Pro Track Speed Setting

[Jethers203 0]

I use to use Skydiver Airspeed but switched to True Airspeed. Which setting is more realistic as to what speed you are actually going. I noticed TAS reads higher then SAS. Please explain.

Clint D-24352

[AggieDave 6]

SAS gives you a more accurate reading of what your real speed is. TAS takes environmental data out of the equation and gives you a speed that is easier to compare to others in other places.

Realistically, I think a majority of jumpers use SAS, since they're able to accurately deterimine their speed in relation to everyone else at their DZ and in the realistic sense of what their actually doing.

--"When I die, may I be surrounded by scattered chrome and burning gasoline."

[wzettler 0]

ProTrack Manual From:http://www.l-and-b.dk/pdf/english_protrack.pdf page 40


Definition
True airspeed (TAS) and Skydiver’s airspeed (SAS)
are two methods to calculate airspeeds.
TAS is a term used in aviation: It is the speed of an object relative to the
surrounding 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 temperature
(+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.
Example: A skydiver (in a fixed freefall position) who has a terminal fallrate of
62 meters/sec at 10,000 feet. will have a terminal fallrate 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 recorded in TAS.

Explanation
SAS
The SAS formula calculates, using the TAS information, 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 the chosen reference 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
little or no variance due to temperature differences and can be compared with the
airspeeds of other skydivers.
This means that regardless of the elevation of the DZ you are jumping at,
SKYDIVER’S AIRSPEED (SAS) will be the same for the same body position.

-Emphasis mine.

Hope that answers your question. I personally use TAS because I like more realistic numbers and I don't really compare my fallrate on my ProTrack to other's ProTracks...

I think when Jesus said "love your enemy" he probably meant don't kill them.

[sundevil777 102]

Quote

SAS gives you a more accurate reading of what your real speed is. TAS takes environmental data out of the equation and gives you a speed that is easier to compare to others in other places.

Flip that - the other way around.

People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

[kallend 2,146]

Quote

SAS gives you a more accurate reading of what your real speed is. TAS takes environmental data out of the equation and gives you a speed that is easier to compare to others in other places.

Realistically, I think a majority of jumpers use SAS, since they're able to accurately deterimine their speed in relation to everyone else at their DZ and in the realistic sense of what their actually doing.

You got it backwards.

...

The only sure way to survive a canopy collision is not to have one.

[AggieDave 6]

Quote

Flip that - the other way around

D'oh, thanks for the correction!

--"When I die, may I be surrounded by scattered chrome and burning gasoline."