Aircraft construction Max Gerner

The aircraft Max Gerner was one of a total of 28 aviation companies in the Frankfurt area between 1907 and 1945. Its founder, Max Gerner , born on April 7, 1900 as the son of a construction materials business in Regensburg had, while studying at the Rheinische Engineer School in Mannheim in 1922 in the Richard Dietrich's newly emerging aircraft construction company worked there as a designer and made his first experience in designing aircraft . Among other things, he was involved in the creation of the Dietrich DP I , a two-seater double-decker that was closely based on the Fokker D.VII . Gerner had taken part in Dietrich's move to Kassel in January 1923, but no longer moved his company to Berlin in 1927. Instead, he went to Frankfurt am Main, where he founded his own company in 1928.

The first plane

His goal was a highly economical light sport aircraft that was easy to manufacture, just as easy to maintain and repair. He was particularly fond of thin-walled steel tubes as a construction element, which resulted in high strength and relatively low weight. So he renounced the then common use of wood, especially for the grand piano. Since he basically used welded steel pipes of various dimensions for all components, down to the smallest with 4 mm diameter and 0.5 mm wall thickness, he was able to offer it under the name all-steel aircraft. With the exception of the engine area, the outer skin was made of weatherproof, varnished fabric. This first aircraft, which he called GI , was a small two-seater double-decker with a wingspan of only 6.0 m, which weighed only 200 kg, but was supposed to be able to carry 200 kg of payload at the same time, an otherwise hardly achieved ratio of payload to empty weight. Gerner built it with just one other helper named Eduard Rottke . It is not known who flown it in. It is also not clear whether this happened before the ILA , which took place from October 7th to 28th in Berlin, or only afterwards. In any case, he could already display the aircraft there. With an Anzani three-cylinder engine of 35 hp it should have been available for 5200 RM , while with an English ABC two-cylinder boxer engine it would have come from 39 hp to 6400 RM. Since it was given the name Frankfurt, but never received official approval, it could only be flown within the Frankfurt-Rebstock airport area. Most of the other test flights were apparently made by Erich Wiegmeyer , who worked as a flight instructor for the local Südwestdeutsche Luftverkehrs-AG , but who also broke with the plane on September 25, 1929, resulting in a total write-off. This debut from Gerner does not seem to have aroused any greater interest, as no other copies were built.

The second aircraft and start of series production

A G II R in 1933

Soon after the GI's first flights, Gerner began to design and build a successor model, which was given the designation G II R (R for "series construction", as a reference to the planned series production of the machine). It had the same characteristics as the GI, but was slightly larger at 7.2 m wingspan. The rectangular wings with rounded corners were constructed in exactly the same way as on the G I. Two seamlessly drawn steel tubes with a diameter of 50 mm and a wall thickness of 1.5 mm were used as spars, onto which the prefabricated ribs, also welded from thin steel tubes, were pushed and clamped in place with screw clamps welded into them. Gerner had this method patented. The middle section of the upper wing was now formed by the 70 liter fuel tank on two N-shaped canopy struts, from which the fuel flowed to the engine through a natural gradient. As a special feature, the wings could be folded back, which meant that the aircraft was only 2.05 m wide to accommodate the hangar. In contrast to the GI, the G II R only had ailerons on the lower wings , the shape and size of which required many attempts. The chassis with a continuous axle was also rubber-sprung here. The aircraft Wnr. 2, registered in June 1931 as D-1936, had a Salmson nine-cylinder radial engine AD 9 with 45 HP as drive , but from Wnr. 6 was replaced by the Hirth HM 60 hanging four-cylinder in-line engine with 60 hp, which was made the standard engine . The flight test was again carried out by Erich Wiegmeyer, who was replaced by Eugen Stein towards the end . Wiegmeyer took over the aircraft for his aforementioned company, where it was used for training. Gerner rented an entire hall from this company, which he later referred to as Plant I. Apparently, the first series aircraft, Wnr. 3, as D-2154, which its owner, Richard J. Kern from Düsseldorf, immediately registered for the flight to Germany , which began on August 11th . Both this and the D-1936 flew at times with five-cylinder BMW Xa radial engines with an output of 54 hp. A four-cylinder in-line engine AFMA with 45 HP developed by the motorcycle company Horex was used in the Wnr. 3 tried, but turned out to be too heavy.

