Mü 17 "Merle" The Dream of a Olympic standard glider
Nothing was more conducive to promoting gliding among the Olympic officials than the 336-kilometer cross-country flight of Budapest engineer Lajos (Ludwig) Rotter (1901-1983) from the Olympic city of Berlin to Kiel, where the Olympic gliding competitions were held. Flying his 20-meter glider, Nemere, which he had designed on a voluntary basis for the Hungarian Aero Association, he took off from Berlin's Rangsdorf airfield on August 12, 1936, and landed at Kiel's Holtenau airport after a total flight time of only 3 hours and 53 minutes. The achieved average speed of 83.7 km/h was a very high value for the time. Rotter had achieved it through his
new dolphin flying style, crossing thermals while staying on course in slow flight, instead of circling time-consumingly. The former motor aircraft designer had come to gliding due to the economic crisis and had already become the second foreigner to receive the Silver Performance Badge (number 19) on February 26, 1934. He developed the driving force behind the Hungarian gliding movement. His early glider designs gained importance beyond the country's borders.
Undoubtedly, Rotter was among the best foreign performance glider pilots when the FAI (Fédération Aéronautique Internationale - an association of national aero clubs with the purpose of international regulation of airsports) selected him to be one of the pilots who had to decide on the Olympic standard glider in Italy in 1939. The other pilots were the Frenchman Eric Nessler, the Italian Adriano Mantelli, the Pole Romuald Szukiewicz, the Swiss Hermann Schreiber and the German Otto Bräutigam.
An initial proposal to include gliding as an Olympic discipline had already been considered by the Executive Committee of the International Olympic Committee (IOC) in Lausanne in June 1932, at the request of the German member, former State Secretary Lewald.
It was approved but postponed. The ISTUS (later OSTIV), the International Study Commission for Unpowered Flight – an association of almost all gliding nations at the time, with the aim of exchanging experience – had decided at its meeting in 1935 in Berlin made a decision to implement this discipline. A year later, during its meeting in Budapest, it submitted a corresponding resolution to the IOC. The IOC then decided at its Berlin meeting on March 28, 1938, to grant the request for powered flight to be an Olympic discipline for the 1940 Olympic Games in Helsinki.
At its 38th meeting at the end of June 1938 in Berlin, the FAI specified the competition conditions: two cross-country flights with additional altitude and speed scoring, to be conducted in a standardized glider. The specifications for this competition had already been prepared by the scientifically and technically active ISTUS and brought along as luggage, so that they could be published on the same day.
It encompassed a whole range of conditions, the most important of which are worth mentioning: Simple construction for rational series or group production; automatic couplings for quick assembly; exclusive use of pine, plywood, and steel as construction materials; wingspan limited to 15 meters (a foreshadowing of the subsequent standard class); 60 cm as the minimum fuselage width; empty weight maximum 160 kg, payload fixed at 95 kg; dive-speed capability limited to 200 km/h by air brakes; skids as landing gear.
Comparison flights of the best models developed according to these criteria were scheduled for February 1939. This left only ten months for design, construction, and testing.
In Italy, a team and a designer got to work. In Switzerland, another designer, and in Poland, Antoni Kocjan began modifying his successful competition glider, Oriik, on the drawing board according to the ISTUS specifications. In Germany, four applicants were found: the state-run DFS (German Research Institute for Gliding), Darmstadt; the Aachen Aeronautical Association (FVA); and the aeronautical engineering groups (FFG) at the Technical Universities in Berlin and Munich. As a result of coordinated steering, all German designs shared common design features: two-piece, straight trapezoidal wings with only slight dihedral and a relatively long fuselage.
Two aircraft were ordered, the first prototype of which had to be flown by January 1, 1939. The second aircraft, intended as a reserve in case of failure of the first, had to be completed by February 15, 1939. will be - four days before the international qualifying event.
The Berliners with their B8 didn't make the deadline. They only managed to get the first prototype flying by January 14, 1939, in order to fail at the national qualifying competition in Darmstadt, as did the Aachen team with their FVA 13 Olympia dinghy, against the competition from the DFS (Meise) and Munich (Mü 17).
