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The reference mark height for configuration 3 was not measured agl, but was measured to be 15.2 cm below the reference mark for configuration 2 or 1.76m-0.15m = 1.61 m. (BUT the height of the configuration 3 reference mark on the profile tower was later measured to be either 1.505m 51m or 1.53m!) The heights of the downwind array sonic booms above the reference mark were measured to be
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There are several statements about the heights of the reference marks in this logbook entry. It is stated that the profile reference mark for configuration 3 = 1.505 m agl, but also that it is 0.027 m "above top of 1.55m sonic" (boom?), implying a height of 1.55m50m+0.027m -0.053m = 1.52 53 m agl. Then it says the reference mark for configuration 4 is 0.040 m above the reference mark for configuration 3, which could be 1.65m, 1.55m or 1.57m agl.
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