Speak for yourself

I still have the "John Willie" calculator and it is still accurate. NO
batteries or complex circuits to fail.

John Williamson (JSW Soaring) set my glider up too many years
ago to divulge and the system still works as well now as then.

Other electronic gubbins have come and gone.

Dave


At 08:20 06 November 2012, Peter Purdie wrote:
The brass valve is a pneumatic switch, and lets a calibrated
leak through
the capillary (the s/s 'wire') into the flask. connected at the
other end
to pitot if using a diaphragm TE compensation, or static if using
a probe.
Flow proportional to IAS squared, which approximates to a
polar curve for
useful speeds. You then have an ordinary vario with the switch
closed, and
a netto (airmass movement) vario with valve open.

Uing the JSW circular slide rule was pretty easy, and
surprisingly
accurate, but computery does it all for you now. Nostalgia
doesn't make me
want to go back to the old methods.

At 03:46 06 November 2012, Eric Greenwell wrote:
On 11/5/2012 3:36 PM, Tony wrote:
This was in the days when nearly every vario (except for
the Ball

series) had a 1/2 liter flask. And when the really fancy
final
glide

computers were plastic wheels instead of cardboard. And
when real
men

navigated with paper maps! And....

no one had time to look outside while trying to figure out
where they
were on the map and if they could make it?



It could be very time consuming figuring out where you were
on the map,
then measure distances to your waypoint/airport, decide on
a wind
component to use, twirl the "prayer wheel" to the right
setting, and
finally discover your arrival altitude.

Shoot, just unfolding and folding the map and switching from
one
sectional to the other was a big challenge! Electronic flight
computers
eliminated almost all this distraction.

--
Eric Greenwell - Washington State, USA (change ".netto" to
".us" to
email me)