A technical committee consisting of the Briton Shenstone, the Frenchman Cartier, the Italian Simone, the Dutchman van der Maas, the Pole Steonievski, and the German Kensche. had already made a technical assessment in advance by reviewing the design and calculation documents and had selected five models: in addition to the two German designs, two Italian models and the Polish Orlik III Olympia. Among these, flight characteristics and performance now had to be the deciding factor. The Olympic comparison flying event took place from February 19, 1939, at the Sezze-Littoria gliding center, an Italian center under construction about 80 km south of Rome. Given the location of the airfield in the plain between the sea and the Apennine Mountains, directly at the foot of the mountains, the southern sun and the rocky surroundings ensured excellent thermals even at this time of year. On the second day of the event, the five glider types were first flown by their own pilots before the FAI pilots began their evaluation. Each pilot had to evaluate each type. This meant that for each pilots were to be towed five times a day to altitudes of up to 3,000 meters and then complete a subsequent evaluation flight lasting up to one and a half hours. Ergonomics and comfort for the pilot were assessed, as well as takeoff and landing behavior, stability characteristics, control criteria, and handling in dangerous flight conditions. According to Professor Walter Georgii, then president of ISTUS, coordinating the pilots' judgment, which was based on their feel for the aircraft and not on direct flight measurements, was extremely difficult, especially since a certain degree of subjectivity depending on nationality could not be ruled out.
In the final session. After a long and drawn-out discussion, the small Italian pilot Mantelli finally decided in favor of the Mot-, and the French delegate of the technical committee, engineer R. Cartier, concurred with this opinion. Her application to designate the Meise as the Olympic aircraft was subsequently accepted with all votes except those of the Polish side. The Poles still consider this decision political – a view that cannot go unchallenged.
Without a doubt, the DFS Meise was the result of extensive experience and was the most mature of all the applicants. After the initial flight by Hanna Reitsch, all subsequent flights by other pilots confirmed that Weaknesses were discovered and eliminated, so that it ultimately had to deliver the optimum level of perfection according to the criteria of the tender.
The Polish Orlik III Olympia, as a mid-wing monoplane with gull wings, was significantly more complicated in its construction and assembly. The Poles' objection that it was more efficient than the Meise is also invalid, because the Munich MO 17 was – apart from a only slightly less favorable glide ratio – even more efficient, also had excellent slow-flight characteristics, and could be turned extremely tightly in thermals.
The Mu 17 Merle (French for blackbird) of FFG Munich remained the only applicant whose fuselage was constructed as a welded steel tube structure. Thus, she proved herself to be a typical representative of the Munich School, which Egon Scheibe (1909-1997), then head of the Munich Akaflieger, initiated in 1932 with the start of the design of the two-seater. Mu 10 had been founded. Besides the steel tube fuselage, this development direction was characterized by the airfoil developed by Scheibe himself. It features – similar to the NACA airfoils with a five-digit number studied in the USA – a skeletal line with a slight aft position of the greatest camber. Designs by the Munich Akaflieg with this airfoil, whose slight underside camber is only in the forward area, generally always soared far higher than all others in the same updraft. This remained the case with the Mu 17, whose characteristics for Alpine soaring proved to be just as outstanding as those of the Mu 10. Lajos Rotter was convinced after the decision in Sezze. that "...the Munich Merle, after refinements, would have had better flight characteristics (than the Meisse). But..." he reported in 1939 in the Hungarian magazine Aviatik, "...we had to make the selection based on the existing, not the possible, flight characteristics. For example, it was impossible to make the Merle spin at all costs, at most for half to three-quarters of a turn, then it would return to normal flight attitude. It could also be pulled extremely hard over, and it would still remain airworthy. On the other hand, it required excessive rudder forces, and, due to the low fuselage, the tail of the aircraft hit the ground hard on every landing." This bad habit disappeared with the installation of landing gear.
Unlike the previous Mu-series designs, the Mu 77 fuselage was constructed using thinner steel tubes (diameters between 8 and 20 mm) with thicker walls (1 mm). The designer deliberately chose them to simplify the welding work. His name was Ludwig Karch. He himself flew the first prototype on December 23, 1938. A second one followed shortly after. Dipl.-Ing. Ludwig Karch (1914-1973), the son of parents from the Palatinate, born in Wurzen, Saxony, was not only a gifted designer, but also a pioneer and arguably the most successful implementer of Alpine soaring. In 1936, he was already flying the original of the aforementioned Mu 10 Milan (which survived the war and 30 years of flight operations and now hangs as a museum piece in the historic hangar in Schleissheim). Karch chose this two-seater as his favorite aircraft and used it for years.
