Fly Steward Fly : a kinematic cable net roof actuated by a modified Steward Gough principle

use, such a platform is composed of 2 parallel planes interconnected with the use of 6 actuators, commonly hydraulic jacks. This 6 degree-of-freedom mechanism has been investigated over years for its potential in architecture and structural engineering. Our approaches are firstly based on physical modelling, secondly on parametric, geometrical and structural simulation (supported by Moritz Heimrath, Karamba, Bollinger & Grohmann Ingenieure) and thirdly on the experience with experimental structures like the “cut.enoid.tower” and “2Landscapes” amongst others.This paper presents the research, the architectural and structural approaches that have been done in order to develop the project “Fly Steward Fly” and which is based on a modification of above described mechanism. By physical models and later by parametric, geometrical simulation we discovered the option to construct a kinetic system, when only one of the modified Stewart – Gough – members is designed to be telescopic. This partly replicates the original intent of the mechanism, that of a kinetic simulator, but it brings its potential use into the realm of the built environment.The project has been commissioned by the organizers of the Solar Eclipse Festival in Oregon, USA, in 2017. By modifying the original concept of the Stewart-Gough platform and providing 5 fixed length and one telescopic connection, the roof structure of “Fly Steward Fly” can be blocked in a spatial position by a minimum amount of 6, basically skew-whiff arranged, linear compression-only and/or tension-only elements. In particular “Fly Steward Fly” doesn´t connect two parallel planes, but a zig-zag-shaped truss and the ground. The truss and its connection details are the result of the analysis of the motion of the pin-joint struts and their varying rotation and angles to the roof structure. The zig-zag-shaped truss spans a cable net roof structure, which has been proposed in two variations: The first option proposes square aluminum panels, which are clamped to the cable net. The panels would eventually catch the wind and start to slightly rotate around the longitudinal axis of the cable. The spring effect of the cable will always bring it back to its initial position. This way a shivering effect is created, which visualized the motion of the air and which simultaneously creates mirroring effects. The second option proposes aluminum stripes, which are hanging from the cable net at the same position as before described aluminum panels. In order to avoid collision and/or tangling of stripes and the kinematic structure the stripes length has been adapted accordingly. This way a “deep” landscape-like, reactive, soft layer has been created, also visualizing air-flow and motion. In both cases the cable-net structure, which is spatially curved and prestressed contributes to the overall structural performance of the roof-structure, since it locks the zig-zag-shaped truss in its geometrical position. The roof has been designed for a size of 12 x 14 meters and 5,5 meters above ground. Its general motion is controlled by functional needs like the solar radiation and shadow, projection, and so on.The initial “Fly Steward Fly” project will be followed up by a multiple-use version for a festival tour in 2019/2020.