On 7/17/2012 7:30 PM, Dave Springford wrote:

> I have a V5 and SB9 in my panel, I find both of them very smooth and
> they compare well to each other.  The V7 has the same innards as the
> V5, so the vario portion should act the same.  On the other hand, I
> find the 302 extremely twitchy and the needle bounces around too
> much, the V5 does not it responds much like a Winter vario.

The needles on the 302s I've used did not twitch and bounce around at
all, and neither should yours, unless it was not connected properly or
malfunctioning. Once it working correctly, you can then easily adjust
the needle response time from fast to slow. Ditto for the audio.

Even the fastest response setting on my 302 does not yield twitchy or
bouncy operation; however, I prefer 1.7 on the needle and 1.3 on the
audio, which is a good match for my preferences and the glider I fly.

-- 
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)
- "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarm
http://tinyurl.com/yb3xywl
- "A Guide to Self-launching Sailplane Operation Mar/2004" Much of what
you need to know tinyurl.com/yfs7tnz 

-----------------

Observations on 302:  

If you are unhappy with it, the first thing to
do is have a look at your pneumatic connections.  First off, the TE
connection must not be shared with flow type instruments (any
mechanical vario, LNav, SNav, SN10, etc.).  You can share a TE line
with other pressure transducer instruments.  As well, the second
static connection on the 302 -- which is used for TAS calculation and
electronic TE compensation  - *must* have a good static source all to
itself.  Sharing with an altimeter or ASI will cause problems due to
excess volume in the system.  The pitot connection may be shared with
an ASI.  It probably should not be shared with any flow type device
(anyone still using a RICO VACS :-)?).  Check for leaks, everywhere.
With that out of the way...

The second thing to do is slow the 302 down (select 3 sec pointer, 3
sec audio).

The third thing to do is tweak the TE compensation for accuracy.  If
using a probe, you will generally find that the optimum setting for
electronic compensation is not zero, but some single digit positive
number.  IIRC I use 6 or 7%.  That's a *huge* difference from 0.  Each
1% change here has a noticeable impact.  Likewise, if you don't use a
probe, the ideal setting probably isn't 100.  Use a final glide in
smooth air at the end of the day to do some testing and adjustment in
flight.  With that working satisfactorily, now set time constants to
taste, but if in doubt, slow it down.

For me, the 302 works great in climb.  Less so in cruise.  I've taken
to using the 302 pointer in netto mode.  Even at "3 seconds", its
slowest speed, it is still faster than I would like in cruise, but the
netto mode works well and I find it useful.

I have a B400 that set to "3 seconds", its fastest speed, is much
slower than the 302 at "3 seconds".  The B400 is a much better
instrument for making the bump or turn decision, generally gets the
numbers right.  My 302 in TE or super netto mode was always rather
optimistic.

-Evan Ludeman / T8 

-------------------

This has not been my experience with the 302 on my ASH 26 E. The 302
shares the fuselage static with mechanical ASI, and at various times has
had the mechanical altimeter on that static. It seems to work properly,
and not noticeably differently than when it was connected to the 3 port
probe on the fin. My explanation is the volumes in the ASI and altimeter
are fare smaller than the flasks used in "flow" varios, and so they do
not affect the reading enough to notice.

Eric Greenwell - Washington State, USA