In any case, in the same year, 1936, when the meteorological conditions were still completely unexplored, he ventured the first attempts at cross-country flying in the Alps.
In 1937, on the occasion of the ISTUS conference in Salzburg, five German gliders took off from the conference venue on May 30th, intending to reach the northern Italian plains via the Hohe Tauern and the Grossglockner.
All arrived, but with a landing in Pieve d'Alpago, 195 km away in the southern foothills of the Italian Dolomites, Karch and his companion Klein achieved the greatest distance in their Milan glider. At the same time, they set a two-seater world record at 2,980 meters above the release altitude (500 meters). The enthusiastic host, Prince Kinsky, President of the Austrian Aeroclub, picked up the pilots in his sports plane to transport them to the Lido of Venice for a "good meal.
new dolphin flying style, crossing thermals while staying on course in slow flight, instead of circling time-consumingly. The former motor aircraft designer had come to gliding due to the economic crisis and had already become the second foreigner to receive the Silver Performance Badge (number 19) on February 26, 1934. He developed the driving force behind the Hungarian gliding movement. His early glider designs gained importance beyond the country's borders.
Undoubtedly, Rotter was among the best foreign performance glider pilots when the FAI (Fédération Aéronautique Internationale - an association of national aero clubs with the purpose of international regulation of airsports) selected him to be one of the pilots who had to decide on the Olympic standard glider in Italy in 1939. The other pilots were the Frenchman Eric Nessler, the Italian Adriano Mantelli, the Pole Romuald Szukiewicz, the Swiss Hermann Schreiber and the German Otto Bräutigam.
An initial proposal to include gliding as an Olympic discipline had already been considered by the Executive Committee of the International Olympic Committee (IOC) in Lausanne in June 1932, at the request of the German member, former State Secretary Lewald.
It was approved but postponed. The ISTUS (later OSTIV), the International Study Commission for Unpowered Flight – an association of almost all gliding nations at the time, with the aim of exchanging experience – had decided at its meeting in 1935 in Berlin made a decision to implement this discipline. A year later, during its meeting in Budapest, it submitted a corresponding resolution to the IOC. The IOC then decided at its Berlin meeting on March 28, 1938, to grant the request for powered flight to be an Olympic discipline for the 1940 Olympic Games in Helsinki.
At its 38th meeting at the end of June 1938 in Berlin, the FAI specified the competition conditions: two cross-country flights with additional altitude and speed scoring, to be conducted in a standardized glider. The specifications for this competition had already been prepared by the scientifically and technically active ISTUS and brought along as luggage, so that they could be published on the same day.
It encompassed a whole range of conditions, the most important of which are worth mentioning: Simple construction for rational series or group production; automatic couplings for quick assembly; exclusive use of pine, plywood, and steel as construction materials; wingspan limited to 15 meters (a foreshadowing of the subsequent standard class); 60 cm as the minimum fuselage width; empty weight maximum 160 kg, payload fixed at 95 kg; dive-speed capability limited to 200 km/h by air brakes; skids as landing gear.
Comparison flights of the best models developed according to these criteria were scheduled for February 1939. This left only ten months for design, construction, and testing.
In Italy, a team and a designer got to work. In Switzerland, another designer, and in Poland, Antoni Kocjan began modifying his successful competition glider, Oriik, on the drawing board according to the ISTUS specifications. In Germany, four applicants were found: the state-run DFS (German Research Institute for Gliding), Darmstadt; the Aachen Aeronautical Association (FVA); and the aeronautical engineering groups (FFG) at the Technical Universities in Berlin and Munich. As a result of coordinated steering, all German designs shared common design features: two-piece, straight trapezoidal wings with only slight dihedral and a relatively long fuselage.
Two aircraft were ordered, the first prototype of which had to be flown by January 1, 1939. The second aircraft, intended as a reserve in case of failure of the first, had to be completed by February 15, 1939. will be - four days before the international qualifying event.
