At 06:46 PM 14/11/2006, David Griffiths wrote:
I am impressed
I did not even know that this type of gear was available.
Is this all prototype stuff or is it in production?
You might like to look at the B500 on our site at
www.borgeltinstruments.com
Australian designed and manufactured, sold worldwide.
Before getting too excited about varios without visual indicators
people might like to consider how they decide whether to turn in a
particular thermal that is encountered. The vario pointer isn't the
only thing but I bet it is an important part of your decision.
Relative netto was designed to help with this - see our website for
details if you don't know what relative netto does(it is in articles).
Changing the audio at the MacCready setting as we do in the B500 and
B50 lets you know to look at the vario but for reasons explained by
John Cochrane in his paper and nearly 40 years ago by Anthony
Edwards, you fly at Macready settings that are quite low compared to
the actual rates of climb you get so you might not make the decision
to turn just based on that audio change.
Likewise when picking a best path through the air, particularly when
streeting, including the vario pointer in your scan is important. To
be really useful here the vario pointer should be high resolution
too. We rejected LCDs on the grounds that the pointer resolution was
too coarse.
When working very weak lift the speed of response and resolution of
the vario itself becomes important. When working 5 knots at altitude
a poor vario will do. When at 600 feet over a paddock trying to avoid
an outlanding by working +/-0.5 knots you need all the help you can get.
With some vario technologies there are unavoidable speed of
response/resolution tradeoffs.
Lastly, Total energy is total energy whether it is done by a probe
providing suction below static pressure or whether you measure pitot
and static pressures and add them electronically to provide the same
thing. They both suffer from horizontal gust effects (see article on
website) to the same extent but the pitot/static scheme has some
additional problems - the pitot and static ports are more sensitive
to yaw and sideslip than the modern two hole TE probe is and you need
to organise the pitot and static signals to arrive at the same time
at the instrument to avoid undesirable transient effects.
Mike
Borgelt Instruments - manufacturers of quality soaring instruments
phone Int'l + 61 746 355784
fax Int'l + 61 746 358796
cellphone Int'l + 61 428 355784
Int'l + 61 429 355784
email: [EMAIL PROTECTED]
website: www.borgeltinstruments.com
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