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The Göppingen Minimoa Mo 2A Two Seater - ("Mozwoa")
This little known version of what must be the most elegant of all old time gliders, the Minimoa, was built by the Schempp-Hirth Factory and designed by Dr. Wenk and Eng. Faber and overseen by the famous It was conceived in 1935 at a time when there were very few two seaters in existence. From its very inception, the standard single seat Minimoa had been designed with the possibility of creating a two seat version. In Flugsport of 21.08.1935, there is a note which states "Based on a payload of 150kg the wing can also used for a 2 seater fuselage, which is still to be designed." 
Hirth thought that stability when thermalling, especially in cloud, would be greatly advantageous, hence the exaggerated gull wing of the Minimoa. This also gave considerable wing-tip clearance. This was a very attractive feature as virtually all gliding sites were on hills, often covered in deep heather which could catch the tip and cause a damaging ground loop. The main spar of the glider was constructed in one piece as a normal straight tapered beam before being steam bent at the gull break to create the famous wing shape. Schempp-Hirth worked hard to meet the deadline for the Rhön Competition of 1937. It was designated with works serial number of 150 and registered as D-15-923. At the Rhön event it was given the nickname of "Mozwoa" according to one magazine of the time. The changes from the standard Minimoa were as follows : 1) The fuselage was built 360mm longer than the single seat version, the extra length being added to the nose section ahead of the leading edge of the wing. The image below shows the two versions of the Minimoa for comparison with the fuselage extension in red.
2) Access to the second seat was over the wing through a removable canopy to a seat mounted between the main spar and rear sub-spar. Also to be seen in this picture is the clear vision panel or direct vision panels similar to more modern gliders using siding panel with clear Perspex frame/runners– always on the port side so you can look out in case the cockpit gets iced up or steamed up. The one in the front windscreen was a hinged panel type.
3) Due to lack of height in the second seat, the usual case Schempp-Hirth wheel had to be abandoned and launching would be by a dropable dolly wheel beneath the skid. You will note in the picture below how the skid flexes. This is a symptom of poor design as the skid is supported either side of this point. From the experiences of take offs using a Dolly, Paul Willimas reports that " On take off there is a real danger of the skid flexing sufficiently to force the release mechanism open, so the dolly releases early. The dolly then slams between ground and skid making an alarming noise whilst one heaves back on the stick to get some height before the dolly makes a large hole in the rear fuselage or removes the tailplane." See this example of what Paul describes
4) The rear pilot had limited vision below because of the wings. To overcome this, two small square windows were cut into the side of the fuselage below the wing seen in the picture below with Flt Lieu. Murray and Eva Schmidt. It is worth noting here that, although Hanna Reich is usually proclaimed as the most famous German woman pilot, Eva Schmidt achieved more sport records and received more awards.
5) Wing flaps were installed
6) The Mozwoa had a nose light installed similar to the prototype Kranich and possibly the Gottingen IV. The idea seems to be to help with an unintended landing when slope soaring through the night for attempted duration records. In reality rows of car headlights were used until duration records were no longer recognised as several deaths had been caused by exhaustion
. Extra reinforcement of the fuselage, wings and tail was not considered necessary.
For the Rhön Competition, the pilots for the doubles competition were named as Wolf Hirth and Richard Knoth and the competition number "45" was allocated. However, only one start was made on the opening day as pain in the leg of Wolf Hirth forced him to abandon further participation in the competition.
On August 29th 1937, almost three weeks late,r Wolf Hirth towed the Mo 2a, piloted by Eva Schmidt, from the Wasserkuppe to Dunstable for the English National Gliding Championships with a Klemm L25 d VII R training plane, registered D-ENHE, which was equipped with a Hirth HM 60 R engine (80 PS). At this event, the female crew of Hanna Reitsch and Eva Schmidt took part in the Championships. Wolf Hirths' plan was to sell the Mo 2a in England, however his plan was to fail because of the resistance of the German Air Ministry (RLM) to provide an export licence. After Dunstable, the German group moved on to Camphill by road, whilst the "Mozwoa" was aerotowed to overhead Camphill where it was released and landed normally diagonally towards the windsock. The Klemm, with two up and flown by Eva Schmidt, also landed normally on a south west runway that passed between the hangar and the first stone pile halfway to the windsock. Unfortunately the Klemm struck a wall root between the hanger and the stone pile and finished up facing back towards the northwest . The damage was mostly woodwork around the port undercarriage leg and the underside of the main spar where it joined the leg. The Klemm was taken into the workshop where 4 or 5 Germans worked hard over two days to repair the damage after which the "Mozwoa" returned to Germany, again under tow
The Mo-2a was also taken on sales tours to Holland and Belgium, but by the end of of 1937, it was reported in the American "Soaring" magazine that "No production is planned for the Minimoa 2a, the two-seater which first appeared at the Eighteenth Rhoen Contest" In November / December 1941, the glider was returned to the Wolf Hirth factory at Nabem-Teck for reconditioning. The glider was repainted and had a clear Plexiglass canopy roof fitted to the front compartment.
Frits Ruth, in the right of this picture, was one of the engineers of the time working with with Wolf Hirth (centre) and made the following report following an air test:- I worked at the Wolf Hirth company at. Nabern-Teck in the design office and I was. was also made part of the existing five man Test Flight Facility, where about once a week we flew new and repaired planes for testing On the 6th December 1941 Hubert Clompe, one of the test pilots, made the first solo flight with the Minimoa-doubleseater and again flew on the 10th December when I was in the back seat. In strong, gusty, westerly wind, we were towed by Richard Glaser in the low powered Klemm 25 near the west mountain slope of the Teck-Mountain. Still below the mountain top and very close to the timber forested slope, we snapped the tow cable and the airplane immediately put its nose steeply downwards. I first thought that the tow plane had dragged us down. On the contrary, Clompe strained with all of his strength until he shouted for me to help him and get more power on the stick, but this did not work. As the tree tops became menacingly close Clompe pulled the tow release and we would shoot off in a sharp right turn from the slope. The tow rope was torn from the coupling on the tow plane and fell into the treetops. The search the next day for it was unsuccessful.
You can download all the drawings in this article as a pdf file. The 3-view was drawn at 1/10 scale and can be easily enlarged for model plan purposes. I have also included the decals etc for vynyl cutting purposes. Also available for download are the images used in this documentation plus many more. Acknowledgements: I am grateful to Bernd Diekman, Manfred Krieg, Frits Ruth and Paul Williams without whose assistance this article would be much less interesting. |
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