MZ ES 250-2 for getaway aircraft

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MZ ES 250-2 motors for getaway aircraft

Escape from the GDR

For many people, motorcycles mean freedom. For aircraft engineer Gerhard Wagner and his family, they meant the hope of a life in freedom. In 1981 two MZ ES 250-2s were the drive for an escape project that was supposed to bring the whole Wagner family from the GDR to the West. A story about the usefulness of motorcycles.

Admittedly, this story could have been dug up earlier. After all, it was 33 years ago and was published several times in various media. However, no one had been seriously interested in the two motorcycles that gave the driving force of the events at that time. The MOTORRAD editor first had to visit the aircraft department of the Deutsches Museum, following his interest in mobility issues. Then one stabbed him there M.Z TS 250, which was standing next to a bizarre aircraft.

MZ ES 250-2 motors for getaway aircraft

Escape from the GDR

The first drafts in 1979

Gerhard Wagner does not want to support the system in this way and despises this state, which now treats its own citizens like prisoners with its wall and minefields. The thought of fleeing the republic is growing stronger and the conflicts with the GDR authorities are coming to a head. Wagner is considering building a submarine and using it to flee across the Baltic Sea. But he doubts his skills as a boat builder. However, his competence as an aircraft designer cannot be shaken. So only an airplane is an option. But how do you build an airplane without anyone noticing? The only living space that offers protection from informers seems to be the apartment. So the family divides the back of their kitchen in Dresden’s Kyawstrabe 8 with cupboards and curtains. Gerhard Wagner starts building a one-way getaway plane for his family. Due to the limited space and the necessity of later transport in disassembled condition on a car trailer, no part may be longer than four meters.

Gerhard Wagner completed the aerodynamic designs in mid-1979. His six-meter-long machine should be able to transport him, his wife and three sons, then 17, 16 and seven years old, sitting close together. The calculated flight weight of 580 kilograms makes a plane with landing flaps necessary. This makes the construction of the wings more complicated, but the flaps increase lift and reduce the necessary span to nine meters. The engine output can now also be much more modest.

Breakable

Manufacture of the box spar and the ribs for the wings in Wagner’s apartment.

Wagner’s 17-year-old son Udo is a motorcycle fan. He plays Motoball in a club in Dresden. Through his contacts he succeeded in acquiring two heavily used MZ ES 250-2s for 4500 Ostmark. Their slot-controlled single-cylinder two-stroke engines produce 19 hp at 5400 revolutions. The ideal aircraft engine? Not necessarily, because in relation to the calculated take-off weight, 38 hp is little power. Wagner therefore uses a constructive trick from the early days of powered flight, when there were no light and powerful drives: he does not position the two-stroke engine in front of, but behind the wings. They then drive pressure screws, which are more efficient.

Son Udo takes over the preparation of the engines. Both are overhauled, then they are alternately built into the better of the two motorcycles and run in again. Finally, Udo dismantles the gearbox, because the crankshafts should act directly on the propellers. To do this, the housing must be sawed. In principle, this is not a problem with a two-stroke engine because the transmission oil and the mixture are not in contact. In the case of the engines used, the gear oil also lubricates the crankshaft main bearings. Udo has to provide additional lubrication here. In addition, he succeeds in changing the polarity of one of the two motors to the left-hand rotation by manipulating the breaker plate. Why? Because in a two-engine machine it is aerodynamically more favorable if the engines rotate in opposite directions. Then the pilot does not have to compensate for the side spin by constantly counter-steering.

Building materials in short supply in the GDR

Next, Udo has the silencers angled by 90 degrees, because the engine is installed with the crankshaft lying lengthways. The aircraft was not allowed to attract attention through excessive volume. It was hard enough to keep the propellers, designed according to plans from the 1930s, quiet. At the blade tips of the propellers there are already around 800 km / h at nominal speed, they must never turn into the supersonic range. The air inlets on the carburettors must also be turned 90 degrees. Together with the motorcycle silencers, they are hidden in the undercarriage pods located outside the hull. The two front wheels of the MZ including brakes and spring / damping elements can also be found in these. There are even narrow air ducts for cooling the cylinders, the cooling fins of which are now perpendicular to the direction of flight.