The Berliners with their B8 didn't make the deadline. They only managed to get the first prototype flying by January 14, 1939, in order to fail at the national qualifying competition in Darmstadt, as did the Aachen team with their FVA 13 Olympia dinghy, against the competition from the DFS (Meise) and Munich (Mü 17).
A technical committee consisting of the Briton Shenstone, the Frenchman Cartier, the Italian Simone, the Dutchman van der Maas, the Pole Steonievski, and the German Kensche. had already made a technical assessment in advance by reviewing the design and calculation documents and had selected five models: in addition to the two German designs, two Italian models and the Polish Orlik III Olympia. Among these, flight characteristics and performance now had to be the deciding factor. The Olympic comparison flying event took place from February 19, 1939, at the Sezze-Littoria gliding center, an Italian center under construction about 80 km south of Rome. Given the location of the airfield in the plain between the sea and the Apennine Mountains, directly at the foot of the mountains, the southern sun and the rocky surroundings ensured excellent thermals even at this time of year. On the second day of the event, the five glider types were first flown by their own pilots before the FAI pilots began their evaluation. Each pilot had to evaluate each type. This meant that for each pilots were to be towed five times a day to altitudes of up to 3,000 meters and then complete a subsequent evaluation flight lasting up to one and a half hours. Ergonomics and comfort for the pilot were assessed, as well as takeoff and landing behavior, stability characteristics, control criteria, and handling in dangerous flight conditions. According to Professor Walter Georgii, then president of ISTUS, coordinating the pilots' judgment, which was based on their feel for the aircraft and not on direct flight measurements, was extremely difficult, especially since a certain degree of subjectivity depending on nationality could not be ruled out.
In the final session. After a long and drawn-out discussion, the small Italian pilot Mantelli finally decided in favor of the Mot-, and the French delegate of the technical committee, engineer R. Cartier, concurred with this opinion. Her application to designate the Meise as the Olympic aircraft was subsequently accepted with all votes except those of the Polish side. The Poles still consider this decision political – a view that cannot go unchallenged.
Without a doubt, the DFS Meise was the result of extensive experience and was the most mature of all the applicants. After the initial flight by Hanna Reitsch, all subsequent flights by other pilots confirmed that Weaknesses were discovered and eliminated, so that it ultimately had to deliver the optimum level of perfection according to the criteria of the tender.
The Polish Orlik III Olympia, as a mid-wing monoplane with gull wings, was significantly more complicated in its construction and assembly. The Poles' objection that it was more efficient than the Meise is also invalid, because the Munich MO 17 was – apart from a only slightly less favorable glide ratio – even more efficient, also had excellent slow-flight characteristics, and could be turned extremely tightly in thermals.
The Mu 17 Merle (French for blackbird) of FFG Munich remained the only applicant whose fuselage was constructed as a welded steel tube structure. Thus, she proved herself to be a typical representative of the Munich School, which Egon Scheibe (1909-1997), then head of the Munich Akaflieger, initiated in 1932 with the start of the design of the two-seater. Mu 10 had been founded. Besides the steel tube fuselage, this development direction was characterized by the airfoil developed by Scheibe himself. It features – similar to the NACA airfoils with a five-digit number studied in the USA – a skeletal line with a slight aft position of the greatest camber. Designs by the Munich Akaflieg with this airfoil, whose slight underside camber is only in the forward area, generally always soared far higher than all others in the same updraft. This remained the case with the Mu 17, whose characteristics for Alpine soaring proved to be just as outstanding as those of the Mu 10. Lajos Rotter was convinced after the decision in Sezze. that "...the Munich Merle, after refinements, would have had better flight characteristics (than the Meisse). But..." he reported in 1939 in the Hungarian magazine Aviatik, "...we had to make the selection based on the existing, not the possible, flight characteristics. For example, it was impossible to make the Merle spin at all costs, at most for half to three-quarters of a turn, then it would return to normal flight attitude. It could also be pulled extremely hard over, and it would still remain airworthy. On the other hand, it required excessive rudder forces, and, due to the low fuselage, the tail of the aircraft hit the ground hard on every landing." This bad habit disappeared with the installation of landing gear.
