On Thu, 13 Oct 2005 11:54:22 +0200, Bruce wrote:


Hi Martin

We looked at the B40 vs Tasman recently for our club ships. In the end we
decided on the Tasman because it has no moving parts, and has the built in
averager.

The B40 has always had a built in averager. Just push the button on
the front. The button even has a remote circuit you can use to to
mount it on the stick etc. Digital averager also available and you can
put that up close to your line of sight or just above the ASI.

So far we are extremely happy with the Tasmans, and I can recommend them and
their service. They contacted us directly about the firmware upgrades, and
shipped the chips to us at their cost to upgrade the varios we have.

The Borgelts are also outstanding instruments, and I may consider moving up to a
B50 in my single seater. For now the V1000M gives me such good information I
doubt I would benefit from the B50. If I ever get my PDA installed this might
change.


Just to clear up any confusion , the B50 and Tasman are not
comparable. The B40 and Tasman are somewhat comparable as neither has
an airspeed sensor, unlike the B50 which does.

Having an airspeed sensor lets you compute the expected sink rate at
any given airspeed for display of netto(airmass) vario or relative
netto (see our website for article on Basic Sailplane Instruments
which explains these terms for anyone not familiar with them and tells
you why they are advantageous) as well as Macready speed to fly
information in simplified "fly faster/fly slower" format and also
provides True Air Speed(TAS) information to glide computers which
gives useful information like real time wind component when used with
the GPS groundspeed.

I am surprised that the Tasman audio was the way it was for so long.
We had that in the B10 vario in 1978 and changed it at customer
request within a few months to the present system and have kept that
ever since for climb/sink mode.


For now my setup is a winter mechanical vario - no power needed to soar.

Given the proliferation of electronic equipment in sailplane
cockpits(computers/GPS/loggers, electronic varios) you really want an
assured 12 volt power supply anyway. This is easy to achieve with two
batteries used intelligently and for the paranoid a back up supply for
the standby vario. (it isn't bad to be paranoid about this)

Putting capacity flasks and mechanical vane type varios in the TE
system is a bad idea for many reasons particularly the effect on
responses of any electronic pressure sensor based instruments. These
effects can be mitigated by splitting the TE line back at the back of
the seat pan or further aft and running two TE lines to the instrument
panel. I still see installations where this has not been done. The
only time you can do without this is with two pressure sensor type
instruments. Getting rid of mechanical instruments makes installation
easier. I haven't had a mechanical vario since 1979 or a capacity
flask since 1983. I've never run out of vario (except when I've had to
pull mine out of the panel to sell to someone in a hurry - one B40
lasted exactly 30 minutes after installation).


+
V1000M set to rapid response + 20s average. It is worth having just for the
average. No problems with legibility on the LCD screen, in bright sunlight, and
with/without polarising glasses.

We looked at this for the planned B30 system in 1986. That never got
beyond the planning stage. as I considered a display resolution for
the vario pointer of 0.4 knots was just too terrible. The Tasman has 1
knot I believe.

LCD's do make for a cheap display though.

The automotive industry has come to our aid with the stepper motor
driven pointer. These are used in all the BMW's, Rolls Royce etc cars.
Interesting that the auto industry hasn't embraced LCD pointers.

By the way - the firmware upgrades are one of the things that decided us on the
Tasman rather than the B40. You get an instrument with virtually unlimited
development capability. No mechanical stuff you can't change.

You are very restricted by the crude resolution of the display and the
lack of airspeed sensor. The Tasman, like the B40, is just a simple
TE vario with audio and averager. There isn't really much you can do
with that which is why we have continued that in to the new B400 which
is shorter than the B40 it replaces, uses a stepper driven pointer
with extremely high resolution, has the same kind of averager as the
B40 with remote push button and optional remotely mounted full time
digital averager display now available in two sizes and a new optional
"competition " climb audio (you can still select classic B40 style)
and a green LED to tell you when you are climbing faster than the
current running average i.e. "things are getting better" which is also
given by the audio in "competition" mode.
We expect to ship the first B400's next week.

The B50 has been replaced by the B500 which is now shipping in small
quantities (and many thanks to our beta testers for your faith and
patience) and we're ramping up the production rate.

The B500 is an advanced vario system with airspeed sensor and has
plenty of room for later expansion as it was designed that way.
Software upgrades will be by download from our website and
customisation is by hooking it to a PC.

Check it out (and the Basic Instruments article and others) on the
website.
www.borgeltinstruments.com

Mike Borgelt