navyspecial
To determine mathematical models, Planar Motion Mechanism (PMM) and rotating arm tests have traditionally been used but with the introduction of the Computerised Planar Motion Carriage (CPMC) 30 years ago, flexibility was added. The installation of a CPMC over a very large basin such as MARIN’s Seakeeping and Manoeuvring Basin adds even more flexibility. And now new, unstationary CPMC tests have been introduced. A recent campaign on the “naval combatant 5415” has been carried out deploying the new tests, which aim to reduce testing time and costs.
T
he naval combatant 5415 (see figure 1) has been model tested at various institutes in the world. As seen, the
model is a typical naval surface ship. At MARIN, this ship is used to carry out Free Running Manoeuvring tests, PMM tests, rotating arm tests, but also the new types of unstationary CPMC tests.
New techniques
The aim of the new testing techniques is to reduce the testing time and hence, improve efficiency and reduce the costs of captive model test campaigns. Usually, these model test campaigns are used when customers require detailed mathematical models. These mathematical models may be neces- sary for fast-time, or real-time simulator studies. The objective of these studies is that a mathematical model can be constructed out of a range of measured combinations of drift angles, rotation rates, rudder angles and propeller revolutions.
Unstationary tests Now, how does it work? In traditional captive tests, each run consists of one combination of drift angle, rotation rate, rudder angle, ship speed and propeller RPM. Each run lasts long enough to get a good answer. In unstationary tests, during a test run the
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