Unlike the previous Mu-series designs, the Mu 77 fuselage was constructed using thinner steel tubes (diameters between 8 and 20 mm) with thicker walls (1 mm). The designer deliberately chose them to simplify the welding work. His name was Ludwig Karch. He himself flew the first prototype on December 23, 1938. A second one followed shortly after. Dipl.-Ing. Ludwig Karch (1914-1973), the son of parents from the Palatinate, born in Wurzen, Saxony, was not only a gifted designer, but also a pioneer and arguably the most successful implementer of Alpine soaring. In 1936, he was already flying the original of the aforementioned Mu 10 Milan (which survived the war and 30 years of flight operations and now hangs as a museum piece in the historic hangar in Schleissheim). Karch chose this two-seater as his favorite aircraft and used it for years.
In any case, in the same year, 1936, when the meteorological conditions were still completely unexplored, he ventured the first attempts at cross-country flying in the Alps.
In 1937, on the occasion of the ISTUS conference in Salzburg, five German gliders took off from the conference venue on May 30th, intending to reach the northern Italian plains via the Hohe Tauern and the Grossglockner.
All arrived, but with a landing in Pieve d'Alpago, 195 km away in the southern foothills of the Italian Dolomites, Karch and his companion Klein achieved the greatest distance in their Milan glider. At the same time, they set a two-seater world record at 2,980 meters above the release altitude (500 meters). The enthusiastic host, Prince Kinsky, President of the Austrian Aeroclub, picked up the pilots in his sports plane to transport them to the Lido of Venice for a "good meal.
The 1940 Olympic Games in Helsinki included gliding as a discipline. The competitions were to be held using the same type of glider. The Munich Akaflieger (academic flying club) had justified hopes for their candidate in the qualifying round.
At the beginning of August 1937, Ludwig Karch and his companion Zimmermann were able to celebrate as the overall winners of the 18th Rhön Competition: They had achieved a total distance of 1,575 km in a Mu 10. At the next ISTUS meeting in May 1938 in Bern, the crew of Karch/Klein crossed the Alps again on the Merltn and landed near the Italian town of Pallanza, 136 km from Bern.
At the 1939 Rhön Competition, which began on July 23 and at often had to be carried out in less than favorable weather.
Ludwig Karch flew his own design, the Mu 17 (specifically the V1 with the registration D-14-252 and competition number 36), in the crew
rank of a pilot for the Luftwaffe group. The second machine (V2, D-14-251, competition number 40) was taken over by Bernhard Flinsch from the FFG Darmstadt for the DVL (German Research Institute for Aviation). Both machines now had a retractable wheeled landing gear and the standard instrumentation consisting of an aircraft clock, airspeed indicator, altitude indicator, variometer, compass, turn indicator, and – for the first time – a gyro-driven artificial horizon by Spencer. After a radio unit had also been installed, which the Stuttgart Akaflieger had developed for their newly constructed aircraft which had crashed before the competition, Karch wrote that the wingspan of the Mü 17 had to be increased to 17 meters in order to handle the additional weight. The radio unit proved very useful for notifying the retrieval crews, and the instrumentation also proved helpful. paid off, because a large part of the flights took place in clouds.
The average performance in this competition was very high. Nevertheless, Flinsch managed to achieve tenth place in his Mu 17. Karch covered a remarkable 1,112 km in 28 hours and 40 minutes, but only managed 23rd place because he lost two scoring days due to a mid-air collision on the very first day of the competition (July 23, 1939).
Karch's diary: "Takeoff at 11:25 a.m. on the south slope. Weak wind from the south, good thermals, cloud base 1,800 m a.s.l. I circled for 20 minutes at varying altitudes when I saw a Mu 13 approaching. I assumed the pilot had seen me. As it approached, the other aircraft suddenly banked towards me. I let my aircraft slide over the wing, but could no longer avoid the collision. The impact put me half in a backward roll, but I managed to right the aircraft. The wing nose was ripped open, the left aileron was twisted off at the outer section, and the fuselage lower stringers were badly bent.
