Heikki Hansen
The Berlin Sail-Force-Dynamometer DYNA
This four-year research project was initiated at the Technical University of Berlin in Germany in 1996 to investigate the relation between model tests, numerical simulations and full size data. A 10-metre full-scale sail force dynamometer named Dyna was designed and built to directly measure the aerodynamic and hydrodynamic forces and moments. The hull and rig are based on a modern 33ft International Measurement System (IMS) cruiser/racer yacht to provide suitable reference results for contemporary yacht design issues. 

In order to measure the force components separately, DYNA has an internal rigid aluminium framework structure in the hull (Figure 1). All the different force components are coupled with the framework structure only. Six component balances are used to connect the hull and keel to the internal structure and a five-component balance for the rudder. All rig components are connected to the framework and load cells measure the forces at the attachment points. 

The focus of the project is the investigation of the hydrodynamic aspects and the full size measurements are compared to the results from CFD simulations (e.g. RANSE), scale model tests in the towing tank and cavitation tunnel tests of different keel designs. The aerodynamic data is only used to obtain the lift and drag coefficients of the rig, which are required to perform VPP calculations. The data is not compared to model tests or numerical solutions as part of the initial project.

Figure 1: The Berlin Sail-Force-Dynamometer DYNA from Brandt and Hochkirch (2000)

The internal rigid aluminum frame allows the aerodynamic and hydrodynamic forces to be measured separately.

Figure 2: DYNA during a measuring sail in the Baltic Sea from Brandt and Hochkirch (2000)

Brandt, H., and Hochkirch, K. (2000). "Entwicklung eines Segeldynamometers zur Erfassung der aero- und hydrodynamischen Kraefte." Technical University Berlin, Berlin.