The measurements were performed on a dummy mirror with a diameter of 3.5 m, made of wood on a support structure of the same material. The altitude axis of the dummy was 2.5 m above the base and its inclination could be set in a range from to . The dummy mirror integrated 13 differential pressure sensors, located as shown in fig. . All pressures were measured at 50 Hz over 82 sec. The offsets of the 13 sensors could drift from one measurement to another. Average data computed from these measurements are therefore not very reliable.
In total 76 measurements were done inside the NTT building where the dummy mirror was located just in front of the telescope. The measurements were performed over the complete range of zenith angles with the dummy mirror mostly facing the wind, with angles between the wind and the azimuth of the enclosure in the range . The anemometer for the measurement of the reference wind was installed on a 2-m mast at the top of the building.
Figure: Position of the dummy mirror in the inflatable dome
56 measurements were performed in the inflatable dome. The center of the dummy mirror was at a height of 2.5 m and was therefore largely shielded by the 3.5-m high concrete wall. The degree of this protection can be further controlled by setting different elevations of the inflatable segments. The measurements were performed over the complete range of zenith angles with three azimuth angles with respect to the predominant wind direction: and . The reference anemometer was located on a mast approximately 10 meters away from the inflatable dome at a height of approximately 10 meters.
All test results are listed in appendix . We will describe here the main results of this work and those of most general application.
Figure: Distribution of the sensors on the surface of the dummy mirror