Nevertheless, I was able to make a smooth emergency landing at the Trinkhof motor tow site." Since the repair on the hilltop was difficult, we drove to Munich at 4 p.m., where we arrived at 8 p.m. The fuselage was already repaired by midnight. The woodwork on the wing could be completed by noon the next day. The departure for the hilltop took place at 4 p.m. Only 24 hours had passed. According to Karch, the collision would never have been so fortunate had both aircraft not had steel tube fuselages. During the war, the Mu 17 had to compete against the competition once again. To compensate for the numerical decline in engineers, the department responsible for young engineers within the DVL (German Aircraft Association) relied on an improved training program. of the technical juniors. Thus, in August 1941, a comparative flight test was held at the Prien airfield on Lake Chiemsee for the products created by engineering schools and technical universities. It was primarily intended to provide the foundations for the engineering-style flying of experimental aircraft. All four candidates for the Olympic aircraft were grouped together in one group of training aircraft. Unfortunately, no results were published. The Merle, however, was also suitable for experiments. In order to be able to carry out glider towing training in winter, even with heavy snowfall, on aircraft with retractable landing gear, the Munich Flying Club (FFG München) designed skis at the end of 1941 that could be replaced with wheels (see illustrations). Two years later, the FFG had developed into one of the leading institutions for lift-towing, which the Gotha-based Waggorv factory was also working on. They had designed a winged auxiliary fuel tank, the P56, which—tethered in a lift-towing tow and flying above a fighter aircraft—could supply it with fuel even at distant operational locations. The fuel developed by the The Munich-developed towing procedure was tested with the Klemm L 25e and Mu 17 towing combination and was demonstrated in Gotha on July 20, 1944.
Meanwhile, the young Ludwig Karch had been appointed lecturer in Prague. Here, an Academic Flying Group had formed at the German University in 1922. After the occupation of Czechoslovakia, this group—like the Academic Flying Groups in the Reich before it—was transformed into an Aircraft Production Association (FFG), supported by the German Aerospace Center (DVL). Even before the outbreak of war, the Prague Aircraft Production Association (FGP) was founded, possibly with the help of this FFG. which
initially worked closely with the Akaflieg Munich, suggesting that Karch initially also led it (later it was Dipl.-Ing. Hans Wunscher from FAG Chemnitz, who in 1944 still designed the reconnaissance motor glider FG 2 with folding propeller according to his patent). As FG 1, Ludwig Karch designed at FGP with geometric accuracy for experimental For the purposes of this, a two-seat model
of the Blohm & Voss BV 238, a six-engined large flying boat under development, was built at a scale of 1:4 with six 22 hp (16.2 kW) Ilo engines. It was designated 8-(FG) 227 by the RLM (Reich Air Ministry) and only entered testing in 1944.
The FGP (Flying and Planning Company) was also selected to build the Mu 17 in the series version with fixed landing gear for the Luftwaffe's gliding clubs, because the design was primarily intended for use as a training aircraft for performance flights. According to the C-Office's monthly report from September 1941, the FGP had 47 aircraft of this type on order, of which 12 were to be manufactured that month. At this point, however, when 36 should have already been delivered, not a single one had yet come out of the workshops. How many Mii 17s were actually built in Prague could not yet be definitively determined. The figure of about 20 is being discussed. This number seems realistic, because in the monthly operational reports of the Air Force High Command (OdL, Chief of the General Staff, Quartermaster General, Chief of Air Force Supply) the following figures are listed in the flight- The inventory for March 1944 still shows nine Mu 17s. For August/September 1944 – the last available – there were finally six. Of these, at least three appear to have survived the end of the war. They were flown by members of the occupying powers. In 1961, the Akaflieg Munich rebuilt two Mu 17s (D-1717 for Karch and D-1740 for the Akaflieg), both of which still exist. They differ in detail from the original version, for example, by a new tail shape and structure, developed by the long-time workshop manager, Toni Tröger. With his aircraft, Ludwig Karch attempted a 500 km cross-country flight with return in 1963, which he narrowly missed within sight of the take-off point.
Countless were Karch's alpine glider pilots after the war. Numerous were his students whom he instructed in alpine gliding. He designed the motor glider Mu 23, was the long-time chairman of the German Alpine Gliding School in Unterwössen, and in his profession as an engineer, he was a successful pioneer for a high-speed rail project, which today is becoming an economically viable magnetic levitation railway.