From Wnr. 8, D-2625, the aircraft carried the type designation G II Rb and had the Wnr. 9, the D-2626, the more powerful HM 60 R engine with 85 HP installed. The production rate at that time was around one aircraft per month. At the German Air Sports Exhibition (DELA) in Berlin in 1932, Gerner was represented with an airplane in the exhibition. The following prices were given for the various possible engine configurations: 7800 RM with the BMW Xa, 8750 RM with the HM 60 and 9100 RM with an HM 60 R. In the outdoor area, the aircraft Wnr. 7 on the ground (assembly and dismantling) and in flight by its owner Herrmann-Otto, Hereditary Prince of Solms-Hohensolms-Lich , a staunch supporter of the Gerner aircraft.

Air sports appearance

Richard J. Kern, who had previously worked a lot with Ernst Udet , wanted to use his aircraft, the Wnr. 3, shortly after its completion, took part in the 1931 flight to Germany. Since he was 35 minutes late at the start, he was only allowed to fly out of competition. The aircraft had a removable canopy over the driver's seat for this flight.

The Hereditary Prince took part for the first time in the reliability flight of the DLV in 1932, as well as in the Rhenish flight tournament in the same year. Four G II Rb had already been registered for the Germany flight in 1933, but only two of them took part. The Hereditary Prince flew one of them with an unknown location, the other Eugen Stein with the owner, the eyewear manufacturer Böhler from Frankfurt. Both crews received RM 496.92 as a cash prize. The Hereditary Prince also flew on the Germany flight in 1934, this time with Josef Jacobs as Orter, but now in the association of the Essen subgroup of the DLV consisting of seven G II Rb. Another association with five Gerner aircraft was provided by the Münster local group, of which, however, the crew Willi Vollbracht and Wilhelm Koch had a fatal accident on the first day of the competition, June 21. This association then gave up the onward flight. The Essen Association also joined in on the second day.

During the Germany flight in 1935, which this time started on May 28, Essen again provided a five-man squadron, which with the competition number B5 survived the difficult flight, but only landed 22nd out of 29 participants. Both Jacobs, this time as a pilot, with Orter W. Schmidt, and the Hereditary Prince with WH Storp flew in this association. The latter two then won the alpine flight from Kempten in September . In 1936 they took part in the star flight to the Summer Olympics, as well as in the 2nd Belgian sightseeing flight, but all of this already with the further development G II Rc . Gerner planes are also said to have taken off during the coastal flight in 1937.

The Adlerwerke take over Max Gerner

The company Adler , also based in Frankfurt , formerly Heinrich Kleyer AG, which was not only successful with its bicycles and sewing machines, but above all with its motor vehicles Adler Trumpf and Trumpf Junior , sought, like many other companies in Germany, to get involved in the to create another mainstay in the promising area of ​​aviation. The company had been active in this field since 1909. The fact that with Franz Röhr as chief designer and the Pour-le-mérite carrier Josef Jacobs as director, two war pilots at Adler had a great influence and initiated the takeover of Gerner's company, was certainly conducive to this . Jacobs was now head of the entire aircraft construction division, while Gerner, now a permanent employee of Adler, remained responsible for his aircraft. Thanks to Jacob's efforts, sales of Gerner aircraft soon increased significantly. During this time the G II Rb experienced some significant changes. Not only the shape of the tail changed, away from the previously rectangular shape toward the trapezoidal shape, but also the chassis has been significantly improved through long-stroke Faudi - shocks , which now abstützten located on the upper flange of the fuselage. This increased the track width from just 1.2 m to now 1.6 m. Then there were the more modern low-pressure wheels. The Gerner planes were apparently on the right track.

