fiber wings, all controls automatically connected, autonomous ground handling. Parallel DG-500 series as modern training aircraft (certification: aerobatics category A).

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ELAN was to take over the complete model and mold construction, as there was no space for this in Untergrombach. Most of the design work on the fuselage was also handed over to ELAN. Glaser-Dirks took over the construction of the wings and tail units as well as the engine, the complete verification process including flight testing and all certification work. ELAN manufactured the complete airframe and Glaser-Dirks in Untergrombach took over the installation of the engine, electrics and equipment.

The DG-500M was to be just as autonomous in ground handling as the DG-400, which was a novelty for two-seaters at the time and is still not common among the competition today. As the DG-500M was designed to roll on the nose wheel, a steerable tail wheel would have been useless, so a steerable nose wheel had to be developed. For the engine, they again worked with Walter Binder, who had already developed an engine with a 60 hp water-cooled Rotax 535 engine and a 1:3 reduction ratio. Due to the larger reduction ratio and the water cooling, the engine noise is much more pleasant than that of the DG-400. The engine was assembled and installed at Glaser-Dirks.
The engine can be operated from both seats, so that 2 DEIs are used in a further developed version.

The first flight took place on 19.03.1987 at Karlsruhe/Forchheim airfield.
A total of 61 DG-500Ms were built.

Particularly noteworthy is the world altitude record of 50671 ft, or 15460 m, achieved by Steve Fosset and Einar Enevoldson with a DG-500M in the Andes. The engine was removed and oxygen bottles and batteries were installed instead. The pilots had to wear pressure suits because of the high altitude. The project ran under the name Perlan I.
At the same time, a DG-500 series was developed as a training aircraft, which was also certified for aerobatics in category A. This DG-500 ELAN Trainer has a wingspan of 18 meters and the same wing profile, but without flaps and no steerable nose wheel. Glaser-Dirks was thus able to offer a modern training aircraft, of which 58 were built.
The first flight took place on 27.01.1989. All trainers and all other glider series were completely built by ELAN. Only instruments and equipment were installed at Glaser-Dirks.

Only 2 months later, the DG-500/22 ELAN, a glider version of the DG-500M with flaps and 22m wingspan, also without a steerable nose wheel, flew, of which 17 were built.

20m class for two-seaters:

In the meantime, the IGC (International gliding commission) made the decision that a competition class with a 20m wingspan should be established for two-seaters. Until then, two-seaters had to fly in the open class.
This was actually a sensible decision, but unfortunately the DG-500M and DG-500/22 did not fit in there.

Consequently, the program was supplemented with a version of the DG-500/22 shortened to a wingspan of 20 m, the DG-500/20 ELAN. The wingtips were fitted with winglets as standard to compensate at least somewhat for the reduced wingspan, which also looked better. The first flight took place on 9.08.1993 and 12 were built.

The next series, the DG-500 ELAN Orion, was much more successful. According to the 3 stars in the belt of the constellation Orion, the Orion could be flown with 3 different wingspans. The Orion has no flaps, the wing span was set further outwards than in the flap series, at 17.2 m span. This made it possible to attach short wing tips for 18 m wingspan, similar to the 15 m wing tips of the DG-200/17 and DG-400. Wing tips with winglets for 20 m wingspan are also available as standard.

The customer could save the cost of the 18 m tips if he opted for the edge disks, which could be bolted to the inner wings and thus resulted in a wingspan of 17.2 m. At 17.2 m and 18 m, aerobatics can be performed, as with the trainer. The Orion is the ideal glider for clubs that want to carry out performance flying with a wingspan of 20 m as well as training flights and aerobatics with the short wingspans. The first flight took place in December 1994 and 90 units were built.

A special feature of the Orion is that in addition to the fin tank, which is operated together with the wing water ballast system, there is a separate second tank for trimming. This means that solo flights can be carried out with the same center of gravity as two-seater flights, a great safety advantage for first solo flights during training. Heavy pilots also have the option of setting a better, more rearward center of gravity position.

Later in the DG Flugzeugbau era, a final series of the DG-500 was developed, the DG-500MB. This was a DG-500M, in which a similar engine to the DG-800B was installed after appropriate modifications to the engine compartment. However, the Solo 2605-2 engine is more powerful (65 hp) than that of the DG-800B and the propeller is correspondingly larger. An additional division was installed in the outer wings to allow operation with a wingspan of 22 m or 20 m with winglets.
The first flight took place in May 1997 and 23 were built.

A total of 261 DG-500s of all series were built.

