Akaflieg München Mü27
The Akaflieg München Mü 27 is a glider student Fliegergruppe Akaflieg Munich, where the so-called Wortmann- flap - so a variable geometry wings in flight - was tested. The aircraft is considered with a maximum takeoff weight of 900 kg was the heaviest glider in the world and is now in the air Schleißheim, a branch of the Deutsches Museum in Munich.
History
One of the problems for high-performance gliders is that two different airfoil profiles are required for climbing in thermals and for the quick flight between two upwind areas: one for the slow circling in thermals an airfoil with large wing area and high camber and on the other for the high-speed flight, a thin airfoil with low resistance. In the 1970s, several Akaflieg groups of aircraft with variable wing geometry worked to solve this problem. For example, while Akaflieg Stuttgart worked with the Fs -29 on a project with a variable spread, the students of the Akaflieg Munich went up the way to adjust the wing area by changing the chord.
Since it was the first built by the Munich students in aircraft composite design and the two-seater had a wingspan of 22 meters and four-part wing, the complex project dragged on through the entire decade. The successful maiden flight was conducted on 24 January 1979 after which very many modifications followed in order to improve the flight characteristics of the glider.
For daily flight operations and competitions, the prototype turned out to be only partially suitable, since both the up and teardown as well as the maintenance was more difficult than normal aircraft. Thus the Akaflieg Munich decided in 2009 to put the aircraft to the German museum.
Construction
On the whole length of the blade a gapless Wortmann valve was attached that can be completely inserted or extended by an electric motor within ten seconds. The wing area varies by 36 percent while maintaining the shape of the airfoil is increased. To realize this system, it was necessary to construct a riveted box spar made of aluminum, which accommodates all the bending and torsion of the wing. This must make the wing sufficiently rigid to prevent tilting of the valve mechanism due to excessive deflection of the surfaces. Another problem that arises from the complex flap mechanism, represent the ailerons, which must be incorporated in the Wortmann- flap due to the construction.
Among the changes that occurred after the first flight tests counted replacing the previously steerable tail wheel by a rigid and magnification of the drogue parachute, which is used for landing. Even very high rudder forces were observed during the first flight, which could be significantly reduced by structural measures on the control.