Larsen & Brusgaard VISO User Manual - Conclusion
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Example: A skydiver (in a fixed freefall position) who has a terminal fall rate of
62 meters/sec at 10,000 feet will have a terminal fall rate of 50 meters/sec at
3,000 feet.
It will be seen that the difference in altitude (air pressure) makes it difficult to
compare the fall-rates when measured using TAS.
SAS. The SAS formula calculates airspeed (using the same metrics used with TAS) as
though the complete skydive had been performed at a fixed air pressure and a fixed
temperature which corresponds to 4,000 feet ASL. 4,000 feet is chosen as the refer-
ence altitude by LARSEN & BRUSGAARD since this is the average altitude at which
the working time of a skydive is normally ended.
Conclusion
Using
SAS, skydivers in any body position can express their vertical speed by a
number (
SAS). This number remains virtually constant regardless of altitude with
APPENDIX
TAS and SAS
Definitions
True Airspeed (TAS) and Skydiver’s Airspeed (SAS) are two methods of calculating
the airspeed of a moving/flying/falling object.
TAS is a term used in aviation: It is the speed of an object relative to the surround-
ing air, regardless of the altitude.
SAS is a new concept developed by LARSEN & BRUSGAARD:
SAS is the speed of a
skydiver calculated from measurements of air pressure and
temperature and converted to a fixed air pressure (875.3 mb) and a fixed tempera-
ture (+7.080C) which corresponds to 4,000 feet ASL.
TAS. A skydiver’s True Airspeed (TAS) relative to the ground changes as a function
of the altitude (air pressure) and temperature which makes it difficult to compare
fall-rates.