At 20:00 29 December 2004, Eric Greenwell wrote:
Andy Blackburn wrote:

1) There is no good source for IAS, so you have to
try to estimate it from GPS ground speed.

This data is available from various instruments, like
the Cambridge 302
that I use. For the 302 it's actually the TAS, which
could be combined
with the air temperature and pressure altitude to compute
the IAS. The
TAS and temperature are not recorded in the 302 flight
log,
unfortunately, but they could be recorded by the Ipaq
connected to it
and inserted in the flight log it keeps, and this log
used for the analysis.

Neat idea - is that a configuration item on the 302
and/or WinPilot, or do you need to write software/firmware
to make it happen? Of course you'd still need to calibrate
the 302 IAS transducer for each sailplane type, but
at least then it would automate the data capture for
the kinds of performance testing Dick Johnson does.
Maybe he already has a rig to do this, but maybe not.
It would also allow collecting data from more than
a single test subject since anyone who could take a
high tow on a calm day and hold a constant airspeed
for more than 5 minutes could contribute a test point.

Of course here I'm assuming that all 302s and sailplanes
of a particular type with the same pneumatic setup
have similar airspeed errors, which may or may not
be true.

9B