Cambridge 302 -or- Borgelt B50 plus data logger

On Tue, 25 May 2004 13:00:32 -0700, "Marc Ramsey"
wrote:


it is difficult to get the polar right for netto and speed to fly,
and changing the polar also requires opening the case, which makes it
unsuitable for gliders with multiple spans.

I'll have to take issue with that and elucidate some of the design and
other points of the B50 seeing as some issues have been raised.
Some of these are of wider interest.

Yes, you do need to open the case (unless we've set the polar for you)
but you will likely do this only once.
We can supply the numbers for the polar if you give us the glider type
and the minimum flying weight of the glider i.e. glider, equipment,
pilot + parachute, no water. Or you can derive the numbers using the
B50polar.exe utility on our website. Please read the accompanying text
for for "how to instructions". Don't use Vne as the high speed point,
use the highest speed you would use for that weight. Don't use a speed
over the "knee" in the polar for standard class gliders.

The multiple span case isn't that hard to accomodate as the polar
difference is small and mainly at the low speed end and while
climbing. While climbing the netto and speed to fly functions aren't
active and the glider polar isn't used.
In straight flight the polar difference is at best about 0.2 knots
Not much more than a pointer width and pretty much irrelevant
operationally. In addition if you simply put in the polar for short
span the slightly lower sink rate at low speeds will mean the
instrument will correctly call for slightly lower speeds which makes
this calculation almost self compensating. In any case at low speeds
the sink vs airspeed is a very flat curve and small errors are of
little consequence. You can't fly that accurately anyway.

The ballast and bugs controls on the front of the B50 allow you to
adjust the polar in flight anyway. You may find your glider isn't
quite as good as the polar that is entered (likely as these are test
flown polars with gliders in excellent condition and clean, in smooth
air). Simply put in 5% bugs and this will likely fix things.

Late in the day if the wings are dirty you can adjust for this easily.
The control knobs mean that Macready, bugs and ballast are instantly
settable without scrolling through menus etc. The netto and speed to
fly both take the bugs setting into account.

I really haven't had too much feedback except of the " it works great
and I know what's going on for the first time " kind. Most seem happy
once the polar has been set once.

The vario now goes to +12/-10 knots on the indicator and +/-19.9 on
the averager and the audio doesn't saturate until at least +15 knots
so you can still center strong thermals.

Only two holes are required for installation. They can both be 57mm or
one can be 80mm for the vario indicator if you have the room. About
half the people seem to have room. No big deal to bolt one extra
indicator into a standard panel hole and plug in a D9 connector.
The display is clear and unambiguous with great contrast and high
resolution neither of which is necessarily the case with LCD type
pointers.

I'm always somewhat bemused by "easy installation". You install once
and use every time you fly. Does anyone seriously want to compromise
useability in favor of installability?

Not enough panel space? Take a look at the instrument panel photo I
took in flight (on our website). That is a Ventus A panel(the glider
is a Ventus C a 17.6 TOP). That is a transponder at the bottom, the
B40 is missing but there is still one spare 57mm hole and another 57mm
hole occupied by the engine instrument.

Someone mentioned the "fly faster sound". It is actually the same as
"fly slower" but the two tones are alternated much faster so it sounds
different. Recent B50's have an asymetric silent band for non zero
Macready settings. You don't hear the "fly faster" until you are
flying slower than than best glide for the air that you are in. This
means it isn't as annoying in gusty air. The visual indicator still
shows correct STF at all times. This is damped somewhat more than the
vario. Older B50's can be upgraded. The mod is very simple.

There is audio warning when you enter lift that is stronger than the
current Macready setting.

Custom configurations of the audio are available on special order but
I'd think carefully about requesting this as what is there is pretty
rational and just requires installation and connection to a good TE
probe, pitot and static to work very well.

We can supply a connector if you are connecting a GPS for retransmit
to a PDA or B2000, or the screw terminals make field installation
relatively painless.

No internal logger means you can choose your own favorite brand or use
a GPS engine or even a handheld GPS as GPS data source. The vario
doesn't go away for logger recalibration either.

There is of course nothing to stop you leaving your logger in the
aircraft and downloading it to a PDA instead of taking it away. Anyway
unless doing a badge or record flight or in a contest requiring IGC
loggers all the PDA programs have flight loggers built in as does the
B2000. If you fly cross country only for your own satisfaction or
practice and want to review your flights this saves considerable money
over buying an IGC logger.

A casual web search yesterday turned up a GPS mouse type device that
stores 15 hours of NMEA data at the one second rate. I'm sure there
are others. It is relatively trivial to turn NMEA data to IGC format
files. Seeing as it appears to be a sealed device if GPS altitude only
was allowed, simple OO procedures make this a low cost logger/GPS
source .(hint, hint)

We've been in the glider instrument business fulltime for 26 years
under the same ownership and management and that doesn't look like
changing anytime soon.

If you haven't already done so check out our website at
www.borgeltinstruments.com

There are some general knowledge and interest articles too.


Mike Borgelt

Borgelt Instruments