1983 to 2006 DG-300

Parallel to the production of the DG-100, the DG-300 was developed as the most modern glider in the standard class and as an answer to the LS4.
The Braunschweig airfoil specialists Karl-Heinz Horstmann and Armin Quast developed a wing airfoil especially for the DG-300 for particularly high performance, which nevertheless has only a low sensitivity to bugs. To achieve low drag, a boundary layer influence was provided by blowing through many small holes on the underside of the profile. After successful testing of the airfoil in the wind tunnel, mold construction began. The fuselage was taken from the DG-100, but shortened by 20 cm. Later, optional winglets were developed, which could also be retrofitted.

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The first flight took place in April 1983 and 387 of this first version were built.

From 1987, a simplified version for club use was offered in parallel, the DG-300 Club ELAN. Here, the elaborate exhaust system was replaced by jagged strips and instead of the large 2-part wing water tanks, only smaller water bags were used in the wings; the fin tank was optional. 81 units were built

Then came the request from aerobatic pilots to perform aerobatics with the DG-300. A recalculation of the wing structure showed that aerobatics could be permitted in category A with a few minor reinforcements. Both DG-300 series were certified in the reinforced version and named DG-300 ELA N Acro and DG-300Club ELAN Acro. A total of 43 of these were built from December 1992.

A total of 511 DG-300s were delivered. This makes the DG-300 the largest DG product ever built.

1987: DG-600

In order to be able to offer a competitive and hopefully better glider than the competition for the racing class, Glaser-Dirks again commissioned Karl-Heinz Horstmann and Armin Quast to develop a special profile for this purpose. This was to be achieved with an extremely thin profile with a thickness of only 12%. Only carbon fiber was an option for the construction. A more constricted fuselage was to save even more drag. The DG-600, which was initially only designed as a glider, was built as standard with a 15 m (with winglets) and 17 m wingspan. The first flight took place on 15.04.1987.

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Unfortunately, the new profile took some getting used to in slow flight. If you flew too slowly when cranking, this resulted in a higher sink rate than at a slightly higher airspeed. For this reason, a system was developed especially for the DG-600 with an instrument that showed the pilot the correct speed when cranking, called “speed control”.

At some point, Walter Binder got in touch and said that his new small power unit with a Rotax 275 single-cylinder engine with 25 hp would fit into the thin fuselage contour. All that was needed was to add a hump to the engine cover. Again, a cooperation with Walter was agreed. Glaser-Dirks supplied him with a DG-600 fuselage, into which he installed the necessary reinforcements and the engine. However, Walter supplied the fully assembled engines for the other fuselages that were then built at Glaser-Dirks.

The first flight took place on 11.11.1989 in Karlsruhe.

The DG-600M could also be certified as a self-launcher with a reduced take-off weight of 440 kg. For higher masses (with water ballast), winch or F-tow launch had to be selected. Due to the large 5″ main wheel, which is relatively far forward, there is also no tendency to go on the nose, so that the take-off can always be carried out with full engine power.

This was a major advantage over a competitor product on the market at the time. The DEI made it possible to operate the engine easily again. On the private initiative of Wilhelm and Dieter Frank, Wilhelm developed 17 m wingtips with winglets, which were then built by Frank-Waldenberger. This version had particularly pleasant flight characteristics.

Somewhat later, Alwin Güntert of Güntert und Kohlmetz developed 18 m wingtips, which could later be fitted with winglets and which were built by his company but certified by Glaser-Dirks.

The 18 m models delivered were then called DG-600/18 and DG-600/18M.

In 1992, there was a fire in production overnight, which mainly rendered the outer sections of the DG-600 wing molds unusable. With a few repairs, the molds were restored to the point where the inner wings could be built in them. The decision was made to equip all further DG-600s with the 18 m wing tips from Alwin.

A total of 114 DG-600s were built, 54 of which were DG-600Ms. The 18 m versions are included in these figures and are not counted separately, as some owners also had the 18 m tips retrofitted.

1991: DG-800

A total of 442 DG-800 aircraft
of all series built. A total of 442 DG-800 aircraft of all series built. DG-800S: Development and production started as a single-seat high-performance glider, without engine (42 units). DG-800A with Rotax engine. July 1996: First flight DG-800B with solo engine (230 units). DG-800C: Further development of the 800B with standard safety cockpit, Maximum permissible take-off weight increased to 600 kg (101 aircraft built).

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Glaser-Dirks was the first glider manufacturer to use state-of-the-art technology in the production of the wing molds. A company that was able to CNC-mill the full-length master models was commissioned to manufacture the master models. The molds were made by Glaser-Dirks from carbon fiber plastic with integrated heating. These methods enable unprecedented precision and consistent quality over the entire production period.

The DG-800 prototype was converted to the new wing and now called DG-800A.
The DG-600 also received this new wing and was named DG-800S.
Both series flew for the first time in May 1993.