Technical Description
Wing Two-piece, single-spar wooden wing with disc airfoil; box spar. Torsionally rigid leading edge due to single- sheeted ribs and plywood skin up to the spar; wing trailing section with auxiliary spar
and truss ribs, fabric-covered. Differential ailerons (1:2), plywood-sheeted on both sides; DFS airbrakes made of wood on the upper and lower surfaces, actuated by a torsion axis. Automatic coupling of the airbrakes and aileron connections; aileron actuation in the wing by cables.
Fuselage: Welded steel tube truss, fabric-covered. Cross-section of the load-bearing structure trapezoidal at the front, triangular at the rear. Complete removable canopy cover, also made of steel tubing, covered with Astralon.
Tailplane: Wooden construction with fabric covering. Horizontal stabilizer with plywood-covered damping fin, vertical stabilizer undamped; rudder actuation by cables.
Landing gear: Football-sprung central skid made of ash. Convertible to retractable single-wheel landing gear; its wheel protrudes from the fuselage contour when retracted; replacement with skis is possible.
Coloring: Prototypes completely painted cream-white, with black registration and the national flag in black-white-red on the vertical stabilizer.
At the 1939 Rhön Competition, which began on July 23 and at often had to be carried out in less than favorable weather.
Ludwig Karch flew his own design, the Mu 17 (specifically the V1 with the registration D-14-252 and competition number 36), in the crew
rank of a pilot for the Luftwaffe group. The second machine (V2, D-14-251, competition number 40) was taken over by Bernhard Flinsch from the FFG Darmstadt for the DVL (German Research Institute for Aviation). Both machines now had a retractable wheeled landing gear and the standard instrumentation consisting of an aircraft clock, airspeed indicator, altitude indicator, variometer, compass, turn indicator, and – for the first time – a gyro-driven artificial horizon by Spencer. After a radio unit had also been installed, which the Stuttgart Akaflieger had developed for their newly constructed aircraft which had crashed before the competition, Karch wrote that the wingspan of the Mü 17 had to be increased to 17 meters in order to handle the additional weight. The radio unit proved very useful for notifying the retrieval crews, and the instrumentation also proved helpful. paid off, because a large part of the flights took place in clouds.
The average performance in this competition was very high. Nevertheless, Flinsch managed to achieve tenth place in his Mu 17. Karch covered a remarkable 1,112 km in 28 hours and 40 minutes, but only managed 23rd place because he lost two scoring days due to a mid-air collision on the very first day of the competition (July 23, 1939).
Karch's diary: "Takeoff at 11:25 a.m. on the south slope. Weak wind from the south, good thermals, cloud base 1,800 m a.s.l. I circled for 20 minutes at varying altitudes when I saw a Mu 13 approaching. I assumed the pilot had seen me. As it approached, the other aircraft suddenly banked towards me. I let my aircraft slide over the wing, but could no longer avoid the collision. The impact put me half in a backward roll, but I managed to right the aircraft. The wing nose was ripped open, the left aileron was twisted off at the outer section, and the fuselage lower stringers were badly bent.
Nevertheless, I was able to make a smooth emergency landing at the Trinkhof motor tow site." Since the repair on the hilltop was difficult, we drove to Munich at 4 p.m., where we arrived at 8 p.m. The fuselage was already repaired by midnight. The woodwork on the wing could be completed by noon the next day. The departure for the hilltop took place at 4 p.m. Only 24 hours had passed. According to Karch, the collision would never have been so fortunate had both aircraft not had steel tube fuselages. During the war, the Mu 17 had to compete against the competition once again. To compensate for the numerical decline in engineers, the department responsible for young engineers within the DVL (German Aircraft Association) relied on an improved training program. of the technical juniors. Thus, in August 1941, a comparative flight test was held at the Prien airfield on Lake Chiemsee for the products created by engineering schools and technical universities. It was primarily intended to provide the foundations for the engineering-style flying of experimental aircraft. All four candidates for the Olympic aircraft were grouped together in one group of training aircraft. Unfortunately, no results were published. The Merle, however, was also suitable for experiments. In order to be able to carry out glider towing training in winter, even with heavy snowfall, on aircraft with retractable landing gear, the Munich Flying Club (FFG München) designed skis at the end of 1941 that could be replaced with wheels (see illustrations). Two years later, the FFG had developed into one of the leading institutions for lift-towing, which the Gotha-based Waggorv factory was also working on. They had designed a winged auxiliary fuel tank, the P56, which—tethered in a lift-towing tow and flying above a fighter aircraft—could supply it with fuel even at distant operational locations. The fuel developed by the The Munich-developed towing procedure was tested with the Klemm L 25e and Mu 17 towing combination and was demonstrated in Gotha on July 20, 1944.
