The controls could finally be finalized. Everything was powder coated to protect the parts long term from corrosion and mechanical stress. For this we would like to thank Schmidt Pulverbeschichtungen in Kirchheim Teck again!
In the meantime, all parts were installed in the aircraft and connected with screws, washers and nuts. The airbrake lever was CNC milled from aluminum. The electric trim is also installed in the fuselage tube at the elevator control rod.
In order to get the flight approval from the federal aviation authorities, the controls have to be put through their paces. For this purpose, all control elements and rudders are tested according to the load assumptions. It was shown that the controls are freely moving and free from excessive friction and deformation. In our tests we are able apply all necessary forces by hand. These forces were measured with spring balances and load cells.
As both pilots tried to push the sticks simultaneously to the right under full load while holding against the ailerons, something unexpected happened. The airbrakes unlocked! The problem was soon found: Both the airbrake and aileron control levers are located in the fuselage on a common frame, which deformed under the reaction load of approx. 180kg by a little more than one millimeter. This was sufficient to lift the airbrakes. So additional reinforcement was attached to the frame and the problem was solved. The rest of the steering was unremarkable in the tests, so we can soon submit the official report to the federal authorities.
