The Mü 32 "Reißmeister" is the newest of the two current projects of Akaflieg Munich. It is currently in the design phase. The "Reißmeister" will be designed as a glider of the competition class Unlimited. For this reason the tear-off behaviour is optimized for cracked figures.

The project

The Reißmeister is designed as a glider of the competition class Unlimited. For this reason, special attention is paid to optimising the tear-off behaviour on cracked figures. At the same time the stall must announce itself for the pilot, so that it does not occur unintentionally for example in the landing approach. In addition, the advantages offered by the Mü 28 with its symmetrical profile and automatic flap flap are to be adopted for the new design. 

Mü32 Reißmeister
 
State of affairs

In the flight test, the stall-characteristics of the existing gliders Swift, Fox and Mü 28 were investigated.
A new profile was designed and measured in the Stuttgart laminar wind tunnel. It fulfils the conditions we set for the stall-characteristics.

A first overall concept with wing, tail unit and fuselage geometry has already been worked out. The wing was designed with manoeuvrability, visibility and efficiency in mind. The inverted flight is to be optimized by the symmetrical wing profile in combination with the automatic flap flap and an angle of attack of 0 degrees to the fuselage axis.

In order to reduce the project duration, a series fuselage has to be taken over. According to an evaluation system, an optimal fuselage has already been selected, which in particular offers sufficient space for pilot and controls. For a reliable evaluation of the flight attitude, the overall concept attaches importance to straight edges and symmetries. The selected fuselage already has a relatively straight fuselage tube, so only minor adjustments will be necessary.

A standard arrangement was chosen for the tail unit to keep the forces on the fuselage tube to a minimum and to facilitate assembly. Aerodynamic efficiency and controllability in spin should be increased. The combination of short lever arms with large tail surfaces and lush rudder depths should enable agile and precise flight behaviour.

The one-piece tailplane was developed on the basis of the requirements of JAR 22 and the load cases decisive for the Mü 32. The load cases were used to create the load assumptions as well as the analytical design of the elevator fin. The calculation was validated by an FEM model. This year, the load assumptions for the elevator were largely completed. The distribution of the forces between tailplane and rudder and an estimation of the hinge moment are still missing. The load assumptions of the vertical stabilizer are also in progress. The aim is to calculate the forces acting on the fuselage by the end of 2018.

The control system of the Mü 32 was examined as part of a student research project. The design objective of the control system is to achieve a control system that is as precise and free of play as possible. Similar to the Mü 28 there will also be a superposition of the variable camber flap and aileron. In addition a landing position of flaps and ailerons is planned. One research objective is to investigate the feasibility of a kinematic system that produces only little rudder deflection close to the stick neutral position, e.g. in order to be able to fly quartered rolls more precisely.

While current sailplanes do not use a special geometry at the wing end, the Mü 32 will be equipped with end plates to increase the roll rate. For this purpose, a geometry was developed that promises a reduction of the induced resistance, especially at high load multiples, and at the same time generates little additional resistance at high speeds. At the same time, this geometry should remain as symmetrical as possible in order to guarantee similar flight characteristics in normal and inverted flight. The solution for this is a swept winglet, which virtually increases the area of the wing end at high lift coefficients, while at high speeds only the actual area generates drag. The testing of this technology will take place next year with test samples on the surfaces of our Mü 28.

The spinning characteristics of a glider can usually only be demonstrated by flight tests. In order to get a feeling for the controllability of the Mü 32 in a spinning situation already during the design phase, the area of the vertical stabilizer shaded by the tailplane was examined. Since the tail fin is essential for the spin exit, the shading allows a statement to be made about the effectiveness of the tail fin in spinning conditions. The results of the shadowing calculation promise a better controllability than with the Mü 28.

 

Work in progress

- Fuselage construction as part of the LuFo program to increase crash safety

- Revision of the load assumptions of the tail units, design of the vertical stabilizer structure

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