Before the motorcycle engines are put in place, a drive unit is mounted on a car trailer. With the help of a spring balance between the car and the trailer, the sons determine whether the thrust of the Zschopau units is sufficient. At the same time, the aircraft is taking shape in the kitchen, although building materials such as plywood, balsa, aluminum sheet, Plexiglass and polyester are in short supply in the GDR. There are no hardware stores, but there are so-called hobbyist shops. In order not to attract attention, Wagner buys in a wide area around Dresden. Wagner’s mother-in-law smuggled in glass silk, high-quality bearings for the rudder suspension, saw blades for cutting aluminum sheet, and the plans were briefly inaugurated by Wagner’s mother-in-law.

Altimeter, airspeed indicator and compass on board

Nothing is left to chance. Wagner calculates and checks whether his calculations can withstand real loads. It not only tests the drive, tail units, landing gear and control elements, but also loads the wing-fuselage connection with jacks and coil springs up to 2.4 times the load to be carried. If you look at the aircraft today, the technical precision, the aerodynamic fine-tuning and the detailed solutions are speechless. Although everything was created in the kitchen, the DOWA81 can definitely compete with aircraft from professional shipyards (DOWA stands for Doctor Wagner and the year of escape 1981). It’s not a hobbyist’s mobile, but a seriously well-designed aircraft that is to be taken seriously. Even the most important instrumentation for the flight is on board: altimeter, airspeed indicator, compass. Partly self-built, partly smuggled or from the black market.

Breakable

Designer Dr. Gerhard Wagner (75) in front of his "MZ airplane". Motorcycles leave him cold today, airplanes are his life.

570 days of work lie behind Gerhard Wagner, 570 days of greatest danger. He meticulously plans the start. The aeronautical engineer wants to take off from a closed lignite mine in Nonnewitz near Leipzig. Far enough away from public roads and buildings. He wants to assemble the DOWA81 in an abandoned factory building. The MZ engines are picked by hand with their propellers, and their carburettors are then controlled from the narrow cockpit. Tea renatured track bed of the former mine railway is 600 meters long, Gerhard Wagner calculated the necessary take-off distance to be 450 m. He plans to do a test flight early in the morning on July 26, 1981, land again, invite his family and fly south along the autobahn below the radar, only to go down on a meadow near Hof in the west after around 90 kilometers.

The day before the start, several officials from the State Security ring at seven in the morning. The escape plan has been revealed, all of the Wagners are arrested, including seven-year-old Gerd, who until the end believed that his father was building a special boat for vacation. The family was sentenced to a total of twelve years in prison. The "State Aviation Inspectorate of the GDR" determines the absolute airworthiness of what is probably the smallest five-person aircraft in the world and lets the two motorcycle engines run for over 30 minutes. That’s how long the flight would have taken. Even so, after a year in prison, the fate of the Wagner family turned for the better: they were ransomed by the West, settled in Kaiserslautern and began a new life.

Data and facts on the topic

Breakable

After the fall of the Wall, Gerhard Wagner ensured that his machine could be exhibited in the Deutsches Museum, where it still stands today.

The DOWA81 initially remained in the Stasi collection of former escape vehicles. All documents were stored in the Stasi university in Potsdam. After the fall of the Wall, Gerhard Wagner made sure that his machine could be exhibited in the Deutsches Museum, where it still stands today (www.deutsches-museum.de). The MZ Museum Augustusburg provided the aircraft with an MZ 250. This is a TS 250 in NVA design, but the drive is roughly the same as that of the ES 250/2 motors used for the DOWA81.

In the west, Gerhard Wagner established himself as an expert for packaging and has been designing airplanes to this day, most recently the GFW 3, an ultra-light glider in the 120 kg class that offers the best flight characteristics. In 2011 he received the Oskar Ursinus Prize as a late rehabilitation. A personal reparation for his prevented German-German escape and its consequences (www.ing-wagner.of). Literature tip on the topic: "Fascination Freedom" by Bodo Muller, Links-Verlag (www.christoph-links-verlag.de). MOTORRAD thanks the Deutsches Museum Munich for its support.

Data DOWA81

Span: 9.0 meters
Length: 5.85 meters
Wing area: 8.61 square meters
Empty weight: 240 kilograms
Take-off weight: 580 kilograms
Wing loading: 67 kilograms / square meter
Drive: two MZ-ES-250/2 motorcycle engines, each 14 kW (19 PS)
Airspeed: max. 210 km / h, min. 90 km / h
Take-off distance: 450 meters
Rate of climb: 1.8 meters / second

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