At 09:37 AM 31/03/2015, you wrote:
Is it able to compensate electronically? The Zander goes wild when I
connect to TE probe, presumably due to the two Winters that are on
that line. And its electronic compensation is crap.
All the best, Paul
Easy fix is to run a second TE line to back behind the back seat and
put the T piece there. This isolates the electronic system from the
pneumatic one. Better still, ditch the Winters and put in a modern
standby vario with its own batteries for emergencies like a B700 or
B900 (B400 also still in production).
Electronic TE using the pitot - static is one of those things that
sounds like a good idea but in practice is very difficult to make
work well. Peter Zander says that in his manual I think.
There are several problems with it.
One is that the static and pitot are more sensitive to off axis (yaw
and pitch) airflow than is a TE probe. There are errors which depend
on the fore and aft location of these when the aircraft pitches and
position error on the static or pitot
will cause problems as the real airspeed isn't the same as what is
being indicated and an especially severe problem when the error
changes with airspeed (bad on the certified statics on most Schempp
gliders and the nose pitot on the ASW20).
You can run from a pitot static probe on the fin but this gets you
the G sensitivity problems of the normal TE probe and then you still
have the problem of getting the signals to the vario at the same time
as the tubing has distributed capacity and resistance which causes
delays in the signals which are unlikely to be the same. The signals
can be large (5000 feet/min) and are subtracted so small timing
errors cause large transients in the vario reading. The timing errors
are magnified if you hang any kind of instrument with a capacity on the
same line (ASI, altimeter and they have capsules that vary in size
inside). Generally not worth the grief and support calls which is why
we don't do it.
The whole gust sensitivity problem is caused by all current TE
systems measuring airspeed using the pitot static - TE probes do the
same thing but subtract the dynamic pressure from the static pressure
by design of the probe.
There have been attempts to compensate for the gust effects but none
have exactly taken the world by storm and I have report of
unsatisfactory performance from some users of recent systems with
difficulty in getting calibration.
In the next couple of weeks at least one and maybe 2 Dynamis systems
will be tested by customers. Dynamis is an electronic TE system
which ignores horizontal gusts and works on principles unlike those
of any other variometer system.
It is an add on to our B600/B800 vario systems as the displays,
audios (including the thermal centering two speaker system) etc of
these instruments are well proven and I cannot think of what else to
do, so no point in designing a whole new vario for this.
Dynamis also provides real time (several times a second - will need
averaging to be sensible) wind speed and direction information and
will soon also do "Natural Netto" so the netto doesn't depend on
knowledge of the glider polar but is provided from the Dynamis sensors
as you fly. Bugs are automatically compensated for and even the
engine running on a motor glider.
There is one innovative new pilot interface that will also be an option.
This has been a 30 year project which needed the right sensors to
become available (I remember discussing this with Peter Zander at the
1985 San Diego SSA convention) and I think will be a game changer. No
more will you be fooled by the vario showing good lift only to
find that no matter which way you turned, there wasn't any worthwhile
lift, just a longish period horizontal gust lasting several seconds.
Remember, every wasted circle cost 30 to 60 seconds. Having done the
research and testing , I strongly suspect the "inertial gust
filtering" isn't going to solve that problem but the Dynamis sensor suite does.
Mike
Borgelt Instruments - design & manufacture of quality soaring
instrumentation since 1978
www.borgeltinstruments.com
tel: 07 4635 5784 overseas: int+61-7-4635 5784
mob: 042835 5784 : int+61-42835 5784
P O Box 4607, Toowoomba East, QLD 4350, Australia
_______________________________________________
Aus-soaring mailing list
[email protected]
To check or change subscription details, visit:
http://lists.internode.on.net/mailman/listinfo/aus-soaring
