Mechanical Vario

Bill, not sure I should disillusion you. What is happening is that you are
entering air that is starting to rise. This caused the speed command
function of the B50 to call for slower airspeed. The warble starting is the
"fly slower" sound. So much of the time there will be some sort of thermal
coming up by which time you are going a little slower and it is easier to
pull in to it. When the relative reading exceeds the Macready setting the
audio switches to the climb "beep" sounds which ought to wake you up if you
haven't already noticed because you were concentrating on something else.

There is an approximately +/- 5 knots speed band where the lights will be
out(it varies with MacCready setting). The fly slower audio starts when the
first blue light comes on. The fly faster audio only starts when you would
be flying slower than zero MacCready for the air you are currently in. This
is more comfortable and means you are never flying slower than best
glide(this might answer the poster who wanted to know how to cross big areas
of sink and note that unless on final glide the wind doesn't matter in speed
to fly theory).

As for the number for the speed to fly, we display that on the B500 . It
does not change with the air as the lights and audio are for that but it
gives you an idea of the sort of speed you are aiming for when you acclerate
out of a thermal. B500 works like a B50 but has lots of extras including a
nav, glide and wind computer and some other refinements.

I had a Piep audio in my Salto along with a PZL mechanical for a couple of
years before I started building my own electric varios. That was nearly 35
years ago. The Piep audio had the problem that the zero point wasn't stable
with temperature - a common failing of early thermistor varios. Your
mechanical vario with flask might make a nice display piece for your office.
There's way better than that around. See B400 on our website. Yes I have
flown with mechanical varios and a Brand X flight computer not that long
ago. Three 4 hour flights in a Nimbus 4DM. Great glider, abysmal instruments
and I had been through and fixed leaks etc. I haven't had one in a glider of
mine since 1979.

Unless installed correctly the flask will screw up other varios on the same
TE line. This will be true even if the flask using vario is an electric
type.

The real problem with all TE varios at present is that horizontal gusts will
cause spurious readings. The problem gets worse with the square of the
TAS(See our website article). If you slow the vario response to get rid of
the problem you get rid of good information about vertical air motion
changes too. I've been going around in a thermal with a PZL and a B21 in a
customer's glider and seen the B21 show 1 knot on one side of the thermal
with peaks of 6 knots while the PZL sat on close to 2 knots all the way
round. Re centering on the B21 got me 5 knots on the averager. This was an
unusually smooth thermal and it was hard to tell by feel. A reasonably fast
responding vario is an advantage but there is a high workload in mentally
filtering the horizontal gust "noise" from the vertical "signals"

This may change soon.


Mike Borgelt

Borgelt Instruments






"Bill Daniels" bildan@comcast-dot-net wrote in message
news
In addition to my old reliable B40, I have a newly old B50. As I'm
cruising along the B50's audio will switch to slow yodel and two blue
LED's will light up indicating the need to slow down "a lot". It's
usually not clear to me why I should slow down but I've learned to trust
it. After I enter the zoom I usually feel a kick in the pants as I enter
a strong thermal. It seems to know a thermal is coming well before I do.

Mike, HOW DOES IT DO THAT?

Bill Daniels

"Mike Borgelt" wrote in message
...


Bill, not sure I should disillusion you. What is happening is that you are
entering air that is starting to rise. This caused the speed command
function of the B50 to call for slower airspeed. The warble starting is
the "fly slower" sound. So much of the time there will be some sort of
thermal coming up by which time you are going a little slower and it is
easier to pull in to it. When the relative reading exceeds the Macready
setting the audio switches to the climb "beep" sounds which ought to wake
you up if you haven't already noticed because you were concentrating on
something else.


Whatever, it's the best STF vario I have ever used.


There is an approximately +/- 5 knots speed band where the lights will be
out(it varies with MacCready setting). The fly slower audio starts when
the first blue light comes on. The fly faster audio only starts when you
would be flying slower than zero MacCready for the air you are currently
in. This is more comfortable and means you are never flying slower than
best glide(this might answer the poster who wanted to know how to cross
big areas of sink and note that unless on final glide the wind doesn't
matter in speed to fly theory).

As for the number for the speed to fly, we display that on the B500 . It
does not change with the air as the lights and audio are for that but it
gives you an idea of the sort of speed you are aiming for when you
acclerate out of a thermal. B500 works like a B50 but has lots of extras
including a nav, glide and wind computer and some other refinements.

I had a Piep audio in my Salto along with a PZL mechanical for a couple of
years before I started building my own electric varios. That was nearly 35
years ago. The Piep audio had the problem that the zero point wasn't
stable with temperature - a common failing of early thermistor varios.
Your mechanical vario with flask might make a nice display piece for your
office. There's way better than that around. See B400 on our website. Yes
I have flown with mechanical varios and a Brand X flight computer not that
long ago. Three 4 hour flights in a Nimbus 4DM. Great glider, abysmal
instruments and I had been through and fixed leaks etc. I haven't had one
in a glider of mine since 1979.

Unless installed correctly the flask will screw up other varios on the
same TE line. This will be true even if the flask using vario is an
electric type.

The real problem with all TE varios at present is that horizontal gusts
will cause spurious readings. The problem gets worse with the square of
the TAS(See our website article). If you slow the vario response to get
rid of the problem you get rid of good information about vertical air
motion changes too. I've been going around in a thermal with a PZL and a
B21 in a customer's glider and seen the B21 show 1 knot on one side of
the thermal with peaks of 6 knots while the PZL sat on close to 2 knots
all the way round. Re centering on the B21 got me 5 knots on the averager.
This was an unusually smooth thermal and it was hard to tell by feel. A
reasonably fast responding vario is an advantage but there is a high
workload in mentally filtering the horizontal gust "noise" from the
vertical "signals"

This may change soon.


The new variometry standard will be noise-free instantaneous response and
zero gust sensitivity, right?

Bill Daniels