WindMaster and WindMaster Pro
1561-PS-0001.
Issue 11 February 2017
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67
W Correction
In addition to the sonic temperature improvements, the following significant ‘w’ corrections are also being
introduced to the WM / WM Pro range. Gill found a ‘bug’ in the WindMaster and WindMaster Pro firmware
(previously unknown to both Gill and the community) from internal research looking at Angle of Attack
(AoA) corrections for various wind vectors. The ‘bug’ is effectively that there is no mechanical ‘maths’
correction applied for the vertical ‘w’ axis wind measurement. All other Gill 3 axis anemometers have this
‘w’ correction implemented correctly. The correction being introduced with this 3 dimensional head is a
significant boost in the ‘w’ wind component (compared to previous outputs from the WM / WM Pro) which
can be seen below:
+W corr16.6% (multiplication factor of x 1.166).
-W corr28.9% (multiplication factor of x 1.289).
This correction will provide excellent 3 dimensional wind accuracy results within stated specification wind
speed and incidence angle from horizontal. (±30 degrees). In addition, this correction will assist in providing
better accuracy at AoA greater than ±30 degrees, although with decreasing benefit, up to ±60 degrees from
horizontal.
It has always been the case that users can measure 3 dimensional wind flows using Gill 3 Axis products
without any head correction applied (so no u, v or w correction). Using Gill Wind software allows the user
to disable Calibration to collect data in a ‘raw’ mode without any correction and also to allow users to
decide if they wish to apply any recent AoA (Angle of Attack) corrections being developed by the
community (Nakai et al, 2012, for example). Users of Gill WM/WM Pro products will be able to post process
collected data to include the above ‘w’ improvements where desired, and Gill will work with the
community to enable this process upon request and mutual discussion.
See the following table for more information on what corrections are applied regarding Gill products and
revisions. Contact Gill if you have any questions in this regard.
The above correction only affects the W Vector, it does not affect Polar or UV wind readings in either digital
or analogue forms.
General
The above improvements have been available from mid-October 2015 onwards and are already
implemented in the WindMaster HS product. Gill provide the above Sonic temperature and W
improvements free of charge with any current purchase. Please contact Gill Instruments for further details
regarding upgrading of existing products should this be of interest.
Part numbers of the WindMaster and WindMaster Pro with the above improvements will be identified with
a /W suffix (e.g. 1590-PK-020/W). Users will also be able to check via software the firmware pre-fix which
will identify which of the above improvements that their unit will have (2329-601 or lower for legacy and
2329-700 or higher for improved units).