To comply with more recent noise regulations, the air-cooled engine was fitted with a noise-insulating cowling and a new propeller. DG-400 owners were later able to benefit from this improvement by retrofitting it.
However, as these measures were not sufficient to achieve the increased noise protection introduced in Germany, through which operational restrictions could be avoided, an identical series was approved as the DG-800LA.
The regulations were met by reducing the maximum take-off mass. Apart from the cockpit data plate and a few pages of the manual, everything is identical. 42 of the DG-800A, LA were built.

The third version, the DG-800B, was added in July 1994. The self-launching DG-800B is the Glaser-Dirks contribution to low-noise powered sailplanes. With a water-cooled internal engine, 1:3 propeller reduction and a large in-fuselage silencer, all possibilities for noise reduction are consistently utilized. The first 5 examples were equipped with an English Mid West two-stroke engine with 50 hp. Unfortunately, production of this engine was discontinued when the Austrian manufacturer Diamond took over Mid-West, as Diamond was only interested in the Mid-West Wankel engines.
A replacement was found in the SOLO 2625, but this engine was still in the development stage, so it was not initially available. Thankfully, many customers agreed to take delivery of their DG-800B without the engine for the time being, so that series production could continue.

Unfortunately, Gerhard’s civil engineering company ran into financial difficulties at the same time, with the result that the company’s bank also cut off the money supply for aircraft construction and the company had to file for bankruptcy in spring 1996.

Fortunately, production was only suspended for a few weeks, as Karl Friedrich Weber and his wife Eva-Maria found investors who were able to continue the production of DG airplanes with great financial and personal commitment. Fridel later said with a smile: “I actually only wanted to buy one glider, but I had to take over an entire glider production.
The first flight of the DG-800B with the 39 KW / 53 HP SOLO engine took place in July 1996. However, it was still a thorny path before continuous series production of the DG-800B got underway, as the SOLO engine still had many teething troubles at the time. But it was worth it: the DG-800B was the most powerful and quietest motor glider in the 18m class at the time. Its outstanding rate of climb in powered flight is still unrivaled today. 230 of the DG-800B with solo engine were built.

As the 18 m competition class had meanwhile been set at a maximum weight of 600 kg, the DG-800B was also to be certified for this higher weight. This required various modifications, such as a more stable undercarriage with even better suspension and a new water ballast system with fin tank and larger 2-piece water bags in the wings. The result was the DG-808C Competition, which flew for the first time on December 1, 2004 and of which 102 were built.
For customers who did not need the high take-off weight, the DG-808C Classic was released, which had slightly softer springs in the undercarriage and the previous water ballast system. However, this version was only sold to 5 customers.
The DG-800S, of which 52 had been built by then, was also loaded up to 600 kg and was equipped with a very special water ballast system that had never been realized before. This consisted of 2 separate systems, one tank per wing and one fuselage tank. This has the enormous advantage that after one system has been deflated, the flight can be continued with the same center of gravity and thus with optimum performance.

The first flight of this version, called DG-808S, took place on 13.03.2003. Unfortunately, the customers did not appreciate these advantages and only 6 DG-808S were sold. A total of 442 DG-800s were built.

2000 Move into the new production facilities

With a major investment, Friedel Weber had new, modern and spacious production facilities built right next to Bruchsal airfield Production was able to begin there on December 20, 2020.This put an end to working in cramped conditions and eliminated the need for transportation to the airfield. A modern spray booth and extraction systems in the floor significantly improved working conditions.

2000: DG-1000 until today

DG-1000S und DG-1000 Club
First flight: July 2000. currently: 185 units delivered. In the new production facilities in Bruchsal, the development of the high-performance two-seater DG-1000 began. The simplified and more cost-effective DG-1000 Club 18m variant was further developed for use as a training aircraft.

DG-1000T
First flight: February 2004, total 58 serial numbers. A non-self-launching version with electric starter. New design of the engine control unit by Utz Schicke: DEI-NT.

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DG-1001M

First flight: July 09, 2009. Currently:
40 units delivered. Self-launching on the basis of the DG-1000. The large landing gear was designed in such a way that the wheel extends further forward. A new version of the Solo 2625 with fuel injection offered better performance, especially at higher altitudes.

DG-1001E

First flight: July 2020. 8 units delivered to date. Analogous to the LS8-e from DG with FES system from equipped by LZ Design. January 2024: GEN4 Batteries certification.

DG-1000TE

First flight: May 2011. One-off. Followed the trend towards electric flying:
Propulsion as folding engine with 34 HP motor. Propeller of the DG-1000T.

DG-1001 GLIDERS:
In principle, all newly built series of the DG-1001 can be equipped with a handicap system (rudder actuated by hand).