The unique aerodynamic characteristic of PrandtlPlane’s box wing system is its natural smooth stall behavior, making the airplane less sensitive to maneuvering errors. The two counter rotating elevators on both wings allow controlling the airplane by a pure pitching moment, with an enhanced precision in maneuvering. On the front wing of this airplane there is a fowler flap, contributing to lowering the stall speed.
The fuselage of the model has been made in several parts and assembled together with internal reference pins, the removable connections of the anchorage bars for the front wings are all inside it. The fuselage has a metallic box with all the interfaces for the strain gauge balance of the wind tunnel of Politecnico di Milano (Italy) with the possibility to adapt the link from the external by proper designed screws with external control through the holes visible in the figure.
The wings are made of different Ureol blocks connected together by calibrated holes, and then they are machined together with automatic tooling machines. During machining, the metallic ribs needed for the connection of flaps are substituted by dummy Ureol thicknesses. Once the wing has been machined, each part is disassembled by removing the dummy thicknesses and sliding each part on the metallic insert connecting them together. The metallic elements are made in Aluminum alloy, referenced by internal metallic pins, assembled and glued together making the four half-wings.
The model has been made by a model company thanks to numerical control machines whereas the metallic parts have been machined by EDI company starting from 3D CAD models and drawings made by SkyBox company. The high lift devices have been handmade by the Aerospace section of DICI. In particular, the front flaps have been made with the same logic of the final wings but with a technique using profile templates located on the left and right side of each block guiding the manual filing of the single part. Each single part is then assembled on the final metallic ribs.