Meanwhile, the young Ludwig Karch had been appointed lecturer in Prague. Here, an Academic Flying Group had formed at the German University in 1922. After the occupation of Czechoslovakia, this group—like the Academic Flying Groups in the Reich before it—was transformed into an Aircraft Production Association (FFG), supported by the German Aerospace Center (DVL). Even before the outbreak of war, the Prague Aircraft Production Association (FGP) was founded, possibly with the help of this FFG. which
initially worked closely with the Akaflieg Munich, suggesting that Karch initially also led it (later it was Dipl.-Ing. Hans Wunscher from FAG Chemnitz, who in 1944 still designed the reconnaissance motor glider FG 2 with folding propeller according to his patent). As FG 1, Ludwig Karch designed at FGP with geometric accuracy for experimental For the purposes of this, a two-seat model
of the Blohm & Voss BV 238, a six-engined large flying boat under development, was built at a scale of 1:4 with six 22 hp (16.2 kW) Ilo engines. It was designated 8-(FG) 227 by the RLM (Reich Air Ministry) and only entered testing in 1944.
The FGP (Flying and Planning Company) was also selected to build the Mu 17 in the series version with fixed landing gear for the Luftwaffe's gliding clubs, because the design was primarily intended for use as a training aircraft for performance flights. According to the C-Office's monthly report from September 1941, the FGP had 47 aircraft of this type on order, of which 12 were to be manufactured that month. At this point, however, when 36 should have already been delivered, not a single one had yet come out of the workshops. How many Mii 17s were actually built in Prague could not yet be definitively determined. The figure of about 20 is being discussed. This number seems realistic, because in the monthly operational reports of the Air Force High Command (OdL, Chief of the General Staff, Quartermaster General, Chief of Air Force Supply) the following figures are listed in the flight- The inventory for March 1944 still shows nine Mu 17s. For August/September 1944 – the last available – there were finally six. Of these, at least three appear to have survived the end of the war. They were flown by members of the occupying powers. In 1961, the Akaflieg Munich rebuilt two Mu 17s (D-1717 for Karch and D-1740 for the Akaflieg), both of which still exist. They differ in detail from the original version, for example, by a new tail shape and structure, developed by the long-time workshop manager, Toni Tröger. With his aircraft, Ludwig Karch attempted a 500 km cross-country flight with return in 1963, which he narrowly missed within sight of the take-off point.
Countless were Karch's alpine glider pilots after the war. Numerous were his students whom he instructed in alpine gliding. He designed the motor glider Mu 23, was the long-time chairman of the German Alpine Gliding School in Unterwössen, and in his profession as an engineer, he was a successful pioneer for a high-speed rail project, which today is becoming an economically viable magnetic levitation railway.
Technical Description
Wing Two-piece, single-spar wooden wing with disc airfoil; box spar. Torsionally rigid leading edge due to single- sheeted ribs and plywood skin up to the spar; wing trailing section with auxiliary spar
and truss ribs, fabric-covered. Differential ailerons (1:2), plywood-sheeted on both sides; DFS airbrakes made of wood on the upper and lower surfaces, actuated by a torsion axis. Automatic coupling of the airbrakes and aileron connections; aileron actuation in the wing by cables.
Fuselage: Welded steel tube truss, fabric-covered. Cross-section of the load-bearing structure trapezoidal at the front, triangular at the rear. Complete removable canopy cover, also made of steel tubing, covered with Astralon.
Tailplane: Wooden construction with fabric covering. Horizontal stabilizer with plywood-covered damping fin, vertical stabilizer undamped; rudder actuation by cables.
Landing gear: Football-sprung central skid made of ash. Convertible to retractable single-wheel landing gear; its wheel protrudes from the fuselage contour when retracted; replacement with skis is possible.
Coloring: Prototypes completely painted cream-white, with black registration and the national flag in black-white-red on the vertical stabilizer.