Kickback and lock

After already on March 10, 1933 a G II R, the Wnr. 7, D-2293, tumbled from a height of about 60 m and a second aircraft, D-2833 (presumably Wnr. 14), had an accident under similar circumstances on February 22, 1934, the above-mentioned crash at the beginning of the flight to Germany caused the Reich Ministry of Aviation (RLM) become aware. All aircraft of the type were blocked with effect from July 1, 1934 and an investigation was ordered, in which the Rechlin E -stelle was also involved. The main causes turned out to be disturbances in the air flow behind the tank located in the upper wing, which caused practically the entire tail unit to lose its effectiveness when pulled over and the aircraft was smeared over one wing. There was also too much tail-heaviness. These results forced an immediate redesign, which led to a heavily modified aircraft, at least in appearance, which was now referred to as the G II Rc . What was new about this was not the backward sweep of the wings by 8 ° to eliminate the center of gravity problem, but also significant aerodynamic improvements, e.g. B. by enlarging the tail unit. The first aircraft of this design did not receive its approval until April 1935, but the production of this design (or the modification of existing aircraft) must have started beforehand, because otherwise five Gerner aircraft, now known as Adler steel aircraft, would not have started a month later. Machines on the Germany flight in 1935 could have participated.

Separation from Adler

Because the economic result in the aircraft sector obviously fell short of the expectations of the Adlerwerke management and the future prospects were clouded due to the crashes and the ban that was imposed, Adler declared the separation from Gerner on April 30, 1935 after lengthy negotiations. He obviously continued to work, now again under his own responsibility as a sole proprietorship, but apparently was able to sell fewer and fewer aircraft. In total, only a little more than fifty aircraft were built, six of which were G II, 34 G II Rb and only 13 G II Rc. It is not known when the last Gerner was withdrawn from circulation.

Gerner repair shop

Obviously, as early as 1936, the repair of aircraft, mainly the Luftwaffe, began to replace its own production . A directory of the repair companies working in 1937 names Gerner as responsible for the aircraft types He 70 , Hs 123 , Kl 25 and Kl 32 , which means that he now had to cover the entire spectrum from pure wooden aircraft to all-metal construction. A little later the type Bf 109 and the cargo glider DFS 230 were added. Increasingly, he was also asked to produce new components for these aircraft. As the volume of orders grew steadily, Gerner converted his previous sole proprietorship into a GmbH on October 4, 1940 . As aircraft Max Gerner GmbH was in the December 12, commercial register Frankfurt a. M. registered. A separate logo was now also to be found on the letterhead. His factories were now located in a total of four locations in the city of Frankfurt, of which the so-called Factory III was a completely new building. The former Plant I in a hall at Rebstock Airport was now called Plant IV. On December 31 of that year, the workforce already consisted of 1,385 employees. That number rose to almost 1,800 by 1943. Air raids soon forced various plants to be relocated. The resulting temporary drop in work performance was quickly compensated for.

post war period

The end of the war brought the collapse of his company for Gerner too. In 1946, however, he opened a machine joinery in Frankfurt-Niederrad , which had up to 45 employees, but was struck from the commercial register again in 1951. Little is known about his further activities, in which the name Flugzeugbau Max Gerner reappeared. He died on March 24, 1977 and was buried in the main cemetery in Frankfurt.

Technical specifications

Parameter	GI	G II R	G II Rb	G II Rc
length	5.2 m	5.6 m	6.32 m
span	6.0 m	7.2 m
height	1.8 m	2.0 m	2.12 m
Empty mass	200 kg	225 kg	275 kg	325 kg
Takeoff mass	400 kg	430 kg	480 kg	560 kg
Top speed	150 km / h	152 km / h	160 km / h	175 km / h
Landing speed	55 km / h	57 km / h	60 km / h	65 km / h
Summit height	2600 m	2700 m	4000 m	4500 m
Range	600 km		580 km	550 km
Engine	Anzani , 35 hp	Salmson AD 9, 45 hp	Hirth HM 60, 60 HP	Hirth HM 60 R, 85 PS

literature

• Lectures by Joachim Feige and Kurt Grasmann: Beginnings of aviation in the Darmstadt and Frankfurt area in DGLR sheets No. XIV, ISBN 3-932182-12-X
• Article by Karlheinz Kens in the magazine MFI - Modellflug international, issues 9 and 10/2002
• Boris Schmidt: Frankfurt's aviator factory . In: Frankfurter Allgemeine Zeitung . July 24, 2017, ISSN  0174-4909 ( online [accessed July 24, 2017]).

Individual evidence

1. ↑ FliegerRevue March 2010, pp. 56–59, Erla-Gerner-Gotha - car manufacturers try their hand at the Volksflugzeug